Drivetrain Advice - CJ7 Restoration

Drivetrain Advice - CJ7 Restoration


Hopkinsville, Ky
1979 CJ7. 304V8, AMC20 Rear, Dana30 Front, T150, Dana20 xfer. 2.5" ProComp Lift. Fiberglass everything.
Looking for some advice on the drivetrain for my 79 CJ7 restoration project. I have the CJ torn down to the frame / rolling chassis. The entire Jeep is all stock. Here's what I'm pretty sure it has: 304V8, AMC20 rear, Dana 30 front, T-150 3 speed manual.

I had the Jeep gone over pretty well by a good mechanic before I brought it home. The engine is solid and does not need a rebuild. Transmission / 4wd works fine and nothing really leaks at all. Jeep has about 70k miles on it. It had been sitting pretty much idle in a barn on/off the last 15 years.

I am ok with cleaning, painting, and some simple repairs. Heck I've even done a little welding on the frame. But, I am not ok with tearing into the front / rear differentials to replace bearings, seals, etc. I just don't have any experience there. I'm just a golf pro that inherited an old Jeep.

But, since I have this thing down this far I know that stuff probably needs to be done.

I've also been advised that if it's not broke or leaking yet, to not mess with it.

Thoughts would be appreciated.

unless there is a problem with axles just change oil and go or if you are going to want a locker then do so but no reason to rebuild if it is not needing it
Welcome. I looks like you inherited a goodie. As far as your drive train the important issue is the AMC20 rear. The hope is that the stock 2 piece axle shafts have been replaced with solid one piece units. The stock 2 piece axle has a shaft and a hub bolted together and when (not “if”) the nut holding the pieces together start to loosen up it gives the hub opportunity to break and spin leaving the axle useless. This can happen as easily in the Wally World parking lot as the trail and without warning. Check you’re the hub on the axle for a big nut. Nut = 2 piece shafts, no nut = 1 piece. Replacement 1 piece shafts are readily available. If you want to wheel hard you might want to just dump the AMC20 for a Dana 44. (Lots of debate on that one to be had.)

The rest of your drive train is solid although the T-150 does not have a low granny gear and the Dana 20 is not the lowest transfer case available either. Again depending upon how you plan to use the jeep you may want to upgrade to T18 transmission (granny gear low) and/or make changes to the gearing for a lower range but nothing to change from a strength stand point

As this jeep has not been hacked and whacked it would be a shame to butcher it up for a hard core wheeler and most important (in my opinion) keep your jeep, jeep. I know the boys at JP and others on this board will tell you all the attributes to dropping in a SBC and I will be the first to agree that the SBC is the King of the Hill when it comes to most everything (cheap, powerful, and aftermarket supported, etc.) but just because you can doesn’t mean you should. CJs with SBC sit on Craig’s List for a long time in my part of the world and in reality sell for less than an equal conditioned unit with an AMC motor.
I would at a minimum, remove the covers and drain the fluid. At which time you can assess the looks of things inside. If the fluid was dirty or had water in it you may want to then spray around in it with some Lectra-clean or Brake-Kleen to wash any remnants away. You may want to drag a magnet thru the fluid to see if theres any metal shavings present that would warrant further inspection.
Being able to see what's inside will also let you know if you have any type of Limited slip or locker, which may require you to add some friction modifier to the new fluid.
Alot of good advice above.
When I got mine it had 150,000 on it so I took the time to rebuild everything while I had it apart. In your case with only 70,000 I probally wouldn't worry about it unless you see something wrong.
Well, since I had to drop these to install 2.5" lift anyway... I just took both front and rear differentials to a local shop for a full refurb. Also going with new 1 piece axles in the rear AMC20. They are also going to sand blast everything for me too. So I'll get these back ready to paint and install.

No problem, because I'm still getting the frame cleaned up and coated with POR15.

The u-joints in both front / rear driveshafts look really good. Not gonna replace these yet.

What else....

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