Q&A How-to: Welding and Metal
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The amount of stress that most Jeep and
other trail 4WD rigs experience makes welding a regular chore. Frame cracks, twisted bumpers, broken
brackets, repairs on broken and damaged equipment and fabricating accessory mounts are just some of the
Jeep 4x4 welding demands. Then there are the trailside fixes...
nowhere, you want things to stay together! If you need advice on how to properly weld or
fabricate Jeep components, here is the place. Whether you're mixing metal types, repairing
castings, welding, brazing or soldering, Moses Ludel can answer your
Just writeout your question on the E-mail form and submit the E-mail directly to the desk of Moses
Ludel! Moses will personally answer questions, as promptly as practical, in the order received...Meanwhile,
look through the '4WD Tech' and 'Q & A' sections for similar questions and
Welding Axle Shafts for Strength?
From: Jay B.
Sent: Thursday, September 27, 2012 2:34 PM
To: 4WD Mechanix Magazine
Subject: RE: Axle shafts...
Hi...I am running a Dana 30 with 33 km2's... looking at upgrading
to a 44 up front eventually... but until then was wondering if stitch welding would increase the shafts strength? I
do know that welding could warp the shaft and could poten
So picking up where I left off... potential to really mess
up my housing.
My plan was to stitch welding the Axle in quarters (one line the
length of the shaft on four opposing sides) down the length of the shaft and the about every six inches making a
loop around the shaft in opposing direction eveytime.
I have searched all over for an answer to this question.
You seem like the best source to help me out.
Thank you for your time,
Hi, Jay...Axle shafts are case hardened alloy, commonly treated by
carburizing method. If the shaft draws too much heat from your proposed welding, this could reduce or
eliminate hardening at the splines. Soft splines will pulverize without proper hardening.
Metallurgically, if you weld the shaft in its case hardened state,
the weld areas become "normalized" (unhardened or even annealed) and have varying degrees of irregular hardness and
stress in the heat affect zone (HAZ) surrounding the weld beads. The stock axle shaft design has a core that
is yielding and ductile, allowing for slight flex and twist, and a hardened surface—at least at the splined
Attempting the strengthening method you describe, I would begin with
"normalizing" the shaft in a heat treating furnace. Once normalized, the shaft could be welded, using care
not to warp it. The weld filler material needs to be heat treatable with the same alloy characteristics as
the shaft's base material. (Weld Mold Company offers niche filler material that is chemically like with the
axle shaft base metal in an annealed state. The filler would be heat treatable with the same results as the
base metal.) Welded and straight, the shaft could then be re-heat treated to the hardness and depth of the
original case hardening.
This all said, the weakness of the axle shaft is around the spline
area, and all of this work would not embellish the strength of the spline sections. In fact, by stiffening
the axle shaft driving sections, you would be placing far more stress at the splined sections. The shaft
would lack its original ability to flex and twist (within the normal range of the alloy's ductility). There
would be a high likelihood of axle spline failure or shearing/breakage of the axle shaft near the splined
Splines are the weak area by design. The undercut metal and
space between splines is a void, lacking the strength of the solid sections of axle material. It is for this
reason that replacement/upgrade axle shafts have more splines; this lessens the void space and provides far better
My recommendation is to "survive" with the stock axle shafts until
you can afford the changeover to the 44 up front—or consider what I did with the XJ Cherokee: keep the 30, switch
to 30-spline axles of quality (Superior in my case), and install lower ratio gears (higher numerically) with an ARB
Air Locker. (See articles at the magazine site.) On both the XJ with 4.10 gear swap and my son-in-law's
YJ Wrangler with 4.56 gears, the 33" tires have been no issue.
The Dana 30 operates only in 4WD modes. In high range 4WD, it
receives 50% of the torque applied to the rear axle in high range 2WD. Low range, there is equal torque
applied to each end. With the torque split, a 30 isn't that bad after all. A "Super 30" with 30-spline
axle shafts, improved alloy and stronger steering U-joints can do the job in most instances. The bigger
concern is actually axle tube diameter and stamina, which does not get better with a stock Rubicon 44, only with a
retrofit heavier (truck or aftermarket) axle. A cross-housing truss can help here if you like fabricating and
Trust this helps, Jay...thanks for the interesting question.
I'm here if you have more.
Reinforcing a Vintage CJ-6 Frame for a Tire
Sent: Monday, October 01, 2012 6:30 PM
To: 4WD Mechanix Magazine
Subject: to box or not to
Sorry, this gets wordy: CJ-6, I removed the drawbar/trailer hitch
assembly and the two drawbar to frame supports for the fuel tank underneath like later models. the owner
wants a BIG rear bumper with a bumper mounted spare tire swing (33" tires). those rear frame rails need
help. if i box the inside of the frame from the rear bumper forward to the first cross member (just aft of
the pumpkin) do i create a stress/fold point somewhere in the not reinforced frame where it passes over the rear
axle ?? or do i plate the outside of the frame rails from the bumper forward over the rear axle to a point
where the frame gets straight and is reinforced some ??
Hi, Raymond…Although you do not mention the year of the frame design,
your concerns are well founded for any CJ-6. All of the CJ-era frames flex—considerably, by design. You’re right in
noting that reinforcing one section of a frame places more stress elsewhere. There are precautions that you can
A traditional way to add frame members or “stretch” a frame by adding
a section is with the use of diamond or “fish” plates. This is a joining process, not an attachment like the
bumper you propose. Here is a recent exchange I had with a friend and hardcore trail runner. He has an ‘80s
CJ-8 with the factory “boxed” frame, and the frame developed a crack. Read my exchange with Mark B. in the next
Some points in my comments to Mark B. apply. An advantage with
the rear section of a CJ-6 frame is that the rear springs trail from anchor points at the front end of each spring.
I’m still not in favor of stiffening the frame much, and my angle-cut plates would have gap areas to allow more
flex yet. This would be a sensible way to “box” the C-channel CJ-6 frame. Following the lower diagram, I
would cut the plate ends at even more of a diagonal angle than represented in that drawing. This would allow
flex while not stiffening the frame in a way that leads to fractures or shearing angles—like straight vertical
lines would do. The diagonal offsets allow some flex yet raise the strength in the frame section. Stitch welding
permits more flex and helps prevent loading at one point.
Keep in mind that the Jeep frame must flex. Consider the frame part of the suspension. Later CJs
(’76-’86) the YJ Wrangler, TJ Wrangler and JK Wrangler models built successively more stiffness into the Jeep
frame. The CJ-6 is easily as flexible as the CJ-7 frame, since the CJ-7s have a boxed frame. Many CJ-6 models use
traditional, riveted cross members.
All of this said, I would consider making a bolt-on setup for the rear bumper/tire mount.
Make long side plates to take forward alongside the frame, or if easier, emulate the forward running, diagonal
braces used on the drawbar hitch. If you’re suspect that the brace bolts will put too much stress on the frame at
one point, consider boxing the frame with shorter plates (6”-12” length) on the inner side. Diagonally cut the ends
on these plates as noted, and make stitch beads around 3” in length.
