New LS1 build clutch/slave question

[cheesepocket]

I was all set, after 3 years, to finally get the LS1 Z out for its first test drive, and ran into a clutch release problem. This is a '72 240Z.

I have a 98 LS1/T56 out of a Trans Am. I bought a new LS7 flywheel/pressure plate/disc package from SD, along with the F-body slave cylinder and pilot bearing. I plumbed it with Earls -3 Speed Flex teflon lined SS hose. I have a speed bleeder from LPP which allows you to run a braided line out of the slave to easily bleed the system. So with all the new parts, I thought I was not going to have any problems...wrong.

 

My question is regarding the 7/8" Tilton master, also new. It seems like my clutch will never release, even after I cut out the clutch pedal stop to gain more pedal stroke. I tried adjusting the push rod from the pedal, from just a tiny bit of lash to actually slightly pushing on the master with the pedal all the way out. I haven't had it on the ground, but while up on stands supporting the suspension, engine running, I tried putting the clutch in and putting it in gear. The shifter was resisting, and I saw the back wheel start spinning, indicating that my clutch wasn't releasing but instead the synchros were trying to match engine speed to wheel speed. If I shut off the engine in gear and crawl underneath and try to spin the dtiveshaft, it won't turn.

 

I searched all over this forum before choosing the 7/8" and again now that it won't work right, it seems like most people are using the same master. The pedal feel is rather constant, not like the feel of the pressure plate springs going over center. I could get a 15/16" and try that, but 1) others on this forum aren't having problems and 2) I worry about shoving too much fluid into the slave and popping it off. I haven't seen any forum posts on having to use a slave cylinder spacer with the LS7 kit, unless it's a CTSV. I've bled, bled, and bled some more, and no air is coming out, just a steady stream of new fluid.

 

So is it possible I've either bound the transmission pilot somehow to the pilot bearing, or the clutch plate isn't sliding away from the pressure plate or flywheel properly? I've done probably 30 clutches in my life and never had a problem. Of course I had to have the problem with the car that requires engine/trans removal to get at it.

 

Anyone have any good ideas? Thanks.

[mpramsey]

I have a Z06 Clutch on my LSx swap and a 15/16 Tilton Master. I was very concerned about getting my earls adapter tight enough prior to bolting the T56 up to the engine and then mounting the engine in the car. I was worried that the fitting would leak and then I would have to pull it all out. When I bled my Master/Slave I inserted a flexible camera extension (you can get one at Home Depot, or Lowes) and then looked at the LCD screen while working the clutch pedal. You could see the Slave engaging/disengauging the clutch. You might go and get you one of the cameras and do the same. It has come in handy numerous times during my build.

[cheesepocket]

I was thinking of going and buying one of those. I'm pretty sure the slave is operating, as I get pedal pressure when pushing in. And if it were leaking, I think I would get fluid trickling out the bottom of the bellhousing. Could be I have a bad master, I guess.

 

I did some more searching on the LS1 sites, and am almost sick thinking of what the problem is. There were a couple guys who received faulty pressure plates on their LS7 kits. The diaphragm spring wouldn't go over-center to disengage the clutch. With the tight fit in the Z, the only way to get at this would be removal of the engine/trans. Which means my goal of a first drive before winter closes in for good ain't gonna happen. (Actually it feels like winter is already here, 10" snow last Saturday and 17 degrees yesterday).

 

I would gladly pay $100 to not have to remove the engine/trans, and that's what the 15/16 Tilton costs, so I think I'm gonna give that a try.

 

Any risk with that 15/16 blowing the slave out? I wonder if I should put the pedal stop back in.

[kj280z]

I was thinking of going and buying one of those. I'm pretty sure the slave is operating, as I get pedal pressure when pushing in. And if it were leaking, I think I would get fluid trickling out the bottom of the bellhousing. Could be I have a bad master, I guess.

 

I did some more searching on the LS1 sites, and am almost sick thinking of what the problem is. There were a couple guys who received faulty pressure plates on their LS7 kits. The diaphragm spring wouldn't go over-center to disengage the clutch. With the tight fit in the Z, the only way to get at this would be removal of the engine/trans. Which means my goal of a first drive before winter closes in for good ain't gonna happen. (Actually it feels like winter is already here, 10" snow last Saturday and 17 degrees yesterday).

 

I would gladly pay $100 to not have to remove the engine/trans, and that's what the 15/16 Tilton costs, so I think I'm gonna give that a try.

 

Any risk with that 15/16 blowing the slave out? I wonder if I should put the pedal stop back in.

 

I have heard that it is not necessarily the bore of the master cylinder as it is the stroke. Obviously both are related, but before just buying the 15/16, research how much stroke one has vs the other. I'm not sure about your clutch kit so you'll have to do some research to find the amount of stroke required specifically for your kit. I'm using a clutchmasters clutch kit that required a 1.4" stroke so I bought a Wilwood master that should do the trick (not quite ready to drive mine yet so it's TBD)

 

Here's an assortment to check out

http://www.wilwood.c...linderList.aspx

Edited November 21, 2010 by kjones

[Ls240sx]

I put a wilwood master in my car and it would not bleed. I bought a new one and it did the trick. They are reletivly cheap i would think about getting a new one.

