TR2/3/3A Mounting Slave Cylinder

[frankfast]

After filling with clean SAE 30W I'll drain it again and put 90W gear oil in it. As far as the problem I'm having I have to believe that it is hydraulic. I'll put the gearbox back in and try another slave cylinder. They're fairly inexpensive and it's probably something I should have done before removing the gearbox.

 

[Graham H]

Thank you, Randall, I use a mac so I asked the question and found out I phone images downloaded on windows software will appear according to which way up you hold the phone so in future, I need to hold the phone with the lens at the top and it should be all good.

Thanks Graham

 

[TR3driver]

FWIW, Supposedly, Irfanview will run on a Mac, using a Windows emulator like WineBottler

https://www.irfanview.com/faq.htm#PAGE15
https://winebottler.kronenberg.org/

Thank you, Randall, I use a mac so I asked the question and found out I phone images downloaded on windows software will appear according to which way up you hold the phone so in future, I need to hold the phone with the lens at the top and it should be all good.

Thanks Graham

 

[sp53]

What I am going to say is sacrilegious, but my experience has been some of the return springs are too strong, and I would have to pump the clutch twice to get it too work. Does your return spring look like the one in Randall’s picture on post 14-- if so, it is correct, but if your spring is supper hard to pull onto the hole and does not look like the one in picture and forces things back supper hard, you might try making up a weaker spring just as an experiment. No one knows more about these cars than Randall and I have debated this with him. I am saying sometimes they sell the wrong spring.

steve

 

[frankfast]

My return spring is very difficult to get into the hole. The one in the picture on post 14 does not seem to have a lot of tension on it. Once I get the gearbox back in the car I'll try a weaker spring to see if it makes a difference with the slave cylinder I have. Thanks

 

[JohnnyMead]

I put a new spring on my TR3A and it was strong, just as you describe. I got zero clutch disengagement. I stretched the spring enough for it to look slightly limp and the clutch worked fine. I think the spring is there to give a slight amount of pull so the throw out bearing isn't running all the time.

 

[TR3driver]

Normal operation involves hundreds of pounds of force at the slave; the hydraulic system is quite capable of delivering much more than that. Remember the master cylinder is the same as the brake master, and the brakes operate at considerably higher pressure.

No spring is going to change that, as long as the slave cylinder is properly adjusted. What a weak spring is doing is not returning the slave piston to the bottom of the bore, so you get good clutch action by starting with the piston already partway out.

I know people who have run that way for a long time; so I can't say it's not a valid workaround. But it is a workaround, not the way it was designed.

 

[frankfast]

Could the spring tension be strong enough to cause the rod on the slave to bend slightly. This was a new slave cylinder when installed but the spring was original to the car. After multiple adjustments to the rod to correct the double and triple clutching, I found the rod slightly bowed. There is a lot of tension on the spring.

Randall - I wrote this post before I read yours.

 

[frankfast]

Interesting that others have the same problem that I'm having. I understand Randalls contention that using a weaker spring is a workaround but if the rod is adjusted properly and there is no air in the system then there is another problem left unresolved. I'm replacing the slave cylinder to see if that makes a difference. Not sure what else to do since it is a very simple setup.

 

[frankfast]

I've replaced the slave cylinder but of course that didn't work. Talking to the owner of an imported car service garage he told me that he had the same problem with a Jaguar that he was working on. He corrected the problem by eliminating the return spring on the slave cylinder and said I should try it. I did and it worked. The clutch pedal is consistently at good level. Now I know that there are other factors at work here. Has anybody else run without the spring in place?

 

[sp53]

I say yes put a spring on it to pull the inner spring and piston of the slave cylinder back enough so the natural weight of the slave cylinder piston and spring does not engage the throw out bearing. Randall and I have debated this before, and I must say Randall is almost always correct plus he is very knowledgeable.

Well here is what I think, yes they are both master cylinders, the clutch and the brake, but the travel of a brake pad is what a 1/16 of an inch, and the slave cylinder needs to move about ¾ of an inch to operate the clutch. The spring is too strong and the slave cylinder is at the end of its travel and cannot get that last little bit. Kinda like when the back brakes are out of adjustment and yet there is no air in the line, they have to be pumped to get that last little bit. I have purchased new slave cylinders, master cylinders, new springs in the past-- bleed until there was no air, but until put a weaker spring on, I needed to pump the pedal.

