Gears for 37" tires

[jeepncrowd]

Bumping this back up. Hopefully more people have jumped to 4.88 or 5.13 can offer their experience.

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[Duke56]

How long does it take a shop to swap out the gearing for front and rear diffs and what is min/max cost including parts and labor?

 

[PUGLIA]

How long does it take a shop to swap out the gearing for front and rear diffs and what is min/max cost including parts and labor?

depending on how busy the shop is a day or two. $1.5-$2k

 

[BreakFixRepeat]

Im really glad i found this thread. Hopefully somebody with 37s on the jt will chime in soon.

 

[Renegade]

Im really glad i found this thread. Hopefully somebody with 37s on the jt will chime in soon.

There an entirely different thread with reports on how the 8-speed auto with 4.10s perform with 37s (Hint- it does just fine). This one is specifically about how it does AFTER a gear swap.

 

[BreakFixRepeat]

There an entirely different thread with reports on how the 8-speed auto with 4.10s perform with 37s (Hint- it does just fine). This one is specifically about how it does AFTER a gear swap.

Sweet. Just read through that other thread And got all the answers i needed. Thanks for letting me know about it. Talk about a thread turning into conversation alley though. Lol

 

[RH 67]

How long does it take a shop to swap out the gearing for front and rear diffs and what is min/max cost including parts and labor?

Parts are not that expensive it`s the labor That`s $$$. An experienced person can do one end in a couple of hours a really good person with Spicer gears could do it in an hour. The shops know that most do not want to do this so they take advantage. I did a gear swap four years ago and it took me five hours total from start to finish.

 

[TennesseePA]

I have read a lot of advice on this thread from people who do not have a JT on 37s. I do have an LE with 37s and a two inch Mopar lift and I can tell you that the truck runs great on the stock Rubicon 4.10s. And before anyone says good luck seeing 8th gear I’ll tell you that I do cruise in 8th gear. It doesn’t pull hills in 8th but it isn’t designed to. The 3.6 pentastar is NOT a torque monster. If you want an engine that will lug along at 2000 rpm and not downshift get a diesel and not a 3.6

 

[WhatExit?]

I have read a lot of advice on this thread from people who do not have a JT on 37s. I do have an LE with 37s and a two inch Mopar lift and I can tell you that the truck runs great on the stock Rubicon 4.10s. And before anyone says good luck seeing 8th gear I’ll tell you that I do cruise in 8th gear. It doesn’t pull hills in 8th but it isn’t designed to. The 3.6 pentastar is NOT a torque monster. If you want an engine that will lug along at 2000 rpm and not downshift get a diesel and not a 3.6

On 37s the Gladiator will hunt/change gears at higher speeds. A gear change is NECESSARY if you want the truck to run like it did from the factory with 33's.

The question is which gears?

I'll be finding out in January I suspect after I get my suspension lift and 37s. Gears will happen

 

[TennesseePA]

Since I have a Gladiator on 37s I can tell you that the difference is negligible if not undetectable. My truck has 9800 miles on it and I have driven it empty on the highway, I have driven it while towing on the highway and I can assure you it runs fine. Not sure why people who DO NOT HAVE THE ACTUAL SETUP BEING DISCUSSED tell the people who DO HAVE THE SETUP BEING DISCUSSED don’t know what they are talking about.

 

[TennesseePA]

If you do the math there is only a 10% gearing change when going from 33 to 37. The 33 to 37 tire size works out to a 200 rpm change at 70MPH. What you did on your JK is of no relevance on your JT. I had a JK Sport on 35s with 4.56 and it was geared too low for adequate highway performance

 

[WhatExit?]

Since I have a Gladiator on 37s I can tell you that the difference is negligible if not undetectable. My truck has 9800 miles on it and I have driven it empty on the highway, I have driven it while towing on the highway and I can assure you it runs fine. Not sure why people who DO NOT HAVE THE ACTUAL SETUP BEING DISCUSSED tell the people who DO HAVE THE SETUP BEING DISCUSSED don’t know what they are talking about.

“the difference is negligible if not undetectable”

Not sure what you’re basing it on but I’m not deciding on hearing based on your “perceptions”

 

[Renegade]

“the difference is negligible if not undetectable”

Not sure what you’re basing it on but I’m not deciding on hearing based on your “perceptions”

I agree with TennesseePA on this (as I’ve said before on this forum, if not on this particular thread). It’s crazy how many people who don’t have Gladiators on 37 keep saying how it’s necessary to regear. The 8-speed auto puts the JT (and JL) in new territory. I know what JKs, TJs, and CJs drove like with big tires. I did it. This is new, and better. Are 4.10 gears and 37s perfect? No, but they’re damn good! Better than my 2015 JK with 4.88s. For reference, the 5-speed auto JK had a 3.59 ratio first gear. The JT has a 4.71 ratio first. That is the difference maker.

 

[RH 67]

Before i bought my Gladiator i asked about 37`s for the Gladiator as my previous Jeeps did need a regear to run 37`s. After getting my Gladiator i was pleasantly surprised at the overall pep and performance of the drive train. After reading here about those running 37`s, attending several shows and off road events and talking to individual Gladiator owners i have no reservations about 37`s with the 4:10 gears. In fact i have been told by several in the industry that the Gladiator has made 37`s the new normal for everyday driving and light to modest off roading. Sure hard core off roading is a different story but then you would want Dayna 44`s or 60`s anyway.

 

[TennesseePA]

“the difference is negligible if not undetectable”

Not sure what you’re basing it on but I’m not deciding on hearing based on your “perceptions”

. I am basing my statements on actual experience. And someone somewhere posted a comparison of gear ratios and rpm differences for different size tires.

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