Dying clutch? Cylinders?
Thread Starter
Instructor
Joined: Aug 2015
Posts: 147
Likes: 9
Dying clutch? Cylinders?
I think the clutch in my 85 is dying, well hopefully just the master and slave cylinders. The pedal started feeling spongy a couple weeks ago then the transmission got really hard to shift. I looked at the reservoir and it was at the low line so I filled it up. Pumped the clutch about 30 times and it turned smooth as glass so I thought it was fixed. I didn't drive the car for the weekend, got back in it, and the transmission was hard to shift again. Pumped the clutch again thinking it had just settled or something and it got better. Went for a drive and it went back to acting up unless I pumped the clutch a few times. The fluid level has not changed from the max line since I filled it after the first problem.
So, am I right that the master/slave cylinders are dying? Maybe it's a different problem? If it's the master/slave cylinders, are there any brands that I should stay away from or definitely buy? I'd appreciate any help you might have.
So, am I right that the master/slave cylinders are dying? Maybe it's a different problem? If it's the master/slave cylinders, are there any brands that I should stay away from or definitely buy? I'd appreciate any help you might have.
Instructor
Joined: Feb 2015
Posts: 184
Likes: 36
From: Ontario CA
Centric master/slave cylinders
I bought my '84 several months ago knowing the slave cylinder was going bad. I finally had to replace it last month and went with Centric cylinders I got from usautoparts.net . Be sure to replace both the master and slave. I'm satisfied with the $100 price tag for both and they work great. 
Melting Slicks
Joined: Jan 2008
Posts: 2,054
Likes: 120
From: AZ
I'd change the (brake) fluid in it and hope for the best. The repeat of the poor action indicates something abnormal. You might need new seals in it or more, depending on the condition of the pistons in both units and the sleeves. I've long wished that someone offered a stainless sleeving service for those aluminum parts.
The slave MUST be bled inclined @45*, as the FSM states.
The slave MUST be bled inclined @45*, as the FSM states.
Thread Starter
Instructor
Joined: Aug 2015
Posts: 147
Likes: 9
Thanks for the replies. I think I'll try clearing out the fluid and replacing it first and see if that fixes it. If not, I'll replace the cylinders. Hopefully I won't have to go any farther than that!
Safety Car
Joined: Aug 2013
Posts: 4,429
Likes: 608
From: Minneapolis Mn
One more thing is you might still have some air in the lines. Had that before and it's no fun. Scenario was the clutch master and slave were replaced by my mechanic and he couldn't get it bled completely. There's a Youtube on getting air out of the master using a brake bleeding kit tip and hose, tried that and got some out air but not everything. Final solution came from a tip from a former GM Mechanic. He said to fill the clutch reservoir with clean fluid, cap off and pump the clutch pedal a half dozen times and hold it down for about 5 minutes. At the end of the 5 minutes, slide your foot off the pedal and let it pop up on it's own. Idea is you pump it up and while waiting it lets the air work back up to the neck in the main line above the master cylinder. When you let the pedal pop up it pushes the air in the curved neck above the master cylinder back into the master cylinder. I ended up doing it twice and my clutch has been working fine ever since and that's been about 2 years now.
Hope that helps. Good luck.
Hope that helps. Good luck.
Thread Starter
Instructor
Joined: Aug 2015
Posts: 147
Likes: 9
I worked on the car yesterday and went ahead and replaced the master/slave cylinders. Here are some tips I wrote up after doing the job that might be helpful if you need to do the same project. Enjoy! https://www.corvetteforum.com/forums...post1590766151
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