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Old 10-18-2010, 11:17 PM   #24 (permalink)
Push370zzz
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Quote:
Originally Posted by BGTV8 View Post
Is the clutch pressure occuring because you are downshifting too early and carrying too many engine rev's for the road speed as you downshift.

Most folks tracking their cars for the first time inevitably can carry one gear higher than they reckon - if you reckon your need 2nd, try using 3rd instead, same for 3rd/4th. IMHO, 2nd gear is only required for a 25mph ultra-tight hairpin - there are no tracks here in Ausrtralia with a 2nd gear corner, apart from some extended gymkhana tracks (Autotest is the nearest US equivalent I think, although Autotest seems to involve higher speeds than I'd expect with a gymkhana, so maybe I am wrong here).

The reason a clutch overheats is because it is slipped. This can only occur if the driver is modulating traction via the clutch and the friction plates overheat and lose effectvieness, OR road speed is too high for engine speed and the clutch is acting as a brake and slipping .... or the clutch pressure plate clamping force is exceeded - which can occur if downshifting at too high a road speed for the gear.

I regulary run 20-25 minute sessions in my Z34 and have never had a clutch problem.

As a rule, downshift is the last thing you do before turn-in .... braking is effectively done, execute the downshift whilst still on the brakes, and turn the car in and get onto the gas in one easy fluid motion as you hot the corner apex - engine speed needs to be such that you do not run out of rev's before most of the steering lock is off the car and you are pointing at the next straight - if you find yourself running out of revs close to the corner exit, then try entering the corner in the next higher gear. The VQ37 engine is torque-rich and can carry a gear at 3500/4000 rpm as well as at 5000 or 5500 rpm.

REmember, corner entry technique is brake, downshift into the gear you need to exit the corner right before turning-in and thengetting back onto the gas as you apex ..... on downshift, gigure that you need to be at or slightly above 50% engine speed 3800-4200rpm ideally, never more than 5000rpm especially if you are using 2nd gear !!

Of course, you may well have a warranty issue with your clutch, but not especially likely.

RB
The clutch is not slipping or being slipped, I only shift to 2nd once on the track and when the clutch is out I'm doing about 4500 RPM in 2nd. I am pretty sure since nobody else is experiencing this it is a problem with my car...thanks all. I will try flushing with a better fluid and lines and see how it goes.
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