Camag Chorus BB Bearing Replacement

[robc02]

I have replaced the larger bearing without difficulty, but can't see how to remove the smaller pair of bearings at the other end of the axle (they seem to be retained by a metal ring fixed to the spindle). Has anyone managed this, if so how?

[Mick F]

Is it this BB?

If so, the bearings aren't a Campag spares item, but I'm sure they're available commercially. Perhaps that's what you've done.

I haven't any experience of changing these bearings, but I would be interested in how you get on as I have a lovely Chorus BB like the one above.

(if I get bored later on today, I'll pull out my BB and have a look!)

[robc02]

Yes, that's the one. There is a large bearing at one end and two smaller ones at the other.

I removed the large one by opening the jaws of a vice just enough to get the spindle through whilst supporting the bearing on top. A few gentle taps with a mallet and the spindle dropped through the bearing. I used a similar technique in reverse to fit a new one. The bearing was a standard item from a bearing stockist.

The other end seems quite different. It looks as if the bearing are pressed on and then retained by a ring. I can't see how to remove the ring. I tried (gently) using the technique above, hoping the bearings and ring would move together, but nothing happened. I didn't want to try too hard in case I permanently damaged the assembly - there was still life left in it at the time. If I use one to the point where the bearings are completely shot I will be much more brutal! I was hoping that someone had already reached that point and done the deed for me.

[robc02]

I've just found this thread which sheds some light on the matter.

It isn't clear how the pressfit ring is removed and how it fits to the spindle (e.g. does it sit in a groove). Also, if it gets damaged I wonder if it can be left out. It doesn't seem to do anything other than stop one removing the bearings! As far as I can see the spindle cannot move sideways as it is restrained at either end by the cups.

Further investigation is needed but I am still a bit reluctant as there is life in the bearings - they just click and there is play developing.

[Mick F]

Thanks for that. Very interesting .....

I'm still not bored enough to take mine off to look!

Can I ask, what distance have you covered with your Chorus BB?
Mine has done 8,500miles or thereabouts, and is still sweet and smooth.

[robc02]

Can I ask, what distance have you covered with your Chorus BB?

Around 6000 - 8000. The first 2000 - 3000 were on a race bike where it led a cosseted life. It then drew the short straw and went on my commute-train-dayride-whatever-the-weather - bike! Everything on that bike has a hard life, especially in the winter on mud and grit strewn Staffordshire/Shropshire lanes.

I reckon to get no more than two winters out of these bottom brackets before play and clicking develops - this particular one has done only one full winter. It still runs, but the clicking is annoying. In the past I have cleaned and regreased the two smaller bearings (as best I can with them on the spindle) and replaced the larger one and this has been an improvement. I keep a spare one so I can service it at my leisure.

I use Chorus because I have an old set of cranks plus I bought more when they were being sold off for the price of the chainrings. The problem is that cheaper bottom brackets are too long so it has to be Chorus or Record. It didn't worry me to start with as I thought it would be easy to replace the bearings!! Having sealed cartridge bearings and making them non-replaceable is just perverse.(Campag do say they are not replaceable).

Stronglight do a 130mm ISO BB that does have replaceable bearings, and Phil Wood does one that allegedly just goes on and on. However, I have three Chorus BB sets so I am keen to find a way to service them if at all possible.

[Mick F]

I'm fond of stating that if something went on, it will come off!

I reckon you have to persevere to get the bearing off. It would annoy me greatly if my BB clicked and I had to renew the whole lot!

[robc02]

Yes, I'm convinced it will come off, but I'm concerned about the damage that might be done in the process! When I first looked into it I decided to wait until I had nothing to lose. Well I'm not quite there yet but I'm becoming irritated by the whole issue so I'm tempted to take a risk on dismantling the worst one - if no-one comes forward who has already done it and can offer sound advice.

It may be a while before I find time, but I'll report back when/if I know more.

[AndyA]

I have one in my spares box, it's borked (cracked cup and rough bearings) but couldn't bear to throw it away. I've just taken it apart, non-drive side came out easily after removal of the circlip but the drive side was a bit tougher. I tried my usual bearing removal process of hitting with block of wood/hammer. It wouldn't budge after 5 hits. I considered heating the retaining ring with a soldering iron, but before digging out the soldering iron I gave it 1 full force hit with no block of wood. Bingo!

Reassembly went ok, I used the large non-drive side bearing to press in the smaller two as I didn't have anything that would hit only the inner races on those small bearings. :edit: The retaining ring was tough to get in straight but clicked in eventually. It sits in a groove on the drive side. If I was replacing the bearings I'd probably loctite them in as suggested in the link upthread

In summary - hit it harder!

[robc02]

I have one in my spares box, it's borked (cracked cup and rough bearings) but couldn't bear to throw it away. I've just taken it apart, non-drive side came out easily after removal of the circlip but the drive side was a bit tougher. I tried my usual bearing removal process of hitting with block of wood/hammer. It wouldn't budge after 5 hits. I considered heating the retaining ring with a soldering iron, but before digging out the soldering iron I gave it 1 full force hit with no block of wood. Bingo!

Reassembly went ok, I used the large non-drive side bearing to press in the smaller two as I didn't have anything that would hit only the inner races on those small bearings. :edit: The retaining ring was tough to get in straight but clicked in eventually. It sits in a groove on the drive side. If I was replacing the bearings I'd probably loctite them in as suggested in the link upthread

In summary - hit it harder!

Thanks Andy - that's exactly the type of information I was hoping for.

Are the two smaller bearings a good snug fit on the spindle? Do they really need the retaining ring? After all, when in service the axle is held in position by the pressure from the cups, via the bearings, at either end. But then, why go to the trouble of machining a groove and fitting the ring?

[AndyA]

The smaller bearings on the drive side are the same internal diameter and fit on the axle similarly to the non-drive side. If you omitted the drive side ring the axle could move towards the non-drive side as there is no internal shoulder for the non-drive side bearing to rest on. I think

[Mick F]

The smaller bearings on the drive side are the same internal diameter and fit on the axle similarly to the non-drive side. If you omitted the drive side ring the axle could move towards the non-drive side as there is no internal shoulder for the non-drive side bearing to rest on. I think

This makes a deal of sense.
That must be why there is a clamping ring.

(if I get bored later on today, I'll pull out my BB and have a look!)

[robc02]

The smaller bearings on the drive side are the same internal diameter and fit on the axle similarly to the non-drive side. If you omitted the drive side ring the axle could move towards the non-drive side as there is no internal shoulder for the non-drive side bearing to rest on. I think

OK. I thought the non-drive side cup pressed against the bearing - but this is an assumption that I haven't checked. What you say suggests I am wrong and makes good sense, unfortunately

[AndyA]

The non-drive side cup presses on a spacer/seal (bbr e117), then the outer race of NDS bearing, then the large central alloy spacer, then the outer races of the DS bearing, then the DS spacer/seal, then the DS cup.

If the NDS pressed on the inner race you'd be able to overload the bearing when tightening up the bb and it'd last 50 grinding miles

Further investigation reveals that I've damaged the retaining ring, it came off with a gentle tap. I'd definitely advise heating the ring before removal and reinstallation. I'd also use loctite 641 or similar on the DS bearings

[gate owner]

is it possible to replace the locking ring with a circlip, if so it would then make replacement easier next time