Bottom bracket problem

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ian peacock
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Joined: 17 Sep 2012, 5:09pm

Bottom bracket problem

Postby ian peacock » 8 Aug 2017, 6:07pm

When I try to screw a Campag Centaur cartridge BB into my 531 steel frame the spindle goes tight (doesn't spin freely, is really rough) even before the cups are fully home. In my modern Aluminium frame they go in fine. Shimano spindles go into the steel frame without trouble. I assume that the threads
on either side of the problem frame don't quite line up. What can be done? Ian

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Gattonero
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Location: London

Re: Bottom bracket problem

Postby Gattonero » 8 Aug 2017, 6:25pm

Sounds like you're fitting the cups x-threaded? Has the frame been chased for BB threads and the Rh edge of the shell?

Sometimes is a good idea to screw the Lh cup first, halfway. If you are not x-threading it will go fine, otherwise it will be very stiff to screw in.
Once done, you can use the central hole of the Lh cup as reference when screwing the Rh cup (with the whole BB core and axle) in, the LH side of the axle ought to be in the middle of the Lh cup.
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Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: Bottom bracket problem

Postby Brucey » 8 Aug 2017, 9:49pm

ian peacock wrote:When I try to screw a Campag Centaur cartridge BB into my 531 steel frame the spindle goes tight (doesn't spin freely, is really rough) even before the cups are fully home. In my modern Aluminium frame they go in fine. Shimano spindles go into the steel frame without trouble. I assume that the threads
on either side of the problem frame don't quite line up. What can be done? Ian


it could be that the BB was never tapped square to start with; this was quite common BITD. If you have the BB thread cleaned up (using a tool that can't be set skew through the BB shell) and faced, you may find it all comes good.

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

alexnharvey
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Joined: 10 Jan 2014, 8:39am

Re: Bottom bracket problem

Postby alexnharvey » 8 Aug 2017, 10:36pm

I don't quite follow. Would the shimano arrangement be more tolerant of this flaw than campagnolo?

ian peacock
Posts: 40
Joined: 17 Sep 2012, 5:09pm

Re: Bottom bracket problem

Postby ian peacock » 9 Aug 2017, 11:55am

Thanks Brucey, I will take the frame down to Rourkie's and see what they can do. Individually, the cups go in easily; it's just the whole assembly that goes tight. Shimano units must have a bit more tolerance than Campag. Ian

raymondchristopher
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Joined: 18 Oct 2020, 8:15pm

Re: Bottom bracket problem

Postby raymondchristopher » 18 Oct 2020, 9:28pm

Issues with installing a Square Taper Campagnolo Centaur 111mm Bottom Bracket (BSA, 68mm)

Hello
I'm having the same problem! I found this thread via a Google search. It appears to be an old thread but it's nice to see that I'm not the only one having trouble installing this bottom bracket. I'm going to assume that it's better to add to this thread, rather than start another?

I'm exasperated/ confused by the whole thing. I've had the same thing suggested, that there's a slight mis-alignment of the threads in the BB shell, however the threads were chased/ aligned before installing. I haven't had the BB shell faced because it measures closer to 67mm than 68mm, though that might be what I need to do. It's an old steel Dave Yates audax frame that I picked up a few years ago. The axle/ bearings feel horrible when the left hand cup is even slightly tightened up, let alone to the crazy 70Nm stipulated. If I tighten it so that it's just snug, the axle and bearings are lovely and smooth, but that would lead to all sorts of wrong when the cups inevitably shake loose, leading to the wearing down of the threads of the BB shell. I'm not going to be checking it's screwed up every five minutes and I'm not particularly keen on the idea of using threadlocker, which I've seen suggested elsewhere. I did think for a second to add a spacer to the drive side cup but of course that would only move the BB over to the right, given the design. I need to use a BB with an ISO taper. I haven't tried installing a Shimano BB just to see how that is, but will try it in the morning. I did use a Tifosi BB last time, which is effectively the same design as the Shimano BB. I suppose I could use a shorter Shimano BB to compensate for the taper difference but that's not ideal. The Tifosi BB didn't last very long and so that's why I'm keen to try something higher end, though it's somewhat moot if the Campag leads to damaging the frame. Has anyone reached a resolution? Hopefully the OP will see my comment. Throw it in the bin? I did find that SKF make an ISO square taper bb, though I don't know who the UK distributor is/ if it's even available in the UK; it has a similar design to the older style Campag bb with flanges on both cups. I'll try a careful facing of the BB shell and see if that makes a difference.

Thank you.

peetee
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Location: Cornwall

Re: Bottom bracket problem

Postby peetee » 18 Oct 2020, 11:59pm

Does the frame have a plastic gear guide under the bracket that is riveted or screwed on? This may be protruding too far inside and preventing the bracket from going in square.
Winter had arrived in the land of Kernow. Along with it came wet roads and cool winds.
“Oh, my wheels and coupling rods!” Peetee exclaimed.

raymondchristopher
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Joined: 18 Oct 2020, 8:15pm

Re: Bottom bracket problem

Postby raymondchristopher » 19 Oct 2020, 12:35am

peetee wrote:Does the frame have a plastic gear guide under the bracket that is riveted or screwed on? This may be protruding too far inside and preventing the bracket from going in square.


