tylerwerrin

Hi guys,

This isn't 100% camaro specific but I figured you guys were the experts so might as well give it a shot.

I transplanted a 93 LT1 from a Camaro with a T56 into a 1984 jaguar xj6. Everything is basically done minus this clutch situation.

The master i have is the Wilwood .75" bore compact master cylinder. It has 1.4" of total available stroke, but because of the pedal configuration I can take advantage of only around 3/4" or slightly more stroke.

I'm using a 1" bore slave cylinder from a 1990 camaro. The 93 camaro also had a 1" bore slave, but the 1990 has a bleeder on it. Anyways... while i was bleeding the clutch this weekend, i blew out the end of the slave cylinder. I'm not sure exactly what this means -- my first inclination was to think that I'm not pushing the pushrod in the slave forward enough, so the clutch is not pushing the fluid back into the slave at rest. I just pumped a ton of fluid into the cylinder and blew it out.

I don't know what the stroke of the original stock master is, so i can't calculate how much fluid gets moved in a stock application. Can anyone help me with ideas? Should I upgrade my pushrod in the slave? would i need a larger bore master?

Any help would be appreciated....

thanks!

Tyler

91 1LE

iTrader: (1)

I don't know the stroke on a stock slave cylinder but I do know you bled it incorrectly. It needs to be attached to the trans while bleeding. And it does have a bleeder, it's just really hard to find.

2. Where the heck is the bleeder screw for this thing?

One of the more difficult things about a T56 is accessing the bleeder screw. You cannot see it without a mirror, so you must rely on feel. If you are beneath the car and you are looking at the transmission where the master cylinder line connects to the slave cylinder, reach straight upward. At the very top of the transmission you will feel a hex-shaped rod about two inches in length. That is the bleeder screw, which comes directly from the slave cylinder.

To bleed the system, you will need a 7/16th” socket, thin-walled, in ¼ drive. It would behoove you to use a few swivels and extensions. I also highly recommend taping the socket to the extension/swivel/etc. If for some reason you drop the socket, it will end up at the bottom of the bellhousing and you will have a hell of a time fishing it out.

If you plan to bleed traditionally, you will need two people. One under the car opening and tightening the bleeder screw, and another in the car operating the pedal.

If you are not squeamish about cutting into your car, you can make traditional bleeding a one man job. Underneath the car, do your best to put a dent in the transmission tunnel, straight across from the bleeder screw, with a punch. Get into the car and pull back the carpet around the pedals, and cut a small ‘access square’ so that you can also fold back the plastic, foam-lined piece beneath the carpet. Under that you will find the dent you made. With a 1” holesaw, cut a small part of the tunnel out. Now, with a 7/16” socket and a few extensions, you can reach the bleeder while being in the car! From here you can operate the pedal with your hand and use your other hand to tighten/loosen the screw. When you are done, simply put a piece of duct tape over the hole and recover with the carpet. It does not introduce any more noise into the cabinet.

Here is what the hole looks like (I had to drill mine a couple times to get it right)


3. Different options for bleeding the system

Your best bet for learning how to bleed would be to search this forum. People have posted many different ways of removing air from the system, from using a traditional way, a mity vac, etc. If you want to do it traditionally (whether by yourself or with help) it is very simple. The reservoir needs to be full of fluid the whole time, otherwise you will just continue to introduce more air into the system. With the bleeder closed, push the pedal to the floor. Open the bleeder (fluid and air will come out). Close the bleeder, release the pedal, bring it all the way back up. This process gets repeated until you have a firm clutch pedal. Don’t panic – it can take up to 30 minutes to get it bled correctly.

The fluid that dribbles out will end up in the bottom of the bellhousing, and it will seep out that rectangular hole in the bottom and take care of itself. If you would like, you can spray some brake cleaner into the cavity to speed the process along.


By using a larger bore on the slave than the master you are also losing stroke length. If their bores are equal their travel will be equal. Increase the master bore size and the slave travel will increase or you could get a smaller bore master, or both.

Jaxom

Are you using the top 3/4" of stroke on the master or the bottom 3/4"? It's important that when the master is released the plunger is at the top of the stroke so that any excess pressure can release back into the reservoir, or fluid can be drawn in FROM the reservoir if needed. This is how the system normalizes and "self-adjusts" for clutch wear. If the plunger is not coming all the way up you may need to shorten the rod going to the pedal arm so that it does.

Jaxom

This description is accurate for an LS1 style trans with the hydraulic throwout bearing inside the bellhousing. NOT for an LT1 trans with a traditional external slave cylinder. The LT1 slave has no bleeder as the hydraulic system self-bleeds with each stroke of the clutch.

FWIW I'm using a '91 slave cylinder with a '95 master cylinder and pressure line. It's been working great for 8 years and two different clutches in two different cars.

The slave cylinder DOES need to be mounted to the trans while bleeding, though.

tylerwerrin

When i let go of the clutch, the master is completely released -- i guess that means that I am using the stroke from the bottom of the cylinder. Like i mentioned above I'm getting about 3/4" or slightly more whenever I depress the clutch. My slave is like you said Jaxom -- it is externally mounted like your 1991. I know there is one slave cylinder size larger available from summit (1.25" bore), which might lessen pedal pressure.

