Help with re-gearing

Bob316

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Ellenton Florida
Hello all, a question for all you guys who know about gearing. I have a 99 tj with 3.07 gears, I want to change to 4.10 will I need a bigger carrier to do this ? Thanks Bob316
 
Hello all, a question for all you guys who know about gearing. I have a 99 tj with 3.07 gears, I want to change to 4.10 will I need a bigger carrier to do this ? Thanks Bob316

Carriers are cheap. Don't worry about it. If you are paying a shop to do the work then let them source the parts.otherwise any warranty will only be on labor.
 
Why?

With 4.56 he’ll be at 2568rpm’s at 70mph. He’ll be downshifting to hold speed on a hill.

With 4.88 he’ll be at 2748rpm’s at 70mph.
I get that, I just believe 4.56 has been heavily recommended for 33's and 5-speeds for years for good reasons. I just don't believe the extra rpms of 4.88 for 33's are of benefit for highway cruising. And offroad the difference when in 4Lo with 4.56 vs 4.88 are insignificant. Just my opinion. Not to mention he lives in flat Florida. :)
 
Hello all, a question for all you guys who know about gearing. I have a 99 tj with 3.07 gears, I want to change to 4.10 will I need a bigger carrier to do this ? Thanks Bob316

Hello from Palmetto, as pointed out you’ll be far better off with 4.56 gears.
 
When I did my Dana 30 I needed a new carrier. I used the Spicer 706008X. It worked great and came with a shim pack. It was nice to have a larger selection of shims when I did my gears.
 
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4.88 is proper for 33’s and the 5-speed. 4.56 is proper for 33’s and the 6-speed. This is simply true based on the numbers and experience verifies. Living in FL is irrelevant. Why choose substandard gears when optimal is an option? Makes no sense. 4.56’s with the 5-speed and 33’s is like me choosing 4.10’s with the 6-speed and 33’s. That abysmal experience would have been a waste of time and money.
 
4.88 is proper for 33’s and the 5-speed. 4.56 is proper for 33’s and the 6-speed. This is simply true based on the numbers and experience verifies. Living in FL is irrelevant. Why choose substandard gears when optimal is an option? Makes no sense. 4.56’s with the 5-speed and 33’s is like me choosing 4.10’s with the 6-speed and 33’s. That abysmal experience would have been a waste of time and money.
I don't want to get into a long disagreement but I've never heard anyone say they were disappointed with their 4.56 gearing for 33's and the 5-speed. 4.56 has been recommended for 33's and the 5-speed since I first got my TJ in '96 when I stupidly regeared to 4.10 for 33's instead of 4.56 that everyone (!) recommended to me. And of course it matters that the OP lives in flat Florida, he absolutely would not benefit from the higher rpms of 4.88 for 33's and his 5-speed.

2748 rpms are simply not needed to comfortably cruise at 70 mph with 33's... especially on Florida's flat road system. Period. Heck you're only turning over 2150 or so rpms at 70 mph with your own 42RLE, 35's, and 4.56. With my 5.38 gearing, 35's, and 42RLE I'm only turning over around 2530 rpms at 70 mph.
 
Heck you're only turning over 2150 or so rpms at 70 mph with your own 42RLE, 35's, and 4.56.

Yes, that’s my current gearing since I did a transmission swap from the 6-speed to the 42rle last month. The fact I’m running it is not an endorsement of it. If I could I’d regear to 5.38, but the deepest I can go is 5.13 (as we both know).

Agree to disagree on the proper gearing for a 5-speed on 33’s, but don’t forget that people often travel and they don’t always stay where they live now. You’re a good example (so am I). So you never regear for where you live. You regear so you don’t have to downshift on a hill at 70mph, which means you want your rpm’s at roughly 2750 or more at that speed. Also, nothing is wrong with your 5.38’s in FL and I highly doubt you’ll regear to 4.88 because it would somehow be better. 🤣
 
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If 4.56 is proper for the 33's and the 6-speed (and many people recommend this, or 4.88), then:

4.5633" tires (32.6" calculated)6-speed2764 RPM
4.8833"5-speed2748 RPM
4.5633"5-speed2568 RPM

4.88 on the 5-speed is pretty close to 4.56 on the 6-speed.

Here in Colorado, I have to deal with tire drag, wind drag, and mountains.

In Florida, he'll have to deal with tire drag, wind drag, and bug drag ( thanks, @BlueC ). That's got to be pretty equivalent. Anybody ever calculate bug drag? :D
 
4.88 is the correct gear for an AX15 trans with 33’s, which is the transmission being discussed.
 
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