AMC360 Drive Train Options (trans and diff gears)

[Theduke]

All,
I've read enough posts that I have a massive headache and my eyes are bleeding. To include so many combination options using grimmjeepers calc.

Currently have a 1989 GW - AMC360 (edlebrock Proflo 4 mpfi to be added), TF727, NP229, 2.72 gears and 33" tires.

I'm trying to decide on the new gearing and that has me thinking about a transmission with overdrive. I'm adding lockers so I need to make the right choice on gears for the dana 44s. If I keep the 727 then I need the carrier ($1,000 elocker) for 3.73 or 3.54. If I use an overdrive trans then I need the carrier for the 4.10 or 4.56. I can afford to do this once. It does not have to all be done at once but I need the full drive train planned out.
I have read alot about the 727's replacements i.e 46rh, etc. But I think they aren't compatible because they were for Dodge not AMC (without adapter plates).
I did get a quote from Novak but the $1,800 th700r4 ends up costing $3,400 with engine and t-case adapters and shipping and that number hurts.
I'm not trying to be cheap and I want to do it right but there is a budget. Just having issues making the decision and am open to opinions.
I'd like to cruise at no more than 65mph with a decent rpm say <2500 if possible. This is meant to be a daily driver with offroading, but not a rock crawler.
Thanks for the input.
Weston

[fulsizjeep]

I ran 2.72 gears on my 88 with 32s for a couple years before I moved to Colorado from flat Florida. Then I went with 33s the next winter. Those gears had to go after that. I found 3.73 was pretty much perfect for highway, off road and rock crawling. It got a Lockright lunch box locker in the back with the gear change. Ran it for 10 years without any troubles. I personally think the idea of an overdrive tranny upgrade is over rated but that is me. To each their own.

[dodgerammit]

I'll chime in. I have 2.72s and love the economy, but need realistic power. Will step to 3.31s when I find a set of axles. Why regear when I can swap? I'm staying stock height, however.

In your case, I'll recommend an AW4. If not dogging on it, it should do fine, even though it isn't as strong as the 727. It is designed for AMC blocks. Some Cheorkees (XJ) and Comanches had the column shift setup, so that is another parts source if needed. I think you'll need a spacer for the factory t case, but that is a minimal expense compared to adapters for both ends. I'd recommend an auxiliary cooler.

Just a possible option for you to ponder.

[Stuka]

2.73’a are horrible with 33’s.

3.54’s with 33’s are doable. Good on the HWY.

3.73’s are pretty good 33’s.

I actually have run 4.56’s with 33’s in two Jeeps. I loved it. But without overdrive it’s over geared.

If you are going with an OD trans, I would say you may want to consider 4.10’s with 33’s. Unless you like cruising at 70+, then go 3.72 or 3.92 maybe.

Also, it’s worth messing around here: www.grimmjeeper.com/gears.html

[rocklaurence]

I ran 4.56 gears in my Ford Explorer with overdrive and 35's. However, it was much quicker with 33's and performed better off road.

[will e]

I run 37's with 4.54 gears an AMC block and 727. It does fine. It's no rocket ship but people are not honking at me speed up faster.

I considered a overdrive transmission but the cost is pretty high. I do wheel my rig so for me the choice was to go with an Atlas 4 speed transfer case.
37's with 4.54 gears is fine for most trails with the typical 2.72 gearing area. The Altas allows me to run 2.0, 2.72 or 5.44. The 5.44 is great for more technical stuff. I tend to run around in 2.0, which is great for shelf roads and dry sandy washes.

It's also twin stick, so I can run low gears but rear only (or front only) if I want, and it is what I do most of the time.

The downside is lots of levers sticking out of the floor board. It's not a problem with my rig but on a nice late mode GW it might not fit in with the overall look.

You mentioned edelbrock proflo. I don't how much that costs. But have you compared your AMC engine based strategy against an LS or other swap? If you did the LS along with the transmission and transfer case you could end up with a nice setup. It won't be cheap but do the math. It might be worth it.