Mr. Brett

iTrader: (13)

Long story short, I picked up a cam/heads 95 Z28 that supposedly had a blown trans. After having the T56 rebuilt, I found that the actual problem was a shredded rear end. Put a set of Motive 4.10's in, all good.

Now since getting it all together, I've had nothing but problems getting the clutch to disengage. The car starts fine, but once it's running, the clutch doesn't seem to be disengaging completely and I have to force it into gear. The car had a Spec stage 2 clutch when I first got it which was way too aggressive for this car. The throwout bearing was also loose since the retaining clip had broken, not sure how long he had driven it like that. I bled the the hydraulics, no change. Replaced the hydraulics with a pre-bled factory linkage, no change. Replaced the clutch/pressure plate with a factory style part from NAPA, no change. New throwout bearing, no change.

Before replacing the hydraulics, I thought the problem was either a bad master or slave. I was able to take the slave adapter off and close the gap about half and inch and was able to get the clutch to release and drive somewhat normally. Figured a new linkage would fix it but no joy. After installing the new linkage, I also noticed that the strap holding the cap on the slave rod did not break after depressing the pedal the first time, as it is my understanding is supposed to happen. Another thing is the clutch fork, it's super loose. I know it's supposed to pivot on the t-bolt, but even after engaging the throwout bearing, it moves over an inch, really sloppy. I've ordered a new fork and pivot, but I want to know that might be the issue before I take this transmission out for a third time. I don't think the fork can be slid onto the throwout the wrong way, can it? It's either on or off I would think. Could the pivot be bad/worn and cause this? Could the fork be bent? I'm at my wit's end with this car. Any help is much appreciated.

SPEC-01

iTrader: (2)

There are a couple of possibilities. I have seen folks have similar issues with using tne incorrect pivot and when having a bent fork or damaged pivot. Do you see excessive wear on any of the parts? The fork should move freely but it should not be sloppy.

Additionally, our Stage 2 is usually very driver friendly. Are you sure you had a Stage 2? Do you have pics of the clutch assembly that you removed? I would be happy to assess the pics if you want to send them to me.

Mr. Brett

iTrader: (13)

This is my first LT1/T56, so I wasn't sure what was normal as far as movement or wear on the fork and pivot while it was out. Now that I have it together, it's pretty clear that something is wrong. The trans is coming out this weekend and I'll be replacing the pivot, bolt and fork with new factory parts, I'm assuming that will fix this problem since everything else in the system is new. I was just hoping to get an opinion from the experts that confirmed my diagnosis. Seems like you've done that, thanks.

As far as the clutch, I was told it was a stage 2. It's not clearly marked, so I can't be sure. Honestly, I wish I would have been able to drive it with the rest of these issues sorted out so I could form an honest opinion. When I drove it briefly with the slave rigged to allow for clutch disengagement, it was REALLY rough. Reverse and low speed 1st and 2nd were awful, bucking like crazy. I'm sure it's possible that this was due to the clutch not engaging and disengaging correctly.

Mr. Brett

iTrader: (13)

Another question: would this explain why the strap on the new slave didn't break when I stepped on the pedal? Would a bad fork/pivot change the geometry enough to not allow full slave piston travel? I know that would also explain the engagement problem, so I'm assuming yes.

Mr. Brett

iTrader: (13)

Found this video on youtube, it seems to be what mine is doing. Is that a worn pivot? Or is the fork not fully engaging the TO bearing? I see there are two flat spots on the bearing, do I need to spin the crank to get it to line up with those flat spots and slide all the way on? The fork is sliding onto the bearing, but I don't get that definitive locking feeling that I've been told it makes once it's seated.

Ocala93TA

iTrader: (9)

That is normal the video , it could be the slave isnt pushing the fork far enough to release the clutch . If the rear was torn up when you bought it i would bet the person who had the car wasnt to easy on the slave either

Mr. Brett

iTrader: (13)

The car has a new a slave now (completely new hydraulic linkage, pre-bled) and the situation isn't changed though....

Today I pulled the trans back from the bell housing just enough to see what the fork was doing. It's engaging the TO bearing completely, but there is still a ton of play once it's on. It moves over an inch. I pulled the pivot and fork, pics are below. It seems like a ton of wear to me, but I don't have a new one to compare it to. Can somebody who knows give me an opinion on whether or not this is the problem? The pivot and fork are the only original parts in the system left.

Another thing to note about this whole situation, this car was driven with a loose throwout bearing for an extended period of time. The clip that holds it to the pressure plate was broken and the bearing was chattering like crazy. My thinking is that this wore down the pivot and fork, leading to the slop that is apparently throwing off the geometry of the fork. Any experts care to weigh in on that?

