Figured I would put out a guide on the clutch hydraulic system since I don't know that I've seen much about it.
I had clutch issues with my '95 and knew it was from the hydraulic system, but I don't drive it enough to really dig into it until recently when I went to get it inspected and the thing crapped the bed on the way to the station. Couldn't shift, had to put it in 3rd and run lights to get home. Terrible feeling.
Got home, no fluid in the master cylinder. couldn't find a leak. Nothing on the master cylinder, nothing on the firewall, nothing on the inside of the firewall (pulled back the foam), nothing on the slave, nothing on the floor, nothing anywhere that I could see. Super annoying, where was the fluid going?
Parked it again and went to bleed some more. Noticed the tiniest hint of fluid on the rubber hose from the hardline to the slave cylinder. GOT YOU! So the OEM hose has a heat wrapping on it. Figured out the line was leaking behind the wrapping, and it only leaked when under pressure. So it wouldn't leak when just sitting still and since the system is soft (not like the brake system where the caliper stroke is very short) the counter pressure is minimal. Not sure why nothing ended up on the floor, but that could be the sitting still time allowing it to soak into the floor after a drive.
Anyway, caught Kyle @ IPP late on Friday, he got me a SS hose delivered on Monday (thanks man!). Removed and replaced the OEM hose. Over my years working on the Z32, bleeding an empty clutch system is one of the most dodgy things to get going. Here's what I learned:
This is Gordo's clutch Auto FAQ - La-Z-Link I started here for information.
Probably the biggest thing I caught was the 'soft' part of the system. Lots of stroke and no bottom before the pedal hits the floor. This makes bleeding more difficult. Easy solution was to put a furniture clamp on the slave to keep it from stroking, creating a hard stop on the cylinder instead of the pedal hitting the floor.
So, this is what I did to bleed the system by myself from empty. It works the same for regular bleeding, but you can just bleed fluid into a container to dispose of. I'll formalize into a TECH page with feedback from this post.
Tools:
1. Need a wood clamp or a C clamp that's 6"? it needs to be big enough to clamp the back of the throwout arm to the front of the transmission flange. 2. 20' of 1/4" OD .170 ID clear vinyl hose from Home Depot/Lowes (<$4) 3. 1 pint of DOT 3 brake fluid 4. Jack/jack stands 5. 8mm & 10mm flare wrenches or box end wrenches (normal wrenches) 6. 2" funnel 7. a tub to catch clutch fluid 8. Permatex No2 sealer 9. Rags to catch leaked fluid
Procedure:
1. Lift the front of the Z, put on jackstands (Make sure you have room to open the driver door and walk around with the car raised, you'll have to get in and out a lot).
2. Put a rag under the the upper bleed nipple (passenger side, top of fender by the HICAS valve if you have that) to keep clutch fluid off the paint (it will eat paint if left too long). Crack open the nipple (10mm) with the box end of the wrench to make sure it can be loosened. Snug it back in place. Get the wrench where it can open and close the nipple without removing it. It only needs to open maybe a 8th-16th of a turn to be effective.
3. Put the upper clear hose on the nipple and run it over to the clutch master cylinder (CMC), making a 'high' point as soon as possible to draw away air in the nipple. Cut the length to comfortably leave the end at the bottom of the CMC reservoir.
4. Get the tub under the Clutch Slave Cylinder (CSC). Do the same thing with the wrench (8mm) that was done up top. Gravity of the wrench handle can help here.
5. Put the clear hose on the CSC nipple and run it out from under the car and over the fender, across the engine and to the CMC reservoir.
6. Clamp the clutch throw out arm across the CSC to the front transmission mounting flange to keep the CSC from stroking. Make sure the clamp's bar does not interfere with the hose or the wrench motion.
7. Position the lower clear hose to get higher than the CSC nipple as soon as possible. Probably tuck it behind the clutch line by the oil filter.
8. Position the lower clear hose to have a high point over the engine somewhere.
NOTE - When pumping the clutch pedal in the cabin, it is helpful to be able to see each hose somewhere in the run through the crack of the lifted hood to watch for bubbles and/or color change.
9. Capture both hoses in the CMC reservoir with the 2" funnel. Fill CMC reservoir to MAX with brake fluid.
NOTE - When pumping the clutch pedal, the CMC reservoir can empty in about 4-5 pumps. Be vigilant about keeping the reservoir filled to the MAX line while bleeding the clutch. If the fluid level goes below MIN it will probably gulp air and the bleeding process has to start over again.
NOTE - Something I didn't do, but probably will next time would be to drain the system at the bottom nipple. Remove the nipples, clean the brake fluid off and put a little of the Permatex No2 sealant (do not use teflon tape) on the nipple threads, not on the taper. When the nipple is opened and the taper is off the seat inside for the fluid to flow, fluid can get out/air can get in through the threads. This will be apparent when pumping the pedal when tiny bubbles keep showing up. They are not in the system, but are getting introduced at the taper/seat and blown out. When two people are bleeding the system, this isn't an issue as the nipple is closed with the pedal down and the system isn't allowed to pull the air back in.
10 - Start with the fender nipple. Crack it open slightly. Pump the pedal 4 times.
NOTE - The CMC is painful to work with compared to the Brake MC. The best method to get it to pass fluid into the tiny clutch system is to press and release the pedal quickly, then wait 2-3 seconds, then pump again. For whatever reason, the cylinder doesn't refill quickly and it takes some 'pedal up' time to get fluid into the cylinder to pump out.
11 - Continue to pump/check CMC reservoir until fluid starts circulating from the nipple back to the reservoir. This will take some work, be patient. Get all the big bubbles out of the system. Close the nipple snugly.
12 - Move to the CSC nipple underneath. Crack it open slightly. Pump the pedal 4 times.
13 - Continue to pump/check CMC reservoir until fluid starts circulating from the CSC nipple back to the reservoir. Get all the big bubbles out of the system. Close the nipple snugly.
14 - Repeat steps 10 to 13, but barely crack open the nipple, just enough to come off the taper. The pedal should be much harder to press now. Continue to work each until only tiny bubbles are seen in the hoses. This is the air being pulled through the threads (unless sealant was applied, I'm curious if that eliminates the tiny bubbles).
15 - Once the fluid is circulating and air free, make sure the nipples are closed snug. Top off the CMC reservoir to MAX. Press the clutch pedal, it should feel like the brake pedal now since the CSC can't move. If it's still spongy feeling, go back to step 10 to get any leftover air out of the system.
16 - Release the clamp from the CSC. Press the pedal a couple times, check the CMC fluid level. It should drop to fill the CSC. Refill the CMS to MAX.
17 - Check pedal feel, it should not be spongy. The throw should look like this.
Later
When was the last time you *really* did something with your Z to call yourself a Z enthusiast?
Clutch Hydraulics (bleeding, etc) - 