Where the bolts go through the plate and frame, insert steel sleeves between the rail and plate.
Use sleeves with decent wall thickness and an I.D. the size of the bolt shanks. This will keep the frame rail and
plate from crushing when you tighten the through bolts. Sleeves will also distribute load more evenly, over more
Bolting the assembly to the frame provides less loading and does not require as much modification
or welding at the frame. Make sure the forward running bumper mounting plates are wide. Stagger the bolt holes.
The OEM draw bar hitch mount points might support a bumper and 33” tire if you reinforce the frame
attachment points and use the forward braces. The Jeep drawbar hitch should have at least a 150 pound tongue weight
capacity, there may be specs floating around from an old install kit that provide tongue rating.
As a footnote, the rear Warn bumper on our XJ Cherokee supports a 33” (hefty) spare and has forward
arms that are quite short. Warn made this a “bolt-on kit”, using factory bumper mount points on this thick sheet
metal unibody. Bolt-on bumper kits may provide ideas. Winch mounts and front plow mounts provide additional
Weigh my comments and opinions. We can continue this dialogue.
Repairing a Jeep CJ-8 Frame Tear
From: Mark B.
Sent: Thursday, August 16, 2012 2:51 PM
To: 4WD Mechanix Magazine
Subject: Frame fix
tnx for the helpful responses. The frame crack is not a big issue
to repair—will grind clean, weld up and maybe a small plate on top of frame rail. i like how it migrated to the
hole and stopped---for now.
Hi, Mark...The hole is a typical stop point…Grind a “U” or “V” at the
crack to permit a full penetration weld. I use a die-grinder with a burr-grinding carbide tip for this. The tool,
available in several diameters, has a round end that makes a uniform, controllable cut.
If you’re using 1/8” electrodes and stick at 120-130 amps (set to
your preference), you can probably do a single pass, forming a decent crown and full penetration through the
frame…Additional plate is okay if you stitch weld it in place. Do not run full length beads on a rectangular or
square patch piece.
I’m into stick process at the welding tutorial section and will
be demonstrating shortly.
Sent: Monday, August 20, 2012 1:59 PM
i discovered the frame is pulling apart-- right at the right rear spring forward leaf
hanger. Cracked about 5" fore and aft of the hanger and the the frame halves are separating. uh oh...
its always something. So now this new crack and the other one = lots of time w/ the die grinder and rotary
Mark, from what you describe, the frame has cracked where additional
loads occur. The area you describe is in some ways similar to the loads applied at the break point on ’72-’75
AMC/Jeep CJ frames. Here, the front frame section breaks where the leaf spring anchors drive force into the frame
rails. For the ’72-’75 AMC/CJ, the issue gets compounded by the boxed front frame section abruptly becoming a
C-channel rail behind these front spring anchors. The front section has been stiffened; the C-channel has to flex
over a shorter distance; the frame breaks at the junction of boxed and C-channel frame.
The combination of your huge unsprung weight mass with the Ford
E-truck full-floating rear axle, the oversized and weighty tires, plus the shock loads of the trail, contribute to
a high stress point at the frame. Also, when you “stiffen” one area of the frame, the normal torsional twisting of
the frame (over the length of the frame) is compromised. (Example: One adds plate to stiffen the mid-frame sections
or widens the track width with a wider, rigid beam axle and wide tires; twisting forces along the frame end
abruptly at the stiff, unyielding frame points, resulting in frame cracks.) Your CJ-8 frame cannot flex or transfer
stress away from the spring anchor points on the frame rails. The frame cracks or breaks right there.
Despite the boxed factory frame approach with the ’76-up CJs (surely
a move forward!), these frames are actually quite flexible. I’ve held one end of a bare (brand new) CJ-7 frame with
someone holding the opposite end. You can twist the frame nearly a foot end-to-end—by hand! When you patch your
frame, keep this intended torsional flex in mind.
Also, when you repair a vertical frame crack as you describe, you
never weld the section together with a butt weld (unless the butt weld is made strictly for alignment while you set
up a patch repair). The only “factory” repairs described for truck frames (like old I-H notes to dealers on how a
farmer or rancher could stretch or add a frame section) use a fish or diamond plate patch. Diamond (four-sided) or
fish-plate steel plates were typically welded inside and outside the C-channel frame rail. The diamond centered at
the cut or break line. In your case, the CJ-8 frame is boxed and not C-channel, so you would need to
The idea is to provide angled lines for the welds, which spread the
stress over this larger area of plate. This way, the welds will not be vertical/straight at the frame break. Note
that with four-sided diamond or fish plate patches, there are no rectangular or 90-degree countering forces in the
Another approach is to make a channel steel section to lay over the
frame at the break point. You could diamond or fish-plate one side of the boxed frame at the break point. At the
opposing side, you would center the channel section over the break point with channel overlapping outwardly in both
directions. Weld with stitch (non-continuous) beads along the straight section (at the top and bottom). That
channel section, from the side view, would have parallel, diagonally cut ends.
You’d have to notch for the frame/spring hanger and so forth, and the
diagonal ends should be more slanted. Note the goal: no vertical welds or stiff, vertical stress points.
By contrast, if you simply grind out the current cracks and weld them
as a vertical butt repair, the force against that weld will continue to be overbearing. Also, you’re messing with
the metallurgy of the frame-versus-welding rod material. This leads to incompatible ductility (yield and
elongation) at the weld. The result can be an even greater load along the weld edges. Then there is the added issue
of tensile strength and the heat affected zone (HAZ) alongside the welds. Gradual, air cooling helps with this kind
of repair—to avoid granular or "crystallized" metal, do not quench with water or cold air.
For each of these reasons, the fish or diamond plate repair, or a
brace section made of large channel material, offers the best fix…Realistically, the CJ-8 frame was not designed
for your large axles, oversized tires, stiff leaf spring stacks, wide track width, hefty unsprung weight mass,
ultra crawl ratios and continual pounding over rock piles with a trailer in tow! You’ve actually done fairly well,
Ready for Welding
From: Dan R.
Sent: Sunday, April 15, 2012 7:37
To: 4WD Mechanix Magazine
Subject: Welding class
Would you be able to tell me how I go about
signing up for the online welding classes. I can't seem to find the link.
Hi, Dan...Thanks for your interest in the
welding sessions! The course sessions online begin May
1st. There is no need to
"enroll" officially. Expect the traditional course approach: gas welding, brazing and cutting, followed by stick welding,
then MIG process and TIG. I will add extra projects to illustrate the processes as the course
Glad to have your participation. Please feel
free to ask questions at any time...I'll add HD video sessions steadily until the full course, covering all of
these processes, is part of the magazine website.
Welding or Repairing a Jeep
From: John M.
Sent: Friday, August 26, 2011 12:34 PM
To: 4WD Mechanix Magazine
Subject: Dumb question...
Sorry to have to 'ask' this and I suspect I
know the answer from contents of your website but- I keep hearing rumors saying that welding on a jeep frame
weakens the frame. Now this makes no sense to me since 1.) I've looked at your website and I see you folks welding
on frames and 2.) I see the guys over on Powerblock TV welding on frames all the time!!
