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TR4/4A clutch problem on brand new TR4a

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TexasKnucklehead

Jedi Knight
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This is getting a little old, so please bear with me...

I am working on a TR4A restoration that started more than 15 years ago. The project moved garages several times while TR3,4,4A,6 parts were joined and disjoined -after the car was taken completely apart. The engine was overhauled by one person, the transmission by another -both more than 10 years ago. The clutch was installed and the engine/tranny joined together by me about 5 years ago. Neither had been tested until recently. The car was nearly all back together (interior, wiring etc) about a month ago when we found the clutch will not disengage enough to put it in gear with the engine running. It will start in gear with the clutch in, and the brakes will hold it in place, but the car really wants to go. All the available clutch disengagement is at the very end of travel of the pedal (the bottom/floor).

The push rod was at an unusual angle as it exited the slave ie. pointed up towards the lever, instead of straight in line with the slave. We took a slave bracket from a TR6, and cut off the section that would hit against the oil pan, and installed it since the center line of the slave seems to have shifted from the TR3/4 to TR4A thru TR6. That 'straightened' out the angle of the push rod to the center hole of the clutch lever on the end of the cross shaft. -Tho it has been argued that the transmissions, in regards to the clutch shaft/lever are the same from TR3 thru TR6 -so there should be no difference. We have the stay-rod (to oil pan) installed to one side of the slave cylinder so the plate cannot deflect.

The MC and slave were new. We installed a(nother) new 'longer throw' slave. We have nearly 3/4" of travel measured at the end of the push rod.

Last week we pulled the transmission and found it has a 3-finger clutch and had the wrong (rounded) throw-out bearing. The cross shaft looks new, the fork looks new, the infamous pin looks new. We got a new (TR4) carrier and throw-out (flat/square edged) bearing. It seems the flywheel on the engine is from a TR3/4, so the 3-finger clutch was installed (since the bolt pattern is different for the TR4A diaphragm clutch). Rather than swap out the flywheel, we chose to go with the older style TO, and put it back together (today).

We still have 3/4" of travel measured at the end of the push rod, but still can't put the car in gear with the engine running. The spring (we added a hole to the bracket) is pulling the slave back to the bottom and we have a slight bit of clearance before the TO hits the fingers.

What are we missing? Is there some other clutch operating difference between the TR3/4 and TR4A/250/6 ?
 
You said the engine and transmission were mated some years ago. When you were working on the clutch did you separate the friction disc from the flywheel? I have had a Motor/transmission mated for a while and the frication disc almost welded itself to the flywheel.Took a lot of work with a paint scraper to separate them.

David
 
I installed a new slave on my 67 TR4a back in 69-70 and had the same symptoms until someone pointed out that I had installed the slave bracket on the wrong side. I can't remember how I did it, but it decreased the throw enough to cause the problems you're having.
Rut
 
The 3-finger clutch was for the TR3s. TR4A uses a diaphragm pressure plate, gearbox input shaft cover is a different length than the 3s, and uses a different flywheel with different drilling for the different PP, and finally different ring gear and starter. All these bits can easily be confused.
 
TexasKnucklehead said:
...The spring (we added a hole to the bracket) is pulling the slave back to the bottom...
Click to expand...

It makes no sense to me but my TR3 slave/clutch will not work if I install that spring. If I omit the spring it works fine and has done so for the past 37 years.

It seems that the spring (on mine) pulls the slave piston too far into the cylinder.

If you haven't already - you might see what happens if you omit the spring.
 
This is confusing. I just read on The Triumph Experience where Randal says the TR4a clutch slave cyl does not require the return spring since that clutch slave has an internal spring. Yet Moss shows their 580-760 clutch slave as being good for TR3A and TR4A? Maybe the 4A clutch slave needs the TR6 slave which is listed as 580-770? Does the TR6 580-770 clutch slave have the internal spring and is this the unit that is supposed to be used for 4A's? Does Moss have it wrong?
 
This is just a little closure... and perhaps in some way a confession?

Yesterday we pulled the TR4A transmission again. The clutch driven plate was installed backwards. I'd like to say that I've never before seen a plate that wasn't marked "flywheel" or "engine" side, but since I installed this one, I must have seen it before. With it installed wrong way around, the smaller internal spring plate will not quite fit inside the recessed area of the flywheel. It will leave a ring of rubbed paint about 1/16" around the perimeter of that recessed area of the flywheel. Backwards, after tightened, the friction material will contact the flywheel enough to drive the car, but even with no hydraulic issues, the plate dragging on the flywheel will not allow enough disengagement to enter gears with the car stationary.

Although I didn't drive the car far yesterday, (with the engine running) I did put it into reverse, back up a few feet, put it in first and pull forward and then back into reverse. The clutch engages/disengages about mid stroke of the pedal and has a very nice feel. To recap, we have a TR4A OD transmission, 3-finger PP, the flat TO on the early style carrier, the TR4 (or 3) flywheel (and matching starter), a 'long throw' (7/8") slave, the long adjustable push rod adjusted with some free play, the slave return spring, a TR6 slave bracket with a section cut off and the bracket/bolt to the oil pan attached thru the slave with the slave on the engine side of the bracket, and the bracket installed on the engine side of the transmission/engine. -and the driven plate installed the right way round.

It works as if it were designed to.
Thanks for all the comments, thoughts and help.
Jer
 
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