Do not disassemble

[Jeep]

My bottom bracket is making a cracking noise every once in a while, only while pushing on the left pedal. It is a 2004 XTR Hollowtech II. I have removed and cleaned the the cranks and spindle but without success so I guess the problem is in the cups or external bearings. There is a clear sign on the bearings housing that says: DO NOT DISASSEMBLE. Nevertheless I tried to remove them from the frame but they would not budge. Before I really start to apply serious force I though I would ask the experts in case there is a reason for the "do not disassemble" inscription.
Thanks
J-P

[loren]

The "do not disassemble" is telling you not to try to remove the cartridge bearings from the cups*. You are clear to unscrew the cups from the frame. Remember, the drive side cup is reverse thread. Your creaking is probably caused by the interface between the cups and the frame being insufficiently lubricated. Clean the threads well, grease them generously (some people prefer teflon tape), and reassemble.


*Actually, there are now tools that allow you to take these bearings out and replace them- with hybrid ceramic bearings, even.

[philvw]

I had a serious creak on my Trek CF Fuel that I was sure was the spindle, the CF BB shell coming apart or something. After much tracking down tightening, disassembling, etc, turns out it was the pedal where it was threaded into the crank, yup, left side only. It was tight, but it needed grease. Greased that (those) and it has been silent and smooth since.

[pirate]

Hehe... The title of this thread immediately made me think of Johnny Number 5... :D

Sorry, back to the discussion.

[werace424]

Yep I have the same issue with my Trek too. It keeps coming loose. I just keep tightening it. I have been offered a soloution by my LBS, I just havn't taken the time to do it yet. He said he has some stuff he puts on the threads that will help tighten up the threads so they don't come loose. Kinda like lock-tite, but without the huge headache if dis-assembly is required. I just need to take off the BB and take the cups to him and he will put it on.

My question is why are the BBs threaded so that when you pedal they can be spun loose if you have a problem? If they were just threaded the other way, you would be trying to tighten them and we wouldn't have this issue.

Anyone?

Paul

[werace424]

Hehe... The title of this thread immediately made me think of Johnny Number 5... :D

Sorry, back to the discussion.

Nice Short Circuit (http://www.imdb.com/title/tt0091949/) reference.

[langer]

Yep I have the same issue with my Trek too. It keeps coming loose. I just keep tightening it. I have been offered a soloution by my LBS, I just havn't taken the time to do it yet. He said he has some stuff he puts on the threads that will help tighten up the threads so they don't come loose. Kinda like lock-tite, but without the huge headache if dis-assembly is required. I just need to take off the BB and take the cups to him and he will put it on.

My question is why are the BBs threaded so that when you pedal they can be spun loose if you have a problem? If they were just threaded the other way, you would be trying to tighten them and we wouldn't have this issue.

Anyone?

Paul
Blue loc-tite should do the job. It will dis-assemble with ease, just stay away from the red stuff...unless you have a breaker bar handy.
-jon

[pepelkod]

My question is why are the BBs threaded so that when you pedal they can be spun loose if you have a problem? If they were just threaded the other way, you would be trying to tighten them and we wouldn't have this issue.

Anyone?

Paul

Turns out that if your bearing are turning smoothly, they will reverse the torque that is being applied to the spindle. Pedaling forward should be tightening the bb cups. (Can't recall where I read that, but it makes sense if you think about it.)

-Doug

here

http://www.sheldonbrown.com/gloss_p.html#precession

[drevil]

My question is why are the BBs threaded so that when you pedal they can be spun loose if you have a problem? If they were just threaded the other way, you would be trying to tighten them and we wouldn't have this issue.

Anyone?

Paul
You'd think, huh? Google "precession pedals bottom bracket". Any results from Jobst Brandt and Sheldon Brown are from Bicycle gods (to some). :D

[walsh]

Turns out that if your bearing are turning smoothly, they will reverse the torque that is being applied to the spindle. Pedaling forward should be tightening the bb cups. (Can't recall where I read that, but it makes sense if you think about it.)
-Doug

This has never made intuitive sense, to me, but it's easily demonstrated.

Put your hands in from of you, palms down (like you were typing.)
Loosely hold a pencil with both hands in this posture
Make a pedaling motion with your hands (remember to pedal forward) and observe which way the pencil wants to rotate.

Now if someone would explain the reasoning behind a French-threaded bottom bracket :rolleyes:

EDIT: I just googled precession like Ricky told me, and just realized that this demo is right there in SB's article . . . so I guess everybody already knows about it . . .

[drevil]

This has never made intuitive sense, to me, but it's easily demonstrated.

