4 speed Trans Tunnel mods

-
Kiddart1

Kiddart1

Well-Known Member
Joined
Aug 27, 2008
Messages
248
Reaction score
139
Location
Macomb Michigan
I have a 4 speed trans tunnel in my demon, has anyone put a 6 or 8speed Automatic trans in an A-body with a 4 speed tunnel. do i have to open any areas up or can it be left alone. I know i have to make a mount i just dont want to cut the floor. I will be happy running my 727 if need be.

let me know if anyone has done it. I have only ran 727 and 904s behind the gen 3's
 
Last edited:
Kiddart1 said:
I have a 4 speed trans tunnel in my demon, has anyone put a 6 or 8speed trans in an Abody with a 4 speed tunnel. do i have to open any areas up or can it be left alone. I know i have to make a mount i just dont want to cut the floor. I will be happy running my 727 if need be.

let me know if anyone has done it. I have only ran 727 and 904s behind the gen 3's
Click to expand...
I put a T60 in my 72 Demon and had to fabricate a new tunnel.

IMG_0315.jpeg
 
The 4 speed tunnel doesn't give any extra room for a T56 so you will do most of the same work as an auto. The T56 is too tall and wide to fit regardless of which tunnel you start with.

@goldduster318 did this conversion here and started with a 4 speed tunnel.

img_20180910_131341355-jpg.1715222331



Pretty sure an 8HP will be similar, but it depends on motor location. I think @HemiDenny got an 8HP to fit under the floor with his COC kit but the motor is forward a little and down to do it if I remember correctly.

Here is @4.7Light's 8HP swap, he cut the whole tunnel out. Can't say for sure, but I really don't think a 4 speed tunnel will make that install any easier either.

img20240421134424-jpg.1716239746
 
DionR said:
The 4 speed tunnel doesn't give any extra room for a T56 so you will do most of the same work as an auto. The T56 is too tall and wide to fit regardless of which tunnel you start with.

@goldduster318 did this conversion here and started with a 4 speed tunnel.

img_20180910_131341355-jpg.1715222331



Pretty sure an 8HP will be similar, but it depends on motor location. I think @HemiDenny got an 8HP to fit under the floor with his COC kit but the motor is forward a little and down to do it if I remember correctly.

Here is @4.7Light's 8HP swap, he cut the whole tunnel out. Can't say for sure, but I really don't think a 4 speed tunnel will make that install any easier either.

img20240421134424-jpg.1716239746
Click to expand...
Mine is based off a six speed transmission install motor trend article. The very transmission your installing
https://www.motortrend.com/how-to/install-tremec-t56-6-speed-plymouth-duster-mopar/
 
I will add this your going to have a blast in that car track mode on 8HP70 8 speed auto is stupid fun. The car with 450 plus HP for little old 360 is stupid fast. I get a good laugh out of twin turbo v6 Explorers and other modern crap and I can walk off. I need a roll cage now the car is way to fast! Even with 2 x Frame connectors and trans is a bit heavier and new interior car is heavier. It will flat out blast a 360 727 car no comparison with what I had. Hear ratios matter and of course the shift maps and stays in the power band never falls out. Manual shift with the ZF it drives like a manual simply magic.

If I didn't have bad hip I would have done the 6 speed manual.
 
I absolutely don't recommend doing mods and just taking the top of the crossmember out or welding some piece of flat plate, that does absolutely nothing at all. You need a 3D shape line in my car. The car has no stiffness then and its even worse with Torsion Bars. That crossmember is very important.
 
You must log in or register to reply here.
-

Back
Top