Wondering about installing 4 spd into auto

[chumstone]

I have a turbo 400 and have been thinking of installing a 4 speed transmission. That 400 probably eats about 20% more fuel. Seems like these older rigs should be easy or am I wrong again? Truck is a 73, 3/4 ton 2x4 454. Thanks.

[benoit454]

Well you'll need all the 4 spd. parts, pedals, frame bracket, z bar, ball studs, upper and lower pushrods, bellhousing, clutch fork, flywheel, clutch kit.

Maybe a different crossmember? not sure on that.

I think they may be different lengths so you'd need the driveshaft lengthened or cut down?

Also if yours is a 2wd and column shift I think you need to cut out the low hump floor in the middle, over the transmission and put in a high hump, That may be only IF you use the sm465. if you use a saginaw like from a car maybe you won't have to switch them, I'm not too sure.

[old Rusty C10]

I had a three speed and the crossmember was ok to use but i had to make a set of holes if i remember right cause it was in a different position that was a 76 2 wheel drive going from 3 speed stick to automatic. both were longbeds and i used the driveshaft from the automatic i dont recall if there were differences in them or not but the automatic one had a new bearing and u joints on it so i used that one

[Srubydo1986]

Well i just took a manual apart and build an automatic. two different truck but same years (1986)

Like they said if you dont have a high hump youll have to cut it out or you might be lucky and its unboltable. Youll nee basicly a parts truck that manual i like the hydrolic clutch cause that what my old c10 was, some like the manual clutch.

The crossmembers are fiferent from auto to manual if you need picture i can take any you might need of the tranny youll need to the member to the hydrolic set up, I have it all. Just let me know ill take some pictures.

But he job isnt to hard it mostly cut a hole in the for for a high hump put another petal in put in the needed parts to go to tranny and put in the crossmember and tranny.

[shadetree]

The high hump will not be needed, if he goes with a "car-type" four speed.

[Srubydo1986]

this is true didnt think of that but wouldnt that be more difficukt then using parts made for our trucks. Iv never seen this conversion with a car 4 speed Does anyone have pics of this so i could see them also so chumstone can get an idea to.

[Roper]

Originally Posted by chumstone

I have a turbo 400 and have been thinking of installing a 4 speed transmission. That 400 probably eats about 20% more fuel. Seems like these older rigs should be easy or am I wrong again? Truck is a 73, 3/4 ton 2x4 454. Thanks.

Are you talking 700r4? If i was you I would keep the th400 and maybe look at a gear venders overdrive.
Actually if I was you I would just leave my truck alone. Those th400 were the toughest auto ever made and for what an overdrive will cost, well your going to have to drive a lot of miles before it would ever pay. I dont think your going to burn 20% less fuel with an overdrive.
My truck at one point had 28" tires and 308 rear ends with a th350. I swapped in 4.10s and 33" tires and my fuel mileage improved. Course most of the time im hauling something with my truck usually at speeds not over 60mph.

[Srubydo1986]

I though t 4 speed would be a manual trans. not a 4 speed auto.

[benoit454]

I agree with shadetree that's why I said maybe not on alot.

I had a 76 c10 2wd short bed with a factory 3 speed, and I got a 74 camaro saginaw 4 speed, it bolted right in no problem, same driveshaft, crossmember and all. I used the 3 speed shifter on it, well the mounting brackets, so it was fine. I later found out it's the exact same length and spline count as a short tail th350.

So a short tail th350, car or camaro saginaw 4 speed, and a truck saginaw 3 speed are the same length and driveshaft. All my ork and linkage all worked fine too. I had already converted the 3 speed truck to floor shift before hand. I can't remember if it was high or low trans hump though.

[swb85]

Originally Posted by Srubydo1986

Iv never seen this conversion with a car 4 speed Does anyone have pics of this so i could see them also so chumstone can get an idea to.

I've got a chevelle m21 4 speed in my '85 swb. What do you want pics of?