How-to: Time-Sert® Aluminum Thread Repair and Upgrade
Aluminum threads are common in automobile, truck and motorcycle assemblies, and aluminum is vulnerable to damage. On the magazine’s Honda XR650R motorcycle, we have steadily upgraded the aluminum threads with Time-Sert® thread repairs. Here is the step-by-step Time-Sert® repair, actually an improvement, at the outer engine case and oil filter cover bolt threads.
My first exposure to a Time-Sert® repair was a cast iron engine block with pulled main cap threads. A hefty carbon steel insert was the fix! Imagine fixing the axle housing bearing cap threads on a Grand Cherokee’s Dana 44 aluminum case rear axle—or a damaged transfer case. Or spark plug threads on a Ford Triton engine, or any other engine, without removing the cylinder head. See the Time-Sert® website for the wide variety of applications possible: Time-Sert® official website.
Use this example for your thread needs. In our independent and unpaid testing, we believe Time-Sert® offers the best, permanent thread repair and upgrade available. The 6mm x 1.0mm Thread Repair Kit is P/N 1610 for 6mm x 1.0 mm pitch threads. The kit can be ordered directly through Time-Sert® or online at Amazon. We use the 16104 stainless steel 12mm length inserts on this application. The blind hole depth is 18mm, and the flange thickness is nearly 8mm.
Though seemingly more costly than other solutions, Time-Sert® is more than just a thread repair! See why we continually step up and use this tooling as a thread solution. Although only one thread was “soft” and likely to go soon, the upgrade involves inserts at each of the four blind holes.
The tap T-handle is not supplied in the kit, the kit consists of all precision tooling. This is the specific drill provided for the inserts’ outer threads. Cutting is done carefully, on-center with uniform force. The shoulders around these blind holes have a limited margin. Respect the wall thickness, or you’ll be buying a new casting! Clean the drill and tap between cuts. Even with a manual T-handle, the OEM aluminum threads peel off readily with this fresh drill bit.
The provided counterbore tool is “self-centering” with its sized pilot nose. It is still necessary to hold the tap squarely on center to avoid wobble or uneven cutting of the insert seat. The insert must seat squarely with its surface slightly below the flange surface. The oil filter cover fits flush with the crankcase cover. The insert outer thread tap has a tap guide. Hold the guide firmly and squarely against the flange while running the tap straight into the drilled hole. Use the tap as you would any tap: Oil the tap, cut some, back off slightly to relieve chips, move forward some and repeat. Do not force the tap in either direction, or you will chew up the fresh threads!
Yes, that’s even more metal coming out of these holes. Run threads all the way, but do not force the tap against a blind bottom. When all threads are cut neatly, we use carburetor/choke aerosol cleaner to flush debris from the holes. Note that the masking tape has protected the engine’s critical oiling system from debris and contamination. A shop vacuum with a pointed nozzle, used continually during this process, can clean up tools, holes and the case area. Once the area is clean of debris, remove the masking tape. Continue to keep debris from finding its way into the engine.
The insert’s length is approximately 12mm. This is just right for the 6mm stud size and 18mm blind hole depths. (Bolts are 20mm thread length; the filter cover flange is approximately 8mm.) 12mm inserts cover the entire thread of the installed bolt. This length also allows the insert driver to cut all the way through the unformed bottom threads of each insert. This completes the threads and also presses the metal outward to lock the insert against the aluminum threads.
Use plenty of the supplied oil on the inside and outside of the driver tool provided! You want minimal resistance of the insert as it turns inward and seats into the cut counterbore. The goal is to seat the insert snugly before the driver starts to form the last few threads of the insert. This added resistance during the thread forming stage further cinches the insert within its counterbore seat. There is no room for error here. Make sure the counterbore seats are cut deeply enough before running the driver through the uncut threads!
Note that the head of the seated insert sets slightly below the flange surface. In this installation, there is no room for the insert to stand above the flange face: The cover must fit flush; it uses an O-ring seal. There can be no cover interference with the insert heads.
Four of the five cover bolt threads are now Time-Sert® inserts. The fifth bolt (long one that reaches into the inner engine case) has substantially more thread penetration and will not need a thread upgrade until such time as the engine requires a complete rebuild or requires a clutch replacement. These bolts by factory standards are set to 9 ft-lbs, which we elected to change. 84 in-lbs seems plenty with the secure, high tensile strength stainless steel inserts. Perhaps the 9 ft-lbs is one of the reasons for sloppy and stripped threads over time? 7 ft-lbs (84 in-lbs) with aluminum threads and housings would be plenty for this grade metric size bolt.
This Honda XR650R engine case is now “better than new” with these upgrade stainless steel insert threads! If you need more information on Time-Sert® repairs for spark plug holes, oil pan threads, engine cases, block threads, covers and more, including the “Big-Serts” for already enlarged holes from other repairs, see the Time-Sert® website online at: http://www.time-sert.com.
Note: Here is the Honda XR650R aluminum spark plug thread repair: http://www.4wdmechanix.com/HD-Video-How-to-Time-Sert-Repair-for-Damaged-Spark-Plug-Threads?r=1. Here are the Honda XR650R swing arm adjuster thread repairs that finish up like Honda should have made these threads in the first place: http://www.4wdmechanix.com/moses-ludels-4wd-mechanix-magazine-how-to-dirt-motorcycle-final-drive-chain-and-sprockets-replacement/. Eventually, all of the vulnerable aluminum threads on the Honda XR650R will be stainless steel or copper-clad steel Time-Sert® inserts!