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Hope for this crank set?(13 posts)

Hope for this crank set?dzrider
Nov 13, 2001 6:10 AM
In trying to swap crank sets, I wound up with a crank puller full of shiny aluminum threads from the drive side crank arm. I removed the bottom bracket and got the crank off it by hammering the pin part of the crank puller. Is there any hope for salvaging the crankset?
re: Hope for this crank set?brider
Nov 13, 2001 9:08 AM
You should be able to install the crank arm, but you'll have to go through the same ordeal every time you want to service the BB or any other time you need to remove the crank arm. There is a possibility that you've damaged the tapers by hammering the crankarm (by placing an impact load off-center to the spindle), but that should become apparent when you install the crankarm.
its shotstr8dum1
Nov 13, 2001 10:45 AM
no way to tighten the arms back onto the BB

buy a new arm and try to be more careful or take it to your LBS
hardly shotTCC
Nov 15, 2001 11:37 AM
The trashed threads only hold on the dust cap (if it has one). The BB spindle thread tightens the crankarm.

That response was the perfect example of this:
concerned citizen "Too many wankers on this site!!" 11/13/01 2:32pm
Probably notKerry Irons
Nov 13, 2001 5:19 PM
So are you saying that the crank puller was fully threaded into the crank arm and it stripped the threads? Ouch. You might consider that you may have trashed the BB with your hammering, so check the bearings by turning the axle with your fingers, while applying minimal pressure. You can feel roughness and irregularities easily with a "light touch."
Exactlydzrider
Nov 14, 2001 6:01 AM
Every thread on the puller had aluminum thread in it; took a good few minutes to pick them all out. I've done this b4 without difficulty. Bottom bracket seems ok, turns smoothly and I can still thread the bolt that holds the crank on it. I'll check out getting it tapped. Thanks for the idea.
Andgrzy
Nov 16, 2001 9:51 AM
Your new crank puller will be made by who exactly?

Probably the best solution would be to design a custom self extracting setup for that side and take it to a machine shop (maybe they can custom make an alloy type of helicoil) OR realize that cranks can often be bought pretty cheaply on sale - as long as they don't say "Campy" on them. I've seen Ultegra stuff for less than $100 and I bought an XT crank arm (square taper) set with 9 speed XTR rings for $89 from Supergo last year. Should've bought five of them. Salvage the chainrings and keep the crank arm as a "last resort" spare and a "trophy" for the shop wall.
re: Hope for this crank set?ljbike
Nov 13, 2001 6:09 PM
Your LBS may have a tap and can rethread the arm.
Lightly coat the BB flats with grease before reassembly so the arms will not freeze on. In auto supply stores they have a ball joint remover tool that has a tapered wedge shaped like a U. With care these can be used to remove stubborn crank arms.
The regular crank removal tool must be fully seated into the arm or stripped threads are almost a guarantee. Good Luck.
Toastgrzy
Nov 13, 2001 6:36 PM
Well you could use it if you don't mind the hammer routine everytime you want to take it off. Either that or install it on someone's bike that you don't like. That would really give me the giggles. Imagine that they may not realize that they've been had for quite some time..... What a practical joke that would make!
buy a torque wrenchWESWU
Nov 15, 2001 9:51 AM
Exactly how tight are you mounting the cranks to the BB anyways? It's a common mistake (for the LBS too) to go WAY TOO TIGHT on the BB. This may be a cause of your problem, but it also leads to early wear of the BB spindle.
Root Causegrzy
Nov 16, 2001 9:36 AM
The root cause was that he didn't thread the crank extractor all the way into the bore. While many crank extractors will work I find the Park tool with the rotating bearin/bushing at the end to be a more efficient means of applying force - without it you have to crank harder while extracting which menas more force applied on the threads of the crank. Actually, most people "under torque" the crank and BB w/out a torque wrench. 50 N-m isn't a trivial amount of torque to apply w/out a wrench.People usually freak when they see how much I'll tighten their crank or BB, but I show them the spec and the torque wrench setting to get their breathing back to normal. Also, realize that Shimano advises no grease on square tapered BBs, but the do advise grease on splined BBs.
Crank taper grease and dandelionsJofa
Nov 18, 2001 3:32 AM
Just to be facetious on much-hammered side-topic:

http://draco.acs.uci.edu/rbfaq/FAQ/125.html

Makes sense to me.

All greasy

Jofa
Suregrzy
Nov 19, 2001 11:04 AM
Yeah, I've always been a grease man (monkey), but thought I'd pass along the Shimano advice - FWIW.

I've actually encountered situations where it has not really been possible to hit the torque spec on an older crank arm. what I mean is I keep cranking and then decide it's not a good idea to keep going since I feel that what I'm really doing is deforming the arm. It's funny but this always happens on the left side and on a crank that has had a "full life." Reading the article by Brandt puts some logical explanation behind things. As a M.E. I agree with what he's written.

Ultimately there are going to be people that will argue one side or the other unitl they die - - and it's really not going to make a damn bit of diffierence. The bike will either get sold/retired or the crank arm will get floppy and fail from not being torqued.