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Automatic trans

alfman

NAXJA Forum User
NAXJA Member
Location
Pike Co, PA
Will an auto trans from a 94 jeep wrangler fit an 87 jeep XJ? As far as I can tell they are interchangable but I wanted to make sure. I have the transfer case with the trans so spline count will be matched. that much I do know.
 
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Will an auto trans from a 94 jeep wrangler fit an 87 jeep XJ? As far as I can tell they are interchangable but I wanted to make sure. I have the transfer case with the trans so spline count will be matched. that much I do know.

Depends. Is the Wrangler gearbox a three-speed (probably a 32RH/32RE) or a four-speed (may be an AW4?)

The later YJs managed to get Chrysler geraboxes instead of the AW4, which means that there could be trouble. The AW4 is an electronically-controlled three-speed plus overdrive automatic, while the Chryslers could go either way on the control (electronic or hydraulic) or the forward speeds (three or three plus overdrive.) You could probably swap in a 32RH, but that would be a step down (losing the overdrive, and the AW4 is a tougher box anyhow.)

Also note that you'd have to swap the transfer case adapter housing (the YJ is clocked differently - it's flatter, meaning you'd have to, er, "massage" the transmission tunnel to make it fit) even if it were the same AW4 automatic. And, the spline count on the input would be different.

Why for do you want to swap? Were you looking for an upgrade, or are you having trouble with your AW4 already? The AW4 can stand up to an incredible amount of abuse, and the only ChryCo slushbox I can think of that would be an upgrade would be the A727 - which won't bolt up to the AMC six anyhow. If you need a new one, find a donor from a 1995-down XJ - if you get one from a 1990-1995, get the transfer case as well (around 1990 was when the AW4 went from a 21-spline output shaft to a 23-spline, and the older transfer case won't mate up without swapping the input gear.)
 
5-90 the trans in my 87 XJ with 260000 miles on it is pretty much toast, fluid is burnt & it slips. A friend has a YJ that had an engine fire which I am picking up for parts for my son's YJ. I figured I could kill 2 birds with one stone as the trans is good in the burn job. I thought it was the AW4 but now i'll have to look at it again.
 
5-90 the trans in my 87 XJ with 260000 miles on it is pretty much toast, fluid is burnt & it slips. A friend has a YJ that had an engine fire which I am picking up for parts for my son's YJ. I figured I could kill 2 birds with one stone as the trans is good in the burn job. I thought it was the AW4 but now i'll have to look at it again.

Simply compare the shape of the sump pans for the transmissions, and you'll see if they're the same or not (that's the standard method for identifying automatic transmissions.)

If the YJ isn't the AW4 - it probably isn't - try this:
1) Change your fluid, using something fairly cheap (not Pennzoil, but some house brand that isn't made by them. Don't bother with synthetic yet.) Drop the sump pan, clean the pan and filter (the filter is just a wire strainer, it shouldn't want replacing.)
2) When you put in the new fluid, dump in a quart of Berryman's B-12 Chemtool with it.
3) Change your transmission fluid in two oil changes (~6,000 miles.) Clean your sump pan & filter again.
4) If you've noted an improvement (likely,) repeat the process. Carry on until you seem to "plateau" with the improvements, then return to normal service.

"Powerflushing" the AW4 isn't recommended, reports from the field are consistently negative. Do not use ATF +3/+4 in the AW4 - the friction modifiers are all wrong and you'll have a Hell of a time getting rid of it all!

Clutch slip or chatter in automatics is most often a product of varnish buildup - since the fluid is also burned, varnish is almost a certainty. The B-12 will gradually break up the varnish and hold it in suspension, drain the fluid while it's hot when you change it (go for a drive immediately before.) Bear in mind that a "service change" like you're doing is only half of the fluid in the transmission, which is why you end up having to do it several times (the torque converter holds about another gallon by itself!)

However, most automatics prefer to be flushed "gradually" in this sort of manner, as it gives them time to adjust away from having all that crud in there. If the varnish is bad enough to affect operation, there's a lot of it, and you'll want to remove it gradually (unless you're going to tear the thing to bits and overhaul it entirely!)
 
5-90, what type of trans fluid (dexron, mercon) do I use? Also where can I get Berryman's at? I've never heard of it before. I had a mechanic tell me to just add Lucas trans fluid treatment to it to make it last.
 
5-90, what type of trans fluid (dexron, mercon) do I use? Also where can I get Berryman's at? I've never heard of it before. I had a mechanic tell me to just add Lucas trans fluid treatment to it to make it last.

Dexron and Mercon are essentially the same set of specs, and you'll usually see it on the shelf as "Dexron (whatever)/Mercon." So, no trouble there.

Berryman's should be available at any well-stocked parts house. You'll see it in two cans - one is an aerosol spray can (works well for light parts cleaning, carburettor/throttle body cleaning, and the like,) and one will be a pourable liquit - get the pourable liquid and dump it in. B-12 will work with engine oil as well, and with the fuel system - but my usual flush for engine oil is to sub one quart of Dexron for one quart of oil and run for a "short change" (2000 miles or so,) and for fuel I just dump four ounces of acetone in once every 4-6 weeks and top off.

I've not used Lucas - I haven't seen a need to - but reports from the field have been uniformly good on it, so I don't see any reason to not use it (I have just been able to forestall any particular problems with my own regimen.)
 
I agree with 5-90, I would not give up on the AW4... most likely will be ok after three or less drain and refills... I unknowingly topped off my burnt fluid with ATF+4, and she would not grab first gear after a couple weeks... It was freezing and raining, so I had a guy drain and refill (well overfill thanks to the mechanic not paying attention) with dexIII + lucas, then because of the severe overfill, he redrained and refilled properly with DexIII + Lucas a day later, and she shifts great ever since! (It shifted great when initially overfilled too, but I was not going to leave it that way)
 
5-90
I found Berryman's B-12 Chemtool in 15 oz cans that says gas tank, fuel injector & carburator on the can. Is this the product? Is one can enough at a time or should I use two?
 
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