Bottom Bracket coming Loose

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Bertieboy
Posts: 22
Joined: 1 Apr 2008, 8:31am

Bottom Bracket coming Loose

Postby Bertieboy » 9 Aug 2019, 9:17am

I have a square taper Campag Veloce bottom bracket fitted to one of my bikes. It is Italian thread and is for a triple thus it is 115.5mm long. I do not use the bike very often but when I do it invariably becomes loose on the drive side after about 40 kilometres to the extent that I can no longer change into the large chain ring and can tighten it by hand. I have removed and refitted it at least three times, done it up as tight as possible and this still occurs. When I fit it I do grease the threads on the BB cups. To solve the problem I was considering using some blue loctite on the shell threads or perhaps PTFE plumbers tape but I don't want the thing to get stuck to the extent it will not move. Has anyone else any suggestions?

slowster
Posts: 822
Joined: 7 Jul 2017, 10:37am

Re: Bottom Bracket coming Loose

Postby slowster » 9 Aug 2019, 10:49am

Is it a cartridge bottom bracket? When I had this problem, the bottom bracket was a non-Campagnolo unit with separate axle, cups and cartridge bearings, and I cured it by replacing it with a standard Campagnolo cartridge. I think the cartridge units are much less prone to the effect of precession(?) unscrewing the drive side cup on an italian threaded bottom bracket.

Bertieboy
Posts: 22
Joined: 1 Apr 2008, 8:31am

Re: Bottom Bracket coming Loose

Postby Bertieboy » 9 Aug 2019, 11:29am

It is a genuine Campag Veloce sealed unit cartridge BB. What I cannot understand is that with the Italian thread it is done up clockwise and that is the direction the chaninrings / cranks are turning so logically, it seems to me, this should keep it from coming undone.

slowster
Posts: 822
Joined: 7 Jul 2017, 10:37am

Re: Bottom Bracket coming Loose

Postby slowster » 9 Aug 2019, 12:11pm

When you say 'as tight as possible', are you using a torque wrench? My Campagnolo bottom bracket specifies a torque of 70Nm (written on the cartridge shell), which is a lot: I have to use a long breaker bar to undo the BB. Campagnolo bottom brackets do usually come with some white threadlock already on the threads.

Bertieboy
Posts: 22
Joined: 1 Apr 2008, 8:31am

Re: Bottom Bracket coming Loose

Postby Bertieboy » 9 Aug 2019, 2:15pm

It was originally fitted by my LBS so I don't know whether it was torqued to correct tension. When I have refitted it using the the Campag BB Tool UT BB100 it did not have a taper for a torque wrench drive thus I have used a large spanner on the tool. I did it up tightly but could not measure whether this was to the correct tension and I did not use a breaker bar for fear of stripping the threads. It did not have any white threadlock on it when I fitted it and I used bike grease on the threads. If I clean this off can I use Blue loctite?

Brucey
Posts: 34868
Joined: 4 Jan 2012, 6:25pm

Re: Bottom Bracket coming Loose

Postby Brucey » 9 Aug 2019, 2:28pm

Bertieboy wrote:It is a genuine Campag Veloce sealed unit cartridge BB. What I cannot understand is that with the Italian thread it is done up clockwise and that is the direction the chaninrings / cranks are turning so logically, it seems to me, this should keep it from coming undone.


thats not quite the case; precession tends to unscrew italian threaded BBs, because the cup tends to 'roll around' the inside of the BB shell. British BB threads have a LH thread to stop this from happening. With italian threads you often need loctite.

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

slowster
Posts: 822
Joined: 7 Jul 2017, 10:37am

Re: Bottom Bracket coming Loose

Postby slowster » 9 Aug 2019, 3:04pm

It was the experience of my bottom bracket unscrewing itself, and seeing the bike shop use a torque wrench to fit the Campag BB which replaced it, which prompted me to buy a torque wrench, because I was determined to follow Campagnolo's instructions after the repeated experiences of being miles from home and finding that yet again my BB was unscrewing.

