I've got a t56 in my car but I'm not running the stock lt1 style bellhousing or slave cylinder/clutch fork. I picked up the trans with the bellhousing and went with a Weir Hot Rod Products housing and hydaulic throwout bearing. Works beautifully for normal driving but whenever I try to abuve the car or slam through the gears the clutch starts to act funny as if even when pressing the pedal all the way down the clutch isn't engaging all the way and it's real hard to get into/out of each gear. Fluid level looks fine all the time, no bubbles or anything. I bench bled it and then vacuum bled it in the car. Any suggestions or help?

 

How's the pilot bearing/bushing? Which did you use?

 

I used a bushing from the clutch kit. Found a socket just a tad bigger and tapped it in. It seemed like it went in fine. Would that affect things only after I've been beating on it?

 

OK, so there's at least something there. Hard to say if it would change from hard use.

A bearing would be better. You might want to try one.

 

what kind of clutch is it? i think i might have an answer for you

 

Stock style from schmucks. Seems great all the time I'm driving except after I bang through the gears once, then it gets stiff on me.

 

And for those of you who dont have a "Schmucks" (Schuck's), it's basically a branch of Advanced Auto, they have the same website basically even lol.

 

www.CSKauto.com

Checker, Schucks, Kragen.

 

It may be this:
Many hydraulic clutch hose assemblies have a crimp on the hose end that allows a retaining pin to be inserted into the mating part (hydraulic cylinder) to ensure the hose stays put.
Sometimes these are crimped down a bit too much. The end result is this- the fluid is forced through the restricted area when pushing down the clutch pedal but the fluid cannot return (clutch re-engage) quickly enough during fast shifts to allow the clutch to fully re-engage.

Sometimes it is progressive- during fast shifting, it may not be noticed during 1st and 2nd, but the clutch wll really start to slip in 3rd and 4th.

It may not be the crimp- but maybe there is some other source of restriction in the clutch hydraulic system.

This condition is often resolved by disassembling the hydraulic clutch assembly and drilling out the crimped piece to enlarge the bore slightly.

Anyway, worth a look.

S-D

 

a lot fo the 4th gen guys have problems with this, and they do whats called a drill mod. They drill the line to the master cylinder little bigger so the fluid can move faster when high rev shifting occurs.

 

Do you know what line they're drilling or where I can get more info on this mod?

I think I know what part you're talking about. The hose that goes directly off the back of the MC? I remember that part from when I first put this in. Problem is, I don't have a stock style MC. It's actually a 1" bore tilton unit. I had to fab my own bracket to get it to mount up correctly because it was set up to mount level. Well this unit has a screw on fitting on the back of it so there isn't any retaining pin.

I appreciate your help, thanks.

 

http://www.installuniversity.com/ins...sity/index.htm
This shows how to install a new master cylinder and do a drill mod on a 4th gen, but will give you an idea what you hae to do.

Just scroll down a little bit and it will talk about how to do the drill mod.

P.S. - if you have any more questions about it go to ls1tech.com and search drill mod there's lots of information on it over there.

 

TTT; Drill mod seems to be only for the ls1's and they're specific MC clutch line.

Anyone have any other suggestions?

 

It still sounds like a restriction of some sort to me. I'm sure you have now ruled out any possible restriction in the hydraulic system.
Have you contacted Weir? Maybe they have been getting calls on their custom throw-out bearing?
Was the tubing kinked or even come close to being kinked during installation?
I really can't think of any other cause for the problem you describe, unless the Weir throw-out binds during fast shifting or something weird like that. Weir would probably be the best source to shed light on that possibility (though they may be biased!)
Best of luck-
S-D

 

Also-
Have you had someone work the clutch slowly while you observe the hydraulic TO action through the inspection hole (maybe where the hydraulic lines come out)? Then have them really jack the clutch rapidly 8 or 9 times and see if the TO bearing is still returing instantly?
Just a thought.

I see the drill mod is for ls1 or some particular style of hydraulic system, but the concept is the same if there is some type of restriction somewhere in the line.

S-D

 

The drill mod is for the ls1's specific clutch line. GM puts some sort of restriction in the line off the MC.

I don't think it's anything like that though. Otherwise it'd happen while I'm slamming through the gears, not start after a few shifts.

I called Weir today and they told me first off that I had air in the lines. Then after talking to the guy for awhile he suggested the line being too small or too long (it isn't, it's actually bigger and within the length of what they reccommend) or that the pressure plate is messed up somehow and not releasing completely. Warped or something like that. I have tommorrow off so I'l be taking a real good look at it. First off, vacuum bleeding the whole system, teflon taping all bleeder screws and then I'll look at the TO extension.

However, I don't know if it has to be at high RPM. It seems like if i quick shift at low R's it doesn't do it... I don't know. Hopefully it's something simple like air in the lines tommorrow.

 

I ripped out the MC today and bench bled it. Put it back in and vacuum bled it there just to be sure. I've been bleeding alot. It works tons better now but there is still some resistence after a romp through the gears. Oh well. Deal with that when I pull the engine.