So what is the real skinny here! I hear that the frames are heat treated and that welding on them is bad, etc, etc,
yet the OEM frame has welds and I see people welding on frames.
Is a buzzbox stick any better than Mig when welding?
Figured I'd ask and have the real scoop!
From: 4WD Q &
To: "'John M.'"
Date: Friday, August 26, 2011, 2:59
Hi, John…This is not a “dumb question” at
all. There are times when metal can be grossly affected by welding. If a piece is heat treated or of
uncertain composition, welding can weaken, damage or diminish the integrity of parts.
You bring up a good point about frames. All frame weldors should qualify why
and when it is okay to weld on a given frame member. The material used in most conventional frames is
intended for production jig or robot welding, and these metals can often tolerate the heat involved in the welding
process if cooling takes place properly. Then there are the structural concerns like whether welding a piece
here or there can actually upset the design intent and function of the frame. (We can discuss “reinforcing”
frames some time and why making a frame rigid in one place can actually cause breakage elsewhere.)
A rule of thumb for field welding an automotive or light truck frame is to “air cool”
the assembly without interfering with that process. Do not quench, water cool or rapid cool the assembly;
otherwise embrittlement or irregular granular structures in the metal will result. Hard spots can be avoided,
or at least reduced dramatically, by the air cooling of parts.
Another overlooked issue is the welding filler material. If the frame is of
special alloy or even a mix of alloyed metals, there may be special requirements for filler material. If you
notice, I am very particular about metallurgy and never take a “seat of the pants” or anecdotal approach in this
regard. I enjoy research and a serious approach to metals fabrication. This includes concerns about
whether an alloyed metal, like popular 4130, is in an annealed (non-hardened) or heat treated state before
welding. Note that in my 8620 cluster gear repair, I first normalize (similar to annealing) the case hardened
metal, then weld it with a 100% compatible material for 8620. I will case harden after welding and machining,
and both the base gear material and the weld filler must behave like 8620 in a carburizing heat treating
So, the matter-of-fact, let’s go weld on a frame approach is not the whole
picture. Especially with modern hydro-forming and other processes, automotive frames may require a special
metallurgical approach when welding. Unitized bodies (like the XJ Cherokee) are even more of an issue, as
they are largely made of heavier sheet metal stampings that have their own chemistry and needs. Here, the approach
would be ICAR-approved methods found in the auto body industry…
I like to be academic and scientific. Others may take another approach.
Expect metallurgical and process insights when I weld, and if you have any questions whatsoever, please feel free
to ask, John!
From: John M.
Sent: Friday, August 26, 2011 4:05
To: 4WD Q & A
Subject: RE: Dumb question...
Thank you for your informative email and quick response! I really appreciate
you taking the time to explain the science behind the concept.
Basically, I was asking as I noticed my Jeep CJ 5 frame has a crack on the inner
boxed portion underneath the cross plate that hold the radiator. I don't believe this crack is due to stress
on the frame per se as the outter potion of the frame is fine and w/o defomation. However it does appear that
at one point either someone took a BFH to the inside portion of the frame (for whatever reason) or else someone did
something they shouldn't have and ended up concaving it the section of frame. Of course there is an OEM
recessed squared section of frame not far from the deepest part of dent and *SURPRISE* it seems that the
corner set up a stress location.
Obviously I'll stop drill the crack but wanted to be sure that I could weld it up w/o
hurting the frame. From what you've told me, it seems as though doing such would be a safe.
By the way: I read your section on the gear repair. All I can say is "WOW", you
really know your stuff and do some very nice work.
From: 4WD Q &
Subject: RE: Questions.
To: "'John M.'"
Date: Tuesday, August 30, 2011, 12:41 PM
Questions are welcome, John. This exchange will
be of benefit to others through the welding Q&A.
You can cover just the hole and damage, that’s okay. I was thinking more cosmetically
and how you could make this all look “factory” while creating a permanent repair.
From your photos, I visualize flat plate covering just the open section of frame
rail, between the welded members. The idea would be a piece that looks at first glance like part of the original
layout. This is not a large area, so plate size would be moderate. The goal is to make the welds look like the
factory bracing welds.
Draw me an illustration or photograph a cardboard mockup (in place) to confirm that
we’re on the same page with the repair…You should still have the winch option when done; you’d simply need to drill
the correct size hole through your fresh plate and the frame wall.
If the plate size is larger than anticipated (provide approximate measurement), there
is the option of a few button-hole welds placed diagonally down the plate. This is done by drilling holes of ½”
diameter through the fresh plate, then button-hole or “plug” welding the plate to the frame rail at these holes.
You would then weld around the outside of the plate as described earlier…If the Jeep were here, we’d have a nice
how-to welding project!
From: John M.
To: 4WD Q & A
Here are some pictures. You'll have to forgive the lack of quality. From what I can
see, the hole in the frame is re-enforced with a spacer. However with the 'dent' in the inner frame it has seemed
to have misaligned the holes. Again, I don't know if this was due to a winch or not but whatever did it was a
From: 4WD Q & A
Subject: RE: Questions.
To: "'John M.'"
Date: Tuesday, August 30, 2011, 6:31 AM
Hi, John…I read each of your latest
replies…Glad you have enjoyed both of my books!
I see this is a ’76-’86 CJ model. You can do the frame repair with wire welding
(MIG with shield gas preferred over flux core). Stick (SMAW) is okay if that's the equipment on hand,
preferably 7018 rod for this repair. Clean metal as much as practical with a wire wheel; use a surface
grinder lightly if needed...Since there are additional steel members near the damaged area, a plate could be
fitted to look “factory”. I would weld the plate at the top, ends and bottom with continuous
The frame being boxed type with cross members, continuous beads should not create a
problem in this short section. (Stitch welding would be smart if frame twist were likely here, which it is
not. If the frame was C-channel design and cracked, I would use a fish plate or a diamond shaped patch and
the stitch welding method.) Stitch welding, beads run with space between them, is an option on your project;
however, continuous beads will seal out rust-forming moisture, which is an issue in some
E70S-6 welding wire, 0.035” diameter would be fine, offering plenty of tensile and reasonable ductility. The
patch plate can be 1/8th inch thick mild steel if you reinforce this
plate with button hole or plug welds. Use thicker 3/16" to 1/4" plate if you only weld around the perimeter
of the plate and do not add buttonhole or plug welds.
Since you’re doing all this, consider a shackle reverse kit. The kit can improve
handling. See how the current shackle reverse kits fit up. You may find it practical to
incorporate a frame repair and shackle reverse.
Be certain to prime and paint the repaired section properly. Rust likes to form
at welds and freshly welded, mild steel plate.
I’m pleased to answer any further questions or clarify concepts. Keep me
From: John M.
Sent: Tuesday, August 30, 2011 2:47
To: 4WD Q & A
Subject: RE: Questions.
Thank you for all your input. I really do appreciate all of it and I'll see
what I can come up with. Right now, I'm just leaning towards fixing the crack and not plating it. I'm
not going for pretty as much as functional and lasting.
