Offical difference between 4T60 and "-HD"?

[z284pwr]

As we are researching for more info on rebuilding the transmission in our TGP, we were looking for possible rebuildable transmissions. Anyways, would anyone know the "official/actual" differences between the regular 4T60 and the 4T60-HD that came in the TGPs. Would they be differences in just the bands/steels/clutchs, or would it bei nthe actually gears and other parts? Question being because we were considering getting just a regular one and rebuilding it while we have the other one still in the car, then this question came up. Would we lose anything using a regular one with the new rebuild kit over the HD, or does this other, "HD," trans have the parts we would want?

[manitcor]

im not sure whats in the TGP "HD" trans but when I went for an HD rebuild this is what I did:

 

http://www.w-body.com/forum/viewtopic.php?t=35572&highlight=dynotech

 

The trans is rated to 350-400hp.

[Bossman429]

I'm sure you've read Jeff's differences sticky:

http://www.w-body.com/forum/viewtopic.php?t=12387

 

He lists a few little differences like hardened gears, and larger cooler lines.

 

I believe that the valve body may be different too, different shift points to use the power.

[mfewtrail]

I'm sure you've read Jeff's differences sticky:

http://www.w-body.com/forum/viewtopic.php?t=12387

 

He lists a few little differences like hardened gears, and larger cooler lines.

 

I believe that the valve body may be different too, different shift points to use the power.

 

Searching old posts I came up with the following.

 

- Our valve bodies are stamped with "turbo."

 

A quote from "Chris A"

 

"Converter is different, stall speed. Valve body is different. The calibrations for the shift firmness and speed are all different. There are a few other things but as far as functionality those are the important ones. Any other 4t60 will bolt up and move the car, but its a crap shoot at how long it will last and how well it will function. I know a Turbo4t60 will act weird if the car is not making boost, and I know that a non Turbo4t60 can SEEM to work ok, but not last very long on a turbo motor. But that is just my experience. Since they have a turbo specific trans, I would say that it wouldn't work. But if you can get one cheap and build it for a turbo car, I would say it would work."

 

And another quote from Chris again(difference between shifting on normal 4T60 vs. turbo 4T60)

 

"Its hard to explain. But there is a difference. The modulation on the TGP trans is alot more progressive, since the car can build boost. IE, TV pressure VS line pressure seems to have an effect on the shift quality more in the TGP, it will be much harder than on an NA car with more TV pressure. This could be why NA 4t60's burn out faster on a TGP, the clutches probably slip more between shifts at the same throttle positions, since they are not being applied as firmly. Other than that the shift points may be differnt, but I never compared them that closely. The biggest thing I noticed was shift modulation."