early turbo front caliper swap (new vs. old calipers).

[zcacogp]

Early pistons had parallel sides and the seal slid along them. Later pistons had sides with a mushroom-shaped head on them with seals that look like a pair of bellows and that didn't slide. Are you comparing the two different types? Oli.

 

[amrbose14]

ORIGINAL: zcacogp Early pistons had parallel sides and the seal slid along them. Later pistons had sides with a mushroom-shaped head on them with seals that look like a pair of bellows and that didn't slide. Are you comparing the two different types? Oli.

Hi, yes I have a replacement set of later calipers for my early ones. So if the later caliper pistons are fully retracted the pistons will look a lot smaller? Perhaps consistent with this the bores of the calipers actually look about the same diameter in both sets (see pics).

 

[zcacogp]

Chris, Yes, that sounds about right. If the bellows-type seals are still on there you will only see the very front of the piston which will be smaller than the bore of the cylinder. Out of curiosity, how much did you pay for those refurbished calipers you are fitting? (The reason I ask is that I have a peculiar braking issue on my S2 at the moment which may be related to caliper performance, and I have old-style calipers on the front of my S2). Oli.

 

[amrbose14]

ORIGINAL: zcacogp Chris, Yes, that sounds about right. If the bellows-type seals are still on there you will only see the very front of the piston which will be smaller than the bore of the cylinder. Out of curiosity, how much did you pay for those refurbished calipers you are fitting? (The reason I ask is that I have a peculiar braking issue on my S2 at the moment which may be related to caliper performance, and I have old-style calipers on the front of my S2). Oli.

I paid 150 + vat & postage on an exchange basis, and I paid £250 deposit. "refurbished" is not quite true. I basically said I wanted something which worked fine, with no plate lift. I didn't care about the paint job. In fact I was concerned that a lot of "refurb" jobs are mostly about the paint job. Whether my decision will turn out to be the right one is yet to be determined! I'm learning, anyway.

 

[amrbose14]

This image shows a late style piston, I think. The top lip has a smaller diameter than the main part. So that is probably the explanation. However it makes determining the actual size of the piston a bit tricky without taking it out.

 

[amrbose14]

For any that might find it useful, this document describes the change from old to new style. https://webfiles.uci.edu/redwards/public/Improved%20piston%20seals%20MY%2089%20TSB%208-12-11.pdf Particularly useful are the inner dimensions of the cups within different pistons of corresponding outer diameter. This has convinced me that the calipers have the same (correct) piston sizes, since they are easy to measure no matter what the piston position. Chris

 

[Diver944]

I've just taken out my Textar road pads and popped in some EBC yellows. They slid straight in and out by fingertip pressure, no grinding required.

 

[amrbose14]

ORIGINAL: Diver944 I've just taken out my Textar road pads and popped in some EBC yellows. They slid straight in and out by fingertip pressure, no grinding required.

I've got mine in now, and I have had to grind a little material off to get them in. Perhaps a little disappointing on calipers that have just had the plate replaced/cleaned up (I can't tell). Oh well. That's the drivers side done anyway. Cheers.