So with that, I'll stop drill the crack and will email you pictures of the project as
Good, John, I understand. Drilling a hole at
each end of a crack can often be practical before welding.
A better approach here would be use of a
round-head burr grinding tool to scarf out the weld crack to its root. That way, your weld root pass will burn
through the backside and fully fill to the depth of the crack and frame metal. I like to burr down to a thin
section of metal that will burn out as you make your root bead. Done this way, you could fully fill the trough and
frame thickness, leaving no voids, then surface grind to mask the repair.
I use an air-driven die grinding tool with a
¼-inch diameter burr tool for the scarf operation. This makes an opening wide enough to burn into the metal and
fully mate with the frame rail material. The weld(s) must have complete penetration, be free of voids and burn into
adjacent base metal. If you make more than one pass, successive passes must burn into base welds as if you are
welding pipe. No voids, occlusions or gaps will create a weld as strong as the original frame.
Want to Learn
following 4WD Mechanix since the premier issue. You hint about teaching shop skills and welding. Can you teach
me to MIG weld the bottom of my Jeep frame—without it looking like one big drip? This weekend I found I was
better off using 6011 rod and the AC buzz box!—Craig T.
Yes, Craig, I plan to teach MIG and TIG. See the magazine's articles and
examples of cast iron TIG repair. (Non-ductile, gray cast iron is tricky!) I plan a monthly series that will
include stick (SMAW), MIG (GMAW) and TIG (GTAW). We’ll include brazing and oxy-acetylene welding,
I have a humorous
story to share about my first encounter with MIG, years before I taught these skills at the adult education
level…I was adept at oxy-acetylene and stick (SMAW). I could do all-position stick and so forth, having schooled
with the Operating Engineers Union at field repairs and working for years with structural automotive welding. My
pal, Kirk Rogers, a budding millwright at Oakridge, Oregon, offered me the use of his home shop, quite a
generous gesture! Fabricating motor mounts with a MIG, Kirk asked if I’d like to try all-position welds at the
rear frame hitch. He was surprised when I could do nothing more than stick the wire! What a disaster…So I know
how you feel about going from stick to MIG. Adding insult to injury, everyone boasts about how easy MIG welding
can be. But it is a different “feel” than stick, and if you trained strictly on stick, MIG is a distinct
transition…After mastering MIG and ultimately teaching the subject, I look back on that first MIG “event” with a
smile. (I’m sure Kirk does, too!) Welding is a process, or I should say, several
I plan to share
all aspects of welding. We’ll take a textbook, professional approach. (No shooting from the hip or anecdotal
nonsense. There’s plenty of that floating around.) Welding is serious stuff, and we’ll get your skills and
confidence up to par. I honed my teaching skills with the tough students at Rite of Passage—many began my
classes with their arms folded. Many completed the program capable of structural steel welding. Of the two star
TIG students, one became an aircraft turbine weldor. Several students certified at advanced I-CAR auto body and
frame repair, so we should be able to get your frame welding and repair skills to that
Battery-Powered Trail Welder?
Note from Moses: Below is a dialogue with Dave
Logan that brings to light portable welder choices and concerns. This exchange prompted the "On-Board Welder
Series," which begins with Part 1, the Ready Welder segment at: Jeep
Trail Welder Series: Portable 'Ready Welder'.
Sent: Wednesday, August 11, 2010 2:52
To: 'Moses Ludel'
Subject: RE: Ready Welder
I have a
quick question. I recently purchased a used Ready Welder kit…without batteries. Any suggestions on what batteries
would be appropriate for welding 3/16” or less steel on the trail? Ten minutes or so of actual welding time should
be sufficient. I’ve been told that back up batteries from computer UPS systems are small, light, and
rarely break anything and will probably carry the welding rig in my tow vehicle most of the time. When I do a
remote multi-day run, I will find the space for it…probably in my M416 military trailer along with the camping
Any help is
From: Moses Ludel
Sent: Wednesday, August 11, 2010 6:11 PM
To: 'Dave '
Subject: RE: Ready Welder
I’m not familiar
with the Ready Welder’s amperage demands. If high (I suspect), most would recommend a deep cycle battery if there
is no alternator/charge input. Gel and mat batteries have become acceptable alternatives for some uses. The main
idea is that a lead acid automotive battery does not do well with high amp, continuous drainage. Automotive
batteries work safely when drain is minimal and recharge amperage is not extreme.
The danger is a
hot, discharged battery or batteries that receive a high amperage charge input. If ignited from the slightest
spark, this can cause a dangerous gas explosion. Avoid discharging a battery to its extreme then hitting it with
high alternator output. Avoid sparks around the battery, too! A deeply discharged battery should be recharged
slowly, without heat exposure.
Let’s look at the
Ready Welder specifications for actual amperage draw and battery recommendations. This will determine the
ampere-hour or CCA recommended. You want batteries that will not fail due to the drain down and recharge cycle.
Likely, they will suggest a deep cycle or gel type. I would think deep cycle if you want a ‘standalone’
(non-charged) electrical source. These welders run typically on multi-batteries, series connected to produce 24V
(two 12V batteries) or 36V (three 12V batteries).
Sent: Thursday, August 12, 2010 10:54
To: 'Dave '
Subject: A footnote...
Dave…I looked at
the Ready Welder and Hobart Trek 180...Each has its pluses. Ready Welder has a sophisticated spool…Well conceived
for what it does. My only concern would be weight, specifically lugging heavy batteries around. Have you considered
a Premier Welder with high output alternator? I’ve always used an onboard, alternator-driven welder, although the
battery welding technique has been around for years.
Let me know how
this works out and please send some photos of the setup! It sounds like a useful adjunct for severe backcountry
travel…A quick story about a Rubicon trip and two guys with a CJ-5 steering gearbox bracket that broke loose from
the frame: They had no welder and were steering the Jeep with a tree limb. When we came upon them, their progress
was 250 yards in two hours! Fuel was near empty…Now that’s a place for your Ready Welder!
I assumed the use
of deep cycle for the reasons Ready Welder cites. Apparently, the battery packs get used without recharging, which
makes safety sense. It does mean that you need to carry a pair of extra batteries. In these group sizes, they weigh
15 or more pounds each. Sounds like AGM batteries, sealed, would be safest for your portable welding plans. Make
sure you have adequate amperage per battery.
This is all very
exciting. I want to hear your experience, how you hook this all up, where you carry the extra equipment, how well
it works in the field and so forth! I have a passion for welding and taught the subject at the adult education
level for five years…I’d like to play with the Ready Welder!
As a footnote, I
use the Battery Tender on each of our vehicle and trailer batteries. This is the greatest boon to battery life. In
the winter, each of our vehicles is continuously charging when parked, without the risk of overcharge, plate damage
or problems. By keeping an automotive battery fully charged (not overcharging), you can extend its life 3-5 years.