Mr. Brett

iTrader: (13)

Ok, so I installed the new fork and pivot, which fixed the problem. Now it surges like crazy at low speeds. Is that a slipping clutch? I'm guessing I screwed up the install or fried the new clutch driving it with everything else screwed up. Thoughts?

SPEC-01

iTrader: (2)

Explain what you you are experiencing. If the clutch is slipping then the RPM's will jump but you will see no gain in speed or momentum. Is that was is happening?

Mr. Brett

iTrader: (13)

The car bucks like crazy at low speeds in 1st and 2nd. It's not terrible once you get up to speed, but still doesn't feel right. It also feels like it doesn't want to rev higher than 3-4k. Can this be anything other than the clutch? I'm ready to pull it back apart and put the Spec stage 2 clutch back in at this point. I'm assuming the driveability issues I had with it before were due to the engagement issues, not the clutch itself.

SPEC-01

iTrader: (2)

You could be having a fuel, timing, spark related issue that is causing bucking to occur. Clutch chatter would happen when leaving from a stopped position and you seem to be saying that this is happening while you are already moving. I would suggest data-logging the car to see if there is any evidence of other issues.

Mr. Brett

iTrader: (13)

Sorry, this is from a stop through 1st and 2nd gear. If I hold the clutch a bit while giving it gas, I can minimize the bucking a bit. This is definitely a clutch issue.

SPEC-01

iTrader: (2)

Thanks for clarifying...that being said if the car is not willing to rev above 3-4000 it could still evidence other issues too. You haven't noted anything that supports the occurence of slippage to this point. Do you have pictures of the parts (even of the Stage 2 you removed)?

Mr. Brett

iTrader: (13)

I just took it out for a bit and can add some more details. First, the issue occurs in every gear, it's just far more noticeable in 1st and 2nd at low speeds and in reverse. It happened while cruising at 30mph in 3rd and 4th as well, but not nearly as bad. Second, there is a lot of vibration in the pedal when it's not being depressed. There is also plenty of noise coming from the trans (clutch chatter maybe?) I have pics of the stage 2 I removed, but it looks great. I also didn't have this problem when that clutch was in, it was simply the engagement problem. This problem started after I got the new clutch in, after replacing the TO bearing, hydraulic linkage and fork/pivot. I can also add that it is still not going into gear as smoothly as it should. I have to force it on startup, then it seems to get a little better after driving for a few minutes. I've been grinding 3rd almost every time, too, so I still don't think it's disengaging properly. Since all of this started after the clutch replacement, can this possibly be an improperly installed pressure plate? I tightened it to 15 ft lbs plus 30* per the specs I found online. I was in a rush and it was my first time though, so it's very possible I screwed that up. I'm very tempted to take this back apart and reinstall the stage 2 clutch, since it was broken in and per the previous owner, worked perfectly.

SPEC-01

iTrader: (2)

Improper torque application could easily affect the way the clutch works. If over-torqued or unevenly torqued you could see the plate deform under actuation or even see the cover crack. At this point removing the parts and examining them for fault would be ideal. Check for cracking and uneven diaphragm fingers as both of these things could evidence issues that would affect clutch function. Does the vibration get worse with RPM? If so then this could also be affecting balance. If you have to force the trans into gear the clutch isn't releasing. You have replaced all the other components so that leaves the currently installed clutch as a potential cause.

Mr. Brett

iTrader: (13)

The stage 2 clutch is going back in and I'm having the flywheel resurfaced. What is the correct torque spec for this clutch with factory bolts?

SPEC-01

iTrader: (2)

Use OE Torque Specs...that is what the kit is setup to use.

Mr. Brett

iTrader: (13)

It was either a bad or incorrectly installed clutch. Put the Spec Stage 2 back in as well as a resurfaced flywheel (which was warped, probably didn't help), torqued it to 22lbs instead of 15 and it drives pretty much normal now. There's a bit of chatter, kind of expected that with a performance clutch though. Thanks to all who helped out, glad to have this thing on the road finally.

SPEC-01

iTrader: (2)

Good deal! Thanks for the update and keep me posted if you need anything else!

jbradhill

Does anyone know the dimensions on the clutch fork pivot when new? Specifically the distance from the radius pivot area to the face where it bolts to the tranny?

I bought a used T56 for a 700R4 swap. When assembly was complete I had the same issue as previously described in this thread. I push the clutch all the way to the floor and it seems to be disengaged, but does not want to shift gears too well. If I turn off the motor, it shifts fine. This makes me think I am not quiet fully disengaged.

I don't think there is air in the master/slave cylinder, but will try to bleed again.

This made me wonder if there is some wear on the pivot, which could cause the disengagment to not quiet complete. If it is in the .010" range, then maybe just remove that amount from the face that bolts to the tranny and I am back to new specs.