Right, so back to work. Today I started rebuilding the calipers. Just changing the dust boots and pistons seals. The dilemma was how to remove all four calipers at once without letting the brake fluid drain out.

Well, I found out that these little guys fit the Cayman's brake lines perfectly.

http://i983.photobucket.com/albums/a...psfp96kbsv.jpg

Not sure how teflon tape will react to brake fluid, but I don't care as I will be replacing the lines next. I just needed them to not leak for the time being.

Here's a rear line plugged up. Zero dripping. Sweet.

http://i983.photobucket.com/albums/a...pstfkeg3ez.jpg

And a front.

http://i983.photobucket.com/albums/a...psij0cijm9.jpg

Calipers ready for rebuild.

http://i983.photobucket.com/albums/a...psyvuejesf.jpg

Rear dust boots looked bad. And this is not the first set.

http://i983.photobucket.com/albums/a...ps8ynhzlu6.jpg

First order of business - pistons out.

http://i983.photobucket.com/albums/a...psjpn6ftku.jpg
http://i983.photobucket.com/albums/a...psot7hykhp.jpg

Followed by removing the seals.

http://i983.photobucket.com/albums/a...pswnnpw8b4.jpg

Pistons out and cleaned.

http://i983.photobucket.com/albums/a...ps6ggdpr9a.jpg

New boots installed.

http://i983.photobucket.com/albums/a...pswbbjrfau.jpg

Just push them back in.

http://i983.photobucket.com/albums/a...psi387ftyn.jpg

Two done two to go.

http://i983.photobucket.com/albums/a...ps5zp7gdyy.jpg

Not my favorite activity. I'm not a huge fan of brake fluid. Gotta do it though...

Oh, that's a good idea I just stole.

Were you able to test for stuck pistons before removing them? Hitting it with compressed air?

Curious if a stuck piston may have been a factor in your VIR brake problem. It looked a lot like what I experienced at Mid Ohio and sure enough I had a couple of pistons that were stuck.

Of the two that I've done (one front/one rear), neither had any stuck pistons right now. I did notice however that the front caliper had no wear on the pistons at all. The rear pistons, however, had some longitudinal marks as if they could have rubbed against the cylinder walls. The "scratches" were not deep at all - couldn't even feel them with my fingernail, but visually they were there. Not sure if that indicates some of the pistons could ever have been stuck.

In your case, you hit them with air as soon as you pulled them off the car and they didn't move? I did do another event between VIR and now, so not sure if that could have loosened them up. Did you notice any visual scarring?

I've come to terms with the fact that a perfect forensic analysis of that event is impossible and this is in fact oftentimes the case in racing as well. Something happens at some point, but it is not easily reproducible. In fact, I hope I'll never reproduce that. :bang:

Your calipers are still surprisingly red as opposed to purple/brown. How many track days are on these calipers?

Yup, just drained the fluid and then shot compressed air into the caliper to see if the pistons popped evenly. All of them moved but a few did not fully extend. Can't say if this is an accurate test or not.

Yes, there were more scratches noticeable on the pistons that were stuck. My calipers were in bad shape with barely any portion of the dust boots intact.

Perhaps others will chime in but I don't think you can read too deeply into a compressed air test. 1) different fluid obviously; 2) different pressure than when under braking with brake fluid (braking pressure at the line is much higher).

The fact that your pistons moved when using such air would tell me they're fine. But I don't think we can glean much more than that -- i.e., how "fine" they truly are.

No argument. But if you experienced what I did under braking, you'd be quick to believe anything that pointed to stuck pistons.

FWIW, we did try to free the stuck pistons while applying forced air and they were stubborn to release. Same test after rebuild and all the pistons popped evenly and quickly. Astroglide ;)

Probably about 30 track days on those calipers. Second set of calipers. I've had PSM completely disabled (hardwired off) in conjunction with using these calipers. It's usually PSM that overheats the rear calipers in particular.

This might be fairly telling.