Ordering gear set today

[Hipbilly]

I went with 4.56. I have 315/70/r17 T/A KO2, they measure right at 34".
I have the 6MT, so I notice the change a whole lot more than you 8 speed folks, but I'm happy.
85mph is now really pushing it in 6th gear, 78 is about as fast as I want to cruise (~2,600rpm), and more importantly, everything leading up to that speed is incredibly more enjoyable.
I can accelerate comfortably anywhere from 70 to 80 on the highway without downshifting to 5th.
My main goal was to take a load of the clutch and make taking off easier, when towing time comes. I also didn't like having to resort to 4lo off road to have any control with the clutch.
All goals are met.

If I had an 8spd and would NEVER go to 37s, I'd say 4.10 would be perfect.
I have the 6mt and MIGHT go to 37s, so I'm glad I went 4.56.
I don't think you'd ever need 4.88, especially for a truck that will only rarely see a flat gravel road.

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[USMC-SSGT]

I went with 4.56. I have 315/70/r17 T/A KO2, they measure right at 34".
I have the 6MT, so I notice the change a whole lot more than you 8 speed folks, but I'm happy.
85mph is now really pushing it in 6th gear, 78 is about as fast as I want to cruise (~2,600rpm), and more importantly, everything leading up to that speed is incredibly more enjoyable.
I can accelerate comfortably anywhere from 70 to 80 on the highway without downshifting to 5th.
My main goal was to take a load of the clutch and make taking off easier, when towing time comes. I also didn't like having to resort to 4lo off road to have any control with the clutch.
All goals are met.

If I had an 8spd and would NEVER go to 37s, I'd say 4.10 would be perfect.
I have the 6mt and MIGHT go to 37s, so I'm glad I went 4.56.
I don't think you'd ever need 4.88, especially for a truck that will only rarely see a flat gravel road.

Real world input is great. If I thought I’d ever tow, travel, or really wheel it, it would be 4.88 without hesitation. Really what I want is for it to behave more or less like a stock rubicon. It’s my daily driver and the bulk of my driving is around my sea level town. I then venture 42 miles down our sea level highway to get to work and back 1x a week.

Other than the tires, the weight is a light arcus bumper and winch plate, and the side steps. Not appreciable change there really. This is honestly the easiest part. Explaining to my wife why our $55k truck that we have put maybe another $10k into isn’t “usable” without changing gears was the real hurdle.

Need to update my title to “ordering gears”…..as most are back ordered.

 

[Hipbilly]

OH, and regarding brand... I went through a local gear shop that generally uses/recommends Revolution gear sets; they received two front sets, packed as a F/R, so went with a Yukon in the rear to get me rolling again sooner.
After about a week or so, the rear gears started howling at~50-55mph, and getting louder.
They tested it and agreed that it was a problem, so they replaced the rear set under warranty with the original Revolution set that showed up eventually; the howling never came back after the change.
They said the quality of cut and factory lapping on the revolutions are good enough that they don't even recommend the oil change @ 500 miles. I did my own anyway at 350, and there was shiny in the oil, glad I did. took off the next day on a 2,300 mile road trip and everything's been hunky-dory since.

 

[Mac]

Maybe a little late now but you are welcome to try mine, I have 4.10s with 35” tires, I am in Lynnfield.

 

[USMC-SSGT]

OH, and regarding brand... I went through a local gear shop that generally uses/recommends Revolution gear sets; they received two front sets, packed as a F/R, so went with a Yukon in the rear to get me rolling again sooner.
After about a week or so, the rear gears started howling at~50-55mph, and getting louder.
They tested it and agreed that it was a problem, so they replaced the rear set under warranty with the original Revolution set that showed up eventually; the howling never came back after the change.
They said the quality of cut and factory lapping on the revolutions are good enough that they don't even recommend the oil change @ 500 miles. I did my own anyway at 350, and there was shiny in the oil, glad I did. took off the next day on a 2,300 mile road trip and everything's been hunky-dory since.

Funny you mention that with the revolution. I’ve done lots of research on the name and they check out as a quality option. Called my local and reputable 4x shop and they said “never heard of them.” They prefer spicer and Yukon ??‍.

