Ok, I guess this is all my own fault for being a tight arse. However, after borrowing a crank extractor a few times (Thanks Roland), I thought it was about time I bought my own one. I looked about on the net, and found I could get one from eBay for half the price of the UDC one. Bargain, I thought!
However, I got around to using it today, and found that the kind of metal it is made from is only slightly firmer than chocolate on a warm day. If it had been exactly the same consistancy as chocolate, then I would have just ended up with some goo in my cranks. Unfortunatly, it was just tough enough to try to work it’s way in to the hole in the end of the hub, and damage the thread.
So, I wasn’t able to get the crank off, and, more worringly, I can’t get the bolt back in.
Has anyone else had this happen to them? How would you suggest I try to repair the hub? Would running a Tap or Dye (can never remember which is which) in to the hub re-cut the thread to what it was, or is this likely to do more damage? If the hole is totally buggered, and I don’t want to buy a new hub, would I be best off getting the crank welded on and accept the fact that I won’t be able to change it again?
It sounds like it’s just damaged the start of the thread. The crank bolt goes quite a long way in, so if you clean up the start of the thread with a tap (it’ll be a normal metric thread, probably M8) so you can get the bolt in, it’ll probably be fine. I doubt “your hole is completely buggered” (yak yak).
How cheap was your crank extractor? They don’t normally cost more than five or six quid, and that’s for a decent quality one like a Cyclo or Park.
OK, that is perhaps a bit too cheap. Save up an extra three quid and get yourself a decent one
I doubt you’ve done any real damage though - just borrow an M8 tap (check it is M8 first, but it probably is) and clean up the end of the thread and you should be fine.
It should have only damaged the first turn or so of thread so you could probably just clean it up a bit. Use a small file or hard pointy thing like a scribe, place the tip inside the good thread further down the hole and work it out to the top by effectively unscrewing it. A tap might work but it’ll probably make it worse. It’s usually an M8 fine thread (not std M8) so it’s unlikely you’ll have one lying about anyway
OK, you could probably clean the thread up the way Nick says. It’s just that I do have things like taps “lying around” so I tend to use them. Either way, get a better puller! (even ShimaNO if you must)
> It should have only damaged the first turn or so of thread so you
could
> probably just clean it up a bit. Use a small file or hard pointy
thing
> like a scribe, place the tip inside the good thread further down the
> hole and work it out to the top by effectively unscrewing it. A tap
> might work but it’ll probably make it worse. It’s usually an M8 fine
> thread (not std M8) so it’s unlikely you’ll have one lying about
anyway
>
Well, that’s worked fine. A combination of subtle filing, pulling with
a sharp hardened pointy thing, slightly rounding the end of the bolt,
and decent light to see by, and I’ve managed to get it all back together
again.
I’m still left with the 125mm cranks on though, until I can save up
enough pennies to treat myself to a top of the range one for £6.50!
have you tried the “hammer off” method?
i find it to work quite well, you just take the bolt out, get a hammer, and a punch(of some sort, large bolts work well) . you then stick the punch through the spokes (w/ a rag or something on the crank to keep it pretty) and hit the other end w/ a hammer, being careful not to hit the spokes, if you choose to do this it may take a few blows before it comes off, and you must be careful of where the crank flys off to. and one more thing, get the punch as close to the axle as possible, you also have to keep the pedal off the ground, try it if you want, but its totally up to you
The thread is an M8 x 1; a standard M8 is a wider pitch M8 x 1.25. An M8 x 1 tap is somewhat rare; in the USA you can buy them from www.biketoolsetc.com.
The problem might not be the quality of the extractor, but rather the age. Older extractors are designed for “nut type” cranks only and do not have a floating tip which is designed to protect the “bolt type” threads on the axle. The use of a domed-end extractor on bolt-type axles will almost always damage the threads.
> The problem might not be the quality of the extractor, but rather the
> age. Older extractors are designed for “nut type” cranks only and do
> not have a floating tip which is designed to protect the “bolt type”
> threads on the axle. The use of a domed-end extractor on bolt-type
> axles will almost always damage the threads.
Ah, that would explain it. I thought it was just a poorly designed bit
of kit. Looking at that picture, I can see that it was probably well
designed, but for a “nut type” crank.
