I recently decided to play around with my old Bridgestone MB-6 and put together a cheap singlespeed with some parts that I have in the mostly used box. I wanted to change out the 10 yr old bottom bracket and make sure it was the right one for the crank I was going to use. I got the old one out but it wasn't easy. The cheap plastic cap was all broken up but it came out.
I looked at the thread and on the drive side there was one spot that didn't look perfect but overall it looked OK. I wanted to make sure so I measured how far in the questionable spot was and it was about 13mm. The old bottom bracket that I had only had about 10mm of thread so I figured it would be OK. I took it by the shop to see what they thought and they screwed one in and said it should be OK. I asked how much to chase the threads and they said $30. They said that it wouldn't really be worth it with this old MB-6. I got a new BB of the correct size and went on home.
I got home and put the cartridge in the drive side and then tried to put the cap in. I wouldn't go. I took the cartridge out and screwed the cap in OK. I then took the old crappy BB which screws into the non drive side and it went in OK too. I can't get both sides in together but separately is OK. I notice that when I thread the old one in the non-drive side the BB cartridge is concentric with the shell. When I thread the new one in the drive side, it is not concentric and is almost touching the bottom of the shell. I also took out the bottom cable guide screw thinking that might be the problem but it seems like the the shell is either not threaded right or bent. There doesn't appear to be any damage to the shell. I suppose the old BB which threaded into the non-drive (straight) side was less susceptable to the maladjusted (malthreaded) drive side because the cap is shorter and the misalignment is less noticeable with a shorter part.
Is there a fix for this and is it worth fixing? The bike is a Bridgestone MB-6 (Tange frame).
I got home and put the cartridge in the drive side and then tried to put the cap in. I wouldn't go. I took the cartridge out and screwed the cap in OK. I then took the old crappy BB which screws into the non drive side and it went in OK too. I can't get both sides in together but separately is OK.
Assuming there is nothing wrong with the replacement bottom bracket, you should be able to fix it with piloted BB taps. Good BB taps are designed to force both sides to remain on the same axis. $30 sounds OK to me, if the bike suits you it's worth fixing at that price.
I got home and put the cartridge in the drive side and then tried to put the cap in. I wouldn't go. I took the cartridge out and screwed the cap in OK. I then took the old crappy BB which screws into the non drive side and it went in OK too. I can't get both sides in together but separately is OK.
Try threading the cartridge on partially, then starting the cap. Tighten them in together. Should work. With a cartridge, you do not need perfect alignment, you just need it to be held steady.
--
David L. Johnson
__o | Do not worry about your difficulties in mathematics, I can _`\(,_ | assure you that mine are all greater. -- A. Einstein (_)/ (_) |
I tried this too. The engagement splines are a little damaged on the plastic cup now so I really don't want to be forcing anything. I don't really want to throw any money at this project so tapping and facing may be out. It is off by quite a bit so if it is tapped, it might not be so secure because of a lack of bite on the threads.
Maybe I can get a cheap cro-mo frame from someone else. I already spent $30 at the lbs for the UN-52 which has a semi buggered plastic cup now.
GP "David L. Johnson" <[email hidden]> wrote in message "]news:[email hidden]...
Quoted message said:
IV said:
I got home and put the cartridge in the drive side and then tried to put the cap in. I wouldn't go. I took the cartridge out and screwed the
cap
Quoted message said:
Quoted message said:
in OK. I then took the old crappy BB which screws into the non drive
side
Quoted message said:
Quoted message said:
and it went in OK too. I can't get both sides in together but
separately
Quoted message said:
Quoted message said:
is OK.
Try threading the cartridge on partially, then starting the cap. Tighten them in together. Should work. With a cartridge, you do not need perfect alignment, you just need it to be held steady.
--
David L. Johnson
__o | Do not worry about your difficulties in mathematics, I can _`\(,_ | assure you that mine are all greater. -- A. Einstein (_)/ (_) |
On my bike the (second hand) UN - 52 bb arrived with no plastic cup so I just screwed it in and used a Cro mo cup from a Stronglight bb on the other side to hold it in place. It seemed as though the curved part for the balls centred and aligned the bb before locking it in place. Sounds daft but it's been working for over 400 miles now, not much of that on road either. I did eventually get hold of the proper part but couldn't get it to fit! Cheers Colin
"George L. Porter, IV @cox.net>" <gporter1970<nospam> wrote in message news:sbw8b.57974$Zw4.37170@lakeread03...
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I tried this too. The engagement splines are a little damaged on the plastic cup now so I really don't want to be forcing anything. I don't really want to throw any money at this project so tapping and facing may
be
Quoted message said:
out. It is off by quite a bit so if it is tapped, it might not be so
secure
Quoted message said:
because of a lack of bite on the threads.
Maybe I can get a cheap cro-mo frame from someone else. I already spent
$30
Quoted message said:
at the lbs for the UN-52 which has a semi buggered plastic cup now.
GP "David L. Johnson" <[email hidden]> wrote in message "]news:[email hidden]...
Quoted message said:
IV said:
I got home and put the cartridge in the drive side and then tried to
put
Quoted message said:
Quoted message said:
Quoted message said:
the cap in. I wouldn't go. I took the cartridge out and screwed the
cap
Quoted message said:
Quoted message said:
in OK. I then took the old crappy BB which screws into the non drive
side
Quoted message said:
Quoted message said:
and it went in OK too. I can't get both sides in together but
separately
Quoted message said:
Quoted message said:
is OK.
Try threading the cartridge on partially, then starting the cap.
Tighten
Quoted message said:
Quoted message said:
them in together. Should work. With a cartridge, you do not need
perfect
Quoted message said:
Quoted message said:
alignment, you just need it to be held steady.
--
David L. Johnson
__o | Do not worry about your difficulties in mathematics, I can _`\(,_ | assure you that mine are all greater. -- A. Einstein (_)/ (_) |