The killer is a discharged battery that starts the vehicle then encourages the alternator to slam high current into
a low voltage battery. Deep cycle batteries are a totally different design: They discharge completely, without
charge input, then take a full charge back up. That’s the reason the welder benefits from deep cycle batteries…If
you have the time, I would use a Battery Tender to recharge the deep cycle batteries, without risk of overcharge or
sulfating the batteries!
Are you planning
to run flux-core with a spool gun? Or stick?
Sent: Thursday, August 12, 2010 9:20
To: 'Moses Ludel'
Subject: Ready Welder II
I did not
consider the Premier Power Welder because I already have a York air compressor system under the hood and space is
limited. And, it costs $1,265.
Hobart Trek 180 is great, but costs $1,100 and that is more than I want to spend right now.
[http://www.hobartwelders.com/products/battery-powered/trek180/] I paid $250 for my used Ready Welder II. A friend
of mine had it and never used it.
battery types, the company’s FAQ section states: http://www.readywelder.com/faqs.php
As per your
suggestion, I do have Battery Tenders for my motorcycle and such, a great product. Regarding the welding method, as
you mention, I’ll use .035 flux core steel wire in the MIG spool gun.
for your advice. I’ll update you once I get the batteries and use the welder in the
Dana 60 Axle Housing Repair
Sent: Friday, October 01, 2010 12:51
To: Moses Ludel
Subject: Dana 60 cracked housing
OK, Moses, I got one for you...I ordered
some Rancho springs and they got here on Thursday. I got them on Thursday night and yesterday I took the Jeep out,
flexed it up and got my shock mounts set at the proper height. All is going well so the only thing I had to do was
finish welding my front drive shaft and weld the mounts for my anti-wrap bar. As I'm under my Jeep welding my
driveshaft (since I found it to be the proper length after flexing the Jeep), I see some oil on the bottom of my
just-installed front Dana 60 axle. It wasn't my pinion seal or my diff cover...I saw what looked like a crack in
the case below the ring and pinion. I pulled the diff cover and it looks like when the axle was under another
vehicle it was jumped and the bottom of the front differential hit a big rock. So, now I have to figure out a way
to weld the casting. I did research and I have welded for 20 years, just not much on cast steel.
My plan is to get some 55% nickel welding rod and weld the cracks on the inside of
the diff and on the bottom. What sucks is I have to pull the front tires, brakes, hub, axle shafts and ring gear
and Detroit locker to grind a notch where the cracks are and then fill them by welding.
If you have input into this I would appreciate it. I know you can weld cast by
preheating it or cold. If I weld it cold it's my understanding that I only weld about 1" at a time so the cast
doesn't get too hot. Otherwise I can preheat it and weld it. After welding both are supposed to be
Let me know if you have input.
From: Moses Ludel
To: Jake M.
Subject: Dana 60 casting
Date: Fri, 1 Oct 2010 13:31:39
Jake, I, too, have been welding a long time (45
years), and I taught welding at the adult ed level for years…We’re each skilled, and I have good news. In my
research on cast iron, I stumbled across Weld Mold out of Brighton, MI. I’ve attached an article I did on a major
cast iron repair. You will see and read some very interesting facts that accompany my TIG repair. If you have MIG
and no TIG, Weld Mold may have 700 and 750 wire for MIG. Read the article and understand why you can use this
material with radically reduced risk of cracking, which is the number one challenge with non-ductile iron. In the
Dana 60, you have some margin, as this is a more ductile iron type and somewhat weld-able.
I am convinced that you can repair this housing
to better than new by following these methods. Better yet, I have preheated to 500-degrees F and I have also run
successive beads without preheat (once the welding has started). The warmed piece and continuous welding did not
cause problems or cracking. I did wrap the axle casting in a welding blanket immediately after welding and between
welding stints to allow very slow cooling. The repair illustrated took place over three days. I would not use any
other rod than Weld Mold; it has the carbon content to produce graphite and allow more yield as the weld cools and
housings are generally more ductile or "nodular iron" and sometimes can be welded successfully with “ni-rod.” I’d
would want to know the metallurgy of a Dana 60 center housing before leaping into the use of nickel-iron rod. Let’s
go from there, Jake!
A cast iron crack is not always easy to
find. On this rare, vintage steering gear housing, a poor casting of gray iron produced this inherently weak area.
Trace cracks to each end.
From: Jake M.
OK, I've read the entire article and
learned a lot, thank you. My problem is I only have a 220V arc welder and a 110V MIG welder. I have access to a
220V mig welder. I'm going to look up the Weld Mold you suggested. Do you have tips for using the MIG? Can I do it
with my 110V? The casting is only 1/8" to 3/16" thick at the most. I feel that with grinding the cracks to a "V"
notch which I have been doing, it should be enough? Thanks again for you help. Also, do you feel that plating it
with some 1/8" mild steel would be wise. I sure do. I KNOW that the bottom of the differential housing is going to
take a beating from rocks. (I know my style of driving way too well!) I have built my CJ Jeep to go where I
Hi, Jake…You can weld the housing
with stick and your 220V arc welder, although removal of slag is more work and must be done thoroughly. You’ve read
my article and now know the “secret” of Weld Mold’s 700 and 750 cast iron rod. It has a high carbon content which
helps form more graphite to help eliminate cracking as the welded area shrinks. Since the graphite content is
higher, there is more “give” that may not be present in generalized “nickel-rod.” Tensile of Weld Mold 750 material
is higher than a standard casting, and the rod is available in “stick” (SMAW) electrode. I only use Weld Mold’s
niche welding rods. Look closely at the photos attached, and you will see that I welded mild steel plate to the
iron axle housing very readily, using Weld Mold 750 filler rod material.
Check out the
Weld Mold website:
Weld Mold 750 (choice number one; read
description at Weld Mold):
Weld Mold 700 (nice to have around; read
description at Weld Mold):
The other item to
note is cool-down. After your last pass, you must immediately surround the housing in a welding blanket and allow
it to cool slowly. I cooled an iron axle for nine or more hours between welding sessions. If you must interrupt
your welding, plan on wrapping the hot housing in a welding blanket (high temp resistant type that will not burn or
melt). Cooling too fast is disastrous. Air cooling is unacceptable with iron.
I have crack-free
results because I do use Weld Mold 700 and 750 on iron. I also peen the weld/piece thoroughly between each weld
pass. Rap uniformly and with a steady, firm hand, using a ball-peen hammer. Do not whack, but be firm, because the
goal is to diffuse the graphite into the weld and make sure it mixes with the iron and other elements. Weld Mold
suggests optional preheat to 500 degrees F with a torch before welding, with restoring that temp between passes. My
experience is that you can preheat the weld area before your first pass, and if you’ll simply stay with the welding
and keep the area at a steady heat during the repair welding, you can complete the job without need for additional
torch heating. This saves a lot of acetylene and oxygen! Results seem the same. The key, again, is the yielding
nature of 700 and 750 rod. From what you describe with the Dana housing, the generic ni-rod welds are shrinking too
much as they cool, and that’s how the cracks form. 700 and 750 will not shrink to that
If you want only
one of the electrode types, I would pick Weld Mold 750 for your axle housing…High tensile and likely to weld
without need for preheating after the first pass…You can join mild steel to the iron with this material. Read
details at the link I provided…
Once the crack was thoroughly discovered,
including die burr grinding to be sure of its fissure direction, a hole is drilled at the crack's end to stop the
You just answered several questions without
me asking them! I don't have a "heat blanket," I do however have welding blankets. Do those work sufficiently? If
not, would it help to get some insulation and put that between the housing and welding blanket? I do have a
non-contact laser type temperature device I could use to measure the temp of the housing before I heat it. Also, if
I use the rod you suggest it sounds like I don't have to wait to weld the entire crack? With the nickel rod they
suggested welding at 1" intervals at the most. With the 750 rod it sounds like I could run a continous pass without
stopping. Is there a way to not have to wait 9 hours between welding sessions? That is a long time to wait!
