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Tips

Sticky Clutch

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TR4MAN,
The inconsistant thing about this is that a perfectly good T/O bearing can squeek. Sometimes this is due to a cold bearing when the grease thickens , glazed clutch fingers or slight wear to the carrier & nose. The problem comes when there are other symtoms like poor shifting or excessive/constant noise. Occasional squeeks are normal.
Now lets hope for some good weather & lots of fun miles this summer.
 
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I gather that there has been a rash of bad TO bearings.


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While there are probably some poor quality TO bearigns around, I'm under the impression that most are just fine. It's most likely improper installation has led to most failures.

However, it sounds like you are doing it right.

A related issue has been much higher than original pressure plate spring rates is found in all the available replacements (I seem to recall they are actually a Volvo part?). That's bound to put a heavier demand on any TO bearing. There has been a lot of discussion of this in the past and there are some websites with well-done comparisons and thorough explanations (sorry, I don't have a URL).

Another thought is that the TR6 (5/250?) did away with the locating pins/dowels on the engine to gearbox flange joint. Some folks feel this allows some potential for misalignment that can lead to problems. There are dowel kits available, or some folks just use the right size drill bit temporarily.

And, the earlier cars had a stud, instead of a bolt, at the 12 o'clock position on the rear of the engine. This makes installation/alignment a bit easier and helps reduce risk of damaging the input shaft by accidentally letting the gearbox's weight hang on it. Simple fix... just permanently install a stud there (5/16 NC on one end, 5/16 NF on the other).

Combine the above issues with the minimal margin for error of the later, non-adjustable slave cylinders and there are a lot of clues why simple clutch jobs turn into problems and need to be redone. A possible solution might be to just install the adjustable type slave cylinder, learn how to adjust it and do so from time to time.

The Gunst kit may be a good solution, too. A bit more expensive initially, but many users say it's solved problems. (As already noted, it comes with the bronze carrier.)

I'm toying with the idea of installing a hydraulic annular release, Tilton or similar, on my TR4 (which actually uses a TR4A-6 flywheel and clutch setup just like yours).

Cheers!

Alan
 
Actually the slave cylinder is self adjusting. BL eliminated the adjustable rod & installed a spring in slave cylinder on the TR250's & up. The spring kept the piston snug up against the rod eliminating the need for clutch wear adjustment. Installing an overly long rod will only force the piston back further until eventually it won't fully release.

I have a friend with the Toyota 5-speed conversion using a hydraulic release & he likes it. It did require a pedal stop to keep from over extending the piston & popping it out.
 
On the second removal of the transmission, I did remove and reinstall the fork pin. I did not find any problem with the pin.

The real clue here is the temperature factor.

When the engine is first started (cold) the clutch seems to work better. The hotter the engine gets the worse it gets.

I suspect that one or more of the fingers (springs) on the 'new' B&B clutch cover fails when heated. This would mean that the plate is not symmetrically moving away from the clutch plate. This would account for the pedal travel required to disengage the clutch and the 'grabbing' problem.

The only way to find out is to pull the transmission again and take it to a machine shop to have it tested.

Comments?
 
Ah, blast. My clutch has gotten a little less smooth recently (another 'new' B&B kit), so I hope I don't have this problem. The clutch isn't sticking yet though, so I'll cross my fingers. I think my car is a malfunction magnet...
 
Guys, don't feel too bad. My 6 does it too. When it's cold it's smooth as silk. Once it gets hot, I look like a 16 year old girl just learning to drive a stick when I pull away from a stop sign. It's either on or off. No in- between. My clutch is a NOS Laycock unit I pulled from a donor car I bought that had zero miles on it (engine and tranny were rebuilt in the early 80's but engine had no oil pressure upon start up so the project was abandoned). I did have the foresight to cross drill the shaft for a hardened bolt to alleviate the broken fork pin issues that are so common in our cars. My t/o bearing is quiet as a mouse and gives no trouble. Again, this is a NOS bearing from the old days of good quality parts made in England and not China. I just wish my clutch wasn't so sticky. If I could resolve that issue, I'd have this TR6 clutch thing licked!
 
ROADSTR6,

Does your pedal get to the firewall before you can disengage the tranny?
 
No, Dugger, it disengages about half to 3/4 of the way down as I imagine it should. It is sticky when it gets hot though.
 
Dredging up an old post, I recently had a clutch problem that occurred just after this thread ended. I had a problem in engaging second gear and occassionally fourth with the onset of hot weather combined with drives longer than just around the block. In my case the culprit(s) were a missing return spring on the clutch pedal, and a plugged vent hole on the clutch MC cap. I concluded that both things were preventing the clutch MC from developing the full stroke that is needed to properly operate the clutch. Not enough "stiction" to make the clutch slip, but maybe a seal in the MC was being partially blocked. Now it shifts great.
 
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