Tsalagi87

I have a 1987 4.0 inline 6, 4x4, automatic. Yesterday while I was driving it I went to accelerate and it would only rev up. It would not go however. After I got it parked somewhere and waited awhile I went to try it again and When i put it in Reverse or Drive it just revs up, no motion at all. Would this be the transmission?

Also if it is, since i am severley strapped for cash right now. Could someone step by step instructions on how to take it off and rebuild it. And diagnose the problems etc.

Another option/question is, could it be changed out with another newer transmission. My friend has a 95 they don't use and are possibly goin to scrap. Could I put the 95 transmission in mine?

cruiser54

Gotta stay with 87 to 90 transmission.
Have you checked the fluid and condition?

5-90

I wouldn't recommend overhauling the AW4 as a "first box" - I've been through a few.

That, and reports from the field on "garage overhauls" seem to be mixed, but generally bad - although I've had good luck, but the AW4 was far from my first slushbox.

If you want to use the later AW4, get a 23-spline input gear for your transfer case or just grab the transfer case from the donor rig as well. I believe the helix angle on the NP231 input gearset changed ca. 1993/1994, so the input gears won't swap (but you should have no trouble picking one up from, say, Novak Conversions - for considerably less than an overhaul would run you. Replacing the input gear on the NP231 is fairly simple, and you'll have it down anyhow.)

Apart from the output splines, the earlier and later AW4 should swap without incident.

If the drivetrain of the 1995 is in "worked when pulled" condition from the torque converter on back, I'd probably just go ahead and grab the whole deal. I do suggest, however:
- Get new torque converter screws. They're a somewhat special head design (called a "place bolt,") and measure M10-1.5x15m/m, so don't expect to find them at the local hardware store. I haven't checked to see if ARP has an application that will work, but they shouldn't cost too much from the dealer.
- Use LocTite #242 on the screws. OEMR screws will usually have it already on them (the blue schmutz on the threads,) but if you don't see it, add it. Consider this mandatory.
- Check the torque on the flexplate-to-crankshaft screws, I believe it's 105 pound-feet (should be on my site, spec taken from the FSM.)
- You'll have to jack down the driveshafts - replace the straps and screws. I do suggest that you get quality socket head capscrews for the straps - they're easier to work with in that area. 1/4"-28x1" is the size you want, don't get Chinese crap! Torque to 14 pound-feet/168 pound-inches, and consider the use of LocTite #242 to be mandatory here as well. Do not reuse the straps in "as removed" condition! They do work harden over time, and can become embrittled (I've reused them after annealing, but I know how to do it. Metallurgy is a bit of a hobby of mine, along with so many other fields...)
- Replacing the front driveshaft-to-transfer case screws isn't a bad idea, either. These are, I believe, 5/16"-24x1.25" or 5/16"-24x1.5". Stick to hex heads here, LocTite is mandatory, use a quality SAE8 piece. I don't recall the torque spec offhand, but it should be on my site.
- Replace the upper bellhousing screws - you'll need an E12 (inverse Torx socket) to remove them. You can usually find a kit from Lisle Tools for a good price at Sears for these. Replacements will be 3/8"-16 thread, match the length under the head (I think it's either 1.25" or 1.75" - and hex heads or socket heads are fine here.)
- Use LocTite #242 on the bellhousing screws. The first AW4 I lost was because the bellhousing screws had backed out - three of them had left, the fourth had a half-inch of daylight between the transmission and engine (I had to disassemble the transmission with a Sawzall.) Avoid this yourself - learn from the errors of others!
- The transfer case stud nuts are 3/8"-24. If you have to replace one of the studs, may as well replace them all - you can cut them yourself from 3/8"-16 threaded rod, and just replace the nuts with 3/8"-16 pieces as well (there's a sound engineering reason for having UNC threads on one end and UNF on the other - but it doesn't really apply here, since there's not enough tensile force. A similar situation exists with the manifold studs, by the by.) Use CRES (Stainless) if you can get it, so you don't have to worry about the cut ends "rotting out" on you. If you can't get CRES, use white lithium grease on the ends or paint them (NB: primer is porous! Primer won't prevent rust at all, paint gives it a fighting chance.)

You'd think I've been through this sort of thing before...