Subject: Re: '91 300ZX Twin Turbo abnormal clutch failure
Date: Mon, 08 Mar 1999
From: zdoc <zdoc@yosemite.net>

Hi John, Doc here, it sounds like you have the mystery "Z"!

If I understand the situation correctly from your description of the problem, the physics seem to indicate that there is a simple problem in the clutch master cylinder's putrid adjustment. If the rod does not have a slight free play at the clevis pin attached to the clutch pedal, then the pressure can build up and cause the hydraulic pressure to hold the slave "on" and the pressure plate from locking up the disc. If the return port in the clutch master cylinder is blocked off, the situation that you are describing, is highly probable. The one other possibility is that the clutch master cylinder is defective internally. The cap needs to have a vent to the atmosphere also, and is possibly blocked. Without this venting, the situation can occur also. Sometimes the dealer does not get enough of the cosmoline off of the engine components, and this can block off the vent. You can see if this is the case simply by popping off the cap from the clutch master when the car is starting to respond in the "slip mode". If the operation returns to normal, then you have it.

If the pedal push rod is too tight, it is necessary to remove the under dash finisher panel to gain access to view the pedal and
master cylinder. There should be a 12mm nut that needs to be loosened to turn the push rod in a CW position (facing perspective). The test is to shorten the length by approximately 1/4 to 1/2 turn, so that the pin that goes through pedal and the clevis can rotate some.

I hope that this is not too technical for your ability and you can understand this discussion. I hope that this will shed some light on the subject....

ZDOC OUT

JMC wrote:

Hi,
I own a 1991 300ZX Twin Turbo that only has ~28k miles. I owned this car since new and is meticulously maintained. It is only driven a few times a month and spends most of it's life in a climate controlled garage garage. In other words, it has better living conditions that I do..

This car has one major problem that Nissan can't seem to resolve. Since I purchased the car the clutch, pressure plate, and flywheel was replaced twice by Nissan after it started to slip for unknown reasons. Now, it's starting to slip again. It appears to be very noticeable after the car is driven a few miles to a point where the vehicle is disabled until it cools. When this happens it is only a short time before total clutch failure occurs. Otherwise, the clutch pedal "feels" normal with no binding.

Is it possible that residual pressure in the clutch hydraulic system can be partially disengaging the clutch when the car warms up causing clutch failure over a period of time? Has there been any other reported cases similar to mine? I've been driving manual transmission cars for years without any problems so please rule out driver error. Any information would be greatly
appreciated.

Regards,
John M. Costabile
New Jersey