Can a 4HDD be put in place of a 6HDD in a 96 VS

[matstar1000]

My 6HDD is stuffed and I have a 4HDD in my shed and I was wondering if anyone has fitted a 4HDD in place of a 6HDD and how did it go and what modifications were required?

Can a 4HDD be put in place of a 6HDD in a 96 VS

[ParkwayDrv]

Each year model has a difference.

VR 1994 - 4HDD/V6 - 4HBD/V8 first electonically controlled auto.
VR II 1995 - 5HDD/V6 - 5HBD/V8 extra solenoid fitted to provide softer "LOCK UP" torque converter clutch apply.
VS 1996 - 6HDD/V6 - 6HBD/V8 the design of the previously added solenoid was changed and is not backwards compatible with the previous model.
VS II 1997-7HDD/V6 - 7HBD/V8 basically the same as the 1996 unit except the thread size of the cooler pipe unions was enlarged.

Although the above units may physically fit other model vehicles,the electrical differences are sufficient to cause a conflict with the computer software thus causing the unit to go into "FAILSAFE" (limp mode).

5H** units and later were equipped with the "PWM" (Pulse Width Modulation) system in order to allow the digital signals from the computer to better control the "LOCK UP" clutch system.

i found this by searching

[Guzzoline addict]

I havent done a 4hdd to 6hdd conversion ,but when i rebuild my 4hdd i used a 6hdd for parts.Didnt notice anything deferent. In the manual i got with the rebuild kit (to suit both 4hdd and 6hdd) it said the 3-2 control solenoid in the 1993-1995 box resistance was 10-15ohms at 20cel and 20-31ohms at 20cel in the 1996-2000 box , The tcc had a resistance of 20-40ohms for the 1993-1994 box and 10-15ohms for the 1995-2000 box,The 1-2 and 2-3 shift solenoids all have the same restance. Hope this can help

[matstar1000]

I spoke with a auto trans mechanic and he said to put a 4HDD in a VS you can simlpy change the valve bodies over, thus it will have the 13 pin connector which will stop the car going into limp home mode. The auto will work fine and will behave as a standard VR auto, he said the VS auto had the other clutch that gave it a smoother change.

So I think I will give it ago if I cant find a good 6HDD by the weekend

[James39]

With that method, it then should work in reverse?
VS gear box in a VR?

[matstar1000]

Basically he said that by changing the valvebody it was just to satisy the computer, so it gets a signal from the 13th pin by being hooked up, thus does not through a fault and go in limp mode, besides this there is no other reason to change it. The VR box has everything from the VS computer it needs to function correctly. So maybe putting a VS tranny in a VR would be crap as the ECU cant activate the clutch lock up or what ever the newer function the VS box has that the 13th pin has to do with.

[matstar1000]

just so everyone knows for the future as this question pops up. I did not end up putting the 4HDD in, I brought a whole 1997 VS for $200 so it became the donner, put the 7HDD in place of the 6HDD, all I had to do was change the brass fittings, that screw into the box that the cooling lines attach, into the 7HDD box and all is fine.