Cycling UK Forum

The bearings on my BB30, erm BB shell, seem to be ok after riding through four winters (avoiding BB deep fords). There's no detectable play on the crankset arms. And believe it or not... there is no creaking sound.

So I thought I'd chance fate by removing the FSA crankset and re-grease the bearings with Finish Line teflon grease (which is what I normally use). Once the crankset is out I plan to leave the bearings in situ, give them a wipe, and then gently prise off the outer dust covers, before squeezing some more grease in. Then re-fit the cover and reassemble the crankset. I'd be happy to get another couple of years use out of the existing bearings. What could go wrong?

For future reference, what bearings do forum members usually replace them with? Something like this? https://simplybearings.co.uk/shop/p368910/NSK-6806DD-Thin-Section-Rubber-Sealed-Deep-Groove-Ball-Bearing-30x42x7mm/product_info.html

Well that was interesting, and worthwhile doing. The crankset came off no problem, only needing a gentle tap with a plastic mallet after undoing the single bolt which self-extracts with a 10mm hex wrench. I removed the wavy washer and plastic outer cover from the non-drive side.

The non-drive side bearing felt very smooth. However, the drive side bearing felt slightly rough. I gently removed the green plastic cover with a blade and could see that the ball race appeared to be dry. So I filled it with grease and replaced the cover. It felt much better and ran smooth. Then I removed the non-drive side bearing green cover and found a second plastic retaining ring (brown but slightly transparent) that wasn't present on the drive side. So either the drive side had a part missing or each bearing is not symmetrical, ie one side has the additional plastic shield. (Perhaps someone knows?) I didn't pull this off but squeezed some grease around the edge and replaced the plastic cover. The extra grease seemed to "choke" the rotation slightly but it felt otherwise good.

I replaced that plastic outer cover and wavy washer and screwed it together again. No problem. May be good for another four years.

Thanks for the write up. It sounds like you were fortunate in the bearing stakes on a BB30

ossie wrote:Thanks for the write up. It sounds like you were fortunate in the bearing stakes on a BB30

Lucky indeed. Which is why I was reluctant to remove and replace them in case they start to creak

LinusR wrote:…. Then I removed the non-drive side bearing green cover and found a second plastic retaining ring (brown but slightly transparent) that wasn't present on the drive side. So either the drive side had a part missing or each bearing is not symmetrical, ie one side has the additional plastic shield. (Perhaps someone knows?) I didn't pull this off but squeezed some grease around the edge and replaced the plastic cover....

It sounds very much like the cartridge bearings had an acetal ball retainer in them, and they happened to be installed in different orientations. Acetal ball retainers can be any colour, but amber/brown is most common. The illustration below shows a sectional view of a deep groove bearing with an acetal retainer;



You can see that the balls are visible from the front/left side of this bearing, but would be largely obscured by the retainer (which would look like an unbroken ring) when viewed from the rear/right side. In your BB bearings I expect there is a similar arrangement hidden behind the rubber seals. Such bearings are not normally intended to be 'handed' and both sides can look identical with the seals in position, so it is no surprise if they were not installed the same way round.

Possibly it makes a real difference to the seal wetting; the grease inside the bearing gets 'churned' and may not be evenly distributed from side to side. If given the choice in a typical assembly I'd instinctively choose to have the unbroken side of the retainer facing outwards, but this is at least as much because this would let me remove it if necessary (without disturbing the bearing) as for any thoughts regarding seal wetting.

cheers

Brucey wrote:

LinusR wrote:
Possibly it makes a real difference to the seal wetting; the grease inside the bearing gets 'churned' and may not be evenly distributed from side to side. If given the choice in a typical assembly I'd instinctively choose to have the unbroken side of the retainer facing outwards, but this is at least as much because this would let me remove it if necessary (without disturbing the bearing) as for any thoughts regarding seal wetting.

cheers

Ah that explains it. I think I'd rather have the retainer facing inwards as I could pack more grease in that way. It was a bit of a fiddle getting past the retainer and difficult to really pack it in.

with smaller (eg hub) bearings, loose or in flush housings, seal out, you can pack grease in using something soft that seals around the edges and then 'pushes in' to the bearing. I often use the base of my thumb for this. A couple of goes at it usually has grease purging through the bearing, out the other side past the seal. With larger diameter bearings this isn't so easy; I have often wondered if there isn't scope for a simple tool to do the same job.

BTW it is usually possible to remove an acetal retainer; this allows any amount of grease to be added to the bearing. However there is always a chance that you will break it (they seem to go brittle perhaps) and refitting it can be a proper fiddle if the balls start moving around.

cheers

Brucey wrote:there is always a chance that you will break it

I would

Hi

Would it not be better to lubricate sealed bearings with a hypodermic needle. Thus leaving the shielding largely intact?
Can you get semi fluid grease in tube form???

Cheers James

Not every grease would go down a hypodermic needle, not at a realistic pressure anyway.

By analogy if you pack Bowden cables full of SFG (of a type that works very well in hubs etc) the cable usually gets rather draggy. Again I suspect that a hypodermic needle might not allow its easy passage.

cheers

Jamesh wrote:Hi

Would it not be better to lubricate sealed bearings with a hypodermic needle. Thus leaving the shielding largely intact?
Can you get semi fluid grease in tube form???

Cheers James

It was quite easy to remove the plastic covers without damaging them so I don't think anything more elaborate would be necessary. It was so easy to do the whole operation - much easier than servicing a cup and cone hub which I also did today - that I would quite happily do it before every winter and again in the spring. I'm wondering how much grease would have been packed in at the factory and would it have been enough. I'd be minded to pull the covers off and check for new bearings.

Brucey wrote:Not every grease would go down a hypodermic needle, not at a realistic pressure anyway.

You can get a range of sizes of needle for your syringe. I still have a drawer full of different sizes from my factory days. They are used for adhesive application on production lines. I keep three syringes with 1mm dia tips permanently full of different greases for bicycle use on my tool board; molybdenum, aluminium and Castrol EP2