View Full Version : TR4/4A TR4 clutch slave cylinder - stuck!

12-08-2004, 07:55 PM
Hi all,

I've got a troublesome clutch slave cylinder. The piston is stuck inside. It's been sitting for a long time.

I was able to push it inwards a little, but have not been able to get it to pop out.

I've tried as much as 120 psi of compressed air. No luck.

Next I reassembled with the pipe, hose and master cylinder, filled with fluid and bled. I was hoping to pop it out with hydraulic pressure, by pumping the pedal, or at least get some fluid to work it's way around the seal to help loosen it in the bore. But, so far, no luck.

Can anyone offer alternative, non-destructive suggestions?

Thanks in advance!

Geo Hahn
12-08-2004, 08:20 PM
Ugly... if the hydraulic pressure of the system can't move it then it is really bound up. Perhaps some penetrant such as PB Blaster would help or heating the cylinder then applying the hydraulic pressure. I like a heat gun for this sort of thing as there is less chance of burning down the garage.

Gotta confess, these are guesses as I have never had one that wouldn't yield to the things you've tried.

12-09-2004, 01:32 AM
Hello Alan,
my favoured method for a really tight piston is to use a gease gun, I drilled and tapped a 7\16" UNF screw so I could fit a nipple to it. Screw that into the cylinder and pump away, I found it to be very effective.


12-09-2004, 09:47 AM
Alan, if it's that bad a replacement is in the works, used or otherwise. It has got to be really pitted. Wayne

12-09-2004, 11:18 AM

I had a couple of old clutch & brake master in the "spares" pile and tried to take them apart for 'experience' before working on the good ones and ran into the same problem.

I pushed the pistons in as far as I could by hand, soaked them in brake fluid overnight. The next day I tapped them straight down on an anvil and with a little effort, the pistons popped out. No scoring or pitting in the cylinder, just dried out fluid that acted like glue.

12-09-2004, 04:35 PM
like T2000 stated, it might be best to get a new slave cyl.

BTW, I see that you live in San Jose. I too live in San Jose, near Oakridge. I usually cruise my 4 on dry weekends.

Here are photos of my 4 URL = https://www.geocities.com/joemad11/TR/tr4.htm

12-10-2004, 03:15 AM

Yes, I'm just to the South of you, in the Santa Teresa area. Your TR4 looks great and very original! I'd try to keep it that way. Mine is in many pieces, I actually seem to have about 1-1/2 TR4s right now, and could use a three car garage! My car is non-original in many respects, and I'm not too concerned about that. It's been a "British Rat Rod" for as long as I've owned it, and before that saw a modest amateur racing career. For one, the interior would be hard to put back to original (currently black). No one seems to have the original color, midnight blue, which is darker than the Shadow Blue all the vendors offer. This combined with a Spa White exterior is a rare combination that I'd like to get back to eventually (it's currently red, was Porsche orange when I bought it around 1977, ugh!).

I agree with the concerns that the slave cylinder might be pitted and may need replacement. I've done a little searching and it appears the early TR4 type is no longer available. So, I want to see how this one looks inside before making a judgement.

The suggestion about grease might do the trick. I'd heard that before, but forgotten it and have never tried it.

I fitted a zerk to the S.C. this evening and started pumping away, only to run out of grease on about the third stroke! The auto parts store down the street closed at 8 p.m., so it will have to wait until tomorrow. I'll let you know if it works, and if the S.C. can be saved!


12-11-2004, 07:52 AM
Alan, if the early cylinder is truly unobtainable, sleeving the existing one is a viable option. I seem to remember an outfit in the Nevada City/Grass Valley area that was doing it.
I've used the grease gun method a few times, always successfully.

12-11-2004, 08:14 AM
Carefull heating of the outside of the cylinder usually gets it apart...then you can see how bad it is and pitch it.
MD(mad dog)

12-11-2004, 08:42 AM
Way to go piman,I use the same trick. With enough leverage this will move a house, "ask me how I know".

12-11-2004, 08:47 AM
Carefull heating of the outside of the cylinder usually gets it apart...then you can see how bad it is and pitch it.
MD(mad dog)

[/ QUOTE ]

Very careful heating...now that you have the cylinder full of GREASE. /ubbthreads/images/graemlins/hammer.gif

12-12-2004, 02:55 AM
Hi all,

I'm happy to report the grease gun trick worked just fine and finally removed the stuck piston from the slave cylinder.

As many of you mentioned, yes there is some pitting on the wall of the S.C. But, it is light and I'll try to hone it out. If that doesn't work, I'll consider sleeving it. I know Apple Hydraulics provides that service, probably others as well.

The piston itself had the most corrosion. But, it's not in a critical area, since it's on the outside of the seal. It cleaned up well, anyway. I've been using the non-metallic "steel wool" from 3M for this sort of thing. It works quite well, but it leaves no fine bits of metal that can be a problem in critical areas or can quickly rust.

Thanks for all the suggestions! One more step on the path to getting CT17602L"O" back on the road!

Alan Myers
San Jose, Calif


12-12-2004, 02:19 PM
I may be missing something but both Vicky Brit and Moss, show a replacement slave cylinder for about $50.00.
I was getting ready to order and spied this and became concerned.


Geo Hahn
12-12-2004, 02:48 PM
Appears tha Moss does offer a 'replacement' - non-Girling with a 7/8" bore (vs original 1" bore). I have no experience with this part -- just reading the catalog.

12-13-2004, 12:08 AM

Yes, I understand a TR4A or TR250 "replacement" is available. I'm a bit leary of that sort of thing, having bought a few things that don't fit or were pretty poorly made. May be a good item for those cars, but might differ a lot from what's on my early TR4.