Stripped thread, helicoil fix?

[sight-pin]

If the hole is is tapped deeper than where the thread is damaged, would it be possible to use a longer bolt to reach the good thread?

 

[gbb]

I'd first go with Illaveagos line, would a longer bolt pick up undamaged thread ?

Looking at the photos, it already looks like the thread is like in a steel insert in alloy. That may create a problem when drilling it out. A helicoil kit comes with a specific sized drill and it might not leave enough meat of that insert (If that's what it is) ...or remove it all together. That may be bad as well because the steel insert will be a lot stronger.
I'm rethinking my original post. A steel insert (if thats what it is) is there for a reason, extra strength. Remove it and insert a helicoil ...probably would'nt last, or even be safe.

 

[Venod]

I would helicoil it, but don't over tighten the bolt.

 

[sight-pin]

It looks as though there might be some thread left further in . I wonder if a longer bolt might be sufficient ?

Beat me to it, didn't notice you already mentioned about using a longer bolt

 

[graham bowers]

I'd be thinking helicoil, but take it to somebody who is knowledgable and experienced in that type of work; somebody who can measure your component and decide based on facts and data if it's a viable repair. I'd be looking at local general machine shops, for example, or perhaps specialist firms that renovate cars / motorcycles. Looks like you are South Coast, but if it were local to me I'd be visiting these guys, I've used them for motorcycle stuff before and they have a well equipped machine shop and more importantly, specialist knowledge. They do mail order if all else fails. rraider's experience is not typical. Hamworthy used to helicoil the theads in their compressors from new, for example.

http://www.sep-kegworth.co.uk/page1.htm

 

[Venod]

If there is some thread left at the bottom of the hole make a stud and loctite it in place, then use a nut to retain the caliper.

 

[Ianboydsnr]

It looks ok to me, a helicoil will work fine on that.

 

[Salty seadog]

Thanks all , some good stuff there. I'll try a longer bolt in the first instance.

 

[sight-pin]

You may need to clear the thread first. If you have a spare bolt you can just cut a few slots in the bolt lengthwise to make a thread tap to renew the damaged bit.

 

[Salty seadog]

What's your fork material? A carbon fork typically uses alloy thread inserts that are fitted into the carbon post mount, those thread inserts don't have enough material to be used by helicoil.

Which thread have you stripped, the upper or lower? If I recall correctly the upper one has less chance of being ripped out of its threads during hard braking than the lower one.

It's the thread on the bottom post mount. I think it's aluminium and it has been suggested up thread looking at the pics it may have a steel sleeve insert.

 

[Tangoup51]

It's the thread on the bottom post mount. I think it's aluminium and it has been suggested up thread looking at the pics it may have a steel sleeve insert.

It very well may be a steel insert, which is problematic because you will not have enough material to drill and chase a new thread in, unless you plan doing it on the Alloy, given it's the bottom mount I don't think that's a safe option.

In regards to your idea of using a longer bolt you need to check how deep the thread is, sometimes the hole itself may be drilled deep but the insert isn't no where near as deep as the hole.

I didn't read how you stripped it, but if you stripped the threads by bottoming out the bolt and kept tightening til it popped, then all the threads are gone. If you just misaligned the bolt and carried on for a little, then you may still find some okay threads. Best of luck.

 

[Fab Foodie]

I know! Just fit proper brakes with rubber blocks ;-)

 

[graham bowers]

Well, you asked a question on the internet and got a variety of suggestions given in good faith. Trouble is, depending on the actual condition and dimensions of the stripped and remaining thread in your fork, they may produce a satisfactory repair, or may produce something waiting to fail. Only you know if you have the knowledge to be confident in a home repair. A pertinent question to test that confidence is whether you'd be happy to make that repair on the bike of a loved one.

 

[Salty seadog]

I know! Just fit proper brakes with rubber blocks ;-)

Haha, you can pipe down, I stand by my stance on discs.

 

[Tim Hall]

It's the thread on the bottom post mount. I think it's aluminium and it has been suggested up thread looking at the pics it may have a steel sleeve insert.

Waving a magnet near it should help work out what it's made of.