No. Nothing interfering at all.

rogerzilla
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Joined: 9 Jun 2008, 8:06pm

Re: Bottom bracket problem

Postby rogerzilla » 19 Oct 2020, 6:42am

The LH cup doesn't go all the way in if the shell is slightly narrow. You notice this more with a cartridge unit than with the old cup-and-cone type, which always left some thread exposed for the lockring.

Brucey
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Re: Bottom bracket problem

Postby Brucey » 19 Oct 2020, 6:46am

there's no point in just facing the BB shell, it needs to have taps run through it too. The reason is that the threads may originally have been cut square to the end of the BB shell, which then distorted during brazing/welding. Cocked threads or a cocked face (esp on the RHS with BBs like this) can hold the cups at a funny angle.

That the previous BB didn't last long is also strongly suggestive that the cups were not properly aligned; the tifosi unit actually has two separate cups (like the campag unit I think) but the RH cup is normally not removed. This means a tifosi unit looks like a (recently discontinued) shimano unit (with the bearings integrated in a single unit with the RH cup) but it isn't.

If the BB you are installing is a used unit the bearing surfaces may not be perfect any more. In many cases an imperfect cartridge bearing can feel OK when out of the frame, but when subjected to installation loads, it can feel rough. If a new bearing is loaded badly enough to feel rough, then the you should assume that something is binding or that the loads on the bearings are extraordinary; the most common thing is that cartridge bearings get overly preloaded and this isn't noticed during installation because the bearing surfaces are nice and smooth when they are new.

Abnormal bearing loading/roughness during installation can arise via a number of sources including;

a)- misaligned threads
b)- misaligned end faces to the BB shell
c)- bad diameter tolerances
d)- bad lateral tolerances (eg shoulders on spindle are set further apart than the length of the centre sleeve)
e) - centre sleeve gets crushed when LH cup is tightened
f) - seals are faulty and get compressed onto moving parts when the cups are tightened
g) - bearings are slightly worn already and any preload (be it normally acceptable or not) manifests bearing roughness
h) - parts are sufficiently badly made/out of whack that you get metal to metal contact in the wrong places when the cups are tightened.
I) - the bearings are actually partially seized, and only turn at all (rather than slide round inside the cup or on the spindle) when the cups are tightened

FWIW I have seen the last of these several times with used campagnolo units of this kind.

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

raymondchristopher
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Joined: 18 Oct 2020, 8:15pm

Re: Bottom bracket problem

Postby raymondchristopher » 19 Oct 2020, 10:39am

Thank you for your comments.

rogerzilla
LH cup goes in with no trouble, without the other part installed. Don't think this can be the issue.

Brucey
Taps have been run through it. I wasn't too concerned with the facing as I didn't think it would affect the alignment, though I've reached the point that I'm running out of possible reasons and so it's something to try.
The Tifosi BB unit is closer in design to the Campag unit yes, with both cups being removeable. The removeable LH cup doesn't have a flange and the BB is installed using the same tool as the Shimano unit. Why Shimano should discontinue the UN55 is beyond me, though it's obviously cost-cutting nonsense. I meant that the Tifosi BB behaved like a Shimano unit in that it was simple to install, and caused no problems!
I'm using a brand new BB, fresh out of the box. I've removed the cups to check the bearings and they're free moving/ feel fresh and new, though I do know what you mean by bearings feeling okay but not when installed. The LH cup is particularly tight fitting on the LH bearing, moreso than the RH cup on the two RH bearings. I have gone through a similar list of possible reasons, and feel it perhaps has something to do with the central sleeve squashing up against the LH cup. It's curious that it's fine with the LH cup tightened to just snug, but not once it's tightened further. Bloody Campagnolo. I'll faff around with it for a bit more and see how I get on.

fastpedaller
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Location: Norfolk

Re: Bottom bracket problem

Postby fastpedaller » 19 Oct 2020, 5:28pm

If you 'assemble' it off the bike, does it result in the correct width?

raymondchristopher
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Joined: 18 Oct 2020, 8:15pm

Re: Bottom bracket problem

Postby raymondchristopher » 19 Oct 2020, 9:28pm

fastpedaller wrote:If you 'assemble' it off the bike, does it result in the correct width?


That's a good question, and I haven't done that. I won't be able to check until I'm in the workshop on Wednesday.

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: Bottom bracket problem

Postby Brucey » 20 Oct 2020, 10:40am

raymondchristopher wrote: ….It's curious that it's fine with the LH cup tightened to just snug, but not once it's tightened further....


if the threads were bad enough before, they may still cock the LH cup over when it is fully tightened even now. But the RH cup is more likely to be cocked if you have not yet faced the BB shell; tightening the cups fully is what causes the bearings to be forced into the wrong alignment.

You can check for 'cocking' using a set of Vernier calipers to measure the assembled length of the BB at various points. If it varies by more than ~0.1mm then some further remedial work is probably required. If the BB shell is bad enough there is something to be said for a BB unit which has plastic cups; these tolerate misalignment rather better.

FWIW it is tempting not to tighten the cups fully. However this would be a mistake; IME the fit between the parts will soon deteriorate in this case.

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

peetee
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Joined: 4 May 2010, 10:20pm
Location: Cornwall

Re: Bottom bracket problem

Postby peetee » 20 Oct 2020, 10:54am

Don’t know if Centaur brackets were ever made for 73mm wide shells but could this be the problem?
Winter had arrived in the land of Kernow. Along with it came wet roads and cool winds.
“Oh, my wheels and coupling rods!” Peetee exclaimed.