Bike Forums

Bike Forums (https://www.bikeforums.net/forum.php)
-   Bicycle Mechanics (https://www.bikeforums.net/bicycle-mechanics/)
-   -   Argh - tried to install press fit bearings myself - one is in crooked. (https://www.bikeforums.net/bicycle-mechanics/841861-argh-tried-install-press-fit-bearings-myself-one-crooked.html)

ravenmore 08-25-12 10:18 AM

Argh - tried to install press fit bearings myself - one is in crooked.
 
Hi all - I'm building up my new Giant TCR composite and have not put in press fit bearings before. I tried it using a home made bearing press (big washers on a long threaded rod with nuts on either end). I futzed it up and one went in crooked. Trying to get it out by tapping on the bearing from the inside with the above mentioned threaded rod and a hammer. It's not coming out with the force I applied and I'm scared to use more. Also it is a sram bearing/bottom bracket and has the tube that is supposed to connect the bearings. This tube is making it hard to access the bearing in places. Any advice?

Kimmo 08-25-12 10:19 AM

Use a tube or rod closer to the ID restricting you, and try tapping on the high spot on the outside from time to time.

Wrap some towels around some bits of wood to chock up the frame from the floor, or otherwise secure it against your impacts somehow.

ravenmore 08-25-12 10:23 AM

Sorry for my lack of lingo but what is ID?

Kimmo 08-25-12 10:26 AM

Internal diameter.

Actually, scratch the chocking idea with the carbon frame.

I haven't worked with these press-fit BBs before; looking down on the BB, is the frame proud of the bearing when it's fitted? By how much?

skeem 08-25-12 10:36 AM

is it a pressfit30? bb30? other?

model notwithstanding, the only real way to get it out is to bang it out. there simply may be some different tricks per each variety.

FBinNY 08-25-12 10:51 AM

The right way to solve this is to avoid it in the first place, but we've already crossed that bridge.

At this point the best advice I can offer is to leave bad enough alone, admit that a little knowledge can be a dangerous thing, and let a pro solve it for you.

There are a number of ways to remove a cammed bearing like yours. Sometimes it's best to go in more, pushing the high side until it squares up, others it's best to try to back it out while squaring it up. Without seeing it, and without knowing more, like how much force you used before you realized the problem, it's hard to give you a best answer.

But if you don't want to see a pro, one option least likely to cause more damage is to insert a shaft through the bearing, and gently lever it in the right direction. This lets the bearing determine the path of last resistance and most likely it'll square up with a sort of pop. Then you can either trust your luck and push it in straight, or back it out to examine the damage. If pushing in blind, watch for signs like excess resistance, or it beginning to cam anew because it's having trouble passing the burr you raised the first time.

I

Kimmo 08-25-12 10:56 AM

I'm thinking if the bearing is sitting proud of the BB shell because it's on an angle, the frame could be put down on a metal surface, the bearing resting on it, with the head tube and seat cluster chocked up and the stays overhanging the table, with an assistant securing the frame, you could belt your drift pretty damn hard on the bearing's high spot with its low spot resting on the table. Might need to buy a new bearing though...

...Or what FB said, except I'd definitely take a squiz to see if there was any carnage.

ravenmore 08-25-12 12:47 PM

Actually I did take it to a mechanic. One of the bearing was a tiny bit high on one side - he said to press it a bit more. I did and it is straight, but the problem is the dang plastic spacer between the two is at a slight angle, and is preventing the crank install.

http://img.photobucket.com/albums/v7...8-25132900.jpg

ravenmore 08-25-12 04:40 PM

Finally got it sorted out. The bearing were in straight. The plastic spacer just didn't insert properly to the bearing cup on the opposite site and 'lipped' it. It cut the bearing cup a little but no serious damage. Am in business. :) Thanks all.

Kimmo 08-25-12 09:16 PM

Sweet.

ben4345 08-25-12 11:39 PM

Next time get yourself a heat gun.

mechBgon 08-25-12 11:46 PM


Originally Posted by ravenmore (Post 14652619)
Finally got it sorted out. The bearing were in straight. The plastic spacer just didn't insert properly to the bearing cup on the opposite site and 'lipped' it. It cut the bearing cup a little but no serious damage. Am in business. :) Thanks all.

If it makes you feel better, I've had a couple bikes come from the factory that way!


All times are GMT -6. The time now is 06:30 PM.


Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.