Mrmerlin

Nicole, on the calipers the lower cross over tube can be removed and transferred to the the bleeder nipple side therby allowing the position of the calipers to be moved around the wheel hub . This is one of the things that must be done when a 993 TT big red brake package is installed on the S4

Jadz928

Pentosin (the mfg. of the PS fluid) contacted me. I explained the situation and he said there should be no problem. Just flush out the PS fluid, flush in twice to make sure I get out all the PS fluid. He said it should not affect the rubber seals as there are also rubber seals in the PS system.

I did my own test, guaging 2 different sized rubber o-rings (2 of each). I soaked them in the PS fluid for 5 days. No dimesional changes noted. Same compression and stretch, before and after.

Based on this info, I'm going to keep the system as is. Most likely, I'll replace the rear brake bits... pads, rotors, and calipers as needed. I'll do a second flush on the system, the old-fashioned way.

I'm feeling much better about this now. Thanks everyone for your advice and concerns. I'll give everyone an update when the car is back on the road.

M. Requin

Thanks for the followup- interesting situation.

Jim bailey - 928 International

Jim that is GREAT NEWS !! far better than "the world is about to end" . You might want to deliberately engage the ABS after the flushes and THEN flush one more time. The ABS drains off some fluid and pressure when it modulates the braking then returns it to the brake lines / master .

Jadz928

Thanks Jim. But wouldn't it have needed to modulate to circulate the PS fluid thru the ABS? No argument since it is doable between flushes, just curious.

Jim bailey - 928 International

I though it might have cycled when the brakes went away....

the flyin' scotsman

Jim D............great to hear that the PS fluid manufacturer and your experiment appears to give the seals a clean bill of health.

Now you must be wondering what caused the intial rear end lock up........did you take them apart?

Jadz928

Haven't taken them apart. My guess is it has something to do with the more viscous PS fluid and an imbalance between the feed and return lines causing the caliper piston not to return.

Another though was the rear parking brake got stuck and this was just a coincidence.

Jadz928

Perl is back in action! Flushed and bleed a final time. Feels good. The rear brakes inspected well... much better that expected. No rotor warp or anything!

Thanks Chris (Landseer) for helping me with the "old fashioned" bleed.

I cycled the ABS system a couple times on some gravel. Probably will give it another bleed in a couple weeks after some driving.

Thanks all who shared here. I think we all learning something. If you can't read the german label on the can, don't just thow it in any hole in your car.

M. Requin

Really! It might be drinkable... Glad things worked out!

Landseer

Jim says he can differentiate between hydraulic fluids by taste now.

Jadz928

LOL ! <------- is that okay to say on RL or has it been banned?

Jim bailey - 928 International

LOL was only banned when used by the poster after his OWN "joke". Think of it as a laugh track on a bad comedy show ! Or a nervous giggle after a statement.

Landseer

Nervous gigglers should ban themselves, or at least stop making statements.

JHowell37

This thread should serve as the ultimate example of why people should use the blue ATE brake fluid. You won't mistake the color for anything else.