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Old 04-05-2011, 03:53 PM
GGR GGR is offline
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Problems with clutch master and slave cylinders

Hi all,

I have purchased these slave and master cylinders new quite a while ago for my project. Now that finally everything is in the car I was unable to have the clutch operate.

I have bleeded the clutch following the procedure described in the w/shop manual via the right front brake calliper. I was able to have fluid go backwards in all the circuitry and fill the small reservoir. But the clutch pedal kept going down with no resistance and the clutch was not operating.

I took both master and slave cylinders out. The piston in the slave cylinder is quite sticky and the spring is not able to push the piston back. I took it apart and all seems in good condition. The bore is not pitted and the seals look supple and not damaged. But still, it's sticky when I put everything back together with brake fluid.

The piston of the slave cylinder is all the way inwards and I have no idea how to get it out. The bore is not pitted, I had it soak the whole night in some WD40 and then tried to bang the slave cylinder on a piece of wood to have the piston come down to no avail.

I have no idea how to solve this. Any help would be greatly appreciated.

Thanks in advance!

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Old 04-05-2011, 07:26 PM
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Location: Northern Va.
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I'll have to bring my compressor over and we can pop the piston out.


Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL


Not part of the in-crowd since 1952.
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Old 04-05-2011, 08:20 PM
GGR GGR is offline
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Hum, we can try, but I'm not sure compressed air would be much stronger than the way I've been beating the cylinder on the piece of wood. I also inserted a long and thin alen key through the bleeder hole and hit it first gently, and then less gently in a try to get the piston move. I stopped when the key started to bend. Finally, I inserted a screw in that little bleeder hole in a try to push the piston down and of course I broke it in there. So now I have to drill it out.

Thanks for coming and help me bleeding the darn thing the other day.
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Old 04-05-2011, 09:35 PM
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i hope the compressed air will work
if not try sticking the thing in the freezer over night
then the "bang" method
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Old 04-06-2011, 06:41 PM
GGR GGR is offline
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I tried the night in the freezer trick to no avail. But I still finally made it to get the piston out of the slave cylinder. I disconnected the front left brake line in the wheel well and connected it to the slave cylinder with its pipe and a piece of fuel hose and two clamps (thread diameters are different). I then pressed on the brake pedal and voila, the piston popped out. It doesn't look that bad in there, but I still ordered repair kits.
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Old 04-07-2011, 09:07 AM
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Location: Atlanta, GA
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Make sure they don't sell you the 6 cylinder 280SE slave and/or kits. 8 cylinder slave has longer stem and different seal diameter. I rebuild mine a year ago, Very easy. Bleeding is the main pain. Also, make sure your return yoke is in good position.

FYI, I have gotten sticky pistons out with bicycle pump air pressure. Prolonged pressure and banging often do the trick.

Good luck,

'70 111 280SE/c 3.5 (4 spd manual) - sold
'63 MGB
'73 MGBGT V8
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Old 04-07-2011, 04:57 PM
GGR GGR is offline
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After some more measuring and comparing my slave cylinder appears to be out of a 350SL. They look the same but bore diameter is 22.2 mm instead of 23.81 mm. This should make my clutch pedal harder by 7% if my calculation is correct.

W111 3.5 slave cylinders are on back order and repair kits for 350SL slave cylinders are NLA. Mine does not look that bad so I will clean it and put it back in.

Seal looks nice and supple but obviously it must have swolen as it makes the piston sticky and the spring inside does not have enough force to push it back. Is this a common problem? Is there a trick to have the "retract"?


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