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: https://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: https://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!
I loved the instructions very good .
The only problem is that in my specific case in regards to the Xr650r it’s the long bolt that is starting to go soft and I suspect will strip soon .
Do you have a “time Sert “ solution for this particular situation .
Or can you advise the modified procedure please for the longer bolt .
Thanks again ‘this video was helpful
Hi, David…The kit for repairing the oil filter cover threads came from Time-Sert. I describe the thread size and tools in the video. You can reach Time-Sert at https://www.timesert.com/. They have suggestions for how long the repair insert should be and how to measure your side cover threads. Look for the blind hole tips in the FAQs at Time-Sert’s site. Review the video again for the sizes I used.
Ever any issues with the stainless inserts in aluminum? Just did a similar fix on my motorcycle but just replaced the two that are prone to stripping out.
Hi, AJ…There have been no issues with the aluminum motorcycle components and stainless thread inserts. I first did this on the XR650R’s aluminum swing arm. The factory adjuster bolts were seized. The arm is aluminum alloy, and for the repair, I used Time-Sert 303 stainless inserts.
I purchased my motorcycle from the original owner who had operated the bike in Texas (high humidity, some on the Gulf). The OEM adjuster bolts had seized in the aluminum threads, and after futile use of spray penetrate, the bolts would not budge. Finally the aluminum threads pulled loose from the force applied at one bolt. The other bolt sheared and required extreme care to drill and extract, as the remaining portion had frozen in the aluminum swing arm threads.
Here is some coverage and images that show the Time-Sert swing arm thread repair:
https://www.4wdmechanix.com/moses-ludels-4wd-mechanix-magazine-how-to-dirt-motorcycle-final-drive-chain-and-sprockets-replacement/ [Start at 12:24 minutes of the video for my thread repair with Time-Sert tooling. This later became Time-Sert’s “kit”. Note that the OEM zinc plated bolts were rusted and had completely seized in the original aluminum swing arm threads.]
http://www.timesert.com/html/1812CORESS117.html [These photos were from my magazine coverage…Time-Sert used the photos from the article and video.]
http://www.timesert.com/html/misc.html [Here is the Time-Sert swing arm repair kit based upon my experience.]
To address your concern…Yes, there is an issue with disparate metals and galvanic corrosion. In the case of aluminum and stainless steel, galvanic corrosion requires an anode (the aluminum) and a cathode (the stainless steel). This corrosion or transfer of electrons from the anode to the cathode also requires an electrolyte.
Common examples of electrolytes would be salt water and high humidity. Without the presence of an electrolyte, galvanic corrosion cannot occur. When sufficient electrolyte is present, the anode material (aluminum) can transfer electrons to the cathode (stainless steel) in a process of galvanic corrosion.
Here is a helpful and insightful quote at Corrosionpedia.com: “An electrolyte is any substance that undergoes ionization when dissolved in water or ionizing solvents. This covers almost all soluble acids, bases and salts. At times, gases like hydrogen chloride can also act in a similar way to electrolytes, given there is low pressure or high temperature…A reaction is formed when two unlike metals come in contact with electrolytes in an electrochemical reaction. This reaction is known as galvanic corrosion. This corrosion occurs when there is the presence of bimetallic couple in between dissimilar metals within the solution or electrolyte. Without all these components, galvanic corrosion will not take place.”
The last comment is the key with our aluminum motorcycle components. Galvanic corrosion can only take place in the presence of an electrolyte. Chlorides, in particular, are electrolytes for galvanic reactions between aluminum and stainless steel. Chloride? Umm…Sodium chloride as in salt water?
When I did the swing-arm repair and the side cover repair, the Time-Sert inserts, as illustrated in the video and photos, seated very securely. This was the result of the Time-Sert counter bore tool cutting a smooth insert seat in the aluminum. This seat can act as a moisture barrier. I was not concerned about exposing the aluminum threads and stainless insert to foreign substances or an electrolyte (water, moisture, etc.).
