Bottom bracket won't screw in

For discussions about bikes and equipment.
Steveo2020
Posts: 215
Joined: 26 Apr 2012, 8:57pm

Bottom bracket won't screw in

Postby Steveo2020 » 30 Mar 2015, 7:34pm

Hi

I am building up a 90s era Woodrup 531c frame. It has an Everest bottom bracket shell which looks in good condition.

I have tried to screw in a hollowtech bb but it binds very quickly - after a turn or so, on both sides. It is a 68mm shell so I assume must be 24tpi. I also can't get a un55 to go in.

I remember reading that sometimes on older frames the threads aren't cut deep enough for modern bb's - is that right and if so will chasing the threads do the trick or is something more drastic required?

Thanks in advance

Steve

User avatar
Mick F
Spambuster
Posts: 50998
Joined: 7 Jan 2007, 11:24am
Location: Tamar Valley, Cornwall

Re: Bottom bracket won't screw in

Postby Mick F » 30 Mar 2015, 8:10pm

Sounds like you have BB shell with Old Raleigh standard threads 26tpi but with a modern width.
Or maybe Swiss?
http://sheldonbrown.com/gloss_bo-z.html#bottom
Mick F. Cornwall

Brucey
Posts: 43043
Joined: 4 Jan 2012, 6:25pm

Re: Bottom bracket won't screw in

Postby Brucey » 30 Mar 2015, 8:24pm

has this frame ever been built up before, or since being painted? If not the threads may well need to be chased; they usually distort during brazing and can obviously get clogged with paint etc too.

Also please forgive me stating the b.obvious but you do know the drive side thread is a LH one on BSC threaded frames, right?

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Steveo2020
Posts: 215
Joined: 26 Apr 2012, 8:57pm

Re: Bottom bracket won't screw in

Postby Steveo2020 » 30 Mar 2015, 8:26pm

It does feel a bit like screwing 24tpi cups into a Raleigh bb but It surely can't be that - even Raleigh never used 26tpi on lightweight frames I dont think.

Swiss also seems a bit esoteric for a British frame, made in the 90s, but I suppose it is possible.

Hoping there is an easier answer than that!

Steve

PT1029
Posts: 976
Joined: 16 Apr 2012, 9:20pm

Re: Bottom bracket won't screw in

Postby PT1029 » 30 Mar 2015, 8:27pm

If the frame has recently been resprayed, are the threads full of paint and/or shot blasting crud. More likely to get this if using a generic sprayer/powder coater than bespoke cycle re enameller.
If paint/shot blast crud, the chasing the threads out should do it.
I had a Dawes tandem frame (1990's or so) where a UN 55 would not fit (RHS frame thread not straight, so BB could not line up with thread as the BB unit hit the LH cup the other end and would not go into the LH cup). A Cyclo thread reamer didn't help (other than clearing the threads a bit), and the UN 55 still didn't go in. A VAR BB reamer took our alarming amounts of metal, but gave the UN 55 unit enough slop on the threads to line up with the BB shell. Hasn't come loose yet!

Steveo2020
Posts: 215
Joined: 26 Apr 2012, 8:57pm

Re: Bottom bracket won't screw in

Postby Steveo2020 » 30 Mar 2015, 8:32pm

It is new to me but fairly scratched so Must have been built I think.

yes am threading the right way

I haven't tried any serious force yet - not wanting to damage the threads - I've
Not encountered one before that didn't go a good way in by hand.


Cheers

Brucey
Posts: 43043
Joined: 4 Jan 2012, 6:25pm

Re: Bottom bracket won't screw in

Postby Brucey » 30 Mar 2015, 9:48pm

if you have an angle grinder and some scrap BB parts in hard steel, you can make a DIY thread chaser set; just grind some slots in some 'all hard' BB cups and weld these to an arbor (eg an old 1/2" socket drive extension, or an old BB spindle) such that you can turn them with a fair bit of force.

If you are lucky you will find that the arbors are the right size that a BB cup can be used as a centring guide in the opposite side, thus preventing you from getting them cross threaded, too.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

andy65
Posts: 43
Joined: 25 Oct 2014, 8:37am
Contact:

Re: Bottom bracket won't screw in

Postby andy65 » 31 Mar 2015, 4:41am

The safest course of action is to take it to your local bike shop to get it fitted. They have the right tools and if all goes wrong it is their liability.

RogerThat
Posts: 831
Joined: 9 Dec 2014, 2:47pm

Re: Bottom bracket won't screw in

Postby RogerThat » 31 Mar 2015, 5:05am

Everest are top end quality bottom brackets and lug sets, are you sure it's bsc threading!? Sounds like it might be slightly cross threaded. Your local bike shop should be able to sort it out without much trouble and only a few quid.

User avatar
Mick F
Spambuster
Posts: 50998
Joined: 7 Jan 2007, 11:24am
Location: Tamar Valley, Cornwall

Re: Bottom bracket won't screw in

Postby Mick F » 31 Mar 2015, 7:44am

Whether Raleigh used 26tpi on some lightweights, I don't know, but I do know my 531 Raleigh Clubman 1982 had 24tpi so you may be correct.

I think it may be possible to assess the tpi.
24tpi vs 26ti isn't much, but from my experience, it is possible to see the difference.
Look closely at a cup and as you look, offer it up towards the BB shell and compare the "fineness" of the threads.

When I modifying my Raleigh Chopper a few years ago, I wasn't aware of the Raleigh standard of 26tpi and tried to fit a new 24tpi BB. It wasn't until I'd got it in a few threads that I realised the tpi count was wrong. I could actually SEE the difference in tpi count, but I had to look closely.

The symptoms you describe seem to be what I felt with my Raleigh Chopper.
Mick F. Cornwall

Steveo2020
Posts: 215
Joined: 26 Apr 2012, 8:57pm

Re: Bottom bracket won't screw in

Postby Steveo2020 » 31 Mar 2015, 1:49pm

Thanks everyone - all sorted. BB threads chased - a pal has the tool - and it went in fine. It might have been some paint from retouching the shell that got into the upper side of the threads, and so was hard to see.

Cheers
Steve