Rear caliper - caged thrust ball bearing(s)

[mangocrazy]

I'm in the middle of refurbishing a bunch of calipers, and I've found that a number of parts are in borderline condition and wonder if replacements are available. The part that concerns me most is the little caged thrust ball bearing assembly that sits inside the piston of the rear caliper. It consists of a pressed u-section brass cage with a number of 3mm ball bearings captive in the cage. Or not, as in my case. The overall size of the cage/bearing is, as best I can make out, 20mm o.d., 12.5mm i.d. and 3mm deep (i.e. the depth of the ball bearings). The whole affair seems a little flimsy and any over-zealous cleaning of the assembly can cause one or more of the ball bearings to pop out, never to be seen again.

Is this assembly available as a spare part (he said hopefully)? Looking in the S2 parts book, it's not even shown on the exploded caliper diagram, so I'm not hopeful. I've had a look through some of the online bearing suppliers and can find nothing remotely resembling this part.

[mangocrazy]

I believe I may have been guilty of over-thinking this.

Loose 3mm ball bearings in either hardened steel or 316 stainless are available for about £3 per 10 from suppliers such as Simplybearings. Gently pop the tired and corroded old bearins out and replace with shiny new ones. I reckon the version in 316 stainless woud be the best bet due to their superior corrosion resistance. Each race takes 11 balls, so for the pair of calipers I'm restoring, 3 packs will be needed.

Interested to hear others thoughts.

[WestonE]

Hi Graham

It sounds like a reasonable approach to me. These are not high speed bearings. Their purpose is for the piston to turn out with wear for handbrake self adjusting and of course back in when pads are changed.

Cheers

Eric

[mangocrazy]

Thanks for the confirmation, Eric. That was broadly my line of thinking as well. Most of the time the bearings will be static, so another reason to use stainless, I think.