kgorman

I have been reading the forums for days about slave cylinders. My head is spinning! I still have a couple questions, so bear with me if you all don't mind. I am dedicating myself to understanding whats going on because I feel so bad about spending so much money and being so ignorant and naive. My wife feels bad for me, I feel bad she feels bad, you know the deal.

The actual part that failed is my logitundinal differential slave cylinder 964 339 775 07. It's the same one as shown in Adrians book pg 219. This is the one mounted on the G64 transmission housing. Garrett has some pics in this thread. Here is a picture of my broken part:

Clearly, the seal has failed. The circlip and actuator are missing from it (shop didn't return to me).

I called the shop today, just to verify again. They are still stating that they believe this part will blow up again because:

"the shift fork/actuator in the transmission is out of tolerance, and will exert too much force on the actuator, and blow it up again" They state it's 5mm out of 'tolerance'. They are not speaking in exact technical terms, and seem to be confused about the whole thing. In 30 years of being a tech, he states he has never seen this kind of problem. But I see about 50 posts here on RL about this part leaking. My part looks like the seal failed, thats all, no catastrophic failure due to pressure (see lame pic above)

After looking in the PET, the tech's statement does not make much sense to me. The only thing I think they might be talking about is what Garrett experienced in this thread where he blew out the guts of the same part. Perhaps the tech is just confused?????? They say, they would not drive the car at this point. They want to go on a fishing expedition to see what is wrong with the transmission. Can I do something to verify the tranny is OK? I am not sure looking in the inspection port will do anything regading this issue.

At this point I am inclined to drive it again. If what I am reading everywhere is correct, there is no real 'adjustment' in the transmission for this part, it's just a replacement, re-bleed, go-drive type of deal. I have the car at home, all put back together. Drives fine, PDAS/ABS seems fine.

I can't seem to find this system in my workshop manual (anyone know what section it's in?).

Regarding the lateral differential slave cylinder. Oh, yeah I was snookered on this one. The part is just fine. The tech stated that "it's good to replace it too". B.S.! I will be talking to the owner tomorrow and get some $ back on this one.

The pressure accumulator was not holding pressure. They tested it apparently. The shop mentioned it's leaking 'internally'. I am still researching, but I think this is B.S. too most likely.

Garrett, I will send it to you once I get this all straight. Hopefully between us we can come up with some solutions for people in the future.

JasonAndreas

Volume II Transmission (Manual) starting on Page 34-26?

Indycam

"I am still researching, but I think this is B.S. too most likely."
Did your brakes work ? Did you ever step on the brakes and feel a "dead" sinking feeling ?
I'm a guessing that the thing was fine cause you never said "man my brakes suck" .
No pressure accumulator = my brakes suck .

I once asked people on this forum to test things , it was to see what shape the pump and or pressure accumulator were in . I got a bunch of flack from a person that my tests were of no use , even when he had know real idea of how the data was going to be used . He jumped to his own conclusion that no real insight could be made from the data I had hoped to collect and therefore the test was damn near worthless .

If you care to send me your old pressure accumulator , I will put it on my test rig and run it .

kgorman

Found the detail I am looking for... Vol 4 D39/45-23. Thx for the help Jason.

kgorman

Brakes work just fine. In fact with Hawk Blues, fresh ATE Blue, and a new bleed they feel fantastic.

I might, still trying to make sure I understand this whole F*%*ing mess. Thx for the offer!!

kgorman

I just got my car back from Rob at http://www.scargoracing.com. It's confirmed that my brake/awd system is OK. Rob is a nice guy and appears quite honest. It's clear they have lots of talented mechanics in-house, and I have had good word of mouth about them. So far, a great experience.

The car has new tranny fluid, a fresh corner balance and alignment,-1.6 negative in the front, and a general going over.

I found out some more info about how bad the previous shop is:

- Horizontal slave cylinder did not NEED to be replaced.
- At my 70k service, they did not replace my valve cover gaskets
- They did a poor corner balance, basically w/o scales and charging me top $$
- They over-stated my oil leak problem trying to get me to do a rebuild with them ($$$$), detailed here

Basically Kahlers had no idea what the heck they were talking about, and this from a specialist. I won't publicly rip them any more other than to say, Kahlers has no idea how to work on these cars. That should do it.

All this for a simple leaking longitudinal slave cylinder. It's clear how a bad shop can really make a mess of things. In hindsight I should have just replaced it myself, I will be doing more of that in the future for sure.

I hope this helps someone when they search later on.

Indycam

Live and learn .

My buddies father took his AH 100/4 in for a paint job .
This car was beautiful , no damage ever , no rust .
He had it from day one .

The paint shop took it out for a spin .
Introduced the car the a tree stump .
When the car came back not only did it now have damage repair ,
it had a bad case of orange peel .

garrett376

kgorman - glad you saw the guys at S-Car-Go - tell Rob I say hello! He is a great guy, and his mechanics are all very nice and honest as well - I've known them for about 10 years now (used to live 1 block from their shop!!!). I am glad to hear you got sorted!

kgorman

Well, I found out what my puddle of brake fluid under my car was, you guessed it. The longitudinal slave cylinder again. It's totally blown.

Now the question is, I got a 1 year warranty in writing from Kahlers on thier work. Should I take it to them, or just go back to Rob at Scargo and get it done right this time (at full price).

I am wondering, if one gets wear in the slave cylinder disks (D39/45 - 21 of Repair Manual), would it cause these cylinders to blow up prematurely? It's been six months, and only < 10 track days on the new one. Anyone know what else might cause these things to blow up so fast?

kgorman

The shop warrantied the part, and installed a new one for free.

However, this lead me to thinking I could rebuild my own slave cylinder. In fact, I did so, so now I have a spare. When (if) I need to use it, I will post a little howto. I need to souce some of the seals because they seem to be the part of the cylinder that is failing, then leaking. I wonder if heat is a component. I might start hitting my cylinders with the pyrometer to see how hot they get with vigorous action.

Anyone know what kind of seals are on these things and if there is a source for spares? Any engineers out there?

Also, I had another thought. If I changed the length of the plunger, doesn't this change the bias F/R? I think so! Hmmm.

kgorman

BTW, the blue thing in my picture at the top is the seal. You can see it's mangled, and obviously the source of the leak.

Wgwollet

Ok, I know it’s a old tread
i have problems with the 928 part and the 964 part

The bellows should be replaced with OEM, my 928 part I bought rebuild seals from ninemisier from U.K., set for both is $100.
but I found the 964 part...964-339-775-07 is $563 cheapest I found from Sunset Porsche.

many believe these cylinders are not needed, little confused about the locking diff but I would think it’s nice to lock the diffs front and back for various reason

can someone speak about the advantage or disadvantages, because they are expensive

Wgwollet

also the 964 part is shot cannot be rebuilt, with new seals, the cylinder is corrosion beyond use.