NoVector

Can a PSD slave be reconstituted? I just removed it from the car—bone dry. I have no idea the last time it’s had brake fluid in it—the PSD has not worked since I’ve owned the car (3 years).

I’m thinking of sitting it in brake fluid overnight but is there a way to bench test a slave and check for leaks? A new PSD slave is around $400 and there is no rebuild kit, my first choice is to see if this one works AND make sure it doesn’t leak brake fluid into the transaxle. And should I spray WD 40 or put some kind of grease in the bore?? BTW - The bleeder screw is currently soaking in mineral spirits.

Background: Rebuilt PSD installed yesterday, internal flush worked great but, no joy flushing the line to the slave. I disconnected the control valve near the battery box. It was crammed full of crap so it’s no wonder fluid was not getting to the slave. That has now been taken apart and cleaned and the lines have been flushed. The slave is the last thing I need to sort out.

Thanks / Bruce

ammonman

Call 928 Intl and get a good used slave. $175 IIRC. No sense in pumping brake fluid into the diff and having to flush the bad fluid out. Someone hereabouts ruined a diff driving it on Nurburgring with contaminated diff grease.

Mike

NoVector

Mike - I called Tom at 928 Intl yesterday, he said they don't have them and have never carried them (?) but said he could see a future need as the cars with PSDs are getting older.

Tom in Austin

Hey Bruce how did you get your PSD rebuilt? Is there someone there in Germany who rebuilds them?

Herman K

I think soaking it in brake fluid may be your best chance if the unit has been dry and moisture in it the cylinder walls may have corrosion on it and it may need to be honed or replaced. IIRC those are made by ATE and you should be able to find a new or used one in Germany. Exercising the PSD slave with the KTS 300 "hammer" and changing the fluid on a regular basis is what will keep a PSD operational and a life.


Yes let us know who did it for you I know Roger has somebody here that does it for him. I have a couple of PSD units on hand my self and I'm interested to learn what can be done to obtain a spare slave or in case where the cylinder walls are not pitted which seal kit is available or comparable

Mark Anderson

We have a good used slave

Dave928S

Here's a German PSD rebuilder that I stumbled across a while back ... http://www.stein-aviation.de/html/psd_engl.html

NoVector

^^^ That's him, Harald Stein. I stumbled on his name from John Speake's website and then Arnoud PM'd me and highly recommended him. Super fast, excellent work and communication throughout the process. Had it back to me in a week and he has a 2 year warranty. He speaks excellent English too. The only drag, he had to use an external filter until the tank with the built in filter is available again--but no biggie, it seems to work fine. I would use DHL to send it to him; it works like a champ here.

Thanks Mark - Calling now. [Edit: left voice mail.] / Bruce

Herman K

On a previous PSD service cycle I did partily remove the intank shoulder that the little mesh screen sits on and that way I was able to get the internal filter out (soked and cleaned it out ) and it was good for another 2-3 years

NoVector

Herman - Harald removed the old filter and did an excellent job cleaning up the old tank. Here you can see the external filter.

I noticed playing around with mine before I sent it to him, I think it would be possible to drop a wire into the tank and loop it under the filter and "pop" it out.

NoVector

BTW - How does a PSD relieve pressure? After opening the pressure valve and seeing how it's made (pictuure #5 in the OP), I was thinking it acted like a check valve where fluid could only flow one way. But if that was the case, how would it relieve pressure and allow the slave piston to return? So if fluid does flow both ways, what is the purpose of the pressure valve??

Herman K

So you are better of now with the internal filter removed you can just keep on replacing the external filter and keep your system clean - pm send

Vilhuer

I'm quessing pressure valve limits how quickly fluid can flow into slave cylinder. Spring is on return side which means pressure can push ball towards it and escape from slave. When pump is pushing ball is in closed position and only set amount of fluid can move into slave. That is if valve internals are put together way I remember them to be.

There is one more plastic piece included in the valve which is not shown in picture. Its probably still inside one of the housing pieces. Happen to have its orientation shown in picture? I'm doing PSd rebuild on friends '90 GT and would like to make sure pressure valve goes back together in correct order.

borland

The PSD slave is very similar to the clutch slave on manual transmission cars. There used to be a rebuilding (rubber seals) kit for the clutch slave. Unfortunately, the clutch slave is slightly larger than the PSD slave, so those seals won't work.

ROG100

928sRus represents Harald in the USA and hold rebuilt units here for instant sale.