My 1991 F250 4x4, with the ZF S5-42 keeps blowing out slave cylinders. I had the tranny rebuilt 6 months ago and have blown out 2 slaves since then. While the tranny was out I put new Perfection flywheel, Brute Force 11" Clutch kit, rear main seal, pilot bearing, mastercylinder, and slave cylinder in. Everything is brand new. Can someone tell me why the slave cylinders keep blowing out? I don't want to pull the tranny out again in 3 months. Could I need flywheel shims? Any ideas would be appreciated.

 

You don`t say but I assume this is a concentric slave cyl (internal)? If so one reason could be that you are not using an OEM Ford one.

 

Where can I get one? I ordered one from the local Ford dealer in town, $160 and then I took it to NAPA and the 2 had the same manufacturer's mark, and exact same casting number, and the one from NAPA only cost $67. Then the idiot at the dealership gave me attitude when I asked why they were selling aftermarket parts. Maybe it is just our local dealer trying to con people and make a little extra money, but the one I got from them was the same make and model as the one NAPA sells, only it was $100 more. How about a LUK slave cylinder?

 

Was the one from the dealership in Motorcraft packaging?

I would guess that NAPA probably gets the part from the same supplier that Ford does. Everyone knows that dealer markup is huge, so it's no surprise that they charge far more than NAPA.

 

Actually it's FORD'S markup that is huge....dealers are getting squeezed more & more every day.
Having said that, the MSRP on that slave cylinder from Ford is $145, so the OP got squeezed a little bit...

 

Get a price from partsguyed.com

 

Lazy K-

IIRC, the ZF's, etc have an EXTERNAL SLAVE CYLINDER....AFAIK, the M5OD has the only Internal Slave Cylinder.........

 

That ZF's from a 2wd '90 F250 >8500#. :)

Alvin in AZ
ps- Got this stuff from Rockauto: (I searched under '90 F250 >8500#)
RhinoPac clutch kit 07057 $115 (LuK disc + diaphragm pressure plate)
RhinoPac slave S0707 $76 (it's holding up good so far ~10 months :)
RhinoPac master cylinder M0706 $37
Dorman hydraulic line 628203 $28

 

Small block ZFs have an internal slave, big block and diesel versions use an external slave.

Was the NAPA slave cylinder new or remanufactured?

 

The NAPA slave was brand new. Same as the one from the ford garage, at $100 less. I think I'll try a LUK slave this time, and see how that holds up.

 

Rockauto has these brands to choose from that includes the throwout
bearing, priced high to low:

WAGNER - SC126890 (1+1/32" bore)
ACDELCO - 386355
SACHS - SH6001WB
RHINOPAC - S0707
BENDIX - 12596
DORMAN - CS37897 (1+1/32" bore)

So which brands of slave cylinders anyone had experience with? :)
I'll switch to the Wagner if I knew it was the best one. :)

Alvin in AZ

 

The first 5 slave cylinders in your list are all the same! The bearings they use may be different, but they are all the same manufacturer. Same stamped I.D. and same exact casting number on them all. Not sure about the Dorman.

 

Cool, thanks for that information. :)

There's always been a lot of that sort of monkey business going on. ;)

When I get around to rebuilding the ZF I'll closely compare the Rhino I got
now to what I took out of the F250. Seems like it had a Ford oval on it?

As far as the throwout bearing part of the Rhino ...it couldn't be quieter!
That 188k mile "company truck" ZF is noisy as anything in idle and goes
-silent- while holding down the clutch pedal. LOL :)

"I'm gonna fix that! :)" -Alvin

Butthead in AZ

 

I know I'll have people jumping all over me for replying to a 7 year old thread, but did you end up using a LUK slave? If so, how did it hold up? I really don't want to drop $110 on a Motorcraft unless its really the only one that hold up.

 

No I ended up using a Sachs one. Made by ZF same as the tranny. I did figure out what the issue was though. My clearances were too high. The slave cylinder was overextending and blowing the seal. I shimmed the flywheel and have not had an issue since. I think I ended up shimming it out .060" But don't remember 100%