TR2/3/3A TR3A Clutch Hydraulics

[MGTF1250Dave]

Aloha All,

I recently replaced a broken return spring on the clutch slave cylinder. The new spring forced the slave piston deeper into cylinder. Since then, I have what seems to be air in the system, the pedal needs to be pumped to operate the clutch. If I keep the pedal slightly depressed after pressure has been built up, there is no need to pump the pedal. There is no loss of fluid from the system. I have bleed the system twice with little improvement. I would appreciate any suggestions as to possible other causes of the problem or solutions. My current plan is to run about a pint of fluid through the system this weekend.

 

[martx-5]

There's a couple of options. The first one is to remove the spring, and everything will go back to the way it was. Most hydraulic clutch release systems don't bother with the return spring. It becomes sort of self adjusting then. The second option, as the Triumph engineers designed it initially, is to retain the spring, and then adjust the actuating rod to give less free play. The manual says to:
(a) Unlock the jam nut on the slave cylinder fork assembly.
(b) Turn the rod until ALL end float is eliminated.
(c) Hold the push rod and turn the jam nut until a .079" feeler gauge will pass in between the nut and the fork end.
(d) Screw the rod together with the jam nut to the fork and lock.

I know, you don't have a .079" feeler gauge. Well, just eyeball it. It's a little more then a 1/16". Besides, you can re-adjust to your liking.

 

[Geo Hahn]

For what it's worth... my TR3A clutch will not work with that spring on there, but works fine w/o it.

I suspect I may have a broken clutch fork pin that allows the clutch fork arm to be pulled forward too far but is broken is such a fashion that it still catches and moves the fork (provided it starts from a position far enough back).

The description is confusing because I'm refering to 'back' and 'forward' relative to the whole car, not relative to the slave.

I don't know that this is your problem (shoot, I'm not even sure this is my problem) but as suggested you might try it w/o the spring. That's how I've driven mine for 25 years.

 

[Adrio]

the only thing you have to do is reset the length of the link on the slave. That is the part that has the fork on the end that attaches to the lever coming out of the tranny.

What has happened is now that the spring forced the slave back in farther you have to gou out farther in order to have the clutch work. The system is designed that one stroke of the pedal will give enough travel to separate the clutch. however now that you have moved the slave back in with the spring (and by the way having the good spring there is the correct thing so don't remove it) you "wast" part of the travel just taking up the "slack". You need to get under the car and adjust the link length so that the "slack" is taken up by the longer (correctly adjusted) link.

It is an easy fix, and you will be happy with it at the end of the day.

 

[MGTF1250Dave]

Thanks for the suggestion, I had totally overlooked the need to readjust the clutch push rod length. I'm guessing the light resistance on the pedal that I thought was air in the system was just the slave plunger moving back into contact with the push rod.

 

[sp53]

Hi Dave I think I have dealt with the same problem (I think), but I can just tell you my experience. I once put a slave return spring on a tr3 that worked kinda ok without a spring and this caused the problem that you are describing. What I discovered was that spring I got from Moss (say 1990) was just too strong. So I went to local parts store and bought a kinda whippy spring and put that on, and it fixed the problem. It just seems to me the spring should be there just to hold the stuff from potentially falling away from itself.

Sp53

 

[Adrio]

SP53,
Sorry to disagree and with all respect, but I feel you can't have a spring that is "too strong" in this application. Well you could but it would be huge. The sping in the clutch is HUGE compared to any spring you could fit in the outside return spot we are talking about.

Dave,
Please let us know how it goes once you adjust it.

 

[sp53]

Hi Adrio oh do not worrier, I long for a dialectic. The point I am trying to make is the master cylinder only has so much through, and if one puts on a strong spring at the slave cylinder, the master cylinder might not have the punch to totally disengage the clutch. What happens is the driver usually has to pump the clutch to get the extra travel because the piston in the slave has been drawn back to the maximum reverse end of its travel. I have only experienced this problem on a tr3 with a stock one inch bore slave cylinder. In addition, I once put 7/8 bore on a tr3 and it took about twice as much push to get the pedal down. Perhaps with that set up, a stronger spring could be used. I have often wondered when I hear the tr6 people talk about how hard their clutch is to push in that they should try a one in bore slave. On the one inch the pedal does not respond quickly, but driving is so much easier.
Sp53

 

[MGTF1250Dave]

Aloha,

Art and Adrio were correct, the clutch push rod length needed to be adjusted. When I installed the return spring on the slave cylinder, it changed the position of the piston in the cylinder. What I thought was air in the system because of little resistance on the first part of the pedal stroke, was the piston moving into position against the push rod.