Trans swap in a '90 GW possible?

[Archangel]

I was perusing BJ's website and came across this:

http://www.bjsoffroad.com/prod-506.htm

Does this mean its possible to swap in another trans into our beauties? What other parts would be needed? Will you have to change TC? Custom driveshaft? I am NOT mechanically inclined, but want to learn on my jeep. ANY information would be greatly appreciated.

[FSJ Guy]

Sure. ANY swap is possible, it's just a matter of how complicated or $$$ it is.

Unless you're married to your AMC motor, if you're looking at a trans swap, I'd recommend a Chevy 5.3 motor and one of its matching overdrive transmissions and a t-case to match. You can swap on OD tranny alone, but it will have to be non electronic 700R4 variety or you'll have to buy an EXPENSIVE stand alone controller for the electronic version (such as the 4L60E). Might as well get the 5.3 motor which has the PCM to control the transmission, too.

If you swapped, you will either need a different t-case or an adapter for your existing one, a NP 229. Driveshaft adjustment of course depends on the final position of the t-case.

[carnuck]

If you like your AMC motor, an AW4 is an easier swap. '90 already uses the right starter. I'm going to get mine done this winter.

[Stuka]

If you are not really experienced, I would say to not look into a transmission swap.

Just off hand, you will need the adapter, the transmission, possibly a transfer case, trans mounts, possible cross member mods, drive shaft changes, possible shift linkage changes, and depending on the transmission, you may need a controller to go with it.

So sure its possible, but you need some good reasoning for the amount of work and cost that it entails.

[Archangel]

If you like your AMC motor, an AW4 is an easier swap. '90 already uses the right starter. I'm going to get mine done this winter.

The AW4 is a 4 speed auto? Would the stock TC work with it? I've got a few mechanic friends, so the technical assistance is readily available. I'm going to be DD my Waggy, and thought the 360 would be more fuel efficient if it had another gear for the trans. Am I wrong? What's the best engine and trans swap for the GW for the buck?

[tgreese]

If you like your AMC motor, an AW4 is an easier swap. '90 already uses the right starter. I'm going to get mine done this winter.

The AW4 is a 4 speed auto? Would the stock TC work with it? I've got a few mechanic friends, so the technical assistance is readily available. I'm going to be DD my Waggy, and thought the 360 would be more fuel efficient if it had another gear for the trans. Am I wrong? What's the best engine and trans swap for the GW for the buck?

You may be disappointed with the fuel economy increase that you get from a transmission swap. The Wagoneer was already a hopelessly dated platform in 1990, since it originated almost 30 years earlier. And the rest of the car is not favorable to economy, even if the transmission is updated. You are probably better off saving the money you would have spent on the transmission swap and instead buying gasoline futures (or RBOB, the gasoline ETF). This way you can hedge your gasoline costs - if gas goes up, you make money on the futures. If gas goes down, you save money on gas. Basic hedging.

Seriously, any major project like this that you do to save gas is probably going to be a money loser in the long run. And investing a lot of extra money in an old car in order to save money in the future is clearly a risky strategy. Things happen ... people have kids, get married, lose their jobs, take a job in Singapore, win the lottery... all sorts of unexpected things happen. Do it for fun and personal growth, but don't expect to save money.

If you want to do the transmission swap, do it for fun and education. Any mileage savings will then be icing on the cake of personal satisfaction. But I think the 5.3L Chevy mentioned above makes the most sense, or maybe a 4.0L drivetrain from a XJ Cherokee would be good.

[carnuck]

A few things are different. Shift rod needs modding. (reversing the link on the trans should be all that is needed). You need a '91 up for 23 spline to match the tcase, then you need a 1" spacer ring unless you find a '93 ZJ one (I'm about to find out for sure, but I was told it has a shorter output shaft for the Dodge style tcases used in Grand Cherokees) The AW4 is 3.5" longer than the 727 or 9XX plus the 1" spacer means the rear driveshaft needs shortening and front maybe made longer. The wiring and trans control box from an '87 to 90 XJ or MJ plus throttle position sensor (I'm grafting mine with a plate to the MC2100 carb) and the TVS cable to handle kickdown.

[carnuck]

If you have 2.72s, I wouldn't bother with an O/D. Even my Eagle with 3.08 is borderline prospect with O/D since I went with 235/75/15s.