Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

Stripped Bottom Bracket Cup

Notices
Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

Stripped Bottom Bracket Cup

Old 09-16-12, 03:43 PM
  #1  
Senior Member
Thread Starter
 
jpsawyer's Avatar
 
Join Date: May 2011
Location: Providence, RI
Posts: 599

Bikes: Civilian Le Roi Le Veut, Kazane Track, Ciocc Designer '84, Serotta Colorado AL 25th anniversary, '85 Guerciotti Pista, '84 Trek 660, Volume Credence

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Stripped Bottom Bracket Cup

So i messed up. I got a Swiss threaded bottom bracket, but stripped the first two threads on one of the cups and now I cannot get it to go in straight. Am I stuck or can i do something to repair the cup and make it usable again? Thank you very much!
jpsawyer is offline  
Old 09-16-12, 04:50 PM
  #2  
Old fart
 
JohnDThompson's Avatar
 
Join Date: Nov 2004
Location: Appleton WI
Posts: 24,842

Bikes: Several, mostly not name brands.

Mentioned: 154 Post(s)
Tagged: 0 Thread(s)
Quoted: 3617 Post(s)
Liked 3,452 Times in 1,960 Posts
The non-drive side is the same as French thread (35.0 x 1.0mm); an established bike shop may have a tap they can use to chase the threads. The drive side is also 35.0 x 1.0 thread, but reverse thread (clockwise to loosen). These are considerably rarer taps for bike shops to have, but you may luck out.

FWIW, I have Swiss taps here, but I'm nowhere near Rhode Island.
JohnDThompson is offline  
Old 09-16-12, 05:59 PM
  #3  
Senior Member
 
Join Date: Sep 2004
Location: boston, ma
Posts: 2,896
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Likes: 0
Liked 1 Time in 1 Post
if its the cup and not the frame just use a thread file to clean it up. 10 bucks for a file or a trip to a shop
reptilezs is offline  
Old 09-16-12, 06:43 PM
  #4  
Senior Member
Thread Starter
 
jpsawyer's Avatar
 
Join Date: May 2011
Location: Providence, RI
Posts: 599

Bikes: Civilian Le Roi Le Veut, Kazane Track, Ciocc Designer '84, Serotta Colorado AL 25th anniversary, '85 Guerciotti Pista, '84 Trek 660, Volume Credence

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by reptilezs
if its the cup and not the frame just use a thread file to clean it up. 10 bucks for a file or a trip to a shop
do you know what the pitch is by chance on swiss threaded bottom brackets? Is it 1? I really do not know much about this stuff. This looks like the best option though and the simplest. Thanks
jpsawyer is offline  
Old 09-16-12, 07:56 PM
  #5  
stringbreaker
 
stringbreaker's Avatar
 
Join Date: Sep 2006
Location: wa. State
Posts: 4,463

Bikes: specialized crossroads hybrid 2006 Raleigh Cadent 2 1971 Schwinn Varsity, 1972 Schwinn Continental, 1977 Schwinn Volare (frame)

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
Use a small 3 corner file its really close to the angle of the thread. Hold the file straight and only file forward around the diameter of the BB cup
__________________
(Life is too short to play crappy guitars) 2006 Raleigh Cadent 3.0, 1977 Schwinn Volare, 2010 Windsor tourist. ( I didn't fall , I attacked the floor)
stringbreaker is offline  
Old 09-16-12, 08:59 PM
  #6  
Retro Grouch
 
onespeedbiker's Avatar
 
Join Date: Oct 2007
Location: Santa Cruz
Posts: 2,210

Bikes: Yes

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 1 Time in 1 Post
I don't mean to add insult to injury, but having done the same thing I make it a rule to always thread bottom bracket cups by hand (at least the first 1/2"); it will save you the grief you are going through.


A for your problem, did you strip the threads on the cup or inside the BB shell?
If you are replacing an old bottom bracket, and the damaged threads are in the shell, you may be able to chase the threads with the old cup.

Last edited by onespeedbiker; 09-16-12 at 09:03 PM.
onespeedbiker is offline  
Old 09-17-12, 01:08 PM
  #7  
Old fart
 
JohnDThompson's Avatar
 
Join Date: Nov 2004
Location: Appleton WI
Posts: 24,842

Bikes: Several, mostly not name brands.

Mentioned: 154 Post(s)
Tagged: 0 Thread(s)
Quoted: 3617 Post(s)
Liked 3,452 Times in 1,960 Posts
Originally Posted by jpsawyer
do you know what the pitch is by chance on swiss threaded bottom brackets? Is it 1? I really do not know much about this stuff. This looks like the best option though and the simplest. Thanks
As above, Swiss thread is 35.0mm x 1.0mm, with reverse thread on the drive side (fixed cup).
JohnDThompson is offline  
Old 09-17-12, 04:08 PM
  #8  
Ride, Wrench, Swap, Race
 
dddd's Avatar
 
Join Date: Jan 2010
Location: Northern California
Posts: 9,205

Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.

Mentioned: 132 Post(s)
Tagged: 0 Thread(s)
Quoted: 1568 Post(s)
Liked 1,306 Times in 869 Posts
I have been able to "start" many a cross-threaded bb cup by firstly threading in by hand to where it binds up, then observing the tilt of the face of the cup relative to the end of the bb shell.

With the tilt angle identified, I use a 3lb hammer and gently tap the face of the cup level, before putting a bit of rotation to it, this time using a wrench.

Using small increments of tapping and turning, the cup can usually be started in the damaged threads of the bb shell, keeping an ever-vigilant eye on any tilting of the cup in the bb shell.


If the cup threads are flattened, they should first be relieved, where needed, with the corner edge of a fine bastard or mill file, as the cup is usually made of a harder metal than the bb shell and thus could distort the entire inside threading of the bb shell.
dddd is offline  
Old 09-17-12, 05:49 PM
  #9  
Senior Member
Thread Starter
 
jpsawyer's Avatar
 
Join Date: May 2011
Location: Providence, RI
Posts: 599

Bikes: Civilian Le Roi Le Veut, Kazane Track, Ciocc Designer '84, Serotta Colorado AL 25th anniversary, '85 Guerciotti Pista, '84 Trek 660, Volume Credence

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Thanks everyone. I took the cup to Circle A Cycles here in Providence, RI and they cleaned up the threads nicely for me. Thanks for the info and help again
jpsawyer is offline  
Old 09-22-12, 12:14 AM
  #10  
Senior Member
 
Join Date: Jun 2012
Posts: 126
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Get some valve lapping compund and slowly thread on working back and forth until it screws on easily. The threads will look new.
otis66 is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
mikewebber2010
Classic & Vintage
17
01-26-24 01:54 PM
bici_mania
Bicycle Mechanics
16
01-23-13 08:34 PM
David325
Northeast
5
11-30-12 07:27 AM
:andrew
Classic & Vintage
8
03-27-11 09:52 AM
rollingrock
Classic & Vintage
1
01-01-11 03:03 PM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

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