TR2/3/3A Bleeding Technique

[CJD]

Air rises if it has no other way to expel. If the valve on the slave is open, then the weight of the fluid overcomes the desire for air to rise and the air is pushed out of the valve. Once the bubble is gone from the master, just opening the slave valve will allow fluid and air to be expelled.

I believe the slave bracket was mounted in both locations over the years. It will become obvious which side the bracket needs to go when you hold up the pushrod to your assembly.

 

[TR3driver]

The photo I posted is of the correct (I believe) Girling arrangement (except I've always found the center hole to line up better than the bottom one). The mounting arrangement changed when the front disc brakes were introduced, as the entire hydraulic system was changed from Lockheed to Girling.

Yes, the spring is really tight if you are tying to move it with your fingers. It's also a special spring with a higher spring rate than normal (a screen door spring won't do). But it needs to be tight to be sure it always pulls the piston back against the stop inside the slave every time; otherwise you'll get inconsistent clutch operation (meaning the point where it engages will roam around depending on how long it's been since you used it last). And your left leg won't care. Even 10 lbf seems like a lot when you're trying to stretch it with your fingers, but since it takes literally hundreds of lbf to operate the clutch, another 30 or 40 for the spring just doesn't matter.

No, I don't know the spec for the force, just what I've learned over the years from trying to substitute cheaper springs. As I've mentioned before, I had to shorten the pushrod when I installed the TR6 gearbox in my TR3, and that made the spring too short; not tight enough to reliably return the piston. So I actually added a little tab to stretch it back to it's original installed length.

 

[sp53]

So the problem is the clutch will not disengage? Or it grinds when you shift gears? Or the clutch slips when you shift gears? Or the clutch is at the floor and will not come up?

 

[frankfast]

That's right, unless I pump the pedal a couple of times before I shift. Then it works fine.

 

[sp53]

I guess you could hook back up your old slave cylinder and see where that takes you. When I rebuild those, I leave them on the car and just push the guts out.

And perhaps the slave cylinder you received is defective. They are simple just an inside spring piston and seal, maybe something is missing inside. I guess you could sneak out at night and not tell Randall and try a screen door spring, but I would use one a little shorter than a screen door. For my way of thinking, the spring just needs to pull the insides back off the linkage. My experience has been those aftermarket springs pull everything back so far into the slave that the pedal cannot extended the rod unless you pump it. But again it sounds like everything worked fine until you changed out the original slave and started using the dot5 and I do not think the dot five is the problem.

 

[Geo Hahn]

I've mentioned this before but will again in case it helps: My clutch works just fine... provided I omit the external spring.

I think I know why and the next time I change the clutch I will find out -- but for now that's how I roll.

 

[sp53]

I have a spring, but it is 20% of the one you would get form Moss. I have it just to keep things back a fuss and a little tight. If I hooked up the spring they sell at Moss my clutch would not work unless I pumped it!!! I have been driving that car since 1972.

 

[frankfast]

The original spring with the original slave cylinder worked fine. Could it be that the new slave cylinder from Moss does not work with the original spring and needs a lighter spring or that the DOT 5 requires a lighter spring?

 

[tomshobby]

I have used this method on my TR4, GT6, in the 60,s and now my TR6. In nearly 45 years it has never failed me and it only takes a few minutes and can be done by laying next to the car and reaching under with a 7/16" box end wrench.
I have been using DOT5 in my TR6 and MG Midget for several years.
The trick is to have the car either on a slope or raised with a jack so it is 5 or 6 inches higher in the front.

 

[CJD]

What Geo is alluding to is the clutch fork pin may be broken. A symptom is you have to pump to get the clutch to work. Removing the return spring allows the slave to take up the slack from the broken pin...thereby preventing the need to pump the pedal.

 

[frankfast]

So it wasn't air in the lines after all. After spending an enormous amount of time bleeding the system, I finally resorted to having a mechanic take a look at it. He spent 15 minutes adjusting the slave cylinder rod and I was back in business. I had done that according to the manual so I didn't bother with it again. When done wrong it simulates air in the lines in that one must pump up the pedal to get the clutch to work. Put it in the memory bank and be on my way. Thanks for all the input.

 

[CJD]

If it was in adjustment and it went out that far...there is a chance the clutch fork pin snapped, adding the extra play. If it was never in adjustment correctly, then you are golden.

 

[frankfast]

It would be nice to assume that the mechanic (through proper adjustment of the rod) would have recognized if the clutch fork pin snapped.

 

[DavidApp]

Especially as it is such a common failure on the TR.

David

 

[Geo Hahn]

What Geo is alluding to is the clutch fork pin may be broken...

Yes, I suspect I have been driving for 38 years with a broken pin by the simple expediency of removing the spring. I think this is only possible if the break is jagged so it catches after some movement.

Someday I will need to replace the clutch and I will fix the fork then - either soon (while I am 'young' enough to do it) or much later when I am past doing such heavy work. I may be nearing the tipping point on that one.

 

[frankfast]

The never ending saga. Having a mechanic adjust the slave cylinder rod seemed to improve the issue until I drove for awhile and realized it was only marginally better than before but at least I was pointed in the proper direction. The problem wasn't with the bleeding but rather the adjustment of the slave cylinder rod. So I put the car back on jacks and checked the manual again. Loosen the jamb nut, take out all the end float on the rod to the fork and set an.079" feeler gauge between the the jamb nut and fork and then tighten the rod and jamb nut to the fork Down off the jacks and off for a test drive. Perfect. I don't know what I did the first time I adjusted the rod but it didn't work.
By the way, on the way home on the test drive the car quit and I had to pull off the road. Luckily I found the ignition wire to the distributor came out of the connector. Always something.

 

[TR3driver]

and set an.079" feeler gauge

Not sure if I should mention this now ... but that adjustment was later revised to .100"

 

[CJD]

Still sounds like the fork pin to me...

 

[frankfast]

Not sure if I should mention this now ... but that adjustment was later revised to .100"

Where is this information? It's not in the supplement to the Service Manual.

 

[martx-5]

You can find it in the Practical Hints For Maintenance...Page 38.

https://www.triumphtr.com/manual_tr3.pdf