Put your hands in from of you, palms down (like you were typing.)
Loosely hold a pencil with both hands in this posture
Make a pedaling motion with your hands (remember to pedal forward) and observe which way the pencil wants to rotate.

Now if someone would explain the reasoning behind a French-threaded bottom bracket :rolleyes:

EDIT: I just googled precession like Ricky told me, and just realized that this demo is right there in SB's article . . . so I guess everybody already knows about it . . .
Another example I've heard is to put a dime in a soda bottle cap and swish it in a circle and watch how the dime rotates.

[Jeep]

Ok I managed to remove the BB, apparently there was some lock-tite on there because it was hard as hell to remove and there is some white stuff imbeded in the threads. It turns out that the bearings on the left side were rolling very roughly.

Using this link: http://www.rothar.com/pages/service_bb.htm I cleaned them and hope it's going to solve the problem.

Also, there was an impressive amount of dirt in the frame. I guess even if the procedure doesn't solve the problem it will save a few pounds!

[walsh]

Another example I've heard is to put a dime in a soda bottle cap and swish it in a circle and watch how the dime rotates.

OK, I surrender. :D

Say, shouldn't you be off painting a bike pink or something?

Apoligies to JP for the threadjack.

[langer]

Ok I managed to remove the BB, apparently there was some lock-tite on there because it was hard as hell to remove and there is some white stuff imbeded in the threads. It turns out that the bearings on the left side were rolling very roughly.

Using this link: http://www.rothar.com/pages/service_bb.htm I cleaned them and hope it's going to solve the problem.

Also, there was an impressive amount of dirt in the frame. I guess even if the procedure doesn't solve the problem it will save a few pounds!
The white stuff may have been some teflon tape, usually ends up stuck in the threads and requires a sharp object to pick out. I have given up on external bearing systems, I went through XT and RaceFace cups in a couple months. Square taper baby, square taper. Just make sure you repack the bearings with high quality grease. I've heard people complain about the quality of grease that the bearings come packed with from the factory, it has a tendency to wash out. If you end up breaking the plastic sleeve, which is easy to do, or the bearings become pitted you might want to look at enduro's replacement bearings...they've always treated me right.
-jonny "colorado bound" lang

[bunky]

You know, the Race Face X Type Diabolus cups (complete) (http://www.jensonusa.com/store/product/BB611D01-Race+Face+X-Type+Diabolus+Bb+Cups.aspx) are only $28.00 and work with Shimano cranks. So long as you are bothering to remove the cups anyway, why not just put in the new cups? That way, in case it really is contamination within the sealed bearings you won't have to do the job twice.

Besides, unlike the S-Corp ones, the threads on these come from the factory with what appears to be red loctite—not my first choice, but I would imagine slippage is a thing on the past!

I recently put these in for my XT FC-M760 outboard bearing crankset and they work great-- plus they are GOLD!

[Jeep]

Hey Langer, have fun in Colorado! Wish I was there :sigh:

It's definitely not teflon as it has somewhat of a grainy look to it. I've looked up on the Loc-tite website and they say any solvent should take care of it.

I've had my BB for 3 years now and it's the first issue I've had with it. The only problem I've had with it is the XTR middle ring that is soft as butter and needs to be replaced every year. (80$ each time)

Maybe your problem with BB come from not changing to the proper gear to go up hills. ;) Oh wait, you don't have another gear? :D

[Jeep]

plus they are GOLD!
Thank for the pointer. I'll remember that if it doesn't solve my problem. Unfortunately this is my only bike so I will need ready for this weekend.

[EJensen]

I have given up on external bearing systems, I went through XT and RaceFace cups in a couple months. Square taper baby, square taper.
I'm fine with that, but what company is still making square taper MTB bottom brackets and cranksets?

Regards,
Eric

[fausto]

Another example I've heard is to put a dime in a soda bottle cap and swish it in a circle and watch how the dime rotates.


for an easily applied to bikes example, track down a road bike with an Itallian thread BB, and ride it around for a while. The right side BB cup will eventually unthread, when the bike starts creaking and doesn't shift into the big ring anymore that's the warning. On mine, the left cup can completely thread into the frame, so as the right side loosens, the left side tightens and the whole thing migrates to the right. First time this happened I didn't know it (because what idiot speced Itallian thread BBs in the first place), it moved right until I couldn't pedal because the left crank arm was rubbing the BB shell.

Anyway, Orville and Wilbur - those guys where pretty sharp!

[langer]

I'm fine with that, but what company is still making square taper MTB bottom brackets and cranksets?

Regards,
Eric
The eno comes to mind for square taper crank. I'm rockin' Race Face Next LPs though they are no longer made. Square taper bottom brackets..shimano, phil wood, sugino, truvativ, campy (not sure if that's JIS or ISO).
-jon