I'm going to pursue the Weld Mold 750 today. Out of pure curiousity, would it help to
use a torch to keep the nickel rod warmer during cool down or would that do something really bad?
I can't thank you enough for the help. The thought of having to exchange all of my
compenents to another axle housing is really discouraging, expensive and time consuming.
Here, I route out the cracks to their root
in the casting, using a round-headed burr tool and air powered die-grinder. I leave just enough original material
at the root to burn through with the first welding pass, assuring full penetration of the
Jake…A welding blanket is fine, as long as it
does not melt or burn through from a nearby heat source. The idea is to contain the heat within the blanket and not
let any cold air get to the weld or casting.
I use an infrared temp sensor like you
describe…That’s a great tool and helps you stay aware of the temp in the weld zone. You’ll find it very interesting
that the just-welded area cools rapidly to less than 300 degrees F. This is still warm enough to keep welding with
750 rod. I weld until the work is done and do not stop longer than the time necessary to peen rapidly with the
hammer. You can see from my article how long each weld is, approximately the length you describe of one-inch...I
would stitch and come back, so as to avoid intense heat and a long zone to peen. Peening is essential for diffusing
the graphite. It just makes practical sense to keep the welds shorter…You’ll be able to peen the weld area
thoroughly before the first section of each weld cools too much.
The nine hours of cool down were when I stopped
for the day. That axle casting was a huge TIG project and took days to do, 2-3 hours each day with the welding hood
on, plus the photography time. Stick will go much faster, you may be able to do the whole job in one session, but
keep the weld area warm the entire time. As soon as you pull away from welding for a lengthy break time, cover the
casting/housing in the welding blanket.
Nickel rod likes a warmer weld area, and since
heat dissipates rapidly into a large casting, it tends to drop temp quickly in the weld area. I would use the
blanket rather than any "creative approach" (avoid cooling the project gradually with a torch). A rosebud is an
expensive use of gas and not really productive for slow cooling. With a big iron casting, the heat will just keep
dissipating. Better to try and finish the job and wrap it safely in the welding blanket while
I understand your concern about swapping
housings. Done properly, this housing should work as well as or better than new. I have a great deal of confidence
in Weld Mold's very specific filler materials for the tool-and-die industry. The web links should clarify and help
assure confidence about these products and how/where to use them…
Sounds like you can shape and weld a nice
mild-steel “skid plate” beneath the repaired crack. If you “V” to the casting root, consider backing up the weld
repair with your skid plate, burning into the mild steel from the inside of the housing. Then, with the steel plate
tacked well to the weld root in the ‘V,’ you can make your successive beads to fill the ‘V’ at the former crack
area. The edges of the shaped/formed mild steel plate can be stitch welded to the outside/bottom of the housing.
This will look very “trick” and should help reinforce the weld area some.
As an important note, I use a carbide grinding
tool/bit and die-grinder to make an appropriate “V” in the crack zone. With iron, always make sure you drill stop
holes at each end of the crack, or the crack will return and spread beyond the original crack lines. Do not try to
“stop” the cracks by welding. Drill the stop holes at the end of each crack and fill each drilled hole with quality
weld as you perform your welding repair.
For additional strength, I back up the open
section of casting with steel plate. This will be TIG welded thoroughly with the root passes. The Weld Mold 750 rod
works well here. The plate is permaent and welded securely at the inside edges.
While Jake talks about stick electrodes, I
take advantage of TIG welding and filler rod. TIG done properly has great penetration with virtually no risk of
undercutting at edges. After practice, predictable iron repairs are possible, especially with materials like Weld
Mold's 750 and 700. This section received several passes with peening after each weld pass.
I did drill 1/8" holes at the end of each
crack before starting. I had learned that before in prior projects and learned that it's even more important in
cast iron. I'm proud to say that I successfully welded the cracks with the high nickel rod I had purchased. It
wasn't that I didn't want to spend more money, it was more of a determination factor at work, and I did it. My arms
are tired from peening the welds! It's come out pretty darn good especially for welding upside down! I can lay one
hell of a bead on flat, vertical...OK, upside down was always hardest. It didn't start out too well; those welds
cracked and I completely ground them away. I did V notch each weld and filled from the botttom up. I'm actually
very excited that I seemed to have pulled it off! Now I just need Glen to plasma cut me a piece of flat mild steel
to weld to the bottom of the cracked area. I don't want to come down on a rock while out on a trail and find all my
gear oil dripping out and have a broken housing again. It just makes good sense to me to put it on. I really can't
believe how thin the bottom of that portion of the casting is! I bet it's not more than 1/8" thick where it
cracked. And it's a big flat area just behing the bottom ridge that the differential cover bolts to. I looked
inside the differential, and it got good penetration. I didn't want to resort to having to pull the axle shafts,
ring gear and Detroit Locker and weld on the inside, too.
I must say, with a Detroit in the rear 14-bolt axle and the tight turning radius of
the front Dana 60, my Jeep turns SSOO great compared to the old welded rear 60 and front 44 that I had reduced the
turning radius on (to save the axle U-joints from breaking when turned hard). The body doesn't stay leaned to one
side like it did before because of the welded rear diff. I haven't even wheeled it yet and I love the
Anyhow, hopefully all is well with the cracked diff now. I sure appreciate you input
and I'm still going to try and get some of the Weld Mold rod on hand...Well, the repair should be finished. Here
are pictures of the weld on the diff, with the plate being put on and then the finished product. I took it out
today and wheeled it a bit in 4wd. So far so good, I've parked it and there hasn't been a drop of oil or any cracks
appearing around the patch. It was all done without heating up the cast prior to welding. I got 55% nickel rod from
Napa (forget the brand) and had to weld very little bits at a time on the cracks and then on the patch I welded
about 1" at a time while rotating sides and letting it cool in between going back to the same place. I pray it
keeps holding, I REALLY don't want to have to go through that again! It was quite a learning curve but once I got
it, it wasn't too bad. This was my first experience welding cast.
Moses, thanks for the help and the advice!
