Clutch Problems Need Some Help
My money is on the MC or the slave. If it was working before without a shim, why would it all of a sudden need a shim? The LS7 clutch doesn't need a lot of travel to disengage.
Andrew
Well I replaced the MC and it was pumping fine when I bench bled it and held firm prior to hooking the QD line up to the slave. If the slave failed, what is the failure mode? It is basically a hydraulic ram correct? Is there any way for it to fail internally and not leak?
If the spring that holds the throwout bearing in contact failed, would that require excessive stroke of the slave to engage the bearing?
If the spring that holds the throwout bearing in contact failed, would that require excessive stroke of the slave to engage the bearing?
Another thing I want to mention. While bleeding the slave, I had my remote bleeder at the same level as the reservoir and had a small clear tube going from the bleed screw to the reservoir so I could watch for bubbles. I would open the bleed screw, have my buddy depress the pedal and shut the bleed screw when he reached the floor. When he let go of the pedal, it would only come back about halfway and it would take several seconds for it to come all the way back up. Is that normal?
Another thing I want to mention. While bleeding the slave, I had my remote bleeder at the same level as the reservoir and had a small clear tube going from the bleed screw to the reservoir so I could watch for bubbles. I would open the bleed screw, have my buddy depress the pedal and shut the bleed screw when he reached the floor. When he let go of the pedal, it would only come back about halfway and it would take several seconds for it to come all the way back up. Is that normal?
Silly me...
I've never use a stock MC in a swap, but have used the Wilwood MC in several. In my opinion the slaves are not nearly as problematic as a lot of people insist, but I think the stock style MC is not great.
Andrew
"When he let go of the pedal, it would only come back about halfway and it would take several seconds for it to come all the way back up. Is that normal?"
I just bled my tick master and it did something similar. I bled the hell out of it, then bled the 'top' portion of the travel and it works perfectly.
I'd also recommend getting a bleed screw with a check valve built into it (speed bleeder). Dorman and Russell makes them, then you don't need a buddy.
Read Post #6...
https://ls1tech.com/forums/manual-tr...-properly.html
I just bled my tick master and it did something similar. I bled the hell out of it, then bled the 'top' portion of the travel and it works perfectly.
I'd also recommend getting a bleed screw with a check valve built into it (speed bleeder). Dorman and Russell makes them, then you don't need a buddy.
Read Post #6...
https://ls1tech.com/forums/manual-tr...-properly.html
I hear that, but the pedal is not spongy anywhere in its travel. It seems to me like it just takes a minute for the fluid from the reservoir to refill the MC. Not sure why but that is why I put it out there to see if others have experienced the same thing yet had a normal pedal when they were done bleeding. The speed bleeder may be an option.
I seriously doubt that this is a pilot bearing issue. Remember, the only time that the input is not spinning with the crank is when the car is in gear and the clutch is disengaged. In other words, maybe 15% of all driving, unless you do a lot of heavy stop and go...
My money is on the MC or the slave. If it was working before without a shim, why would it all of a sudden need a shim? The LS7 clutch doesn't need a lot of travel to disengage.
Andrew
My money is on the MC or the slave. If it was working before without a shim, why would it all of a sudden need a shim? The LS7 clutch doesn't need a lot of travel to disengage.
Andrew
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Well I am back from 10 days in Colorado (vacation) and I was able to pull the trans today. Everything inside looked normal, so I removed the slave from the trans and hooked it up to the clutch line. I had my buddy push on the clutch while I tried to hold it against the spring. I couldn't resist the force against him pushing the clutch. Then we measured the travel and got about 13/16". This was by eye using a 6 inch rule, so I could have been more than that. Then I used a large socket and C-clamp to hold the slave pushed against the spring and pushed on the clutch pedal. The pedal moved maybe 1/4" and then was hard as a rock.
Next I took measurements to see if I needed a shim and got about 1/4" free play with the slave. Since all the numbers out there said that was too large I added .163 of shim to get about .087" of free play. Then we put the trans back in to try again. I temporarily installed the driveshaft into the trans so I could see if I could spin the output shaft of the trans. In neutral I could spin the driveshaft. WIth the trans in 1st gear and clutch not engaged I could not spin it (expected). Then in 1st gear with the clutch engaged I still couldn't spin it.
WTF is going on?????? I know the slave is engaging the clutch and pressing on the fingers and should be disengaging it. Is there a way for the clutch itself to fail which would not allow it to release the clutch?
Next I took measurements to see if I needed a shim and got about 1/4" free play with the slave. Since all the numbers out there said that was too large I added .163 of shim to get about .087" of free play. Then we put the trans back in to try again. I temporarily installed the driveshaft into the trans so I could see if I could spin the output shaft of the trans. In neutral I could spin the driveshaft. WIth the trans in 1st gear and clutch not engaged I could not spin it (expected). Then in 1st gear with the clutch engaged I still couldn't spin it.
WTF is going on?????? I know the slave is engaging the clutch and pressing on the fingers and should be disengaging it. Is there a way for the clutch itself to fail which would not allow it to release the clutch?
I will be pulling the trans again today and will remove the pressure plate to see if anything looks off.
Also, we got a hold of a scope and we were able to watch the slave cylinder push against the pressure plate fingers, so it looks like it has to be the pressure plate.
Also, we got a hold of a scope and we were able to watch the slave cylinder push against the pressure plate fingers, so it looks like it has to be the pressure plate.
Sometimes the simplest things cause the biggest problems. Here is what I saw when I pulled the pressure plate and clutch disc. The pressure plate had some scarring on its inside edge like something had been in there. I didn't hear anything hit the ground when I removed everything but I went back and saw this little mangled screw on the floor.
I put everything back together, without the screw, and I reduced my shim pack to .050" and when my friend pressed the clutch pedal with the trans in gear, the driveshaft spun easily. In fact with the shim I put in, the clutch release is closer to mid travel as opposed to right off the floor as it was before. I realize I may have a problem with slippage when the clutch gets near end of life, but as few miles as I put on this car, that will be 10 yrs down the road.
I put everything back together, without the screw, and I reduced my shim pack to .050" and when my friend pressed the clutch pedal with the trans in gear, the driveshaft spun easily. In fact with the shim I put in, the clutch release is closer to mid travel as opposed to right off the floor as it was before. I realize I may have a problem with slippage when the clutch gets near end of life, but as few miles as I put on this car, that will be 10 yrs down the road.
Alan,
Are you kidding here? A screw? Where did that come from?
Don't worry about the clutch release down the road. The LS7 clutch has a self adjusting pressure plate that compensates for clutch wear (I actually thought this mechanism was somehow going bad on you...).
I am glad you found the issue!!!
Andrew
Are you kidding here? A screw? Where did that come from?
Don't worry about the clutch release down the road. The LS7 clutch has a self adjusting pressure plate that compensates for clutch wear (I actually thought this mechanism was somehow going bad on you...).
I am glad you found the issue!!!
Andrew
The source of the screw is a definite mystery. Maybe it fell into the pressure plate during manufacturing or when I was getting ready to install it. Who knows, but at this point, who cares, it is fixed!!!!!!