LS2-240z

I have an intermittent problem (that means it doesn't do it all the time). I have all new parts in my clutch system from the master cyl to the flywheel. I installed a Mantic ER2 clutch kit from Eastcoast Performance. Insulated lines, remote speedbleeder (basically all the good stuff). I have bled my system until I'm blue in the face. I even changed from one color of brake fluid to another to ensure that I've exchanged all the fluid (and I assume all the air). Well sometimes the pedal is nice, firm and high BUT, at other RANDOM times, when my foot remains lightly on the clutch pedal awaiting the next shift, I can feel the clutch pedal moving down as the engine rpms go up. Then, when I push in the pedal for the next gear, it is as if pressure only builds from about an inch from the floor and naturally, the clutch dissengages insufficiently to allow the next shift. All I gotta do is let the pedal come back up and push it again and all is well.

Any ideas? How could this happen? If you think I've still got air in the system, then where? And, how do I get it out?

Also, should I be putting plumber's tape on AN fittings associated with my clutch system?

SPEC-01

iTrader: (2)

There are a few possible causes for this issue. You mention leaving your foot on the pedal between shifts. If you are pre-loading the clutch enough to push it over-center then its possible that the clutch is falling as a result of centrefugal forces. You should not keep your foot on the pedal between shift.

If you are experienceing bleed-by within one of the cylinders this too could cause the pedal to drop. If this is occuring you are passing fluid beyond the internal seal. The solution is to replace the Slave and or Master.

First try shifting without your foot resting on the pedal and see if that changes anything. Let me know. Thanks,

Sales@Tick

iTrader: (3)

I agree with this 100%.

Try a different way of shifting without leaving your foot resting on the pedal then report back.

LS2-240z

Thanks for the suggestion. But, come-on!: I shift all my other cars this way an always have. My S10, and this car when it had a stock master cylinder and an external slave. I'm just resting my foot on the pedal for the time it takes to go from 2nd to 3rd and to 4th, like a second or two. There's not time to put my foot on the floor and pick it back up again. I'm shifting 4 gears in 7 seconds-its not like I'm "riding" the clutch. It's not ME-it's the damn car! Funny thing is how this problem is inconsistent-I guess that is why I'm asking questions. The pedal doesn't come down everytime I drive it (and I always drive like this). If I always drive it the same way, why doesn't it drop everytime? I may eventually ditch the T56 and get a tranny with a mechanical clutch linkage that doesn't have these gremlins. I see all the posts about this, and it doesn't seem anybody who has this problem ever solves it, or perhaps they just never take the time to post the fix. Thanks guys.

SNLPerformance

iTrader: (15)

What did the manufacturer say?

We can do nothing but give you recommendations, you may not like them but you're asking peoples advice and you're getting it.

If you're applying pressure to the clutch pedal while you're expecting the clutch to hold it's going to slightly release the clutch. If the pressure you're applying to the clutch pedal isn't enough to depress it then this isn't the issue.

I would check the hydraulics for leaks or for bypassing, if it's not that then the clutch is slipping which is building heat in the diaphragm spring causing the clutch to lose it's holding capacity.

The absolute first thing I would do is call the manufacturer, they know their clutches better than anyone.

LS2-240z

Thanks for the advice on decorum, sorry, I'm just so frustrated, but that is noone's fault but my own. What is "bypassing?" Please explain that concept to me (I'm all ears), maybe that is what is happening....I'm certain that this is a hydraulic issue. By the way, when I say rpms climb, I only mean from 1500 to 3000 - I'm babying the car around while in the clutch breakin period. I am so glad that I put a big hole in the bellhousing, because I can see how much the throwout bearing is moving, and that the clutch is fully engaging, but not fully disengaging. I just wish I had a hole that I could see in when I'm actually driving. I talked to tilton and dan, the rep, said to put a plug in the outlet of the master cylinder, and if the pedal creeps down with constant light pressure, then it is the master. AN3 plug arrived from Summit today. Going out into garage to try it. How often is a tilton master cylinder defective right out of the box?

HioSSilver

iTrader: (8)

PP got weak....??? I have seen this happen at higher rpms .

LS2-240z

Took a couple of videos to show that the clutch disengagement is unpredicatble. Installed a new master cylinder tonight and we'll see tomorrow if that solved problem.....

SNLPerformance

iTrader: (15)

Bypassing is when the pressure is bleeding off internally and not being transferred through the fluid. (hopefully that makes sense)

I've only seen a handful of Tiltons have issues, they are very robust units.

What did the guys at Mantic say?

SPEC-01

iTrader: (2)

LS2, Keep in mind that every car and every clutch are not the same. Some require more travel than others (from application to application) to over-center the unit. The suggestion I made above isn't intended to cause frustration. It is simply a reference to a potential cause for your issue.

Fluid bypass occurs within the cylinder and is not as easily found as fluid leaks would be. You can disconnect the line that connects the Master and Slave and then try pressing the pedal. DO NOT TRY TO PUSH THE PEDAL TO THE FLOOR LIKE THIS OR YOU CAN DAMAGE YOUR MASTER CYLINDER. Just push lightly on the pedal and see if there is give/travel. With the line disconnected there should be no real pedal depression. If there is then you are bypassing fluid within the Master.

LS2-240z

Bypassing for the win! You guys seem to be right. I can't seem to get the videos to post. I did what the Tilton rep said and put an AN3 plug in the outlet of the master cylinder. I could then very reliably reproduce the problem. If I pushed abruptly, the pedal acted normally, but if I pushed lightly, the pedal would go all the way to the floor with no firmness, top to bottom.

SPEC-01

iTrader: (2)

Good deal! Thanks for the update. Good luck getting this remedied and let us know if you need anything else.

LS2-240z

I have decided to add a shim to the slave cylinder next weekend to get a little more pedal without the risk of over-extension of the slave. None of the shims I see have a "shoulder" to keep the throwout bearing centered in the bellhousing. So, I guess it would be unwise to shim so much that the shoulder inside the slave is filled up flush. Is that right-that I'm limited in my shimming to less than the depth of the recess in the bottom of the slave housing? Of course I'll measure, but I think I could use about 1/8 to 1/4".

SPEC-01

iTrader: (2)

Send me your email and I can provide a sheet that outlines the proper way to measure for needed shim thickness. You may or may not need a shim but measuring will let you know for sure.

LS2-240z

Using the inspection hole I cut into the bellhousing, I have determined that a shim is unnecessary. I'm back in business and shifting well at any rpm. Problem was bad (brand new) Tilton master cylinder. I increased from 7/8 to 1". I am not overextending the slave and I am very happy with my clutch release location in the pedal stroke.

HioSSilver

iTrader: (8)

Thanks for reporting back.

SSwanner

iTrader: (128)

anyone have this problem with ls7 clutch?