[Zzeal]

"Any risk with that 15/16 blowing the slave out?"

 

 

Going to a 15/16" master will give you LESS pressure than with the 7/8" one.

 

The smaller the master cylinder diameter, the higher the pressure.

 

I'm using a 3/4" master, the same diameter as a stock '06 LS2 GTO.

 

Steve

[cheesepocket]

Going to a 15/16" master will give you LESS pressure than with the 7/8" one.

 

The smaller the master cylinder diameter, the higher the pressure.

 

I agree. I was thinking more in terms of volume. For an equal length pedal stroke, the 15/16 will push out more fluid.

 

Thanks for the suggestions, fellow Z-heads.

[Ls240sx]

..to finish my story about my faulty master...

 

I put in a new master pushed the pedal a few times and POW! blew the rubber seal out of the slave. so yes it will happen. You need to make a stop and basically go little by little until you get enough pressure to work the clutch. At least thats the way i did it.

[kj280z]

..to finish my story about my faulty master...

 

I put in a new master pushed the pedal a few times and POW! blew the rubber seal out of the slave. so yes it will happen. You need to make a stop and basically go little by little until you get enough pressure to work the clutch. At least thats the way i did it.

 

How much stroke did the master cylinder have that you were using when you blew out your slave??

 

I have been told - it's more important to get a master cylinder with the correct stroke - if you get one with more volume (which I believe is done partially to change the pedal effort) you run the risk of blowing your slave.

[Ls240sx]

it had the stroke of a factory 91 240sx.

[kj280z]

it had the stroke of a factory 91 240sx.

 

Which is?

 

The point here is that you can't just make assumptions - In some cases it can cause you to blow out your slave thus requiring you to pull the engine/tranny to fix it... pretty expensive mistake if you don't know that the clutch master is compatible with your slave

[Ls240sx]

yes i know what happens from experience. well i know of a lot of people that are using the 3/4 master from willwood so i know it works. All i can say is it works, just make a pedal stop and go from there.

[SUNNY Z]

it had the stroke of a factory 91 240sx.

 

91 240sx not = 2000 Camaro. However, I've switched to a higher volume master ( larger diameter) in my camaro, with an adjustable throw. You DO NOT want to have a throw extensively longer than stock. If you over-extend it, you will damage the slave. I would check the throw of a stock ls1 master, and then buy a new master accordingly

[cheesepocket]

The Tilton master has a 1.1 inch stroke per their specs, both the 7/8 and the 15/16, and fitted to the 240 it looks like that provides about 1" stroke.

 

I got a second new master, still a Tilton, but 15/16". I was super careful to ease it in so I wouldn't blow out my slave, but still even with full stroke the clutch doesn't disengage.

 

I'm going to try this weekend to bleed several quarts through to eliminate the possbility of air, but now it's pointing more and more to full removal to see if it's the slave or the pressure plate. This is super frustrating, of all the things to go wrong....

[Zzeal]

Here's a shot of the clutch master that came in an '06 GTO LS2. It's 3/4" in diameter and the plunger has a movement of about 15/16" without forcing it. Its cute little reservoir is only 1-1/4" in diameter. Not a whole lot of fluid needed here.

 

I did the math of going to a 15/16" cylinder, it only provides 64% of the force provided by the stock 3/4". The 7/8" cylinder you first used provided 73%.

 

I talked with Tilton tech some time ago when I was sourcing a cylinder and they recommended a 3/4" unit for my stock LS6 clutch rather than a 7/8".

 

Still, lots of people are making 7/8's work, you've gotta have something else going on. I feel for 'ya.

 

[cheesepocket]

Problem solved! A traditional style bleed with a friend on the clutch pedal was not going to solve this. But I used a Mityvac to pull fluid through the bleeder hose attached to the slave, and I saw air bubbles for awhile, then none. I also didn't want to depend on the speed bleeder so I closed it up when not pulling the vacuum.

 

I put the 7/8" master back on before all of this as I sure didn't want to blow out the slave.

 

Thanks to all the Z help on this forum.

 

So much for the 1st drive, it is 5 degrees outside and we've had snow on the ground for 3 weeks. Pretty tough having to wait another 4 months before I get to drive it.

[kj280z]

Problem solved! A traditional style bleed with a friend on the clutch pedal was not going to solve this. But I used a Mityvac to pull fluid through the bleeder hose attached to the slave, and I saw air bubbles for awhile, then none. I also didn't want to depend on the speed bleeder so I closed it up when not pulling the vacuum.

 

I put the 7/8" master back on before all of this as I sure didn't want to blow out the slave.

 

Thanks to all the Z help on this forum.

 

So much for the 1st drive, it is 5 degrees outside and we've had snow on the ground for 3 weeks. Pretty tough having to wait another 4 months before I get to drive it.

 

Go out and do some donuts in the snow! Just because it's cold out it shouldn't stop you from going out for a good shake down run!

[SUNNY Z]

Yeah, I'm not sure what's worse; having a car you can drive, with weather that won't permit, or, in my case, having weather that's nice enough, and two cars that aren't mobile. I feel your pain, believe me.