clutch slave cylinder woes

ray greenwood · Post by **ray greenwood** » Thu Feb 07, 2002 6:40 am

Let us know how the bus slave sylinder works. It is longer, and slightly smaller in diameter...but should work. As long as you get the holes in the ears resized correctly, I can't see that you would need any type of bushing to make it fit snug in the opening of the bellhousing. But...Its stokr is different. Its longer. What will be required, is to take a flywheel, disc and pressure plate assembly and put it on a press in someones shop. Apply pressure to the fingers...evenly...until the disc spins freely. Measure how many mm the correct opening stroke is. Take a look at the bus cylinder. Now you will have a n idea how thick of a shim to put between the cylinder and the mating surface of the tranny to make the stroke correct. I just havn't had time to do this. The cylinder from an Audi 5000 is also a candidate. Use your original pushrod. Ray

ray greenwood · Post by **ray greenwood** » Wed Feb 27, 2002 3:49 pm

Sorry...this slave cylinder was only used on this vehicle. Except for an occasional lucky find of an NOS cylinder complete (which will be suspect due to shelf age) or an NOS rebuild kit....that are almost extinct. I have been able to rebuild them by going to commercial seal shops and getting a standard size (sae) seal that is almost a little too tight. Since it will not be of the shaft seal variety...meaning it does not have the inner lip seal ...you will find that it is not as thick. You will have to ask for a backing o-ring or washer to make up the space difference. This seems to work very well. You must hone ..carefully all rust out. Do not remove much metal. Then polish very smooth with 2000 grit sandpaper. This piston design was rather peculier. Instead of just being either straight hydraulic..or straight seal driven... it was a combination, which meant for very high seal wear. The back edge of the piston is the very same diameter as the main section. This means that little or no fluid passes by to both lubricate and pressurize/flare the seal cups against the cylinder wall. Take a fine file and cut about three evenly spaced grooves in the back section of the piston. Probably no more than .010" deep...to allow fluid to pass to the cup. Then polish the grooves carefully with steel wool. I use the the shifter boot from a very early ghia or bug (about $3) for the boot. It works well. I have been trying to get around to retrofitting a slave cylinder from an 091 bus. It will need a spacer to have the correct dimension, plus the holes in the ears will have to be re-sized. I'm sure it will probably work...but it is a little smaller in diameter and generally works with a fulcrum on the bus/vanagon...we'll see. You can rebuild the slave cylinder from basic seals pretty well. Expect to pull it out once a year to check seal condition. NOTE: USE only black Buna-N rubber. Neoprene will fail with disastrous results to you clutch. So will urethane. Hot weather makes this worse. The really correct factory rubber is actually buna-n. Some of the late model EPR seals will also work. I have not found a viton seal to fit, but that should work also. EPDM rubber will not. If the person you get the seal from does not know the ecat material...move on. Ray

farmer · Post by **farmer** » Wed Feb 27, 2002 3:50 pm

Havent checked.
But is´nt there a chance that it might fit from a T3 bus?
How is your turbo setup running these days?
Have you had it on the chassis dyno ???

njv · Post by **njv** » Wed Feb 27, 2002 3:55 pm

hello.
small world do you want a slave cylinder from a bus? i have a bus with that part still attached to the g/box i could pull it and post it and send it to you ?

now the only problem is im off on course on saturday to england till may 11th!!

email me if this may be of help.

grusse neil verdon.

------------------
neil verdon 1966 t3 sqr on irs pan.

farmer · Post by **farmer** » Wed Feb 27, 2002 3:56 pm

Allright Ray,
two minds, one thought.