I do not know this for sure the, but again it is my belief the spring the venders sell fits the old Lockheed system and those slave cylinders are different. They are shorter and must have less movement than Girling. But, again I am not sure. But to make things work I use a weaker spring, but I use a spring to keep the cylinder from engaging the throw out bearing.

When I bought my first tr3 it did not have a spring and everything work, but the pedal felt spongy.

steve

 

[frankfast]

Thanks Steve

 

[frankfast]

Excuse me for belaboring this issue but can someone help clarify the adjustment process on the slave cylinder rod. The manual is not quite clear enough. It seems that in order to eliminate the free play on the lever the spring would need to be detached. I did this and forced the piston all the way back in its bore. The problem is the rod is barely long enough to engage the clevis in order to take out the free play. Is it possible that the piston only needs to return in the bore as far as the spring allows and then remove it to adjust the rod. In other words the slave doesn't completely use all of its bore. I am using the spring although I've stretched it a bit since the new one was even stronger than the original. Graham, Steve can you comment on your procedure. Thanks.

 

[sp53]

I understand, I was where you are at with this thing. After fighting it for a month, I decided if the piston is supposed to be pulled back all the way into the salve cylinder with the strong spring then the master cylinder will run out of power before the clutch operates or I will have to pump it to get that last little bit. What I did then was let the slave cylinder piston come forward a little with a weaker spring.

When setting the adjustment I operate the clutch slave by hand the best I can to feel the end play and then make a spring that would be a happy medium and hold the piston back some and still shorten the overall travel without riding on the throw-out bearing—sacrilegious.

You will not find it in any book and that is why Randall’s way makes more sense—I could not get it to work, and came up with my theory about the lochead and girling systems being mixed together.
steve

 

[TR3driver]

IMO, if the return spring is not bottoming the slave piston, then there is no point in trying to adjust anything. Ditto for trying to operate when the pushrod is too short. There should be plenty of threads to remove all free play (with or without the spring); if not, there is something mechanically wrong.

The weak spring "works" only because it doesn't force the slave piston all the way into the cylinder. Where it stops is going to wander around, depending on temperature, how fast you take your foot off the clutch pedal and so on. No point in trying to adjust that, since it won't stay the same anyway.

 

[frankfast]

There are three of us in this discussion that are having the same problem and one other that I have spoken to. If there is a mechanical problem that keeps the slave from being adjusted what could it be? Clutch, pressure plate, throw out bearing? Would you venture an opinion?

 

[bobhustead]

I was a line mechanic at a BMC dealer in the 70s. We regularly had this problem with replacement slave cylinders. I concede it was a workaround for some unknown non-conformity in the replacements, but we fixed them by gas welding an extension onto the pushrods.
Bob

 

[frankfast]

I was a line mechanic at a BMC dealer in the 70s. We regularly had this problem with replacement slave cylinders. I concede it was a workaround for some unknown non-conformity in the replacements, but we fixed them by gas welding an extension onto the pushrods.
Bob

And I was thinking about making a longer push rod.

 

[sp53]

The spring I use is fairly strong it holds the piston back into the salve, just not as strong as the strong one they sell, maybe 50% of what they sell-- which is strong . So it can be adjusted by the information in the Haynes Manual page 114. The leakage is fluid and all you are looking for in the adjustment is that the slave cylinder has some slop at the clutch arm an 1/8 of an inch, so it does not push on the clutch. The book say .079 –really- what is that an 1/8 of an inch at the rod or cup or eye at the nut of the slave -- I wiggle for it and feel it. You can have the spring on or off— you just want some play. I drove for years without a spring and many others have also but it could damage the TB.

Set the clutch by the Haynes Manual and try the spring that Moss sells for tr3A and then try a spring with half the strength like in the picture. That is what I did-- then you tell me which one works better.

The rod I use is 4-/3/4 and the piston is 1 inch. The picture should give you some scale. I drove this car yesterday and the clutch works fine; maybe you can get some scale from the pictures.
steve

 

[Graham H]

If you are using a 1-inch slave piston that could be your problem, the master is 3/4" bore so I think the slave should be the same to give full travel. I think they changed to 1" for the TR4 I got a new slave from TRF some years ago and they supplied a 1" piston as it turned out the piston cup had been installed badly and it leaked so I had my original reconditioned and didn't reinstall the 1" job. You get an easy clutch push with the bigger piston but you may not get enough travel.

Graham