'80 CJ7 trans Q

[Jackpine877]

Gentlemen. In process of getting a recently acquired, lightly modified, '80 CJ7 into reasonable condition to hit the trails next spring. Swapping in a Dana 44 rear out of a '71 Commando, re-gearing and adding traction to both the Dana 44 and stock Dana 30 front, re working all fuel and brake systems and putting in a painless harness to cap things off. The AMC 258 i6 / 4.2l power plant is in good shape, minor tinkering already finished. The problem is, in between all the new updated goodies is an SR4 . It's in decent shape (from what i can tell) and doesn't seem to have given up the ghost yet, despite the horrible reputation. Do I go for the gusto and drop in a Muncie 465, T-18 /19 or AX15 while i've got the tub off now? Or do I wait til it finally goes? I know its my call but I want some justification before I drop 2k to Novak on a new gearbox.

 

[Torxhead]

The AX15 is good if you want an Overdrive to get to the trailhead. The other three are pretty serious heavy duty, low first gear, no Overdrive transmissions. Also consider adding the 4:1 low gear Transfer Case addition and the price of adapters.

 

[Lumpy Grits]

Do you want a 4 or 5 speed?
What size tires?
LG

 

[inthegarage]

I have an 80 CJ7 with SR4 as well. I found an SM465 and used Novak's adapter and rebuild kit.

I haven't gotten back into the Jeep yet and driven it, but in hindsight, I think I would have just bought a "modern" 5 speed instead (probably the NV3550). After all the money I spent on the adapter and rebuild kit, plus a few internal pieces to make the SM465 good again, it would have been easier/same money to go with the 5 speed.

The SM465 is literally a beast though. I pulled SR4 out by basically pulling on it with my hands while under the Jeep. The SM465 weighs more than I do and almost gave my a hernia when I was moving it from the bench to the ground . I decided to pull the engine to mount the 465, and well that has led to other issues.

Also, while the SM465 is very short, especially with the Novak adapter, it is very tall. I'm concerned about the belly clearance once everything is replaced.

 

[Jackpine877]

Thanks for the responses fellas. Definitely giving me a few things to think about. Lumpy, I would prefer a 4 speed as this is going to be a bare bones trail rig. I'm not opposed to a 5 speed though. Tires are 33x12.5R15's. I dont think I would ever want to go larger on these axles considering they are the narrow tracks.

Things have taken a bit of a turn however and there are now even more questions concerning powertrain. Basically I somehow neglected to notice a few "inconsistencies" with my engine. After noticing a small head gasket leak on the furthest back cylinder yesterday I decided to just pop off the head and take care of it now. Upon further inspection stupid me somehow hadn't noticed my head is yes from a AMC 258 i6 / 4.2l AMC 258 i6 / 4.2l but cast into the block plain as day "4.0L-1" followed by a proud Chrysler symbol and a casting date of 1994.This is my first CJ build, but honestly I have no idea how I hadn't noticed it before. Going to create a new thread about this. Advice is welcome!

 

[hole]

Since it has a 4.0 head, are you sure its the head gasket, or a poorly sealed head? The water jackets on a 4.0 head are not used and need to be sealed off. Some guys just use JB Weld (or equivalent), but the best route is to have it welded closed and machined flat.