For the swing-arm, I also applied a generous amount of Permatex Anti-Seize (which happens to be aluminum based) to the new OEM swing-arm bolt threads. The swing-arm adjuster lock nut acts as an additional barrier to any moisture finding its way between the snugly fitting, seated stainless steel insert and the aluminum threads. If a concern existed, RTV sealant could be placed between the nut and swing-arm surface.
Worth noting, when the OEM adjuster bolts seized in the original aluminum threads, corrosion had thoroughly etched through the zinc coating on the adjuster bolts. The bolts and nuts were clearly “rusted”. (See that video for details.) Fortunately, there is no other area on the bike with corrosion.
I also inherited the loose filter cover case threads. I used a similar repair method with the filter cover threads. The Time-Sert inserts enter blind-hole threads and seat securely against the smooth shoulder cut with the Time-Sert counter bore tool. There was no sign of corrosion on the OEM bolt flanges or any reason to suspect that moisture or water had reached the original aluminum threads. Again, without electrolyte, there is no galvanic reaction.
I have not experienced any deterioration of the aluminum threads in either the swing-arm or the oil pump/filter cover threads. The fact that the original engine case threads failed as readily as they did is of greater concern than a galvanic reaction between 303 Stainless Time-Sert inserts and the aluminum alloy casting threads. The OEM torque setting for these screws, as I note in the video, seems too high. I believe the OEM aluminum threads are susceptible to stripping at that torque.
Both the swing-arm and the XR650R’s side case are not pure aluminum but rather aluminum alloy. Additionally, a swing-arm by design requires heat treating after factory welding. While galvanic reaction is a legitimate concern from a metallurgical/chemical standpoint, I would be more concerned if we were working with exposed pure aluminum sheet and stainless steel screws in an environment with constant exposure to electrolytic agents like seaside fog, salt water or corrosives.
If I thought there was a chance of moisture wicking between the cover and case, or between the screw flanges and the cover, I would dab RTV or Gasgacinch at the outer face of the insert where it meets the aluminum case. Also, Time-Sert does use Loctite 266 in some applications for sealing and heat resistance. (I would never use this strength Threadlocker with aluminum threads unless the fasteners were being permanently installed. Red Loctite can pull aluminum threads loose when the fastener is removed.) I would consider using 242 Loctite (Medium Blue) on the outside of the insert to seal and act as a barrier, installing the insert with freshly applied Loctite that is still fluid.
Loctite 242 or equivalent (blue) would act as a thread sealant and likely provide some resistance to galvanic reaction if an electrolyte were present. I researched this a bit and found some interesting comments at a boat/marine forum. Surprisingly, there are many marine hardware applications with stainless steel fasteners going into aluminum threads. This is a salt water environment and highly electrolytic. You will find this interesting:
These salt water boat owners talk about commonly manufactured aluminum components with stainless steel fasteners. The topic addresses ways to prevent galvanic corrosion. Reading about their challenges increased my appreciation for riding motorcycles, especially the XR650R. Running the risk of costly corrosion is a constant issue for boaters.
To further allay your concern, a prominent supplier of motorcycle upgrade parts offers a well know brand’s stainless steel replacement chain adjuster bolts and flanged nuts. The supplier also offers stainless steel thread inserts similar to a Heli-Coil for a rear swing arm repair. (They created a YouTube video of the repair for their website.) The upgrade is similar in ways to what I did years ago with the Time-Sert repair. These stainless products are each intended to fit directly against aluminum alloy. Other size stainless coil thread inserts are available for motorcycle repairs. (The limited casting margins around our oil filter cover threads would be a very poor place to drill out and crudely tap for a coil wire insert!) Apparently, manufacturers do not have concerns about galvanic reaction or corrosive damage to aluminum threads.
The Time-Sert repairs that we did are the best thread repair method available. Our stainless inserts fit better, offer superior thread contact, seal better at the shoulder and present less risk of electrolyte seepage into the space between the “anode” and “cathode” than stainless wire/coil inserts. I have no concern about the side case threads. A swing arm is far more susceptible to atmospheric and environmental exposure. Here the Time-Sert provides superior fit, provides a “machined” shoulder seal and creates optimal thread alignment.