In your shoes, I would get a socket that fits your BB tool and allows you to ensure that you are using the correct amount of torque. My torque wrench is 38cm long and my breaker bar/pole combination for undoing the BB is a lot longer. If you are using a relatively short handled spanner, it's probably going to be more difficult to apply enough torque, as well as harder to judge the amount of torque by feel with a shorter handle in the absence of using a torque wrench.

Personally I do not like the Veloce type of BB which has cups with notches on the flange, and which uses the tool like yours with pins to engage the notches. I think you need to be more careful with that design that the tool does not slip off the cup as you are applying lots of torque. My BB is the splined type used on Centaur, Chorus and Record, which uses the same tool as Campag cassette lockrings, which I think is a slightly more secure fit in the BB (although frankly using so much torque on a splined interface is not something I like doing).

As for using threadlock like Loctite 243, I cannot see any reason not to. The Campag instructions I have to hand that came with the BB do not make any comment about grease or threadlock. However, I would personally always use grease, i.e. I would not install the BB 'dry' with just threadlock. Whilst italian BBs do create an unnecessary risk of the BB unscrewing, there still remains the risk in the longer term of the BB seizing in the shell. I think I've read guidelines that the BB should be unscrewed once a year or so to prevent this. I only use that bike very rarely and in summer, so I only unscrew the BB every few years.

I'm afraid I cannot give you a definitive answer or provide you with complete reassurance - my approach was to follow Campag's instructions and ensure I used the specified amount of torque, and that has worked for me.

Brucey
Posts: 34868
Joined: 4 Jan 2012, 6:25pm

Re: Bottom Bracket coming Loose

Postby Brucey » 9 Aug 2019, 7:11pm

https://en.wikipedia.org/wiki/Precession_(mechanical)#/media/File:Animation_of_mechanical_precession.gif

shows how mechanical precession works. In this case an ACW rolling contact causes a slower movement of the blue part (BB cup) in a CW direction.

Reversing the directions above shows what happens with a RH BB cup, and why Italian BB threads are much, much more likely to unscrew themselves.

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

AndyA
Posts: 386
Joined: 21 Mar 2009, 9:16pm
Location: Edinburgh

Re: Bottom Bracket coming Loose

Postby AndyA » 9 Aug 2019, 11:10pm

This is very common with Italian threads, put threadlock on the drive side and if your threads haven't taken too much damage during the previous unscrewing events they might hold with threadlock. Check for damage on the threads of your BB and frame. If there's a lot of damage on the frame threads, you could consider an approach that Brucey has suggested previously, which is to epoxy in the drive side cup. This somewhat locks you into this kind of BB, but a bit of heat will soften up the epoxy enough to get the BB out if you do decide to change. The driveside cup is held onto this BB by a lip on the cartridge unit, you can drift the two apart quite easily. You don't need to do this until you wear out the first BB, maybe 10000 miles in my experience

NickJP
Posts: 97
Joined: 24 Sep 2018, 7:11pm

Re: Bottom Bracket coming Loose

Postby NickJP » 10 Aug 2019, 3:49am

Bertieboy wrote:It is a genuine Campag Veloce sealed unit cartridge BB. What I cannot understand is that with the Italian thread it is done up clockwise and that is the direction the chaninrings / cranks are turning so logically, it seems to me, this should keep it from coming undone.

Not the case. Look up "precession" for an explanation of the reason why: https://en.wikipedia.org/wiki/Precession_(mechanical).

Bertieboy
Posts: 22
Joined: 1 Apr 2008, 8:31am

Re: Bottom Bracket coming Loose

Postby Bertieboy » 10 Aug 2019, 10:32am

Thanks for the replies and suggestions. Must admit had never heard of mechanical precession, very interesting and at least I understand why this is happening.
I don't like the Veloce BB tool either. Think the Chorus, Centaur BB's with the slines are much easier to fit and tighten. Have often wondered if it is possible to use my Veloce chainset with the Centaur BB? Do they have different tapers? Will attempt to use a large wrench to tighten the thing up using loctite and see what happens. The BB is fitted to a Colnago Master Olympic that I use very infrequently and I do wonder if the chainline is outside the normal limit / tolerance but I am too old to use the Campag double of 53 / 39.

