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2G Not your typical clutch engagement issue

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jakk220

10+ Year Contributor
1,319
312
Nov 13, 2010
Akron, Ohio
Trying to figure this issue out asap before the shootout. Ill make this as short as possible.

A few weeks ago my front diff chipped a tooth. I took it and got it rebuilt and then installed a new flywheel faceplate, clutch disk, TOB, and reused my low mile pressure plate that tested good with feeler gauges (Southbend B series with ssx pressure plate).

The car shifted beautifully and the engagement point was perfectly in the middle of the pedal on the first few drives / 200 miles. Awesome. Time for some shootout test hits.

I launched the car and everything went well and felt good. The car pulled hard off the line and shifted fine. As soon as I stopped at a light, I noticed the pedal engagement was at the floor. Then, when I went to drive off, I noticed the engagement point was super long. Like the car would start moving with the pedal right off the floor, but fully grab at the middle of the pedal where it should. When it does this the clutch might even be slightly dragging honestly. But still goes into gear and shifts.

After a while of driving, the engagement travel range seems to shrink back up so its not so long. But the engagement is still lower than it was the first 200 miles. And after that first launch, the pedal has never been back to its old engagement point. Its more towards the bottom than it used to be. After everytime I launch it, and stop the car, it moves down to the floor again.

So I bled the clutch and the fluid looked black. So I changed it, but not matter how much I bleed, its still coming out black. Weird and not sure why.

Things I have checked / done:

1. Bell housing bolts are all there and tight (including the rear one)
2. Step height is correct on the flywheel
3. Pressure plate bolts torqued to 15 ft/lbs. Alignment dowels are there.
4. Flywheel seated completely and torqued to 100ft/lbs with red loc-tite
5. Bled the clutch and changed the fluid. No apparent leaks nor was the fluid low. Dot 3/4.
6. Adjusted the clutch with the proper method
7. Clutch fork sits in the proper spot. Actually a tad closer to the driver side because I add a shim for assurance.
8. New OEM throw out bearing
9 *edit* Braided stainless clutch line to slave
It seems hydraulic but I wanted to see if anyone else has ever had this issue. Its a weird one. I am going to try to swap out the master and the slave with new and see what happens. But they did not appear to be leaking. Any ideas here?
 
Last edited:
Do you have a stainless clutch line yet? I have had some issues in the past with old rubber lines expanding with heat causing engagement issues.

Agreed. If you still have the old hard/soft line combo, I bet it's deteriorated and giving you hell between debris and swelling under certain conditions.

Braided stainless line and it is maybe.....4 years old or so.
 
What clutch disk?

South bend B-series full face ceramic disk with the SSX pressure plate. Same setup I ran last time and it worked flawless. Worked good this time too until that first launch
 
Is it possible for the slave or the master to be bad without it leaking? like something wrong with the auto-adjust relief valve or whatever its called in the master? Maybe something is clogged somewhere?

I will be replacing them here in the next few hours more than likely just to eliminate the possibility. But the behavior of the engagement is just so odd.
 
Is it possible for the slave or the master to be bad without it leaking? like something wrong with the auto-adjust relief valve or whatever its called in the master? Maybe something is clogged somewhere?

I will be replacing them here in the next few hours more than likely just to eliminate the possibility. But the behavior of the engagement is just so odd.

I have had slave cylinders let air into the system and never leak a drop of fluid. It wasn't on a dsm, but it is possible.
 
I have had slave cylinders let air into the system and never leak a drop of fluid. It wasn't on a dsm, but it is possible.

Interesting. I wonder if that is whats happening here. Either way I will replace them and report back. Just wanted to see if anyone had any other suggestions in the meantime.
 
I recently experienced (and still am experiencing) a very similar thing. All of a sudden my clutch fluid went dark, like almost black, with fine black residue sitting at the top of the reservoir (looks like black grit when you wipe it on a towel). This is not more than 1000 miles after an engine rebuild and therefor brand new fluid (DOT 4) being put in. I'm also using a reinforced line going straight from the MC to the Slave.

I believe it's due to the liquid getting really hot (from all the launches, I do those quite a lot) and hard driving, as well as constant stop-go traffic situations. The heated fluid eats at the old master and slave cylinder seals, which are a form of black rubber. They still seal, but little by little they're getting dissolved, almost.

I'd suggest 2 things. Firstly, take both your cylinders out, disassemble them and give them a thorough cleaning. While you're in there, you can decide to order and put in replacement seal kits (as well as the little piston). That's the cheaper option. Or, just order brand new OEM or good quality MC and SC and be done with it. Putting brand new DOT 4 fluid is a given.
 
I recently experienced (and still am experiencing) a very similar thing. All of a sudden my clutch fluid went dark, like almost black, with fine black residue sitting at the top of the reservoir (looks like black grit when you wipe it on a towel). This is not more than 1000 miles after an engine rebuild and therefor brand new fluid (DOT 4) being put in. I'm also using a reinforced line going straight from the MC to the Slave.

