Adjusting a Clutch on a 90+ 300ZX
By Thomas Bell
The process is in two parts:
1. Adjusting the clutch rod is straightforward. The rod screws into a fitting on the back of the pedal arm. It is held in place by a 14-mm jam nut.
2. Bleeding the hydraulic lines is also straightforward – except that there are two of them. You’ll need a friend to help you. You’ll also need to get the car up on jack stands or ramps, so you can get at the transmission.
The clutch master cylinder is located down on the firewall, just below and to the outside of the car from the brake master cylinder. Here’s a picture of the area in a TT.
It’s the smaller black topped unit in the inset on the lower right of the picture:
The slave cylinder is mounted underneath the transmission, at the lowest point on the car. This is a prime place for water to go, as it is denser than the clutch fluid. Many slave cylinders rust from the inside out, and start to leak a bit.
Take the top off the clutch master cylinder reservoir – CAREFULLY, so the fluid doesn’t spill or get on any other surface. The system is filled with brake fluid, and that’s corrosive stuff.
The process is relatively simple. Have your friend sit in the driver’s seat and put their foot on the clutch pedal. Go underneath the car, and attach a small section of appropriate size rubber hose to the bleed nipple, and put the end of it in a clean glass container, like an olive jar. Take the 10-mm wrench, and loosen the nipple about half a turn. Then, have your friend press the clutch pedal to the floor SLOWLY, and hold it there. The hose should squirt a dark colored fluid into the jar. Close the nipple, and have your friend release the pedal. Repeat this process again, and then look
Repeat this process until you get no bubbles and clear fluid coming out of the hose. If it goes dry, you have to do this all over again until there are no air bubbles coming out…Then, close the nipple, and tighten it snugly: do not over-tighten.
Next, go inside the engine compartment, and look at the top of the passenger’s side fender (the left side, as you look into the engine bay from the front bumper). Here’s a picture of the area in a 1990 TT. The bleeder is the brass-colored tube on the left side, with the black cap over the nipple in the inset on the upper left of the picture.
Attach your rubber hose to the nipple, and put it into the glass jar again. Open the nipple slightly with the 10-mm wrench, and have your friend press the clutch pedal in again, just as you did for the slave cylinder (including refilling the reservoir as necessary). Repeat until clear, fresh fluid comes out. Then, close and retighten the nipple, and put the cap back on the clutch master cylinder’s reservoir. You should have a clutch pedal that is firm to the foot, and that works in the limits I’ve described.
Improvements: DOT-3 fluid you’d normally use is still likely to let water form in the lowest spot, so you may be repeating this process in a year or two. You can use a silicone-based brake fluid instead, as it’s formulated so that water will not form. However, you can’t just start by pouring it into the system and pushing it through, like regular DOT-3 fluid.
If you’re going to change over, then open the bleed valve on the fender, take the top off the master cylinder, and then open the bleed screw in the slave cylinder, and let all of the fluid drain out by gravity.
Then, have your friend fill the master cylinder slowly, while the slave cylinder’s bleed screw is still open. Wait until it starts draining out of the slave cylinder: let it drain out several ounces, so the line is clear of any leftover fluid. Then, close the bleed screw, and top off the master cylinder’s reservoir.
Now comes the hard part: attach a hose to the bleed screw on the bleed valve on the fender, and bleed that section using the above procedure into a clean, fresh glass jar. Press the pedal in SLOWLY: the silicone-based fluid is a bit thicker than the regular stuff.
Hope this helps. –Tom Bell
Updated April 25, 2001