Area built up with weldment to produce a
strong surface after machining. This will be a better casting than when new. I found the project challenging and
gratifying, as there were no replacement castings available. TIG is controllable and produces these
Nice, Jake…I like the “finished product.” The
steel plate is an additional leak seal and helps prevent impact damage at the welded area. The crack repair welds
look ample, especially for the awkward welding position. Looks like a winner! If it’s leak free, you nailed
Finished vintage steering gear assembly is
a "blueprint rebuild" with a repaired and improved cast iron housing. I milled and finished the casting (upper and
middle photos) to receive the internal, close-tolerance components. It is gratifying to bring a rare or obsolete
assembly back to "as new" or even better condition! After primer/sealer paint, there is no trace of a cast iron
Note: For cosmetic touch-up work or
minor porosity fixes on cast iron, I use high tensile, high temperature silver brazing rod, special flux and an
oxy-acetylene torch. For repairing a load bearing piece like the vintage steering gear housing or Jake's cracked
Dana 60 axle housing, I opt for bona fide fusion welding, using cast iron specialty filler rod like the Weld Mold
750 and 700. TIG (GTAW) is my preference, MIG (GMAW) and stick (SMAW) would be my next choices—in that order. TIG
requires exceptional cleanliness at all times during the repair work, making TIG my in-shop approach. Jake did well
with his "field repair" method, with overhead access only, using stick technique. (See Jake's photos
Thanks, it definitely wasn't easy to weld
underneath the axle! I'm glad it is still holding and not leaking. I took the CJ Jeep out yesterday and wheeled it,
put some torque on the front axle, etc., and it held. Again, I appreciate the help.
Good job, Jake! The mild steel skid should
help, too…Weld Mold 750 has higher tensile strength than the typical nickel rod. Smart to get some 750 for future
use and store it dry…
My guess is that
this will all work out fine, because the nodular iron dilutes with the ni-rod during the welding, which creates
additional strength. Also, the area of your axle housing that cracked is not a structural zone, and the nickel
is somewhat ductile and yielding, more so than chromium. With the skid, you’ll be fine as long as the weld zone is
non-porous and oil tight! And, yup, those housing castings are thin! They aren’t designed to support the weight of
vehicles on rocks. Good lesson for others here. Send me some photos of the repair, I’d like to see your overhead
stick job—good work, Jake!
Jake chose to weld his cracked Dana 60
housing in-position (overhead), with all gears and shafts still within the housing! This is much like a trail
repair—if you can get all of the oil out of the unit and weld area. With an on-board welder, Jake would be a
popular guy on a rough trail in an emergency. (Jake's three photos.)
Jake's Jeep is a rugged trail runner,
mostly Sierra trails like the Rubicon and Blue Lake Area. He knows this axle housing will meet rocks regularly. To
protect and reinforce the housing, he shaped and welded a steel plate to the bottomside of his weld
Partly for cosmetic reasons, partly for
protection and added thickness, Jake welded a mild steel plate to the bottom. Fresh paint has this hard trail beast
looking good again. The CJ boasts a Dana 60 axle at the front and a 14-bolt G.M. axle at the
The photos look good, Jake...This will likely
hold. If iron survives the weld process, it usually goes for the duration. 55% nickel is ductile enough to take
severe trail pounding, which you will likely provide with this axle! From your description, the repair area is not
a structural stress point or load area, unless you plant the Jeep axle on the rocks…Enjoy your success and keep me
Jake Moves to the CJ's Rear Axle
From: Jake M.
Sent: Friday, November
05, 2010 10:38 PM
Subject: Rear 14-bolt
The one ton axles are holding up
GREAT. I've been pushing them hard and doing minor adjustments to the steering, suspension, etc. So far it's
working great. I love how sharp the 60 turns, the four wheel disc brakes, how the updated suspension feels and so
far the weld-patch on the 60 is holding up great. I've actually been trying to hit the bottom of it so I can
make sure it's going to hold. I've hit it pretty hard so far and not a single leak or new crack (knock on wood for
me, please!). I unfortunately found that my rear 14 bolt was bent by a prior owner. I know it's not from the kid I
got them from. He had them under a Blazer that never saw more than about 1,200 miles on it and just drove it to
work once in a while. They are bent exactly where the stock spring perches were.
I'm thinking of doing surgery on the bends. Tell me what you think of my
idea. With a straight edge, I'm going to identify the exact point they
are bent. Once I do that I'm going to cut the bottom 3/4 of the axle tubes with all the weight off of the axle
housing (obviously). I will do that with the shafts removed. Once that is done I'm probably going to have to heat
the un-cut portion of the axle tube, bend them straight and with a piece of very strong steel clamped onto the
axle housing, re-weld the cut. I'm going to use a very good, powerful 220V welder to do that and obviously "V"
notch out the cut that I'm going to make with a bandsaw or cut off-wheel on a grinder. I really think I
can straighten it. Each side is bent between 2 and 3 degrees. The worst that will happen is I have a bent
14-bolt and I already have that. I just really, really, really don't want to have to pull it out, set up the R
& P in another housing, grind off my brackets and start over.
Do you think it could work?
From: Moses Ludel
Sent: Monday, November 08, 2010
To: 'Jake M.'
Subject: Rear 14-bolt
As a rule, you never apply heat to a chassis or steering member.
This rule is firm with regard to tie-rods, pitman arms, steering knuckles or other critical steering
parts…However, in this case, the axle tubes are unlikely to become brittle or too soft if you do the process
right, and there’s enough remaining stamina in the tubes to allow for adequate strength—especially a 14-bolt,
one-ton axle under a lightweight CJ.
For a bent axle housing, the customary approach
is to cold-bend the housing tubes back to straight on a high-tonnage frame straightening
rack. If I were to apply heat at home, the approach would be to identify the section that has
stretched. Then heat the axle tube section at the bend and apply cold, wet rags over the section to get the
stretched area to shrink.
The rags get applied only to the stretched section. Do not chill the area that needs to stay the original length...Heat the tube over a wider area on the stretched
side (presumably the bottom of the tube) and bring heat in a “V” shape to the area that does not require
shrinkage (presumably, the top of the tube). When heated to red over the area described, carefully apply the wet
rags to the bottom section. This will shrink/shorten the stretched area. Again, the un-stretched areas need to
I would not
do the V-notch, because the stretch is over a section and not just one point. The V-notch approach would end up
with a bowed section of tube and likely an out-of-center axle
The axle should be suspended during this work, with no weight on
it. Place your stands under the Jeep’s frame if you’re not doing this work with the axle removed from
the frame. (I’m not sure whether you plan to disconnect the axle from the springs or not. Loosening the
U-bolts would be wise.) Once the shape is correct and alignment confirmed, you can allow the axle to
In this process, measure straightness carefully (at 90-degree
points on the tubes) as you heat and shrink the tubes. To reduce risk of stress
and to control metallurgical changes, try to straighten the tubes in one heating and cooling
I’m assuming your 14-bolt is a full-floater design and not a
semi-floater. A full-floater would be more tolerant of misalignment. In any case, the overall
objective is to be sure that the axle shafts run as straight and
on-center as possible—from the differential side gears to the wheel
As a footnote, be absolutely certain that there is no flammable oil or
solvent within the tubes, or you will have an internal fire and possible damage to sealing points. Keep
heat away from the areas where tubes press into the axle center section. Otherwise, you will damage the
tube-to-center section seal and create an oil leak there. The spring perch areas are, fortunately,
somewhat away from the tube sealing points.
