Clutch nightmare continues

[sp53]

I think that is good thinking to get new quality brake and clutch MC cylinders. I have been using BPNW for them and have been pleased with quality and service, they stand by their product. Having said that you could still have a clutch problem that is mechanical, and you have simply blown the hydraulic seal and the pedal will drop to the floor because the linkage itself is not mechanical but hydraulic. Moreover, if you are replacing so much of the hydraulic system you might consider dot 5. It does not eat paint

 

[TR3driver]

I think the master cylinder is allowing the fluid to back up from the system.

Actually, it is supposed to do that. When the pedal is released, there is a valve inside the MC that is supposed to open and release any trapped pressure (due to expansion or whatever) back into the reservoir. If the reservoir is full and there's no fluid on the floor, I'd guess that valve is not closing for whatever reason.

It's too bad you've got a hydraulic problem now, but I still think there is a mechanical problem as well. When the pedal 'stops', most likely that means that the pressure plate is stroked as far as it will go. It doesn't have much more range than what it takes to lift off of a new friction plate.

Wouldn't have to be the plate backwards ... but I can't think of any other explanation that fits all the observations. It's been a long time since I've done a TR3 clutch, but I don't recall having to use the bolts to pull the PP down over the locating dowels. I'm pretty sure it would at least partially engage the dowels without having to be compressed.

 

[tdskip]

+1 on getting a high quality MC / slave at this point.

Keep us posted on how you get on. Hang in there.

 

[CJD]

Wouldn't have to be the plate backwards ... but I can't think of any other explanation that fits all the observations. It's been a long time since I've done a TR3 clutch, but I don't recall having to use the bolts to pull the PP down over the locating dowels. I'm pretty sure it would at least partially engage the dowels without having to be compressed.

I was thinking a couple possibilities. One that the clutch is sitting on top of the dowels, as in not touching the flywheel. A second possibility is that the release fork pins are behind the bearing carrier, and not in the slot where they belong.

I bet the hydraulic issue is something simple...if it worked at first, I don't think it's likely something broke that fast.

John

 

[TR3driver]

For anyone who has stuck with me, The push rod is 4 3/4" long.

Sorry, I don't have that measurement. I even took a dig through the parts bin, but couldn't find one. Must be in another coffee can somewhere. And the one on the car is shortened (since installing the TR6 gearbox moved the slave closer to the lever).

But the basic relationship is that, with the lever up against the clutch and TOB (as far to the rear as you can move it by hand), the lever should point slightly forward. Then with the slave piston fully bottomed in the bore, the pushrod should only leave 0.1" free play.

One way of measuring that with the spring installed is to loosen the locknut and unscrew the pushrod from the clevis until it removes all freeplay. Turn the nut on the rod until you can measure 0.1" between the nut and clevis; then turn the rod back into the clevis (without turning the nut) until the nut just touches the clevis. Tighten the nut and call it done.

But the freeplay isn't critical, as long as there is some, so I just pull the lever to the rear as hard as I can and check that the pushrod will rattle around a bit.

 

[TR3driver]

I bet the hydraulic issue is something simple...

Maybe the "no pedal" condition is just from the return spring slowly pulling the pushrod back into the slave, until the piston bottoms. My experience has been that, when the spring is too weak, the point at which the clutch engages can become rather erratic because the piston doesn't return all the way immediately after using the clutch. So in traffic (frequent clutch use), the engagement point stays near the top of the pedal travel, but after not using the clutch for awhile (even 5-10 minutes), it is lower. Kleykamp has said that the spring is not returning the piston as it should ("I can take my hand and push the rod farther back into the slave cylinder. It moves slowly, like the piston is going back into the cylinder.")

Might be worth double-checking the adjustment of the pushrod at the MC and the pedal motion. With the pedal up and the MC piston out against the stop/clip, there needs to be some slack in the pushrod. If that is adjusted properly, the pedal does not have enough travel to bottom the MC piston. Normally, this is a "set and forget"; in fact some of the books just say "don't mess with it". But that little dab of clearance is important. I suspect that problems with this adjustment is part of the reason they deleted the adjustable pedal stops from the later cars; and then later on took out the pushrod adjustment as well.

 

[CJD]

That makes sense Randall. If the slave piston does not seat all the way in the cylinder and the free play is adjusted to that mid point, the pedal would only press till the slave piston hit the outer snap ring and then the pedal would go hard. Later, if the piston moved farther in from loosening up with the return spring pressure, it would end up with a lot of free play in the rod, and the pedal would go to the floor without pressing the clutch lever very far at all.

Your diagnosis fits pretty much all the symptoms! Kleykamp, it sounds like it is worth checking to see that the rod is adjusted with the piston absolutely all the way in the cylinder.

John

 

[sp53]

I am confused as usual, but if the problem is in the slave cylinder would he not be in direct drive all time and unable to disengage the clutch?

 

[Kleykamp]

OK, first...thanks to all for sticking with me. As absolutely sure as I was the clutch disk was not in backward, I went ahead and pulled the transmission again. Boy is my face red. I'm really not a novice at TR's. Took me all of 1hr to pull the trans and turn the clutch around and spent the next 4hrs.trying to get it back in again before folding in frustration. At 60 y.o. crawling around in the floor is not as attractive as it used to be. I'm taking a break for a couple of days to get my boat ready and in the water. I'll come back to the car later. If anybody has any tips on getting the input shaft lined up and fitted, that would be appreciated. The first time it went pretty easy. Only took about an hour of fiddling. Thanks again. Joe

 

[bnw]

Broomstick

 

[HerronScott]

Glad to hear that you found the problem!

Scott

 

[DaveC]

I just got 3 bolts, each 5/16" UNC and 8" long, that will hopefully help guide the bell-housing back in quickly. I already have an alignment tool for the clutch plate.

dave

 

[Geo Hahn]

I just got 3 bolts, each 5/16" UNC and 8" long, that will hopefully help guide the bell-housing back in quickly...

That's pretty much what I use -- headless bolts with a screwdriver slot cut in them for easy removal...

 

[hermanmaire]

glad your figuring this out.