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 Post subject: Lubricating BB
PostPosted: Mon Sep 06, 2010 11:33 pm 
Retro Guru

Joined: Tue May 11, 2010 4:13 pm
Posts: 636
Location: Scarborough
I've been trying to build up to lubricating the bottom bearing on my various 70's bikes. I've got as far as looking at it in a stern way, but then I always start to think about losing ball bearings all over the floor and a lot of tears. Can anyone tell me what I'll see when i knock the cover off the thing? And also, can I re-use cotter pins?


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 Post subject:
PostPosted: Tue Sep 07, 2010 11:14 am 
Dirt Disciple

Joined: Sat Aug 21, 2010 6:57 am
Posts: 74
Location: Hemel Hempstead
There is a nice photograph showing an exploded view of a bottom bracket here: http://www.flickr.com/photos/kevoh/4433257157/

On each side, the ball bearings sit in the cup, and nustle against the outer edge of the raised section of the spindle.

To avoid the ball bearings falling out all over the place, firstly take the lock ring off and undo the non-drive side cup a little - we want to get that initial tightness out. Now undo the non-drive side cup a little bit more and once you have got it moving grab hold of the spindle on the drive side so that its ball bearings are being held in the drive side cups. Now tilt your bike over (or lay on its side) with the non-drive side down, whilst still holding onto the other end of the spindle. Put a rag underneath the bottom bracket, to catch any ball bearings which may escape. Keep pulling that spindle against the drive side cup, as you remove the non-drive side cup. It will come out with most, if not all, of its ball bearings. If any are stuck on the spindle you can pick them off with a screwdriver.

Now you have two choices - you can either let go of the spindle - some ball bearings will fall out and others may stay in the drive side cup; winkle the remaining ball bearings out with a screwdriver. Alternatively, grab hold of the free end of the spindle and keep pushing it against the drive side cup whilst you undo the it, allowing you to remove the cup and spindle together without any ball bearings dropping out. However, the drive side cup is usually very tight and, if you don't have the right tool to undo it (and even if you do) it is best just to leave it in place. If you do decide to remove the drive side cup, the chances are that you will have an 'English' bottom bracket which will have a left-hand thread, so needs to be turned clockwise to remove.

This is a bit of a conservative way to take dismantle the bottom bracket. To be honest, the ball bearings do not usually travel far, since they usually still have grease on them. If you put a rag underneath you can just dismantle the bb with the bike standing vertically without losing any bearings.

Before you reassemble, check the cups, bearings and spindle for pitting or wear, and replace if necessary. If you removed the drive side cup, ensure that you really tighten it up. Put grease in the drive-side cup and pop half of the bearings in there. While you have grease on your hands, do the same with the other cup. Stick the spindle in and then hold onto it while you screw in the non-drive side cup. Adjust the cup so that the spindle is running freely but without any play; hold the cup in place there as you tighten it off with its lock ring.

As for reusing cotter pins, it is so long since I have used them that I can't remember what to do. I think that the general advice was to use new cotter pins each time, but I am sure that somebody else will be able to give a more informed answer on this.


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 Post subject:
PostPosted: Tue Sep 07, 2010 11:46 am 
r.B.o.T.M. & P.o.T.M. Winner
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I reuse cotter pins if they are serviceable and the threads are good. They can be b*ggers to shift if they have been in situ for some time. A little oil to penetrate the hole and hitting the pin with a hammer and wooden block protecting the threads usualy does the trick.


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 Post subject:
PostPosted: Tue Sep 07, 2010 9:03 pm 
Devout Dirtbag
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Joined: Sun Sep 05, 2010 9:57 pm
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Location: Kent
Regarding greasing the bearings, its a good idea to go for something like teflon grease as this has lower friction and will get you running smooth. Having said that, I use vaselene more often than not as I have it to hand. It's ok but on headsets it tends to leak out in the summer :cry:
Luke


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 Post subject:
PostPosted: Thu Sep 09, 2010 2:21 pm 
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It's not too bad a job really. I don't even have a C spanner or a spanner with the pins out the side. I use a sturdy screwdriver and a mallet to loosen the lock ring and if it's the type that needs the pins I put my scriber in one of the holes and tap it with a mallet. It's worked so far.

I've found the balls are often encased in solid old grease, so I've never lost any. Just keep a hand underneath just in case and count how many there should be.

I picked out the worst of the hardened grease and cleaned the cups and balls with petrol. Then for re-assembly - and this is the secret - wipe some grease in the cups and use it to stick the balls in place, then you can just slide it all back together easily. Don't forget the lock ring will slacken the bearings slightly, so you have to overtighten them a bit before you nip up the lock ring.

It's an easy job and can make a big difference if they are gummed up and a bit loose. Give it a go.


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 Post subject:
PostPosted: Thu Sep 09, 2010 3:29 pm 
Devout Dirtbag
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Joined: Sun Sep 05, 2010 9:57 pm
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I too use a mallet and a punch to remove the cup, and i did use a screwdriver for the lockring until i got a proper spanner. I've only chipped one cup and thats because i slipped ;p
Luke


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 Post subject:
PostPosted: Fri Sep 10, 2010 12:26 pm 
rider | rBoTM Winner
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I would suggest not using Vaseline for any 'permanent' lubrication on a bike. It's possibly OK for an emergency but it has a very high water content and won't last under the pressure of a BB. Rust is the usual result eventually.

Some short distance racers would strip their BB down for every race and lube with light oil to reduce friction and drag. I wasn't one of them!


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 Post subject:
PostPosted: Fri Sep 10, 2010 12:37 pm 
Devout Dirtbag
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Joined: Sun Sep 05, 2010 9:57 pm
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Location: Kent
Rust?!? I never thought vaseline would cause rust, well i'll be buying some more teflon grease and redoing all the bb's... Thanks for that info
Luke


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