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TR6 Sticky clutch

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airlifter

Jedi Hopeful
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I posted earlier about the clutch sticking after I replaced the clutch assembly. After reading the article at Buckeye I pulled the transmission to check things out.

The sleeve slides easily on the front cover using the fork and linkage. There does't seem to be any excess friction in any position. I have not yet measured the clearance. Both ends of the sleeve have a small bevel so I don't think sharp edges are a problem.

I was looking at the clutch assy in the Brinkly manual and was wondering how far the throw out bearing actually moves. It does not look like it would be enough for the tilting mentioned in the Buckeye article to be a problem.

Any thoughts or ideas on what to check next? I would really hate to put everything back together and stoll have the same problem.

How is the best way to pull the transmission? I know the way Brinkly says but I need Specifics. Is it better to use a jack, engine lift or something else. I got the transmission back using a transmission jack but I am not sure that was the best way
 
I forgot to mention that there is a small flat spot worn on the clutch side of the fork where it engages the throw out bearing.

Thanks
 
Can't help with the stick other than to mention when I took mine apart the taper pin in the release fork was broken but still together with barely noticeable play.

For putting the gearbox back in a cheap HF jack worked well and a 4"x4" with a hole for the drain plug. My wife held a loop of rope around the tail standing in the cockpit.

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There is a bit of oil in the front transmission cover. Is there a weep hole to keep the throw out bearing sleeve lubricated or do I need to change the seal and gasket?

No hints about the t/o bearing sticking?
 
When I release the clutch it will not release smoothly. It seems to stick and then releases with a jerk. Makes it very hard for a smooth start.

I replaced the complete clutch assy about five hundred miles ago when I rebuilt the engine. The problems started then.

To eliminate the hydraulics I operated the clutch manually with the car on jacks and engine running and it still sticks.

I hope I have explained well enough and thanks. Pete
 
It sounds like you may be going over center. By that I mean you are depressing the diaphragm clutch spring too far and when it returns it hangs up just a bit as it comes back over center. What causes that? Wrong pressure plate or pressure plate spring, wrong release bearing, adjustment issue, maybe a broken clevis pin, wrong mounting position on slave cylinder to trans bracket or bracket to transmission. Those are the things that I can think of which can cause this to occur. I'd be looking closely at the bracket / slave / transmission arrangement for your problem. I seem to remember that some of the photos in the repair manuals are wrong. It does not take much movement by the slave rod to disengage the clutch. Hope this helps.
Perhaps someone can supply Pete with the correct mounting arrangement for the slave to bracket and bracket to transmission mounting for a TR6. I'm sure a 4A is the same but I'm not at home currently to look and it's 9 degrees in the garage this morning.
 
Well....he checked it manually..same...so eliminate slave and hydraulics.
He says the marks on the nose of the trans front bearing retainer/t/o bearing sleeve show the bearing where it should be.
Leaves an improper, defective pressure plate. POSSIBLY a too-much-milled flywheel surface combined with wrong mix of plate/fingers and bearing/holder.
Since this happened when he replaced the clutch...first rule of automotive repair states, "Just because it's a new part doesn't mean it's a good part", and last part changed is the area to look.
Dave
 
I'm not certain what checking it manually means. If it means somehow manually moving the cross shaft lever he could easily take it over center as there would be no stoping how far the lever could be rotated. Also it's easy to get the slave / bracket / trans combination wrong. There is one correct way and maybe 3 or 4 incorrect ways so I'm still in favor of looking at that arrangement for the problem.
 
Oh, I know. Many's the time I've had one dragged to the shop mis-assembled. Would take a bodacious pipe wrench to work the exposed clutch arm.
That said, I've seen slave cylinders and pistons so badly worn they do just that when trying to release.
 
The issue started after installing a new clutch. My assumption would be that the piston and slave cylinder were OK before and are still OK after the new clutch. Confirm the slave, bracket and transmission installation is correct. Once that is confirmed if the issue is still there then it's the pressure plate in my opinion.
 
I also operated the T/O bearing with the linkage after the transmission was removed. Seems to work fine unless I do take it over center. Does anyone know how far the T/O bearing actuall moves when operated?

i checked the slave cylinder mounting and the clutch linkage before removing the transmission.the slave cylinder is mounted according to the Bently manual. I swapped holes in the linkage to every possible configuration. None of this helped.

i bought the clutch assy from Moss Motors. I am going to call them today.

thanks, Pete
 
It may be that the Bentley is wrong. I know that there are manuals that show the wrong position of the bracket or the slave to the bracket, unfortunately I don't recall which manual or manuals show it incorrectly.
Also moving the TO Bearing with the linkage and the transmission out of the car really doesn't replicate whether the PP is going over center. The TO Bearing does hang up in that mode but it's more associated with the fork to TO Bearing binding as the TO bearing is moved to the extreme end of it's travel.
As far as how far the TO actually moves to release the clutch, I don't know but it doesn't move very far, maybe 1/4 inch once it contacts the spring fingers. There are many levers involved by the time the TO Bearing moves the clutch spring fingers and then there is the mulitiplyer of the clutch spring itself.
 
Thanks for the link to the calculations. I read their discussion on the sticky clutch problems and I have been checking the things mentioned.

I talked to moss tech today and they said that the original sleeve was steel and they came out with a bronze sleeve to remedy these kinds of problems. I might order the bronze sleeve if I don' find any other problems.

i am going to pull the front cover to replace the seal and gasket. I will check the clearances then.

i am probably not going to get to do much work on the car until after new year. Family visits etc.

thanks, Pete
 
Finally getting back to the car. I have the front cover off and I am going to take it to a machinist friend to get it fine sanded and polished. Not going to remove any material, just clean it up.

I checked the clearances between the cover and the sleeve as best I could with what I have to work with. It appears to be around .008. This would seem to be about right according to the article at Buckeye.

I am also going to order a bronze sleeve and new pins for the clutch fork. The current pins are worn flat where they engage with the sleeve.

I asked earlier about a weep hole in the front cover to lubricate the sleeve. There is a small shoe where the sleeve slides on the cover. It looks like it could serve that purpose.


Anything else I should do or check while I have it apart?
 
Very interesting thread. I have nothing to add, but I seem to have a very similar problem with my '74 TR6. My clutch was occasionally sticky last summer, and during the last 20 feet I wanted to drive it last year, the clutch failed to disengage entirely. That last 20 feet was up into the garage for the winter.

I will follow this thread intently, good luck with your work and please post what you find out.
 
Check your crankshaft end play. The flywheel will move away from the disc when you step on it , and come back when you release.
 
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