zippy Posted September 18, 2004 Report Share Posted September 18, 2004 I recently purchased a 2000 Sherco 2.9. I love the bike but have to fix a couple of things. One of the holes for the front axle pinch bolts is stripped out. Has anyone tried to drill and tap one of these holes in the forks, or should I use a helicoil? The weld on the rear skid plate mount on the left side of the bike is cracked, and the skid plate has a small crack near the radius of the plate. How common are these cracks? "obviously whoevever set up these sections thinks I ride better than I do." Quote Link to comment Share on other sites More sharing options...
charliechitlins Posted September 18, 2004 Report Share Posted September 18, 2004 That stripped thread is a tough one. If you drill oversize for a heli-coil, you have to go through the outer hole and make it bigger too. I don't think the threaded hole could be welded because it would be too hard to get to it. You might helicoil the thread, then have the outer hole welded and drilled to size. Although....that piece has to flex and take a beating, I wouldn't want to be the one to say that the heat from welding it wouldn't make it more brittle. I've never used one, but there are chemical thread restorers (glue). Loctite makes one, and they claim it makes a permanent repair that will take quite a bit of torque. Quote Link to comment Share on other sites More sharing options...
its a kinda magic Posted September 18, 2004 Report Share Posted September 18, 2004 you could always tap it out to 1/4" unc thread. this would make a good thred and not make it too big. all you lose is that you need a slightly diferent size alan key to suit when you take the front wheel out. Quote Link to comment Share on other sites More sharing options...
zippy Posted September 20, 2004 Author Report Share Posted September 20, 2004 Thank you for your advice, I am going to think on whether to use the helicoil or the glue type stuff. Maybe I can convince my bank account that I just gotta have a whole new set of forks. Yea that'll never happen. "whoever set up this section obviously thinks I ride better than I really do." Quote Link to comment Share on other sites More sharing options...
zippy Posted September 20, 2004 Author Report Share Posted September 20, 2004 Magic, what is "unc" thread? Quote Link to comment Share on other sites More sharing options...
dfwilson Posted September 20, 2004 Report Share Posted September 20, 2004 UNC is unified coarse thread, UNF is unified fine thread. In 1/4" UNC there are 20 threads per inch and UNF has 28 threads per inch. Both are SAE (Society of Automotive Enigneers) or American Standard. Quote Link to comment Share on other sites More sharing options...
charliechitlins Posted September 20, 2004 Report Share Posted September 20, 2004 I'm not sure how the existing hole compares to the 1/4" SAE coarse thread, but it sounds like it could be a good idea. Quote Link to comment Share on other sites More sharing options...
kevin j Posted September 21, 2004 Report Share Posted September 21, 2004 I would do the helicoil. That restores the original thread size, no drilling out of the mating parts. I have used 6mm (case bolts) and 5mm (master cylinder screws) with good success, as well as larger heavy equipment uses. If the threads are stripped out, you may not even need the pilot drill. Just run the tap in. Properly done, a stainless steel helicoil is stronger than the original threads in aluminum. I think the glue product is a one time deal. Unless there is some sort of mold release applied to the bolt, the glue would stick to the bolt also. kcj Quote Link to comment Share on other sites More sharing options...
biffsgasgas Posted September 21, 2004 Report Share Posted September 21, 2004 Hey Zippy we need to veto these rock sections they are puting us through! This crack on the frame you speek of. Is this what you think is causing your 4th gear noise? Sounded like a loose motor mount but a loose skid plate would do it. Either way if you need to bring it over to my garage and I can weld it up for ya. Now the skid plate is that also cracked? We can do a job on that too I just need to get the correct wire. I have also helicoiled and used the loctite synthetic thread maker multiple times. Your bolt hole for that fork is too small to give a good helicoil but the loctite would probably work. As long as your axle doesn't fall out i think your good to go. My rear swing arm, skid pan, and front forks all saw a lot of action this past sunday. DOH! I have an idea for swing arm protectors that I am trying out this winter. I will post pictures on here if it goes well. Biff! Quote Link to comment Share on other sites More sharing options...
zippy Posted September 21, 2004 Author Report Share Posted September 21, 2004 VETO!! The skid plate may make that noise. I have noticed a "scraping, Clunking" type noise if I am sitting on the skid plate on a log or rock and rocking back and forth. I may take you up on the offer to weld the mounting point for the skid plate, and the skid plate has a small crack. But gotta wait at least 2 weeks then the season is done. Quote Link to comment Share on other sites More sharing options...
charliechitlins Posted September 21, 2004 Report Share Posted September 21, 2004 Unless there is some sort of mold release applied to the bolt....There is. Quote Link to comment Share on other sites More sharing options...
alan bechard Posted September 22, 2004 Report Share Posted September 22, 2004 I had mine and Christina's fork legs in my hands last night, and pulled out those bolts. It would be fairly trick to get the helicoil in there and started, you would have too use one of the cheap "key" type inserters, and oversize the "pinch" hole some. I would definetely try the 1/4" X 20 trick first if it was mine, then you could always step up to the Helicoil. Try the thread making stuff in between. My 2 cents. Quote Link to comment Share on other sites More sharing options...
ronm Posted September 22, 2004 Report Share Posted September 22, 2004 I would use a 1/4-28 UNF instead. The M6 screw will have stripped a hole bigger than the recommended tap drill size for either the coarse or fine thread 1/4 inch screws. However, the tap drill for the fine thread is .012 in larger than the 1/4-20. The 1/4 -28 will probably work ok, but I would always be careful to not over tighten it. Quote Link to comment Share on other sites More sharing options...
fanticisti Posted September 23, 2004 Report Share Posted September 23, 2004 Another option would be to JB Weld-epoxy (UK-Araldite) a stud into the damaged hole with a nut on the outside of the fork leg boss to do the clampiing. In case you are concerned about future thread damage then the nut and stud threads would be more durable than the softer aluminium of the fork leg. Quote Link to comment Share on other sites More sharing options...
alan bechard Posted September 23, 2004 Report Share Posted September 23, 2004 That is a great idea. Quote Link to comment Share on other sites More sharing options...
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