42RLE Transmission Woes

RossAlGhul

RossAlGhul

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Joined
Mar 10, 2020
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11
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Tyler, Tx
Hey Everyone,

Apologies if this is the wrong thread. Looking for some advice from some of you knowledgeable folks. I've just purchased a 2005 Unlimited. It's an automatic with the 42RLE. It was great for the first few weeks, but today I discovered that the transmission slips in reverse. Only happens if I'm parked on a downhill, and try to reverse uphill. All other gears work fine, no slip that I can feel anywhere else. Is there a solution short of rebuilding or replacing the whole transmission?

Any thoughts or ideas are appreciated. Thanks.
 
Your transmission is very likely just low on ATF. Park on level ground, start the engine, then check the ATF level with the transmission dipstick (comes out from under the firewall on the passenger side) while the engine is running and the transmission is in Park. If it's low, as I suspect it is, add enough ATF+4 to bring it back up to the full mark. Don't use ANY other ATF, it has to be ATF+4. If it doesn't say "ATF+4" in big letters on the front of the bottle it's the wrong stuff.
 
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RossAlGhul said:
Hey Everyone,

Apologies if this is the wrong thread. Looking for some advice from some of you knowledgeable folks. I've just purchased a 2005 Unlimited. It's an automatic with the 42RLE. It was great for the first few weeks, but today I discovered that the transmission slips in reverse. Only happens if I'm parked on a downhill, and try to reverse uphill. All other gears work fine, no slip that I can feel anywhere else. Is there a solution short of rebuilding or replacing the whole transmission?

Any thoughts or ideas are appreciated. Thanks.
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What is your gear ratio and tire size? That will tell a lot more about what the issue is. The reverse gear is pretty tall on the 42rle
 
I agree. I bought it this way, but would like to put 4.10 in it. Although I hoping to have a couple paychecks come in first.

Yes it will still go backwards, but definitely feels like it's slipping
 
RossAlGhul said:
I agree. I bought it this way, but would like to put 4.10 in it. Although I hoping to have a couple paychecks come in first.

Yes it will still go backwards, but definitely feels like it's slipping
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If the hill is steep you could be feeling the play in the torque converter. With almost 33s on 3.73 that will experience a lot of TC slip. For your tire size I wouldn’t go with 4.10. You need 5.13s to be in the right powerband/efficiency range.
 
Regearing is not going to fix a busted transmission. If you aren't slipping in first and you are in reverse save your money until you get the transmission figured out.
 
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If you noted your tire size correctly, those are basically 33". With the 42RLE, you'll want at least 5.13 gears. If you have a Dana 44 front axle, you could go to 5.38.
 
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nk24 said:
If you noted your tire size correctly, those are basically 33". With the 42RLE, you'll want at least 5.13 gears. If you have a Dana 44 front axle, you could go to 5.38.
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With 4.10 on 33”s, I felt the same slipping he is saying. His situation is even more extreme at 3.73. That all went away at 5.38s :)
 
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