Clutch Slave Cylinder Piston Replacement

Shucks! I cannot find the thread that gave me this idea including the p/n for the Isuzu repair kit to repair the E-Type S-1 clutch slave cylinders. If someone knows it, please link it here?

My solution to the slave cylinder was to buy the cheap one from SNGB. I know, I know, the better one comes from England, but they get it from China anyway. Regardless I bought it with the intent to replace the piston and cup style found in the original E-type with a more modern piston with integral seal. So I made that swap today. The kit I bought was from Rock Auto WK124280 for $8.45. With shipping it was $13.28. Can’t beat that! Here is the box label.
It is very easy. To make this modification. First I traded out the metric bleeder valve for the original. Threads are the same, but the nut was 10mm on the metric.

I then used the air gun set at 5 psig to blow the piston out of the aftermarket Jag cylinder. Put a rag over the end so it will catch the piston. DO NOT use high pressure.

Here’s the piston that came out. It is the Jag cup style.

Comparing that to the Isuzu piston from the rebuild kit. And I then swapped the spring from the Jag part (I know…don’t give me any grief about using the spring!)

Here is the comparison between an original and the SNGB cylinder with the Japanese piston in it.

And the newly reconfigured clutch slave cylinder with the push rod in place. It was interesting to note that when I pushed the rod in, that weak spring did push it back out (but not so much as to eject the piston).

Finally it is installed in the car. Note I’m swapping the bleed valve to be on the upper side of the slave cylinder. The bleed valve is accessible from the top but I will also bend a wrench to turn it from under the car. It just doesn’t make much sense to me to have a bleed valve on the bottom that allows an air bubble to float upwards while bleeding the cylinder. (I have to attribute this idea to @Dick_Maury .) The pipe shown is a test sample I’ll use to get the configuration correct.

And there you have it. Out of all the projects I’ve done on this car that have taken excruciating amounts of time to complete. This took about 15 minutes from swapping the pistons to installing the slave cylinder. Yeah for once!!


It’s here in this thread: E-type clutch slave cylinder upgrade

Good write-up, Scot. :sunglasses:

Thank you Gary. That is the link! Such a good idea and so easy to do.

Once I got the shape of the tubing with the steel one I was working with, I went to the auto parts store to but a simple female union to couple to the flex line. That didn’t work as the modern unions are too short and the English-style fittings don’t mate to it. So, I bought a Cu-Ni pipe 1ft long that came with fittings on it. One long and one short. Well the short one doesn’t work! Then I simply cut one end and removed the fittings, cut my steel line and transplanted those “Jag” fittings to the Cu-Ni line after shortening the pipe by 1-1/2". It was easy to make one double flare and bend it to the now known shape and fitted that between the slave and the flex line junction. A good project and I’m anxious to see if it leaks!

I happen to be doing this installation at the moment, and I also have the Isuzu piston and spring installed. Before putting everything back, I measured the depth of the piston at rest, and it was very close, if not exactly the same depth as the stock slave. But when I installed, there was considerable tension pushing the lever forward. I have to go back tomorrow and do some adjusting, but I’m not sure there’s enough turns left on the rod to give me 1/8" of free play. Did you have any problem with the adjustment?

BTW, here’s a source for British spec hydraulic fittings:

Dumb question: what’s the problem with the cup style seals? I used them in all kinds of things, and never saw a problem with them.


Paul, you know Jaguar could never get anything right! :grinning: :grinning:

I get the jocularity… but, the design of a cup-style seal is perfectly serviceable.

10s of millions of rear wheel brake cylinders used them quite successfully.

Beats me. I bought the Isuzu piston kit because folks were raving about “modern lip seals”, and it was dirt cheap.

Cheap, I get: the rest of it smacks of a solution in search of a problem.

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Is it that the seal kits for the Jaguar are often of poor quality, being targeted to a market that seems to accept that, whereas the more modern Isuzu application has more dependable quality?


Dont know: I can go to NAPA and buy good quality cups: sleeving a pitted cylinder is a doddle.

I thought I remembered in a past post someone complained the cup would in someway turn sideways. I have no idea how that could happen. I do not understand the attraction to this change.

Other than installer error, neither do I: it is a dead simple system… which is why it is so widely used.

Mike, I don’t have an answer to that as yet. I have to now make the fluid pipes to connect to the master cyl.

I cannot argue with you Paul. In my case the decision was two-fold. 1) I bought the cheap Chinese version of the slave cylinder and don’t have confidence in the rubber in it. 2) In the past I owned a TR3 and the only repeating problem was that slave cylinder leaking, and the wheel cylinders for that matter. Hence I decided to provide a solution before I had a problem; and it was only $13.

Mike F, thx for the link to the British brake fittings. It is now in my list of valuable links.

I can certainly understand the fear of cheepie Chinese rubber, Scott.

The other issues were likely because of cylinder damage: my experience was the opposite, with good bores and good rubber cups.

For that matter, Margaret’s clutch slave is OE, far as I know, and working like a champ.

Someday, Imma gunna step on the clutch pedal, and it’s gunna feel like stepping on a rotten grape…:yum:

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Back in the days when I owned the TR, I replaced the cylinders as they were, like $7 or something a college kid could manage. And I lived in Scottsdale…not much moisture to be absorbed into the brake fluid. Not sure about rotten grapes though…

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$7/cylinder: now, THAT gives away your age!


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Well, I spent some quality time with it. I had to make a shorter actuator rod, about 3.5" long. I slid my IPhone under the car and took a video as I pressed the pedal. Here it is, the obvious question is whether the piston is hitting the tail of the seal. If I stick with the mod, I may go to the Isuzu accordion seal:

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