[attachment=4264]Hi this is my first post, but I have been lurking for a while and have searched but not found any similar posts. I have been using my 1992 Nishiki Backroads MTB as a daily commuter. I noticed some grinding from the bottom bracket and figured I could make it to the weekend to address it. As I was riding the crank bearing failed. I took it to an LBS and they had it two weeks, the shop owner stating he has not been able to get the bearing race from the bottom bracket on the ring gear side. I brought it home as I need to get back on the road. Any suggestions?
You might clean it up & take another picture. It looks like the cup has been eaten away & "smeared" & peened into the frame on the right side of the pic.
Run a hack saw thru the bottom bracket and cut slots into the remains of the bearing race. Obviously, you want to be very careful not to start cutting into the frame. But scratching the threads on the frame a little won't hurt. If you cut one decent slot and then tap the cup with a hammer, it may break free. If not, cut another 180 degree away. A couple good pops with a hammer and screwdriver should break the cup free.
You'll want to get the BB threads "chased and faced" before installing a new BB.
Thank you for the replies. I figured it out earlier today and just had a chance to post with pictures. DaveM, we were thinking along the same lines.
I used a Dremel with a diamond blade (I bought a pack of them from Harbor Freight for something else months ago. I think they were about $6 for a pack of 4 or 6.) , A screwdriver and a rubber mallet.
First I cut a groove in the cup deep enough to form enough of a ledge for the screwdriver to get a firm bite.
Then I put the screwdriver edge into the groove and angled it so that by tapping it with the mallet, it would rotate the cup in a clockwise manner to loosen it (reverse threads)
As the cup would rotate I would cut another groove and repeat until I could turn it with my fingers.
No threads were damaged.
The LBS had it for 2 weeks, I was done with it in 10 minutes or less.
Good job, Amazing that the LBS could not do it, I doubt he even tried.
Next time use a small chisel it will get a better bite and save the screwdriver. Also presoak with penetrating oil.
Well done indeed..
AS per Dave's Idea similar system is used to remove steering head races on motorcycles. Cut with dremel almost completely and than with chisel give it a sharp rap, to split the race and remove.
Never Give Up!!!
Just a follow up to anyone else with a similar problem. If the cup is badly seized in the BB shell and can't be removed by unscrewing, I've had good luck breaking them free by cutting a slot all the way through the wall of the cup. I think once one slot is cut, the cup can then flex a bit and a good tap with a hammer breaks the bond between it and the BB shell. Two cuts (turning the cup into two separate pieces) works even better, but a single cut often does the trick.
Thanks for all of the help, kind words and encouragement. I appreciate all of you taking your time to encourage me. I hope to add value when I can in hope of helping someone else find a solution to a problem. That seems to be in the spirit of this forum.