I believe it's due to the liquid getting really hot (from all the launches, I do those quite a lot) and hard driving, as well as constant stop-go traffic situations. The heated fluid eats at the old master and slave cylinder seals, which are a form of black rubber. They still seal, but little by little they're getting dissolved, almost.

I'd suggest 2 things. Firstly, take both your cylinders out, disassemble them and give them a thorough cleaning. While you're in there, you can decide to order and put in replacement seal kits (as well as the little piston). That's the cheaper option. Or, just order brand new OEM or good quality MC and SC and be done with it. Putting brand new DOT 4 fluid is a given.

I believe you are right. I was thinking maybe it was eating at the seals. But the heat amplifying it may have some truth. It sounds exactly like my situation. I am in a pinch because this car needs to run flawless like now. So I'm going to get a set from AutoZone and see what happens. The one on there is an AutoZone one anyways so it's highly likely it's failing. If this fixes it, I will replace it with oem when time permits. I'll keep you updated. Going to pick up parts now.
 
Replaced the master and slave and bled well. Issue is still there. Clutch is dragging in 1st off the 2 step. Clutch fork has plenty of movement and pressure plate fingers are fully moving. I'm lost. 1 launch and it went to hell
 
is your braid line the teflon lined type made for brake fluid? if its just the less expensive rubber braid line made for fuel & oil the black crap is from the braid line not the seals in the master or slave.
 
is your braid line the teflon lined type made for brake fluid? if its just the less expensive rubber braid line made for fuel & oil the black crap is from the braid line not the seals in the master or slave.

No it's made for brake fluid.


UPDATE: I fixed it and don't really know how. But here's what I did.

I replaced the master and slave with 0 change in the clutch even after being adjusted by the proper method. So I decided to listen the nut for the pedal stopper and back it out a few turns just on a limb because I was out of ideas. I readjusted the clutch and nothing. I heard stories of pressure plate fingers rubbing disks from being over adjusted. So I decided to back the rod in all the way. Which made the clutch drag worse as I thought it would.

I readjusted the proper method again except this time after it was adjusted I backed it out even more just to see what would happen. I expected to get the "pump up" but instead, the clutch worked properly. I then got under the car and was able to push the slave rod into the cylinder. Which makes 0 sense. Because it got rock hard when the rod on the clutch was further into the pedal. Which is the opposite of what should happen. I have no idea why it worked. But it does. Time to try to cut a 10.xx at the shootout. Thanks for the input guys. This one still has me stumped.

It makes 0 sense as to why it was fine, and then one launch threw it off. All the lock nuts were tight.
 
I readjusted the proper method again except this time after it was adjusted I backed it out even more just to see what would happen. I expected to get the "pump up" but instead, the clutch worked properly. I then got under the car and was able to push the slave rod into the cylinder. Which makes 0 sense. Because it got rock hard when the rod on the clutch was further into the pedal. Which is the opposite of what should happen. I have no idea why it worked.

This is what's supposed to go down when doing the proper clutch adjustment. You thread the master cylinder rod in (clockwise) half a turn at a time until you can no longer push the slave cylinder rod inside the cylinder by hand (a lot of force). When you get to that point, you back off the master rod (counter-clockwise) one quarter turn, and then tighten the lock nut. This takes care of the sweet spot for that notorious pump up effect. I'd say you currently have it properly adjusted, since it should now be able to be pushed in by hand (the slave rod). Also, you did yourself a favor by changing both cylinders anyway.

Keep an eye out on the color of the fluid. If it goes really black again, then it must be from inside the braided line. Good luck at the strip!
 
This is what's supposed to go down when doing the proper clutch adjustment. You thread the master cylinder rod in (clockwise) half a turn at a time until you can no longer push the slave cylinder rod inside the cylinder by hand (a lot of force). When you get to that point, you back off the master rod (counter-clockwise) one quarter turn, and then tighten the lock nut. This takes care of the sweet spot for that notorious pump up effect. I'd say you currently have it properly adjusted, since it should now be able to be pushed in by hand (the slave rod). Also, you did yourself a favor by changing both cylinders anyway.

Keep an eye out on the color of the fluid. If it goes really black again, then it must be from inside the braided line. Good luck at the strip!

No I know that. But I didn't back it in a turn after the slave was not able to be pushed in. I backed it out more (clockwise) and then I was able to push the slave again. The opposite of what is supposed to happen. I'll keep an eye on the fluid for sure though
 
Further update: time to blow some minds. After every launch the issue comes back. If I rip the ebrake all the way and preload the crap out of the transmission after I park the car in the pits, the problem instantly goes away. Everytime. Consistently. On the bright side I won 11.5 index at the shootout. Just had to pull my ebrake and load up the transmission after every damn pass so my clutch would stop dragging. Wtf.
 
"Once installed new motor with new clutch there was not
enough travel on the clutch adjustment. Had to pull out the
clutch pedal assembly and add a nut to the clevis."

This was on my last invoice from English Racing. I never asked them to explain this to me. But I wonder if this does you any good.
 
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