91 Hardbody clutch problem

SteelerMan · Sep 23rd, 2004, 07:09 PM

First a little history of the problem. About a month ago I was having difficulty shifting and the clutch pedal felt soft. (Clutch and all related parts were replaced one year ago) I looked at the slave and master cylinder boots for leakage and found the master cylinder leaking. I replaced it and all was well for a month, till pedal felt soft again and was hard to shift. This time the slave was leaking. Replaced that and back to the same problem after only a week.

Bleeding the system stiffens the pedal some but it isnt right. My question is on the bleeding. If I gravity bleed, the pedal feels the best but it is not totally there. If I have someone push the pedal like you would do on brakes, I can never get the air out. The clutch is unusable this way. Gravity bleeding gets the best results but if feels like there is some air in the system still. Is it possible for the master cylnder to have an internal leak or something and let air in the system?

Thanks

SteelerMan · Sep 29th, 2004, 08:35 PM

All right, how about an easier question. I am starting to lean away from the clutch hydraulic system as being a problem since bleeding does not improve it now.

Ont thing I noticed while laying underneath bleeding the slave is that the clutch fork does not retract by itself. What makes the clutch fork return back??? With it being this way, the slave is almost fully extended all the time with nothing to push the cylinder back in. I took the rubber boot off around the fork and looked in the bellhousing and saw or felt nothing out of the ordinary. The fork does slide back and forth easy. So what makes the fork push the salve cylinder back in?

aaronford · Sep 30th, 2004, 02:42 PM

Well... the spring pressure exerted on the throwout bearing originates at the diaphram spring of the pressure plate. You say the fork moves back and forth easily. I don't think it should. There should be alot of pressure generated by the diaphram spring to keep it tight. The slave should actuate toward the rear of the truck. There is a ball pivot halfway down the fork that forces the throwout bearing foward against the diaphram of the pressure plate, releasing the flywheel, clutch disc, pressure plate sandwich. The fork has a spring clip that mounts it to the ball and the fork positively engages the throwout bearing. So the should be no play, if all is well.

Hope its a 2wd, cause 4wds are alot harder to drop the tranny from.

Cusser · Sep 30th, 2004, 02:54 PM

SteelerMan (are you from Pittsburgh, I was born there and lived there 14 years) I had similar problem on my 1988 Mazda truck. I replaced my clutch master cylinder to fix it, and replaced the slave cylinder due to a leak (both were on lifetime warranty anyway). In my case the pedal wouldn't always reurn as well. Apparently the pressure plate spring, the spring in the throwout arm, and the return spring in the clutch master can be involved with this. By the way, I've always bled the clutch system like brakes, having helper pump slowly a few times, then tightening the bleed screw while the next slow pump is being done.

SteelerMan · Sep 30th, 2004, 04:52 PM

aaronford, With the slave cylinder removed, the fork travels freely until I touch the pressure plate. With everything hooked up and having a helper step on the clutch pedal, the slave cylinder will push against the fork and disengage the clutch on the first try. Works normal at that point. The fork will then stay out. My soft pedal is due to the slave cylinder not retracting all the way, but the problem lies within the fork I think, because if I remove the slave when its stuck out, the fork does not go back on its own. The fork looks good, not bent or cracked, pivot point is intact along with the spring. I have to find me a picture of this fork somewhere and compare it to what I have, I think I'm missing something. Thanks for your help

SteelerMan · Sep 30th, 2004, 04:59 PM

Thanks for the info Cusser. I think I'm down to pulling the tranny again. I replaced the clutch last year myself, so its not too big of a deal for me. But, I don't think I am going to invest anymore money into this vehicle. It's been a great truck since we bought it new in 1991 and this is the first problem with its 150,000 that is making it sit. So if I cant come up wiht a cheap fix by this weekend, there will be a 1991 4wd nissan pickup on Ebay for parts or whatever.

Never lived in Pittsburgh but visit often. I'm from the Harrisburg, PA area. I make the 200 mile trip to see the Steeler games about 4 or 5 times a year. I'll be there this weekend taking my son to his first Steeler game.