IMPI · Post by **IMPI** » Wed Feb 27, 2002 11:15 pm

Could any one please help me to find a slave cylinder kit (44.5mm) i would really like to know if there isn't a cross match to another car or maybe truck. original kits do not seem to exist in South Africa any more

IMPI · Post by **IMPI** » Sat Mar 02, 2002 9:23 am

Hi all thanks for the info. I removed the cylinder and found basically nothing wrong. there were no leaks either from the master or slave. I removed the cylinder and replaced the seal with a better one from my stock the same problem the clutch works well most of the time but goes soft if you use it for a long time such as at a stoplight. I know the classic symptoms of a leak. The problem is i do not lose brake fluid. as to the dyno It is going on the 16th if I can fix the darn thing. Could it be lining related. The pedal feels low if that is help. this is a problem which appeared on its own ie without me fiddling with adjustments etc.

ray greenwood · Post by **ray greenwood** » Sat Mar 02, 2002 12:12 pm

Aaaaah Gwasshopper...welcome to the mysterious world of the 44.5mm slave cylinder. Its a flaw....what is happening, is one of several things...in combination. You are getting air in the cylinder. The 44.5mm slave has a problem because of its large diameter, with sucking just a little bit of air back into the cylinder ..usually because of either overheating...butmostly from the rust ridge that forms at the outside edge. It doesn't really leak....you don't notice a fluid drop at all...but the air bubble is there. It tends to stay just in the cylinder. Since there is no real fluid bypass of the piston..except for a small amount, during operation, there is no real pressure to fill the cup/seal. This is because the portion of the piston behind the seal is the same diameter as the front part of the piston and has no fluid bypass valve like the master cylinder. Thats why I cut a few very fine grooves in the piston skirt with a file. It works better. That little bubble of air ends up at the back of the piston, expands when it warms up, and makes a cushion that compresses...losing power. For the very last year...there were some cylinders manufactured with two seals just to combat this air leakage. I have never personally seen one except in the shop manuals. Beware...the other problem that can be happening is the seal starting to swell or bind to the wall of the cylinder. Especially if the cylinder wall has some rust or pitting. Its worse when it gets hot...and will sooner or later fail...leaving you stranded. Ray

IMPI · Post by **IMPI** » Mon Mar 04, 2002 11:16 pm

Gues what the seals in a Mercedes Benz truck wheel cylinders wii fit (part no A 000 420 10 44) they are also slimmer so the o- ring spacer is needed
I did some checkin into different sizes but it will be extremely difficult to match
the master cyl is 19mm and has a 30 mm stroke the volume displaced is enough to move the slave 5.5mm
if the stroke at the master cylinder is reduced to 20mm you could get away with a slave of 36mm
a 32mm slave would require a stroke of 15.5 mm
this would probably make the clutch pedal feel like a switch

A friend who is a master machinist is going to try to sleeve th cylinder with a brass sleeve pressed and locktited in place then honed to the correct size. what do you think
BTW the wheel kit comes with two rubbers and is made by the same crowd who made the original rubbers.
Regards armand

ray greenwood · Post by **ray greenwood** » Tue Mar 05, 2002 1:03 am

Believe me...it will be easier to go with the longer Audi 5000 or vanagon master cylinder. They already have this done. They all use the same bore and stroke on the master...with extended stroke bores to match the fluid volume on the slave. Its just a matter of spacing them back from the pressure plate the correct distance. The vanagon slave is already the same configuration, with the same mounting ear width, the same hose hook-up and bleeder location...and its under $75. Brass will probably be a poor liner for the cylinder due to softness, corrosion issues and expansion rate. Stainless or regular steel would be better. Ray

IMPI · Post by **IMPI** » Wed Mar 06, 2002 10:10 am

Gues What it was the clutch master. the primary cup wore out and the secondary cup kept it from leaking. all is well now
regards
armand

ray greenwood · Post by **ray greenwood** » Wed Mar 06, 2002 12:59 pm

You can use the outer shaft seal cup from either a type 3 or rabbit cylinder to rebuild the clutch master cyl. Just make sure you stay either with fag or ate when swapping seals. They are slightly different. Ray

IMPI · Post by **IMPI** » Wed Jan 08, 2003 10:56 am

I just posted to revive this for the newbies