hydraulic clutch

[closedknuckle]

Anybody know how to adjust a hydraulic clutch on an 1985 GMC 3500? It has a hyd master and hyd slave.
Thank you

 

[m16ty]

Every hyd. clutch I've seen didn't adjust. It either works or it don't. If your clutch is slipping you'll have to replace it. If it won't release it could be your hyd. system.

 

[closedknuckle]

I have to push it all the way down and sometimes it seems like it's not quite disengaging all the way?

 

[gsomersjr]

Might try bleeding the system.

 

[drgreg]

It may have linkage on the slave that is sloppy or loose, there may be an adjustment nut on it.

 

[badgmc56]

On some 80's Ford trucks, there was a firewall flexing problem that they fixed with a brace kit on the clutch master cylinder. Does the pedal feel normal and not too much play? The guys here have pretty much covered all the other causes.

 

[OLDCHEV4X4]

I just did one of these ,and it is a PITA without a "mighty vac" hand held brake bleeder. Since mine is a plow truck, the clutch gets over used. So when the clutch master cyl started leaking inside the cab i replaced the slave cyl, clutch master cyl. and the hoze to the reservoir. It would not bleed out like brakes. I had to buy the vacume pump and suck the brake fluid through the system from the bleeder screw on the slave. Putting grease around the threads on the bleeder screw helped make a better seal. I also had a second person working the pedal slowly while i was underneath. I must have put about 3 pints of fluid through there before i finaly got pedal. The next day the pedal was even better. I think some of the air bubbles worked there way up.
I hope this helps.

 

[M880 GC]

Look for loose and sloppy components in the pedal cluster. Any lost motion will reduce the total release bearing travel. Your clutch needs about 5/8" travel at the bearing for a full release.

You should have an external slave cylinder. You can remove it from the bell housing and leave it attached to the hydraulics. Create a fixture using a steering wheel puller for example and block the pushrod from moving (be carefull) now have someone else push (15-20 lbs) on the pedal and look for clutch pedal movement. If it moves a couple of inches, you have air or a cluster problem.

Bleeding tips.

Vacuum as mentioned at the bleed screw is a good tool and sealing the threads is also correct. The taper on the screw is the actual hydraulic seal seat, not the threads.

Vacuum is now also recommended by GM and Ford on top of the reservoir to pull bubbles out. MitiVac attached to the top, fluid catch trap in the line and then apply 15-20 inches, have a Coke, come back and release the vacuum. When you push on the pedal, it may take a stroke or two to get release.

Also a good tip is just to point the S/C pushrod down and then push the piston in a few times allowing the spring inside the S/C to push back against you. The idea is to flush a bubble out the top, go up, not down. Look at the line routing for any high spots, if you can temporarily relax the line to allow bubbles to go up, let it hang overnight.

Pull boots back to look for leaking.

Remember, the release bearing is in constant contact with the clutch on these systems, there should be almost no perceptable free play, it's not like the old 1960's and '70's systems with 1 1/2" of freeplay.

I really do not suggest going to the shop and making any rod longer, that can just creat a bigger problem instead of fixing the real problem.

I teach clutch seminars at work.

 

[southdave]

Did you recently replace clutch? There is focrum ball that is adjustible try screwing it in alittle.. GM has like 7 or 8 different size throw out bearing dependin on set up.. so when you order clutch it a pot luck what you get..did you try shiming out the slave with couple washers?
I bleed the by laying on belly and exercising the slave by pushing it againist the floor about 100 times, it will be super hard when it bleed..