cj7 tranny question

[pedalhappy]

i have a friend with a '79 cj7 with the 304 and he's wantin to swap out the 3 spd for a 4. i've tried doin some research on it tonight and running on very little sleep, i haven't found squat. whats a good, easy, and relatively cheap swap?

[Ray H]

Originally Posted by pedalhappy

i have a friend with a '79 cj7 with the 304 and he's wantin to swap out the 3 spd for a 4. i've tried doin some research on it tonight and running on very little sleep, i haven't found squat. whats a good, easy, and relatively cheap swap?

If Im not mistaken, in 79 the auto trans that was used behind the V8 was the Chevy turbo 400. Thats an outstanding heavy duty trans. Personally I would never think of swapping it out.
If hes just set on doing it though, probably his bet bet is to look at other Chevy transmissions like the 2004R, 700R4, 4L80E. He will have to buy the computer wiring harness to go with the new tranny because I think those are all computer controlled. Im not much of a Chevy guy so I cant say for sure if he will need adaptors or if the swap would be a bolt it. My guess would be that he will need at least one adaptor, maybe two.
Another option would be using an AW4 transmission from an XJ Cherokee. Its not nearly as heavy duty as what he has now but its still a good reliable medium duty 4 speed transmission. You may get by with needing only one adaptor with that swap but will still need new electronics. Whatever swap he does, the Quadratrac t-case is going to be the problem. Nothing mates up to it and to swap it out would also require swapping rear axles out. A hole can of worms.
Send him here
http://www.jeepsunlimited.com/forums...splay.php?f=36
Someone will be able to fill in the blanks.

[pedalhappy]

to be more specific about what i asked, its a 3 speed manual and he wants to keep it a manual but a 4 spd

[Stouttrout]

Originally Posted by pedalhappy

to be more specific about what i asked, its a 3 speed manual and he wants to keep it a manual but a 4 spd

What Tcase does he have. This is going to be the real clincher. There are several Trans out there that will work. The t-176 is one of the best and strongest.

[pedalhappy]

i'll be going to his house in a little while. i reckon we'll climb up under and see what we can spot. so you know, i'm completely clueless as to what i'm looking for, and i doubt he has much of a better understanding so i might end up just coming back with a bunch of gobbldy goop numbers.

[pedalhappy]

ok..i took a look on the tcase. on the (output shaft snout?) was the most promising number, but i couldnt read it completely. its looked something like 518-19-something. the only ones im sure of are 5 and 19. i know thats not much help

[Ray H]

Originally Posted by pedalhappy

ok..i took a look on the tcase. on the (output shaft snout?) was the most promising number, but i couldnt read it completely. its looked something like 518-19-something. the only ones im sure of are 5 and 19. i know thats not much help

Someone will correct me if Im wrong but I think the only T-case available was the Quardratrac. Is the rear pumpkin offset to the pass side? If it is a Quadratrac, his options are limited without the expense of adaptors. There was the T18 4 spd manual that was available for the Quadratrac. Its actually a really nice strong option with a granny first. It has no overdrive if that what hes after though.

[pedalhappy]

as far as i can remember, the rear pumpkin is not offset.

[cj8er]

The CJ series came with 3, 4, and 5 speed manual transmissions. The 3 speed ran a Dana20 transfer case, the 4 speed is a Tremec T-176 and runs a Dana 300 transfer case as does the 5 speed manual, which was also a Tremec trans. If you swap the 3 speed for a 4 then you'll be looking for both a transmission and a transfer case. I recently swapped a 3 speed for the 4 speed for the gearing and rock climbing flexibility. Then later went back and swapped back in the 3 speed when I converted it back to a daily driver. If you do the swap, don't forget to swap the pilot bushing in the rear of the crankshaft, you can use the same bellhousing. You will also be looking at swapping out your transmission cover plate and shifter boots but neither is any big deal.
Good luck.