BB Cartridge -threading problem

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Drake
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BB Cartridge -threading problem

Postby Drake » 24 Mar 2013, 10:04am

OK,i give up !!!
I know this sound stupid,but i just don't seem to be able fit them . I've spent over a hour this morning trying to fit one,but to no avail . I cannot get the threads to start either side .
I'm fully aware of LH and RH threads and i'm fitting the cartridge from the correct side .
Maybe i'm to concerned about cross threading . . possibly abit of brute force and ignorance is required .
Anyway,a cup of tea and a biscuit is calling . Perhaps i'll give it another go afterwards .
If it's no success . . then ho hum another visit to the LBS tomorrow . :(

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Mick F
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Re: BB Cartridge

Postby Mick F » 24 Mar 2013, 10:29am

I take it you're fitting a new BB?

Will your old one go back in ok? - just to test the fact you're doing it right and there's nothing wrong.
Mick F. Cornwall

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meic
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Re: BB Cartridge

Postby meic » 24 Mar 2013, 11:05am

Maybe i'm to concerned about cross threading . . possibly abit of brute force and ignorance is required .


Keep being concerned, brute force isnt required here it will only wreck the threads and make it even harder to get in right.
Have you tried cleaning the threads with some maintenance oil (or whatever else you have) and looking for any damage?
Yma o Hyd

tatanab
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Re: BB Cartridge

Postby tatanab » 24 Mar 2013, 11:12am

Can we assume that both the frame and the new BB are UK threaded?

PT1029
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Re: BB Cartridge

Postby PT1029 » 24 Mar 2013, 11:25am

If you are replacing a previous cartridge, bit of a mystery - may help to ensure the frame treads are completely clean of debris. But see cable guide blurb below, incase the new BB cartridge barrel is fatter then the old one.
If replacing an old cup and cone BB, then look inside the BB shell. Does the frame have under BB cable plastic guides?, in which case is the rivit/screw that holds the guide in place sticking too far into the shell? - you might see rubbing marks on the end of the cartridge. If its a screw, unscrew it until its flush with the inside of the shell. (If it does not screw in fully afterwards, not a problem). If the cable guide is held in by a rivit, get a punch (flat, not round), or an old screw driver and knock the protruding part of the rivit off. You could file the protruding bit down, but its a bit of a faff, and you have to be careful not to file the frame treads.
To prevent the risk of cross treading, screw the LH cup half way in by hand. The screw in the cartridge - you can use the LH cup as a guide (get LH axle end in center of cup) to ensure the cartridge is in straight. Secure the cartridge fully before tightening the LH cup. If the cartridge is reluctant to screw in correctly, screw it the wrong way (as though unscrewing it), usually you will eventually feel it slot in the threads correctly, then screw in by hand, or by pushing lightly[b] on a spanner[/b]
You might be unlucky, the above didn't work on a Dawes tandem frame once (the RH BB thread wasn't strainght/square, so the cartridge wouldn't align with the LH cup). I ran a VAR BB threading tool through the frame - it seemed alarmingly vicous (compared to the cyclo tread chaser I had already put through), ie, quite a few metal shavings. The made the (Shimano) cartridge sloppy enough in the frame threads to allow it to line up square with the LH cup, but tight enough (so far) that it has not worked loose.

Brucey
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Re: BB Cartridge

Postby Brucey » 24 Mar 2013, 2:38pm

is this a refinished frame?

If so, it wouldn't hurt to run a tap through the BB threads.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Drake
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Re: BB Cartridge

Postby Drake » 24 Mar 2013, 3:11pm

Brucey wrote:is this a refinished frame?

If so, it wouldn't hurt to run a tap through the BB threads.

cheers

Yes it is . Although the threads do look clear,i'm beginning to think it's the same problem we had last time,slight heat distortion of the BB housing . Or at least that's what the LBS thought it was last time,and i've no reason to doubt him .
Being that this LBS charges 35pounds to cure this problem,how much does a suitable thread clearing tool or tap cost . Bearing in mind that we will have had to spend 70pounds having two frame sorted,time has come to have our own tool .
Any ideas where we could get one .

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RickH
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Re: BB Cartridge

Postby RickH » 24 Mar 2013, 3:23pm

Drake wrote: Bearing in mind that we will have had to spend 70pounds having two frame sorted,time has come to have our own tool .
Any ideas where we could get one .

A quick Google on "bottom bracket tapping and facing set" makes me think that, if it was me, I'd rather pay the £70 as they seem to cost in the region of £300-450! :shock:

Rick.

Brucey
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Re: BB Cartridge

Postby Brucey » 24 Mar 2013, 3:32pm

you can get a tool that is suitable for clearing threads for about £100 here;

http://www.framebuilding.com/economy%20workshop%20and%20framebuilding.htm

a posher one is £150, and you would need further tool to face a shell if you needed to do that too.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

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Mick F
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Re: BB Cartridge

Postby Mick F » 24 Mar 2013, 3:33pm

Brucey wrote:is this a refinished frame?
Drake wrote:Yes it is .
A little story, and a little advice:

I have had my frame since 1986 and it went back to Mercian for a 21st birthday refurb. When I tried to fit the (new) BB, it wouldn't go in, so I scratched my head for a while. Nothing had changed with my frame except the paintwork.

I tried an old pair of BB cups and lubricated the threads with oil and tried and tried and tried very very very very gently working the cups in and out repeatedly by degrees, and eventually they went in nicely. I put it down to primer and undercoat contaminating the threads and my efforts eventually cut the contamination away.

The new BB went in easily and smoothy.
Mick F. Cornwall

tatanab
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Re: BB Cartridge

Postby tatanab » 24 Mar 2013, 3:36pm

Brucey wrote:you can get a tool that is suitable for clearing threads for about £100 here;
Or about £10 cheaper here
http://www.webbline.co.uk/default.asp?pID=2

Brucey
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Re: BB Cartridge

Postby Brucey » 24 Mar 2013, 3:41pm

better than that they do some taps for £28 on the same site, a little lower down...!

cheers
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horizon
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Re: BB Cartridge

Postby horizon » 24 Mar 2013, 3:44pm

This is really useful - I'm grateful to Drake for sharing his problem! I have one BB underway and another in prospect after a potential respray. This tool would pay for itself after a couple of uses and for me would mean a saved journey of at least 20 miles. Just knowing these tools are available is pretty good news (even if you try MickF's method first).
It's autumn in England with the trees turning golden. So we say leaves mean leaves.

Brucey
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Re: BB Cartridge

Postby Brucey » 24 Mar 2013, 3:51pm

as has been mentioned before, old style loose-ball BB cups are made from hard steel and can be 'modified' to make thread chasers quite easily, using an angle grinder.

I guess a note of caution concerning these (or indeed, any tool which doesn't use a guide of any kind) is that it is easy to go cross-threaded. The posh tools make this much less likely.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

robc02
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Re: BB Cartridge

Postby robc02 » 24 Mar 2013, 3:59pm

Tracy Tools do a range of cycle specific taps and dyes. Here are their BB taps. A bit dearer than the one from Webbline, but maybe worth bearing in mind for some of their other stuff.