Clutch hydraulics
Thread Starter
Drifting
Joined: Aug 2009
Posts: 1,972
Likes: 243
Clutch hydraulics
Hi all,
I replaced my clutch hydraulics a handful of years ago with aftermarket units (master + slave). After problems this spring, I replaced them again with aftermarket units and have put less than 500 miles on that set. They worked fine all summer.
My car sat for around a month and today I took it for a ride. Before I started it I knew the pedal felt too light. After I started it it was hard to put in gear. I pumped it 25 or so times and got a normal feeling pedal which then allowed me to shift normally and was fine for the duration of my 30 minute drive.
Does it I'd sound like this hydraulic set went sour already? The only thing in the hydraulic system that has not been replaced is the hose between master and slave. I don't think it's at fault, simply because after I pump the pedal the resistance comes back. If it was the hose I imagine pumping would not resolve. I'm not sure if the hose is even available?
I want to get the hydraulics working right, consistently. Are there any diagnostics I can perform to determine if the issue is master, slave, hose or other?
I replaced my clutch hydraulics a handful of years ago with aftermarket units (master + slave). After problems this spring, I replaced them again with aftermarket units and have put less than 500 miles on that set. They worked fine all summer.
My car sat for around a month and today I took it for a ride. Before I started it I knew the pedal felt too light. After I started it it was hard to put in gear. I pumped it 25 or so times and got a normal feeling pedal which then allowed me to shift normally and was fine for the duration of my 30 minute drive.
Does it I'd sound like this hydraulic set went sour already? The only thing in the hydraulic system that has not been replaced is the hose between master and slave. I don't think it's at fault, simply because after I pump the pedal the resistance comes back. If it was the hose I imagine pumping would not resolve. I'm not sure if the hose is even available?
I want to get the hydraulics working right, consistently. Are there any diagnostics I can perform to determine if the issue is master, slave, hose or other?
Melting Slicks
Joined: Jul 1999
Posts: 3,214
Likes: 101
From: Decatur, Alabama
there was a run of incorrctly manufactered oe slave cylinders and same supplier sold to an aftermarket company (don't remember which) but if you got one of those it could well have gone bad. Search the forum for this many years old multiple threads on this as well as the zfdoc.com website
Last edited by corvette95; Nov 13, 2016 at 08:15 AM.
Melting Slicks
Joined: Nov 2013
Posts: 3,451
Likes: 336
From: Greater Cincinnati Area.
Generally speaking, if you can pump it a few times and make it feel normal. it has trapped air. If you don't see leakage? I would try bleeding it before I tossed anything, or spent any effort on diagnosis.
These systems are very small and very low volume, and you can get air trapped in them from bleeding that is exceedingly fine.. Like soda pop bubbles.
When you park the car, this air kind of floats up and turns into a larger pocket of air, collected in one place, that has a much more disproportionate impact on clutch operation.
I know here it isn't uncommon to swap a master and slave, bleed it as completely as you can with a power bleeder, and still have to go on a test drive where the clutch must be pumped a few times to work. Bring it back, and burp it again, and it is perfect and it stays perfect.
Good luck.
These systems are very small and very low volume, and you can get air trapped in them from bleeding that is exceedingly fine.. Like soda pop bubbles.
When you park the car, this air kind of floats up and turns into a larger pocket of air, collected in one place, that has a much more disproportionate impact on clutch operation.
I know here it isn't uncommon to swap a master and slave, bleed it as completely as you can with a power bleeder, and still have to go on a test drive where the clutch must be pumped a few times to work. Bring it back, and burp it again, and it is perfect and it stays perfect.
Good luck.
Heel & Toe
Joined: Jul 2015
Posts: 18
Likes: 0
My slave cylinder went this spring. The best diagnostic procedure I can recommend is keep a close eye on your fluid reservoir. If it keeps using fluid you are headed for a problem. It could be just a trapped air bubble up by the master cylinder, which will bleed itself. But if this keeps happening, or happens more frequently, or your fluid keeps dropping, you have a leak. If you don't see any leaks anywhere, it is probably the slave cylinder. I was really amazed at the amount of clutch fluid that can leak into the bell housing before you can see it.
Thread Starter
Drifting
Joined: Aug 2009
Posts: 1,972
Likes: 243
Thanks for the advice all. I took the PCM out so I could get to the reservoir and the fluid still looks full. Beneath the car is dry. I know when the slave cylinder goes it leaks into the bell housing but given the fluid level is ok I think this was just air. I drove the car again yesterday and the pedal was fine. I'll keep an eye on it over the next week or two before it gets tucked away for winter. Thanks again
Drifting
Joined: Mar 2011
Posts: 1,693
Likes: 144
From: on Barnegat Bay Joisey
While we're on the subject, does anyone rebuild factory original units? Is a quality rebuild kit available? When my '90 was new GM replaced/rebuilt? at least 3 sets of master and slave in a very short period of time, as my memory serves me. Then it was fine for the next 25 years. Now it feels a little soft but still operates properly. probably should check the clutch oil.
Melting Slicks
Joined: May 2013
Posts: 2,692
Likes: 349
From: Sacramento California
While we're on the subject, does anyone rebuild factory original units? Is a quality rebuild kit available? When my '90 was new GM replaced/rebuilt? at least 3 sets of master and slave in a very short period of time, as my memory serves me. Then it was fine for the next 25 years. Now it feels a little soft but still operates properly. probably should check the clutch oil.
http://www.powertorquesystems.com/
Even if you can find aftermarket clutch cylinders with the seals installed correctly, the aftermarket parts are inferior to OEM. So you will spend more money getting your original parts reconditioned but it's well worth the price.
Last edited by DGXR; Nov 14, 2016 at 03:29 PM.
Thread Starter
Drifting
Joined: Aug 2009
Posts: 1,972
Likes: 243
^^this.
I shied away at this advice last time due to the cost and its been it's been less than a year and I'm having issues with the aftermarket parts. I'm still hopeful that it's just a bit of air I didn't bleed out but if, or rather when, these aftermarket cylinders fail I'll be going to Jim for the real deal.
I shied away at this advice last time due to the cost and its been it's been less than a year and I'm having issues with the aftermarket parts. I'm still hopeful that it's just a bit of air I didn't bleed out but if, or rather when, these aftermarket cylinders fail I'll be going to Jim for the real deal.
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