pnhigg

iTrader: (3)

This may be a little out of normal for many of you guys, but any help would be great, as I am about to pull my hair out.
I have a 92 fullsize chevy truck with a 5.3/5t6 combo.
The tranny was recently taken apart at KeislerAuto, and previous to that myself and all the internals look as good as new.
I recently changed the stock fbody clutch with a ls7 clutch and flywheel.
At the time I also put in a new slave cylinder, and a new master cylinder (from the truck)
Since the clutch change, I am having a little trouble getting the truck to take the next higher gear if I am accelerating much at all.
At very, very slow speed, the gears change fine, but under even half throttle, the change is challenging.
Also the when I was out driving it trying to figure out what was going on, I was rolling along at about 40mph with the transmission in 4th gear and the clutch on the floor. With the clutch pushed to the floor, I spun the engine quickly up to about 3500 rpm, and when I do that from some point behind the engine to the rearend, there become a loud thrashing sound and the truck begins to pull, like the clutch is being released.
To me it sounds as though I am not getting complete clutch release, but I want to be sure as I have had the tranny out three times over the past couple months for various reasons, and would like to get some ideas before taking it out again.

Any and all help will be greatly appreciated.
If anyone is in the Lexington KY area and has some familiarity with t56 issues let me know, as I would love for you to drive it as the symptoms are slightly difficult to describe.

wrencher

iTrader: (2)

Sounds like hydraulic issues.
How does the pedal feel?
Maybe need to make the clutch master adjustable to get the free play out of the pedal.

pnhigg

iTrader: (3)

The pedle feels ok, but you don't start feeling resistance until about half way down. It feels similar to how it was with the old tranny in it.
The clutch picks up right on the floor, and I have read that a lot of the ls7 clutches begin life releasing right against the floor, but then move up after a few miles, but I am afraid to drive it much because I don't want to break something more expensive.

Thanks for the help

wrencher

iTrader: (2)

Ya that doesnt sound right. You really dont want the engagment point at the maximum pedal travel. ( off the floor)

You said in the first post " a new master cylinder (from the truck)"
So it is a hybrid hydraulic system then? The stock F-body master bore is 3/4" just a FYI
You would benfit highly IMO from an adjustable master. Assuming you have absolutely no air in the hydraulics that would be your next step.
You could adjust that freeplay out of the pedal. Then instead of all that 'cush' when you first push the pedal. You can have it working when you intially press the pedal & likely improve it to release/ engage 1/2 way.
That would likely make a world of difference.

pnhigg

iTrader: (3)

That's right it is a hybrid hydraulic system. Truck master, and fbody slave, both of which are new.
I have my old master from the truck.
I will take it apart one night this week to measure the bore to see how it compares to the fbody master.
I have bled the system well, so I feel sure I have no air.
The confusion stemmed from the fact that the hydraulic system worked ok with the stock fbody clutch.

Thanks for the help.

pnhigg

iTrader: (3)

I added an adjustable master which moved the release point up to about mid way down the clutch throw.
No change in the performance of the clutch.
Do I need to try to shim the clutch so it is closer to the pressure plate? If so, how thick should I go?

Thanks guys

Proud2bSS

iTrader: (2)

My SPEC shim is .115". This shim moved my engagement point from the floor to 1/3 up the pedal.

pnhigg

iTrader: (3)

Thanks for the ideas.
I took the tranny back out today, and found a completely exhausted pilot bearing.
Could this be the culprit for the above symptoms?

Thanks again.

snake charmer

iTrader: (118)

Adjustable is the way to go my friend .

pnhigg

iTrader: (3)

It has an adjustable ms already