Sounds like the 14-bolt axle may have been from a grossly
overloaded truck. Trail pounding of an axle this large seldom bends tubes at the spring perches—if these were
the factory perches and not installed later. If someone changed the perches earlier, they may have
warped or softened the tubes during the cutting or welding processes.
We can discuss this further…
keep in contact with Jake, as he is the current president of the Sierra
Stompers 4x4 Club. Jake has trail-tested this Dana 60 axle housing repair and reports that it works well and leak-free so far. Tests
include rock knocks directly against the patch
Treating and Shortening Axle Shafts
From: Rich B.
Sent: Friday, December 03,
2010 3:12 PM
To: Moses Ludel
Subject: 1980 Scout 2
Dana 44 front end, Now a CJ front end.
Moses, I picked up my Scout/CJ Dana44 front end from the
machine shop today. I had cut off the ears and spring pad has 3:73 gears and now a Spartan locker. The shop
cut the housing on the long side 3 5/8" added caster and camber and rewelded the ears back on. They reset the
pinion angle, added a drain plug, new bearings, seals, breather, and they cut, resplined the axle shaft and
I gained a front locker with L/S, larger ring and pinion, larger axle shafts, bigger
[86 CJ7 258,T18
,Scout TC146 Dana 300,Twinstick,Dana 30 L/S 3:73
(Spring 2011 Dana 44 front with Spartan locker 3:73's)
Dana 44 Rear Locker 33" mud tires, 8274 Warn winch, York OBA]
In a message dated 12/5/2010 1:35:59 P.M. Eastern
Standard Time, Moses Ludel at 4WD Mechanix Magazine writes:
Sounds good…I’m assuming that the machine shop re-heat treated the newly cut axle shaft
Reply from Rich B.:
No should I have that done?
In a message
dated 12/5/2010 6:21:59 P.M. Eastern Standard Time, Moses Ludel writes:
Most OEM axle
shafts are usually induction hardened to a specific case depth. A typical OEM shaft (made of material like 1039 or
1050 steel) has a case depth of 0.125" to 0.150". (This varies due to shaft diameter, the material used and design
intent.) An OEM axle shaft of this material might have a hardness of 50-54 Rockwell C.
performance axle shaft manufacturer, known to build stronger than stock axle shafts, uses 1541-H steel with a case
hardened depth of 0.300" at the 56-59 Rockwell C hardness range. This provides a 25-30% strength increase over a
stock 1039 shaft of the same length and spline count.
By contrast, furnace through-hardened axle
shafts made of 4340 alloy (chromoly) steel strive for only 46-48 Rockwell C hardness, and for good reason. For a
4340 axle shaft to have the needed ductility and torsional characteristics of a 1541-H shaft, the
through-hardened 4340 shaft must have less hardness. For the 1541-H shaft, the core of the shaft is
negligibly affected by the induction case hardening (at 0.300" depth only). The softer core provides the
necessary flex or torsional and ductility properties. Simply put, the shaft must
be hard but yielding at some level. Too hard and rigid, and the axle shaft would be vulnerable to
Thru hardening is a process by which an axle
shaft is usually heated in a furnace, resulting in a shaft that has the same heat treat from the center to the
outside diameter. Thru hardened axles have a hardness of 46-48 on the Rockwell "C" scale. By comparision, the hard
case and softer core of an induction hardened 1541-H shaft may have similar torsional strength to the 4340 shaft
with better bending or flexing capability than the 4340
load-bearing axle shafts that bend slightly in service, the OEM 1039 (for press-on bearings) or 1050 (for C-clip
and needle-roller bearing demands), or a custom axle shaft like the 1541-H, offer the flexing necessary to support
the vehicle's weight. With the bearing inboard of the axle shaft flange, the axle must be ductile enough to flex.
The softer core enables flexing over time without fatigue.
The 4340 axle
shafts definitely offer superior tensile strength. They are also stiffer, especially when through hardened. 4340
works well on full-floating and non-weight bearing axle applications. Since vehicle weight is not extreme on a
trail-oriented Jeep 4WD, the semi-floating rear axle might be as well off with the more flexible 1541-H custom axle
shafts. Given the lighter curb and trail weight, however, a pair of 4340 rear axle shafts would meet the weight
demand and offer superior strength for torque loads and big tires.
Rich, if your
Scout Dana 44 axle shafts fit within this 0.125"-0.150" case hardening depth, the new splines could cut below the
axle shaft's case hardening. Soft splines will not hold up for any length of time. The only way to know the depth
of hardening (case or through) is by Rockwell C testing to the root of the newly cut splines. If there is a need
for heat treating, do so to OEM depth—enough to give the splines factory Rockwell C
This is a
balancing game. If the shaft was case hardened with an intentionally softer core, then the heat treatment should
leave the core torsionally softer. Too hard could make the shaft unyielding and failure-prone under load. At the
same time, the splines need sufficient hardness to prevent them from failing under load. This suggests the need to
heat treat the splines and their roots sufficiently—without compromising the softer core.
A heat treating
shop should know the surface hardness needed and required depth of heat treatment. For a comparison, they can Rc
test the other (OE) axle shaft’s splines as a place to start.
Rich shares follow-up comments from the machine shop that cold-cut
the new splines:
"No, Rich, we cut the shaft cold, so the
hardness doesn't change at all. Same as if we didn't cut it..."
Rich, I would take the two front shafts to a shop with a Rockwell hardness
tester. (Your machine shop may have a tester. A heat treating shop surely would have one.) Have
the shop Rockwell test the hardness of the splines on the unmodified factory axle shaft. Have them test the
splines that were just cut. If the splines are the same hardness at the base/root of the cut, that would be
okay. If the new splines are not the same hardness at the root/base of the cut, then the shaft
was originally case heat treated, and the newly cut area reaches below the case hardening to the softer
If the axle
shafts were case hardened, that hardening is only so many thousandths of an inch deep. If the original shafts were
through-hardened (doubtful for OEM), then cold cutting the new splines, and not allowing metal to heat enough to
normalize or anneal, did not distort hardness. In any scenario, the quickest answer is a Rockwell C hardness test
to the base/root of the splines. If splines and roots are hard enough, the axle shaft should be good to
shops have a Rockwell hardness tester. If yours does not, every heat treating shop has a hardness tester. Make sure
the spline hardness is tested to the root of the spline cuts and not just at the shaft's surface. If the shafts
were originally case or surface hardened, the top of the new splines could be hard while the root or base of the
cut is soft. (Machining new splines could cut through case hardening depth.)
shop did the right thing by cold cutting. This is not about the
machine shop's cutting method or the caliber of the work. It’s about the original axle shafts—were they case
hardened or through hardened?
Let me know the
outcome, Rich…I am curious what the new splines read compared to the old ones—when measuring spline hardness at the base/root depth of the