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42RH/46RH, '93 ZJ


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1993 ZJ, 5.2 46RH, 4WD. No reverse. All fwrd gears good. I have a good 42RH from a '96 XJ 4.0. Any reason why I can't swap it into the '93 ZJ? They used the 42RH on both 4.0 and 5.2 but only used the 46RH on the V8. I think. The only difference I can find between them is the 1st and 2nd gear ratios. Before I do that, I'm going to remove the valve body and make sure the reverse valve isn't sticking or the rear band can be adjusted. I'm gettin to old for this crap, but it keeps me busy.

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I'm pretty certain that the 42RH was ONLY used on the 4.0L. The 44RH and 46RH were used on the earlier model 5.2L V8 ZJs until they changed over to the RE-series. First and foremost, the 42RH is a weaker transmission than the 44RH and 46RH so you're already at a disadvantage there. Second, I'm not sure if the bellhousings between the V8 Magnum-series engines and the AMC/Chrysler 4.0L are the same, so look into that and you'll likely have your answer. The good thing about the RH-series transmissions is that they're hydraulically controlled (hence the 'H') so you don't have all of the plugs for the shift and TC lockup solenoids to futz with.

 

When I got my '98ZJ with the 46RE, it had no reverse. There was a snap ring on the Overdrive clutch pack that had broken off. It takes out reverse, but leaves all forward gears. It also does a number on some of the components in the OD housing located on the end of the trans. Drop the pan on the transmission and see if there are pieces of a snap ring inside.

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There were no broken pieces in the pan. Just the usual shiny bushing residue found in any high mileage unit. I'll check the things you mentioned tho. Weaker unit sounds like a good enough reason not to use it. I'll check on the bell housing mounts. They look the same but I didn't measure anything to make sure. The fluid and filter looked like original factory stuff. Don't think it's been touched since it left the factory. 200K. Engine runs like it was a new one.

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First , 96 means an electronically controlled trans , not compatible with the OBDI on your 93 , it's trans is hydraulically controlled .

 

The 96 XJ should have the AW4 IIRC . The 42RE (RH was pre 96) was used more so in the ZJ . Either way , it's easy to tell . Just look at the shifter , the AW4 has this pattern

P

r

n

d

3

1-2

The 42RE/RH has this

P

R

N

D

2

1 , and will have an overdrive button on the dash

 

You also will not find a match in the bolt pattern on the bell housings .

 

The Direct drive snap ring fails. It's common to loose reverse like this . You are looking at a full rebuild and maybe some hard parts due to damage .

 

When you do rebuild/find another trans , make sure to remove the check valve on the line about 12" back from the rad . They restrict , and get clogged up , common failure cause . I have 200K on my 46RH , lots of service , no issues . Check valves were removed on both my 95 and my 98 5.9l Grands when I bought them .

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