CentralCoaster

This should be self explanitory. Hard parts were pulling the piston out of the cylinder. You can tap it on a wood block to get it most of the way out, but I needed to use the snap ring pliers to really grab ahold of it (on the non sealing surfaces) and pull hard. The other option would be to pop the piston out with hydraulic pressure while its still attached to the clutch hose.

Getting the seal flipped was tricky too. Remember, both the ID and OD of the seal do the work and can't be damaged. I crudely jammed a screwdriver under the seal, (make sure you get all the way under) and pryed it off. If you're not handy, I'd pay someone else to do it.

The CORRECT seal position is as shown on the bottom right.

FWIW, this is a Raybestos slave I bought 6 months ago and have about 3K miles on.

tobijohn

Are you saying your replacement slave went bad that fast?

CentralCoaster

Yes, it came defective out of the box. As did about 80% of all the zf slaves sold in the past 5 years or so.

mik

The problem was the seal was put on backwards allowing the fluid to pass by the seal when pressure was applied. As shown in the pictures, the trick is to turn the seal around so it actually seals properly.

DieL

So what actually happens when its backwards? if it allows fluid to leak past does this mean the slave will leak? Does this mean the slave might not perform properly etc?

Im wondering because im having sealing issues with my Mcleod master cylinders. I did just replace the slave with a new one from GM a few weeks ago.

bogus

great job!

-=Jeff=-

Excellent,

But also inspect the seal, verify all 5 Micro edge lips are on the seal all the way around, or the fix will be stop lived.. I have 3 slaves, 2 are still good, the 3rd is not, slave was used LESS then 1K miles.

From your pictures the Micro edges seem to not be there

Jerris

Excellent information, thanks for the clarification guys. Perhaps with some added instructions on how to remove and bleed the slave it could be added to the TECH TIPS.

Scooter 94

Hmm...so if I remove the Raybestos I installed in April, there's a good chance it's bad too....I HATE re-doing stuff.

You wait and see...I'll take that thing off and it'll be one of the good ones. Or could continue to use it and hope for the best.

tobijohn

When the slave goes, is it immediate or does it give you a little time to scramble? TIA..

Scooter 94

I'm thinking it would almost have to be gradual. May watch fluid for leaks and fix when obvious.

What say the experts?

tomtom72

The "experts", from GM or other mfg's are not telling us anything that could help us....I think they know what's up & don't want to own up to it.

The slave will either work or not almost instantly....well all mine failed within the first hour of use...even the ones with the seal in wrong(before I knew about that) would work for me for about an hour and then gear clash would happen out of the blue you would sit at a light in neutral and go step on the clutch and go to 1st and bingo the noise would start....and sometimes it would not...and as it gets worse you get the clash going to do upshifts in normal driving. None of my slaves with the seal in wrong leaked any fluid that I could find but they would not push the fork far enough or hold the fork at max travel long enough to not give gear clash when shifting. That is my experience with OEM/GM boxed parts and the aftermarket stuff that looks exactly like GM stuff.

Tom

tobijohn

Well that's just lovely. The LT4 I got a month ago just had the slave replaced under warranty because the previous slave (and master too, I think) had been replaced 3000 miles before that. Car had 42K on it when I got it....

CentralCoaster

Mine worked with the seal backwards for 6 months, it just slowly leaked fluid past. I haven't checked for fluid loss yet with it fixed.

DieL

Are GM slaves all AC delco? I've read on many posts the ac delco are junk, and also read that the Gm ones are the way to go..

Scooter 94

Figured I better take a look while I had the car jacked up for oil change. Sure enough, after only 120 miles on Raybestos slave (purchased 4/06), there was some moisture on the boot end. Removed it, took the plunger out, and the seal WAS ON BACKWARDS!!

Corvette Forum to the rescue! Thanks for the great info.

Scooter 94

Forgot to mention, factory original slave was still working at 54K miles, but had a slow leak (top off once a week), since 30K or so. Dunno if it was AC Delco. Threw it away before seeing this thread, or woulda took it apart and checked that seal.

tobijohn

OK, Are there any aftermarket alternatives to Raybestos/AC Delco/GM, etc. that do last? TIA...

-=Jeff=-

Possibly the Wagner Cast one...

GM knows what is wrong with the slaves now. I have an email conversation regarding it. I need to email the gentleman that I got it from Prior to posting it..

DieL

I can see GM giving us a GP on slaves in the near future ..


I'll be the first to replace it regardless if mine isn't leaking. Just for peace of mind i would want a 'fixed' one.