87v6Bird

iTrader: (1)

Transmission Setup:
96 Camaro T56
96 Slave and Pedals
Tick Adjustable MC. (When this began I was using the stock MC. I replaced it in an attempt to fix my problem.)
SPEC Conversion Flywheel (2pc RMS to LT1 clutch)
RAM Pressure Plate
RAM Clutch disc (Since replaced with McLeod.)

My car's been down since February due to the transmission issues I'm about to describe. I'm at my wits end at this point. Any help is appreciated. I had already put 20,000 miles on this setup with no problems. It is not a fresh swap.

I was heading home from work when my trans stuck in second gear. I forcefully pushed it out of second and coasted to a parking lot. Once there, I noted that my clutch felt no different than usual. Engine off, it would go into all gears but not with the ease it had before. With the clutch depressed engine running, my trans would not go into 1st or 2nd. I could force it into 3rd-6th and Reverse though. In those gears, it made some nice noises that told me some thing was wrong. I called a wrecker and got it carried home.

I had/have no knowledge of the transmission's history before I got it so I assumed something had broke internally and it needed rebuilding. I dropped the transmission myself and carried it to a local shop while I took the down time to install SFC's on my car. Upon pickup of the trans, the shop had discovered badly worn synchro's, a chipped tooth on the 5/6 gear cluster, and a reverse retainer (or something along those lines) floating in the transmission. During all of this I never touched the clutch or its hydraulics.

When I finally reinstalled the transmission, it still would not go into to gear with the engine running. I called the shop and asked for their opinion on what could be wrong. Their suggestion was that my hydraulics needed bleeding so that is what I did. The problem was still there. I looked around online and saw that the stock MC is a source of problems with these cars so I decided that a Tick MC should solve the problem. With it installed, I adjusted it until the fork was hitting the pressure plate but my transmission still would not go into gear.

At this point, I had the car carried to the shop that rebuilt the transmission in hopes that they could identify the problem. As part of their investigation, they identified that my pilot bearing was non-existant and that my clutch disc was damaged. I had not discovered these things because I had operated on the assumption that it was a transmission problem. I provided them with a new pilot bearing and clutch disc and assumed this would solve my problem. It didn't. I received a call yesterday from the shop saying they were experiencing the same problem as before. I was personally at the shop this morning to look at it and talk face to face.

The shop suggested that there could be something wrong with the clutch fork and pivot. I've looked around online today and found some mention of others having the same problem who solved it by replacing the fork and pivot. Does anyone have any other suggestions?

Sorry for the long post but I want full disclosure on what I've done in case anyone sees any clues that I may have missed.

87v6Bird

iTrader: (1)

Here is a picture of the busted clutch disc. What you can't see is that it is also cracked on one of the webs going to the hub.



This video, although not mine, shows how much play my fork has. Is this normal?

87v6Bird

iTrader: (1)

The car is now back from the transmission shop unrepaired. They have no idea what is wrong and admitted as much to me.

I have disassembled the clutch that is on my car as well as the actual stock clutch that came with the transmission in a search for any clues to what is wrong. I can see no differences between the pressure plates. The clutch discs measure at different thicknesses but I expect that since one is used and worn and mine is brand new.

I have examined the pieces that make up the clutch linkage and although none of them in particular look too worn my thinking at this point is that I have tolerance stack up because so many different places are worn. With that said I am going to order a new throwout bearing, clutch fork, and t-bolt.

These pictures show the various places that have worn.

T-Bolt


Throwout Bearing




Clutch Fork

jmd

iTrader: (4)

Yes the fork is sloppy, riding on the pivot tee like a hot dog in a hallway. That's how they are and that's how we like them.

The flywheel is too tall (crank face to clutch surface) Or:
The disc is too thick, preventing release Or:
The pressure plate is internally at fault.

The easiest fix is to mill the tee shorter as compensation for aftermarket parts that are dimensionally thicker than original GM / Valeo clutches.

You might find more at-length posts by me and others searching like so: https://www.google.com/search?q=T56+...A+thirdgen.org

87v6Bird

iTrader: (1)

Thanks for the reply. I have since realized that my problem is not quite as unusual as I originally thought and have seen your posts along with others. Since I started this thread I'm going to finish it with a solution. I feel like all the reasons you list should have manifested themselves before which is what puzzles me so. I'm not saying one of those things isn't the problem it's just odd.

For reference, the disc that came out of my car measured 0.320", my replacement measures 0.331", and the disc that came with the trans measures 0.280".

87v6Bird

iTrader: (1)

I've finally got everything working. Replacing the clutch fork and t-bolt were not the answer though. It still would not disengage with the new components.

My solution was to weld more material onto the contact points of the clutch fork. I added about 0.125" to the pads. So it went from ~0.435" to ~0.460" diameter.

jdpolzin

What flywheel are you using? I'm having the same issues but I can get my clutch to disengage before the fork hits the pressure plate. I have a 383 externally balanced with the SPEC sc66s-400 conversion flywheel. This flywheel uses a 3/16" thick spacer between the flywheel and the crank. I'm thinking this spacer is my problem but after talking with SPEC, they don't make a bolt in style counterbalancer.

87v6Bird

iTrader: (1)

I am using the same flywheel. I looked through my receipts until I found it. I thought that I would need the spacer like you are using but when I received the flywheel it had a bolt in weight. I don't have any vibration issues.

I definitely agree that the spacer could be the cause of your problem. This clutch setup is sensitive to the heights of everything.

jdpolzin

Is yours an sc66s-400? Or is it just an sc66s?

87v6Bird

iTrader: (1)

You're right. Mine is just an SC66S. I don't remember seeing any other option for a 2PC RMS to LT1 clutch on SPECs website. What is unique about the SC66S-400?

jdpolzin

Apparently it uses the spacer instead of the bolt in weight. I've gone rounds with the guy at SPEC before I installed this and after, which of course it doesn't work. He refuses to admit that this is wrong. So I'm going to call again today and simply ask for the bolt in weight....again. This is the first SPEC product I've ever bought, and it will be the last.

TFS355S10

iTrader: (2)

The LT1 style clutch is a POS, (IMHO), but I just wanted to share how I adjust mine. It's probably not the correct way, but it works, takes a few minutes and should work with any parts combo.

When I first got my T56 I didn't get the clutch slave cylinder spacer gizmo with it.

Stole this pic off ebay to show the piece I'm talking about;



Anyway, at first, I got a rough measurement from a forum member somewhere, (dunno if it was here or not), and built my own because I couldn't find one on ebay at the time. Kinda ugly, but worked fine.



At least until the throwout bearing came apart. (The whole clutch set was used when installed. Have no idea how many miles).

So I install a new, (stock replacement), clutch set and put it all back together to discover the new clutch wouldn't release or engage, (one or the other, but at the moment I can't remember which).

Being pressed for time and needing the truck, (it's in a Sonoma pickup), I look for the most obvious reason it's not working and decide it's probably my home made slave cylinder spacer.
Since I wasn't sure if it was too thick or too thin, I remove the spacer and start experimenting without it. Just using the nuts to adjust the slave cylinder distance to where it releases and engages normally.
I ran out of time that weekend to rebuild the spacer so I double nutted the slave to keep it in adjustment.
That's been about 20,000 miles ago. I never have got around to rebuilding my spacer lol, and it's still working just fine.

87v6Bird

iTrader: (1)

I don't think there's anything inherently wrong with a pull style clutch. You see them in plenty of other applications. GM just tried to fit everything into too shallow of a bellhousing. As a result, the tolerances on everything are tighter than they are for other clutch setups.