Brucey
Posts: 34868
Joined: 4 Jan 2012, 6:25pm

Re: Bottom Bracket coming Loose

Postby Brucey » 10 Aug 2019, 10:42am

campag square tapers in 'modern' stuff (after about 1985) are interchangeable and use the ISO taper. The exception to this is the 'pista' kit which still uses the 'old' campag taper, which is different.


So yes you can use a different campag sealed BB, provided the length is correct.

If you want to be able to get the BB out again, my advice is not to use one with the small splined fitting; it just isn't strong enough to allow removal of a slightly seized BB. It is only just strong enough to allow the BB to be correctly installed.

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

slowster
Posts: 822
Joined: 7 Jul 2017, 10:37am

Re: Bottom Bracket coming Loose

Postby slowster » 10 Aug 2019, 12:32pm

Another option which would cost more, certainly initially, but might be better in the long run, would be to replace the Veloce triple with a Spa RD2 triple*, and a UN55 bottom bracket.

* Or the TD2 triple if you want the option now or later of fitting a 46t or 44t outer. (Edit - assuming the Master Olympic takes a braze on front mech, that will limit the minimum outer ring size. I've fitted a 48t to an italian frame with a braze on front mech with no problem.)

Advantages of this:
- choice of chainrings/options for lower gears
- Shimano UN55 bottom brackets are a lot cheaper than Campag bottom brackets
- the splines on the UN55 allow a lot better purchase than Campag, and the available tools for the BB are much more substantial, e.g. Park BBT-22 which takes a 3/4" drive as well as having 32mm spanner flats, or tools like this one from Var and this one from Unior, which use a bolt and spring to lock the tool onto the axle and ensure it stays snug on the bottom bracket while you tighten or loosen it.
- there is a wide range of UN55 axle lengths, so getting the 'right' chainline should not be a problem, although you would probably just need the 113mm recommended by Spa for the RD2 and TD2.

Bertieboy
Posts: 22
Joined: 1 Apr 2008, 8:31am

Re: Bottom Bracket coming Loose

Postby Bertieboy » 10 Aug 2019, 1:22pm

Slowster I actually use the Spa triple chainset with the Shimano BB on the bike that I tend to use the most because it is set up for a 48, 36, 24 chainring combination. I use Campag ergos with a Comp front and rear derailIeur with a Shimano cassette. I do agree that the Park BBT-22 tool is much easier to use than the Campag Veloce tool. The only reason for fitting the Veloce crankset was that it is an old Colnago and I wanted to use Campag components. Getting Campag Italian thread BB's is becoming increasingly difficult thus I had considered fitting a Veloce compact 50 - 34 to it but this is "out of character" with the bike. Stupid really as it hardly ever gets ridden but when I do ride it I want the wretched thing to work properly!

Brucey I think Token make Campag compatible square taper BB's, do you know if these are any stronger or do they suffer from exactly the same problem due to the small splined fitting?

slowster
Posts: 822
Joined: 7 Jul 2017, 10:37am

Re: Bottom Bracket coming Loose

Postby slowster » 10 Aug 2019, 4:18pm

Brucey will probably confirm one way or another, but I'm pretty sure the Token BBs use the same spline pattern as Shimano, as do Tifosi (albeit they don't make a 115mm version), i.e. you could use your Park BBT2 tool.

Although Token list a 115mm italian thread ISO/Campag taper bottom bracket, it looks like most retailers only stock the 102mm and 111mm sizes. If you cannot get hold of one, I wonder if a 111mm would fit on your frame without the inner ring touching the chainstay and with an acceptable chainline? Interestingly, on its website Token differentiate between the 111mm and 115mm sizes by stating that the former is for triples with 28.6mm seat tubes and the latter for triples with 32mm-35mm seat tubes, although according to my vague recollection Campag made BBs as follows:

102mm - Record and Chorus double (splined)
111mm - Record and Chorus triple (splined)
111mm - Centaur double (splined) and Veloce double (notched)
115mm - Centaur triple (splined) and Veloce triple (notched)