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TR6 Clutch Adjustment / TR6

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brucebotti

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I'm working on a friends 1974 TVR with a TR6 drivetrain. We just had the trans rebuilt by Quantum Mechanics (John is a great guy!). We also installed the TRF magic clutch with the Gunst bearing and all new hardware, new slave, rebuilt MC, etc. When its cold, the trans grinds a little on a normal upshift. Even when warm, you have to make sure the clutch is fully depressed and that you shift precisely otherwise you get a slight "hangup" (less than a grind). It may be because everything is new and needs to break in. Its probably the same on my TVR but I just never noticed it. Finally my question...I have the clutch slave push rod in the center hole on the cross-shaft. In your experience, if I move it to the upper or lower hole, will this increase the throw at all?

Thanks in advance!

Bruce
 
I think you should be able to figure out whether or not you are getting the clutch all the way out fairly easily. If there is a significant clutch drag the car will creep forward if you are sitting on a level road in first gear, engine running, brake off, clutch depressed. You might also sense the change in engine load between neutral and being in gear by a change in idle speed. Also, you should feel that when you start to let the pedal up, you come up a way and then get to a definite engagement point. If you feel that as soon as you start to let the pedal up you're already starting to go, chances are you're marginal on clutch throwout for some reason.

I have found on the two 2 TR6 boxes I have had that in cold weather before warmup, getting into second is dicey (synchro?). I got into the habit of going straight to third for the first couple of blocks (which was never a problem given a light car and torquey motor). Last summer I put in full synthetic RedLine gear oil, which did improve warm-up shifting but had the side effect of increasing seapage/leaks (it's much much thinner). Many will advise you against using it. The sum total of what I have found on the net indicates to me that it is basically safe for the brass parts and the overdrive clutch (if that's even a factor for you). Anyway, you'd want to go with what is recommended/warranted by the guy who rebuilt the trans.

Hope some of that is of some help. Good luck - Pete
 
You might look at how much movement your're getting on the slave pushrod. I just make a mark with a sharpie pen where the pushrod leaves the boot, then measure how far out that mark is with full pedal down. Could tell you if the problem is hydraulic.

Yes, the arm hole selection could help a little -- also there is a way to get an adjustable pushrod on the MC -- braided metal flex line can also help -- but with an all new/rebuilt set-up you shouldn't have to resort to such tricks I think.
 
Hi Bruce,
Moving the rod to the top hole should increase the T/O bearing movement & increase disc/pressure plate seperation.
The problem here is determining if this is a problem in the clutch or the trany. If it wants to move into gear & then grinds , I would suspect a synchro or improper fluid problem. If it's a fluid issue , it should improve as it warms.

If it's hard to shift in to the gate itself & feels very notchty , I lean toward the clutch not fully disengauging, especialy if this gets worse when the car is driven a while. This usually shows up in first & reverse.

All this assumes that the clutch fork shaft pin is intact & the fork pins are in good shape, since these two parts can cause similar symtoms if worn or broken.
 
Thanks for all the info. Everything is new with the exception of the clutch hose. I have the GL4 fluid in it and it was below freezing, so I'm sure that has something to do with the slight grinding when cold.

The notchiness when it is warm is likely to be due to the rebuild needing to break in. I've sent John at Quantum an e-mail to get his thoughts. In the meantime, I'll bleed the system again and get a measure on the throw.

I'll also try my nearly identical TVR. Its trans was rebuilt nearly 20 years ago. Its likely that it shifts the same.

I also don't want anyone to think that I am bad-mouthing John's work. Thanks again, and I'll keep you all posted, along with my observations with the Gunst setup.
 
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