Stronger drive train setup for CJ7

[PhattyX]

Quite some time ago, Jps4Jeep said that a beat 73-87 chevy 1-ton pickup would be a good buy to upgrade axles.

http://www.jeepz.com/forum/showthread.php?t=16521

Since there seems to be an abundance of these and the transmission also sounds nice, I have a couple questions:

1. Gearing. Should I be concerned about the gearing in them or are they all going to be the same? What gearing do they have? I'd like to be around 3.73 - 4.10.

2. Strength. The plan is a 4" lift with 34" tires. The D60 / 14bolt should handle that, right?

3. Locked. Way in the future, I think locking the axles would be a good idea. Any issue with that on these axles?

4. Unimformed. Anything I'm missing or should also consider while I'm thinking of doing this?

Thanks as always,

-X

 

[PhattyX]

1. http://www.chuckschevytruckpages.com/73-87specs.html - Lots of spec info. Gearing is about 3/4 of the way down. Looks like a lot of variety in axles over the years. It's good info if you're looking at the same swap.

-X

 

[redrooster]

1. Gearing is commonly 4.10 and 4.56. Check first though. Some had 3.73. IMO go 4.56 if you have a choice.
2. One ton axles will be overkill for 34" tires and the clearance under the differentials will suck. Your factory Jeep axles will handle 34's. One tons are really only necessary for 37" and up (this is not meant to be an arguing point...I know that you can run larger tires on smaller axles depending on how you drive)
3. Lockers are common aftermarket items for one tons. The CUCV (Chevy Army pickup) already has a Detroit in the rear 14 bolt.
4. Uninformed...the Chevy front ends are made for a passenger drop transfer case. Your Wrangler has a driver side drop. You will have to swap to a passenger drop case. This will mean buying a case and adapter or new transmission with the right case and adapter to the engine or just putting all Chevy stuff in the drivetrain. Very expensive.
You can buy Ford one tons from an older F350 that will have a driver side drop that to work with your transfer case.
I assume you know that there will be issues making your steering work with the new axles. You will also have to upgrade your master cylinder for the larger brakes to properly work. There are a lot of samller things to do as well.

 

[PhattyX]

Redrooster -

1. Still researching what top end will be with 34's and 1:1 final drive (even though my current trans has 5th), but would like to be able to comfortably do 65mph.

4. You mentioned "Wrangler" in your post. It's for an '84 CJ7 w/ pass side drop, so I'd stick to the chevy stuff instead of Ford, right?

2. That being clarified, I recall seeing a number of posts that the D30/AMC20 combo should be upgraded before going taller than 33" tires. I think you've been on the trail once or twice. In your opinion, would simply converting to 1-peice in the AMC20 support the 34"? Finally, I've got the 360 ci (so if you go crazy and want to donate your old FI...) and intend to "squeeze" some more power out of it. I'm not easy on this Jeep at all; I'd rather something "overkill" than "just enough".

Thanks for the input!

-X

 

[redrooster]

Sorry. I don't know why I was thinking YJ. The CJ is a passenger drop, so the Chevy's would work.
If you've got the Dana 300 case, you would be fine as far as TC's go.
Here's one thing else to note. The 60 is already set up to be spring over, so instead of getting a lift, do a SOA. If you have never done one, get help and use YJ springs for the SOA. They are wider than the front CJ springs and won't sag like the CJ's.
Here's what I would suggest. Do a lot of research before buying any parts and go to a Jeep ride and check out some of the other vehicles you like. This sport is expensive and even more so if you do like I did and evolve it in stages. It's much cheaper to build it big and strong the first time than to slowly upgrade. Also check out some of the places like Blue Torch Fabworks that sell kits to do the full width and SOA conversions. They aren't bad considering the amount of fab time you would save. They are pimp too.
IMO, 34's and one tons will look kind of silly. With the SOA you will easily be able to fit 36's, possibly 38's with some trimming. I trimmed a lot and ran 40's. Trimmed more and run 42's.
I sold my 360, so no parts left. It's a good engine though.
Lastly, the D30 and AMC 20 aren't worth sinking money into. You couldn't even recoup the cost of a locker if you tried to sell them later. There is just not much of a market, at least not around here. If you think you will ever only desire to run 34 to 36" tires then you may consider just using some half or 3/4 tons, ie 44/44 or 44/60 out of a Chevy or Dodge.