Stick shift - strong judder on pullaway

Question

I learned to drive in a manual transmission car and have been driving them for years; while my clutch control is not perfect, I'm generally very good with it, except in my 1985 Supra. Often when pulling away with 1,200-1,500RPM of power, the whole drivetrain shudders as if the clutch is missing half its friction material. It lasts until the engine and transmission are up to the same speed. The shudder is most pronounced when the engine and transmission are cold.

I've experimented with many different throttle settings and release rates for the clutch and nothing reliably reduces the shudder. It only happens in first gear, and only until the clutch is fully engaged - after that, first gear is as smooth as the others. Once the car is moving, I have no trouble changing to any other gear. There is, however, noticeable resistance shifting into first from either neutral (standstill) or second (decelerating), which I have been told is just a worn synchro.

The clutch was replaced at around 99,000 miles and the car currently has 117,000 on the clock. The clutch is still under warranty (miles, anyway) and when checked at the recommended intervals, the fitters have said there is no problem with it. The transmission is original. The previous clutch had completely worn out and the flywheel had to be reground to accept the replacement. The clutch is a standard (non-racing) and is hydraulically operated.

Since this only happens at pullaway in first gear, I'm unsure what the cause is. Although it generally lessens as the engine and transmission warm up, it's very uncommon it's completely eliminated, and I can get it after a reasonably long drive. I accept it could be poor clutch control, but I am able to drive other manuals without this sort of pullaway (with smaller engines, granted), so I am just curious what the cause could be.

Answer 1

This is a common occurance, it happens when the clutch friction material and flywheel face have a problem mating during the clutch bite.

There are a few reasons why this might happen:

• Contaminated flywheel:

If the flywheel is not cleaned with brake/clutch cleaner spray before fitting, there may oil or other residues present on the flywheel. Similarly, an engine oil leak could cause the same issue to persist if the oil made its way on to the clutch or flywheel area - normally a bad rear main seal. Other causes of contamination include moisture, if for some reason the car is left in a damp area and there is some situation where moisture makes its way into this area then it would cause a shudder (this one should be eliminated after the engine warms up and you use the clutch a few times).

• Wrong clutch and hydraulics:

Are you certain the correct clutch, release bearing etc. were used when they were replaced?

• Bad flywheel:

I'm not sure what the service procedure is for a 1985 Supra, but for some models, grinding or resurfacing the flywheel is not the correct procedure. An OEM clutch replacement includes a new flywheel, the service manual highlights not to reuse or resurface the old one. Again, I'm not sure if this is true for your Supra but I thought I'd mention it because you said it was resurfaced.

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You could do some further research by googling "clutch shudder". One of my old Toyotas does this when its cold or just after the first start of the day, once everything warms up there is no more shudder so it's being contaminated by moisture or oil, which gets wiped away with repeated use of the clutch - the heat probably helps too. I would go back to wherever the clutch was fitted and have them check the rear main seal and check the flywheel to see if its within tolerances.

Answer 2

I would suspect a worn / broken or even soft mounting on the engine or gearbox. I had a volvo 240 that had a horrendous judder on pulling away and it was the rear mount that had failed.