I removed a combined carbon hugger & chain guard to inspect the nylon chain guide (a part of the lower guide had detached, so I wanted to give it a check). Simple enough job, I thought. One bolt is attaching the hugger to the swingarm (the anterior one) was attached near the ride height adjuster and was at a bit of an odd angle, tucked right into the curve of the carbon hugger. Anyway, it was hard in there but once I managed to get it to move, it then came out easily enough. However, when putting everything back together, I must have misaligned the bolt from perpendicular in that fiddly little space, as after a few turns I got that sensation of cross-threaded resistance. I backed it out and took a look at the bolt hole...it's a mess, and I'm not sure it was all me (I didn't check the hole before attempting reattachment of the hugger)... The inner thread seems intact but the upper 4 - 5mm is shagged. Anyone had this problem before and got any advice on best way to repair it? There's not a lot of room to manoeuvre, alas. As it happens, this caused me to take a closer look at the bolt I removed and I could see that the first few turns of the thread on the bolt were totally crowned, whereas an identical bolt (from the rear mounting point) was nice and true. I suspect that crowning together with non-perfect alignment may have been what chewed the thread, because when I test fit the other bolt, it appears to bite ok (I didn't attempt to tighten it) and the crowned bolt won't bite in the other mounting hole either. Thanks folks!
the original was probably an M6? maybe get a handful of short stainless bolts, taper them at the end then cut several slots in them so they resemble a tap. maybe even try similar with M7s and resecure using an M7
Or…get a longer same sized thread bolt - this will engage with the good thread remaining in the hole.
agree, looks like quite a few threads left, and luckily it's only a hugger being attached, clearing the thread/starting the new screw as above, needs a tap if you can get there with lots of patience.
You could helicoil or timesert it, I'd run a same size tap through it and put a slightly longer bolt in first.
Thanks very much all, I believe it is an M6 and I'll try to clean it up with a M6 tap. The existing M6 bolt should be long enough to reach the remaining good thread (I may run it through the die first to clean up that crowning - or get a new one). Failing that, I'll go down the helicoil route. Much appreciated, everyone!
I wouldn’t mess about with the original bolt as it sounds like it is knackered in the area where the only good threads remain in the hole? Just get a new bolt. One can buy them from eBay or even from your local Halfords.
not to long that it bottoms out. that's when the real issues start. it will bell out slightly at the end and take ALL the thread out should you ever attempt to remove it in future.
A quick and temp fix is to use a suitable sized plasplug and a self tapper. But drilling and helicoiling would be a better more long term solution.
hmm, good idea. these are 6mm. used for securing all manners of stuff on cars. quite often in some pretty vulnerable areas that get a fair bit of abuse.
Developed due to all my threads on flywheel and head cowl of any lambretta I've ever owned threading. I'd use a rawlplug or a plasplug and a screw with one of those countersunk washer things. There's nothing worse than a rattly head cowl. It'll drive you nuts.
Being Ali I would just retape it with the original size thread. If that doesn’t work I would upsize it
