35s on 4.56 42RLE

Egadz

Egadz

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Aug 7, 2018
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Calumet, MI
Oh boy. I just ordered a new bolt on rear axle geared 4.56 on a chart I found somewhere in the interweb. Then found a chart here that takes the xmission into account. How badly am I going to hate this? I'll be in a little mud eventually but this is mostly a fun weekend vehicle. I don't expect this will see much, if any, interstate use. And my old knees don't like the 35s. I'll probably go to 33s next time around.
 
You screwed up. Both for 33s and 35s.

33s need 5.38, but the deepest yours can go is 5.13.
 
We just installed 4.88 gears and 33 inch tires with the 42rle . It is a great combination , but still only turns around 2000 rpm at 60 mph in overdrive . I turn off the overdrive unless I'm going 60 plus .
 
The 42 tranny would be sooo much better if the overdrive only reduced rpm by 400-550 vs off.

I’m on 35’s with 5:38 gears....

33’s will be better with 4:56, 4:88 is optimal.
 
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Harold&Cat said:
We just installed 4.88 gears and 33 inch tires with the 42rle . It is a great combination , but still only turns around 2000 rpm at 60 mph in overdrive . I turn off the overdrive unless I'm going 60 plus .
Click to expand...

It's even better with deeper gears.
 
You're going to hate 4.56 with 35's and your 42RLE, really. I hated the 4.88 my present TJ came with with its 35" tires and 42RLE, I ended up regearing it to 5.38 which improved it dramatically. My mpg was never better than 11 mpg with the 4.88 gears because the engine was lugging with the 35's. Regearing is improved the mpg to 14.6 due to the engine no longer lugging.

I wouldn't even like 4.56 with 33's, it'd be about like I had with 4.88 and 35's after I first bought it.
 
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Jerry Bransford said:
You're going to hate 4.56 with 35's and your 42RLE, really. I hated the 4.88 my present TJ came with with its 35" tires and 42RLE, I ended up regearing it to 5.38 which improved it dramatically. My mpg was never better than 11 mpg with the 4.88 gears because the engine was lugging with the 35's. Regearing is improved the mpg to 14.6 due to the engine no longer lugging.

I wouldn't even like 4.56 with 33's, it'd be about like I had with 4.88 and 35's after I first bought it.
Click to expand...

After my first 4:56 job, i went 4:88 on my next TJ. No regrets.
 
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Thanks all for straightening me out. Great news, the leadtime on the new axle is 100days and I called soon enough they were able to change the gearing from 4.56 to 5.13. No charge. It was the best thing I heard today.
 
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Egadz said:
Thanks all for straightening me out. Great news, the leadtime on the new axle is 100days and I called soon enough they were able to change the gearing from 4.56 to 5.13. No charge. It was the best thing I heard today.
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Woo Hoo!
 
Egadz said:
Thanks all for straightening me out. Great news, the leadtime on the new axle is 100days and I called soon enough they were able to change the gearing from 4.56 to 5.13. No charge. It was the best thing I heard today.
Click to expand...

Good move. I like my 33’s at 4.88 although some would go even deeper. Jeeps were not geared properly from the factory in my opinion.
 
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Egadz said:
Thanks all for straightening me out. Great news, the leadtime on the new axle is 100days and I called soon enough they were able to change the gearing from 4.56 to 5.13. No charge. It was the best thing I heard today.
Click to expand...

So what axle did you order
 
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