Aston Tibs

iTrader: (3)

I have a 68 Camaro LS-1/T56 conversion using the complete system from the 99 Firebird donor. I did replace the clutch with the LS-7 clutch kit and got a new slave cylinder. I got the car running about a month ago and finally got everything sorted out last week. I drove the car back and forth to the tuner, alignment shop and tint shop with no issues. I even drove the car to work last Friday. Then last Saturday all of the sudden the clutch would not disengage and I barely made it home by using the starter to start in gear. SInce the master was the only old part in the system, I replaced it tonight, bench bled it, put everything together, bled the **** out of the system and it is doing the same thing. I cannot get it in gear. Here are the parts I used. From GM parts direct "PKC6LS7CLUTCHKIT and Slave cylinder #24264182. I set the pedal up so that it is within thousandths of the end of its stroke fully up and I can adjust it to go to the end of its stroke on the floor with a pedal stop I have so I know I am getting full stroke from the master. This whole thing has me sick to my stomach. It was working fine and all of a sudden it stopped disengaging.

I have been told no shims are needed with this setup, but that is the only idea I have left unless the slave just failed, but I would think it would leak fluid if it failed.

Aston Tibs

iTrader: (3)

Went on GM Parts Direct and it pointed me towards a 24264180 slave when I put the LS7 clutch kit in the cart. I wonder if I got the wrong slave.

But that still doesn't explain why it worked and then stopped working.

SNLPerformance

iTrader: (15)

Is there any fluid leaks under the car? What's the bore size on the master you have?

Give us some more info and we'll see if we can't help out.

Aston Tibs

iTrader: (3)

There were never any fluid leaks under the car and the level in the master never changed. The feel of the clutch pedal also didn't change. I am using the stock MC which I am told is a 3/4" bore and 1" stroke. I modified the pedals to maintain the 1" of stroke.
One thing I didn't mention is that after it failed Saturday halfway home it did start to work although gear changes were a little rough. On Sunday morning it was working fine again and I even sat in the driveway with the car in first gear engine idling and my foot on the clutch and the car didn't move. I shut it down and came back 15 minutes later and I couldn't get it in gear again. If I shut the car off and put it in gear and then started it with the clutch depressed, it would lurch forward. the new MC hasn't changed anything and I bled until there were absolutely no bubbles.

SNLPerformance

iTrader: (15)

If that's the case I'd pull the trans and inspect the clutch. Verify the hardware is torqued and the SAC part of the pressure plate looks right/not mis-adjusted. Something is amiss, if there are no leaks and it's working sporadically I'd very the setup first and foremost.

Also, while you're in there, I'd measure the setup for a shim to verify the setup height is correct. It never hurts. Once you've done this get back to us and let us know what you see/what comes of this. We'll go from there.

Aston Tibs

iTrader: (3)

Exactly what I was planning to do, thank you.
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?

SNLPerformance

iTrader: (15)

Not a problem.

That's not the way I'd have bled the system, flushing/bleeding is the way we do it. This way it cannot trap/recirculate the air in the system.

Project GatTagO

iTrader: (7)

Alan,

Maybe try bleeding with a vacuum bleeder. And remember, bleeding a clutch (or brakes) is not about pressure, it is about moving fluid through the system and getting the trapped air out. When I bleed, I always go nice and easy on the clutch pedal. I also always submerge the end of the bleeder in a glade jar filled half way with fluid. That way I can watch the bubbles escape and the bleeder does not have to be closed when the pedal comes up. I also wait 10 seconds before pushing the clutch pedal down again. Rinse, repeat...

Andrew

lizeec

iTrader: (57)

I had a similar situation, I installed a 8k mile ls2 & t56 out of a 2006 GTO in my 1966 Gto, I installed a fbody slave in the t56 and put a new 98-02 master cylinder from G.M. and all worked fine for a few months. I let the car sit for about 2 weeks one time and one morning it would not go into gear, I bled the system and it made no difference.

I saw some slight seepage at the master cylinder plunger and replaced the master cylinder with another brand new G.M master cylinder but still no difference, I had no fluid leaks and the fluid in the reservoir was at the same level. Like your situation it didn't make sense as it was working fine and then it wasn't. I was out of ideas, I dropped the trans and replaced the slave and still no change, I was close to lighting the car on fire.

Well I pulled the trans again and installed a new flywheel, clutch and pressure plate and it cured the problem, why? I still don't know why the new clutch fixed the problem, the old 8k mile clutch and pressure plate looked fine, I am a heavy equipment mechanic and know **** doesn't magically fix itself. It has been working fine for a few thousand miles, but I am not convinced it is fixed, the car still sits for weeks at a time and I feel like one day after it sitting for a few weeks I am going to get in and have the same problem all over again.

Aston Tibs

iTrader: (3)

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?

Aston Tibs

iTrader: (3)

Lizeek, I hear you on your situation. It doesn't make sense. My troubleshooting to this point points to the pressure plate, but what is the failure mechanism????

Aston Tibs

iTrader: (3)

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.

lizeec

iTrader: (57)

Good deal you found the problem, now the next mystery question is where did that screw come from all of a sudden and how did it get in there?

Aston Tibs

iTrader: (3)

That is a mystery, but at this point, I am just glad it is fixed. It could have got into the pressure plate during manufacture, but more likely, it happened while I had the parts out ready to install.