I measured my clutch pedal ratio -- it is 6.5 -- perhaps that is contributing to the stiff clutch. That could leave only a push rod that is too short in my slave, and not pushing the actuator arm. Do you know what the stroke on your master is? I could compare how much fluid is being pushed -- although I still don't get why my slave burst unless my push rod is too short but since it works for you, I'm guessing the rod is the right length! Ahhh!

Jaxom

If the plunger in the master cylinder comes all the way up to the retaining clip when you're off the pedal, then you're using the top part of the stroke, which is how it needs to be.

Using a larger bore slave will make the pedal easier to push, but will also reduce how far the slave travels, and might cause the clutch to drag (or not disengage at all) especially with a small bore master.

I don't know offhand what the stroke is on a factory master, but I'm quite certain that the small-bore master you're using won't move NEAR enough fluid to blow out the slave on it's own. It very well may be that your slave rod is too short...to be honest I don't remember if I used the T5 or the T56 slave rod when I put mine together. It's been a long time. When you go to bolt the slave up to the trans, and the rod first contacts the clutch fork, how much space is there between the slave's mounting flange and the trans spacer where it bolts up? You should have to compress the slave cylinder at least an inch or two before the flanges meet.

Lemme suggest something else: If the clutch fork is not engaged to the throwout bearing and fork pivot properly, it can throw the geometry off at the slave cylinder rod. I saw a guy blow a slave on his '97 once by doing that...he had the "fingers" of the clutch fork on the wrong side of the throwout bearing flange. Definitely worth checking.

tylerwerrin

Thanks for the info Jaxom -- let me try and answer your suggestions:

I bought the engine and trans while it was still installed in a camaro -- i never took them apart. The clutch system seemed to work well while the trans was still in the car. I then dropped the engine/trans into my current set up. I don't think anything was installed backwards, or off tilt -- although it is possible that something like that may have happened. I'd have to back off the tranny to see for myself.

I think the slave blew because i was pumping too much fluid into the slave, and the pushrod on the slave was fully extended. I don't know if the T5 pushrod is the same length as the T56 pushrod. It may also have blown due to faulty bleeding. Asking around on various forums, it may have been me bleeding too quickly -- I pumped the pedal a few times after closing the bleeder valve, and that is what caused the slave to blow out -- only after a few pumps did it feel like i was getting any clutch at all.

When i worked out the math, (again, doubled checked with a physics major i went to school with back in the day), the slave traveled worked out to be 1.06cm (possibly a little more if i'm getting slightly more master cylinder stroke). I have no idea how much i need the slave to move to disengage the clutch. What's more, the pedal effort was very very high (when i finally got clutch before it blew out... although maybe that was just the piston bottoming out....).

I guess the question becomes, how far does the pushrod have to travel to disengage the clutch properly... any thoughts?

Jaxom

You don't have to back the trans out to check the fork installation. If you take the two nuts off the slave cylinder and remove it, you'll find that the spacer in between the slave and the bellhousing slides off the studs. Once it's off you can inspect the fork, and even disengage it from its pivot and the throwout bearing. Try to wiggle it back and forth in the direction of the slave rod movement. If it moves much at all, then it's likely the problem. It may have gotten jarred loose during the removal/installation somehow.

I'd have to pull mine apart and measure to give you accurate stroke numbers. I want to say my slave travels about an inch, but it releases near the top so you could probably get by with significantly less. Regardless, too little of stroke and/or fluid movement won't blow the slave cylinder. It'll just keep the clutch from disengaging fully. And you certainly don't have too much.

The bit about the clutch getting stiff before it blew out definitely sounds like the slave plunger hitting its retaining clip, but that brings us back to the hydraulics and geometry, because that SHOULDN'T EVER HAPPEN. Pumping the clutch should only cause the slave to move back and forth, not farther and farther out. The tension of the clutch pressure plate should be pushing the slave plunger back in, and thusly pushing the clutch pedal up. Which brings us back to the clutch fork/slave rod geometry.

If I had the car in my shop the first thing I'd do is unbolt the slave. See how far off the flange the internal spring pushes it...should be at least and inch, maybe two. If that looks good, pull the spacer off and just look up inside the bellhousing. If the fork is loose that's an obvious problem. Try to see if the fork is in the groove of the throwout bearing. I'm betting there's something amiss in this area, although the slave rod being too short is still a possibility. I don't suppose you can get your hands on the slave cylinder from the donor car, can you? To compare the rods? I've also seen the clutch fork pivot bolt pull out of its threads if it isn't torqued properly, but that shouldn't be a problem if you never disassembled it.

tylerwerrin

I never removed the spacer that goes between the transmission and the slave cylinder. However, with the slave removed i could see the clutch fork arm. It had a tiny bit of lash and then it got stiff when i pushed on it -- i got maybe 1/3" of movement. The damn thing was so stiff past that 1/3" of lash i couldnt move it at all. The guy i bought the setup from said he had just installed a stage 1 clutch, which i'm guessing means stiff.

I'll try and remove the spacer next time I'm under the car and see if I see anything suspicious. Another buddy of mine said something sounds like it's locked up/frozen up but I just don't see where that could have happened. Thanks for your trouble shooting advice -- if anything else comes to mind, or you have any other tips let me know.

Summit has a slave cylinder that is 1.25", which would be easier on the foot but move less -- i don't have the old master/slave setup (shoulda snagged it when i had the car, but its long gone now). I've got a few things to try...