dukvet76

Thought I'd post this as I wasn't getting a response in General. Can anyone assist:

I was having trouble with my t-56 transmission in my 2003 vette. The mechanic diagnosed the problem as an internal shifter mechanism fault. He recommended I replace the transmission.

I purchased a rebuilt transmission and had my garage install it. The car was now able to select all gears, but with grinding when selecting second gear. The transmission would grind when when up shifting and downshifting, and also grind when selecting while vehicle was stationary.

I then decided to get another rebuilt transmission, to minimize downtime and have the second one installed, and send the first one back for warranty/DOA. Once it was installed, the second transmission did not select 5th gear and would pop out of reverse, and pop out of 6th on the highway.

With no luck I returned this second transmission to the rebuilder and put the first rebuilt one back in the car. The rebuilder called me and notified me that the second transmission that I returned to him had the 5th and 6th reverse gear, 5th and 6th reverse shift slider, and all shift keys damaged.

He said that the cause of the damage was due to an improperly adjusted clutch hydraulic system. So now I have installed 2 transmissions and still am having difficulty.

Is there something that the mechanic is doing wrong with the install? Is there something other than the transmission that is causing this?

Bill Curlee

There are several questions that need to be answered before we can provide you proper and accurate guidance.

The VERY FIRST thought in my mind after only partially reading your post was CLUTCH.

YES,, you have a clutch that is NOT fully disengaging.

1. What clutch are you using?? Old OEM, New OEM, aftermarket?

2. What Clutch Components/drive line components were replaced and was it with OEM or aftermarket parts?

3. What clutch fluid are you using?

4. What transmission fluid are you using?

5 What shifter are you using and are the rubber bushings that secure it to the torque tube in good condition?????

You MECHANIC should have been able to tell that the clutch was NOT working correctly when the engine was first started and the car was moved 10 feet!!

First test drive by the mechanic should have put the car back on the rack!...

If you put the car in first hear and rev the engine,,, the car should NOT MOVE. I b et you a cold one that yours did..

Who is rebuilding your trannys?????

Bill C

Paul 75 L82

The geometry of the clutch pressure plate and the throw out bearing has to be right. Us old guys can remember when we just found the throw out bearing that was the right thickness and used it. It's not as easy now to do that but the importance of the relationship between these parts makes everything work right. Bill is spot on, all of those questions have to be right or your going to have problems.

Bill Curlee

When you go from old OEM to new OEM,, its pretty much an easy no worry repair. There are however specific things to look for and make sure that they are done correctly.

HOWEVER,,,,,,,,,,,,,, anytime you introduce ANY NON OEM part/s you may be introducing geometry errors that effect clutch engagement/disengagement.

There are a whole set of measurements that need to be taken to insure that the clutch will work as designed.
When some aftermarket clutches are installed, they require the addition of a SHIM placed behind the hydraulic slave to achieve the correct disengagement. The ONLY way to know if it needs to be shimmed and how much is by taking measurements.

Now that I know about the measurements and how important it is to be correct, I wouldn't even install an OEM clutch without taking the measurements.

Bill

lloyd

Bill is dead on! You have to many variables and several unknows. That will almost guarantee disaster.

dukvet76

So is this something that a regular mechanic should not be dealing with? It looks like there is more involved in properly installing a corvette transmission vs. a regular vehicle transmission, especially the T-56. We did not replace anything in the vehicle other than the transmission. The clutch, flywheel, etc are all original.

Bill Curlee

How many miles do you have on the drivetrain???

BC