You paid good money for the Time-Sert kit and its precision tooling, which should last a lifetime for aluminum repairs. With these tools, you can use carbon steel or stainless thread inserts from Time-Sert. I prefer the anti-corrosive properties and good tensile of stainless steel for these alloy castings.
For an automotive iron block thread repair, I would definitely choose a carbon steel Time-Sert to achieve metallurgical likeness. My first exposure to Time-Sert products was a master automotive machinist restoring main cap bolt threads on a valuable iron block. No wire insert is capable of providing the strength, fit and restorative quality of a Time-Sert. Expensive, yes. Permanent repair solution, yes.
Thank you for the in-depth response! I had special ordered the 1610V kit (M6x1.0 kit with (5) 12mm stainless inserts substituted, also has tap guide and driver oil) directly through TIME-SERT, thinking I was beating rust corrosion. However, I didn’t think about galvanic corrosion at the time. I wasn’t too worried about it because we generally have <10% humidity in my area. There was a thought of the stainless steel corroding the case of my already 16 year old bike, though when the time comes I'll just pick up a spool gun for my 211 and retap them.
The real reason I was asking is that I recommended TIME-SERT to a friend for some stripped out crash bar/engine mounts on his $15,000 BMW adventure bike. I'd hate to recommend stainless inserts if they are detrimental to the engine/frame. Sounds like he should be fine with whatever material he gets, especially with thread sealant like the boat guys use.
TIME-SERT does sell aluminum inserts though… I wonder how those would fare in a low torque application such as case covers? They're intended for BMW Aluminum fasteners so that doesn't give me much hope.
Hi, AJ…You likely saw my comments regarding the aftermarket aluminum swingarm “upgrade” adjuster bolts and flange nuts made out of stainless 303/304. Like the marine hardware, these manufacturers are apparently fine with an aluminum swingarm and stainless hardware. The fit between an 8mm stainless bolt and OEM aluminum alloy threads in a swingarm is looser than a Time-Sert fit! The whole point to Time-Sert tools ($$$) is their precision cutting ability to fit the precision Time-Sert inserts. I’ve been to the Time-Sert operation at Reno, Nevada, the machining is exceptional.
The stainless swingarm replacement bolt manufacturer has likely weigh the advantage of stainless corrosion resistance against the pitfalls of zinc-coated OEM adjusters sloughing off their zinc coating then rusting. Regarding insert alternatives, carbon steel inserts would be compatible with aluminum but could lose the zinc phosphate coating over time and rust, possibly seizing to the fastener or the aluminum.
This would be similar to what occurred with the Honda OEM XR650R swingarm adjusters (hardened carbon steel bolts and nuts with zinc plating). They wound up frozen solid in the swingarm’s aluminum threads and took out the aluminum threads during their removal. The aftermarket adjuster manufacturer took the path less likely to cause seizure. I’m sure my bike’s fate with the OEM adjuster bolts is common.
I would be okay with a coating of wet Locktite 242/Blue on the outside of the Time-Sert to act as a sealant and galvanic/electrolytic barrier. If concerned, I would try the alternative sealants that the boat builders suggest. For crash bars, the flange mate-up junction could be dabbed with either the alternative marine sealant or 3M UltraPro High Temp Gasket Silicone. The risk of “electrolyte” (i.e., water or chlorides) wicking between a quality Time-Sert and precisely cut aluminum threads should be nil.
As you suggest, either carbon steel or stainless Time-Sert inserts will work. For a crash bar, I would only run the aluminum inserts if there is a need for metallurgical and cosmetic matching. The Time-Sert aluminum is heat treated 2024/T351 with tensile equivalent to mild steel. It is rated at less yield strength than the carbon steel insert. The original threads stripping out of the BMW case may call for a higher strength solution.