Just good a good “deal” on a full set of front and rear including master install kits. In stock and shipped free for $849 so going with that. Of course
now that I’ve read this I’m hoping yours was a 1 off issue on the rears. Funny- you mention the 500 mile being optional. They said the exact same thing. I mention this only because they are a bit of a drive and they said “anytime between 300-700 miles and even then totally optional.” Said the same thing you did that you can crack the case in the driveway and DIY.

 

[USMC-SSGT]

Maybe a little late now but you are welcome to try mine, I have 4.10s with 35” tires, I am in Lynnfield.

That’s great, thanks. If I’m headed out that way I may take you up on that. More just for an excuse to talk Jeeps.

 

[USMC-SSGT]

Guess that settles it.

 

[mrmo]

Guess that settles it.

Not a bad price...figure ~$300 per gear set and $100 for bearings/shims/gear oil x 2 = $800, add tax etc

 

[USMC-SSGT]

Not a bad price...figure ~$300 per gear set and $100 for bearings/shims/gear oil x 2 = $800, add tax etc

Best I could find so far. Lowest around $899 and highest around $1,199. Also most showing backorder for 4-10 week ranges. Likely won’t do this till January, but will be happy to have materials on hand.

 

[Wheelin98TJ]

Dang, I remember when you could get a regear package for about $400.

 

[USMC-SSGT]

Dang, I remember when you could get a regear package for about $400.

Tell me about it. Starting with the JL/JT they got real expensive in a hurry.

 

[NewGladdyOWNR]

Just need some validation. I’ve read arguably every thread for the last 5 months and “decided” on 4.56 on 35s.

Stats:
-overland on 3.73
-35” MT Baja boss with 2.5” lift
- live at sea level 1 mile from the ocean
-no load or heavy gear
-no towing other than a utility trailer a few times a year.
-daily driver
-70/30 around town and a 1x/weekly 80 mile highway round trip at 75mph

What I want:
-overdrive back
-ability to merge onto the highway and the truck shifting instead of winding out to 5k rpm’s before up to speed
-ability to go up a 3% grade without downshifting to 5th/6th
-use adaptive cruise and not have it downshift 3 gears when it needs to go from 73 back to 75mph
-tow my little trailer out of 5th gear
-best mpg possible. That may end up being 15…I’m ok with that and would take that over 14. Not looking for a Prius, but a best case scenario.

Lastly:
- this Jeep doesn’t wheel, ever. My Cj does. This one gets me down my logging road to get to camp.
-I’m not looking for best performance. Don’t need to beat anyone off the line because I drive like an 80 year old. (Not the kind that mistakes the gas for the brake and drives through the front of a 7/11)
-I may do 37s in 50k miles when my MT wear out. I’d do light ones, and may not even do this at all.

What I’ve come up with based on all my reading- 4.56 is ideal for 35s. If you EVER want to go 37s, do 4.88. However looking at this chart, and being unloaded, not towing, sea level, and not wheeling, it looks like 4.56 could be optimum for either tire under my set of circumstances. I want to keep the RPMs lower and keep the performance closer to OEM.

Experts, what do you think? I am not married to any idea, just going to make the purchase and want to do my best diligence. Reason for this thread being that ALWAYS 4.88 doesn’t necessarily mean always as there are difference scenarios which could call for something else. Looks like based on this chart, in a vacuum,
37s on 4.56 would behave like factory 33s on 4.10.

Note: I used actual inches for simple math, not measured tire size

This chart seems way off, compared to the other charts out there...this is basically saying with 3.73 gears at 32's, it's still undergeared coming from the factory. What people need to pay attention to when regearing is effective gear ratio..

 

[OMTBiker]

I paid just under $1200 for Dana Spicer gears, master install kits, and diff covers back in January.

 

[USMC-SSGT]

This chart seems way off, compared to the other charts out there...this is basically saying with 3.73 gears at 32's, it's still undergeared coming from the factory. What people need to pay attention to when regearing is effective gear ratio..

I agree. I don’t believe the grimjeeper one is a ton better… but likely within +-100 or so.

 

[Wheelin98TJ]

You can always check a chart against the RPM formula.

RPM = (MPH x axle ratio x transmission ratio x 336) / tire diameter

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