Gears for 37" tires

[immaechu]

I have 4.10 from my max tow on 37s with 2.5" lift

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[WK2JT]

Does anyone getting a high pitched hum coming from the transfer case with 5.13s? We originally thought it was the gear installation but we've gone back twice now and that's spot on. I'm the only one that can notice it but was told that it is likely to do with the driveline spinning much faster than before. I test drove 2 other 5.13 JTs this weekend and they had the same hum. What is it?

5.13’s and 37’s... no high pitched whine or hum. Sounds the same as when it had 3.73’s. At what speed or RPM are you hearing it? Are you in 2wd or 4wd when you hear it?

 

[Geekjeep]

I did 4.88s as many others. Very happy with result. Kinda wish I did 5.13 cause why not

 

[duvinclunk]

5.13’s and 37’s... no high pitched whine or hum. Sounds the same as when it had 3.73’s. At what speed or RPM are you hearing it? Are you in 2wd or 4wd when you hear it?

It doesn't sound like a gear whine but almost sounds like an a/c blower but obviously not that. I hear it at 30+mph. It does not increase in intensity or speed as speed of the vehicle increases. It is both in 2wd and 4wd. Sounds like its coming from directly below the center console.

 

[hjdca]

Does anyone getting a high pitched hum coming from the transfer case with 5.13s? We originally thought it was the gear installation but we've gone back twice now and that's spot on. I'm the only one that can notice it but was told that it is likely to do with the driveline spinning much faster than before. I test drove 2 other 5.13 JTs this weekend and they had the same hum. What is it?

What gears are you using ? I am running Dana Spicer 5:13s on a Rubicon with a manual tranny and I get no high pitched hum. The day I drove it home, it sounded no different than the 4:10s.

 

[duvinclunk]

I am also running Spicer 5.13 gears on a Rubicon, auto. I'm just going to have to bring it into the dealer. The Jeep shop that installed the lift has broken into the diffs two times after the installation and checked over the bearings and pattern and everything is perfect. Doesn't necessarily sound like it is from the front or rear but right below.

 

[duvinclunk]

We found my issue. It was a bad carrier bearing inside the diff. Replaced the bearings and everything is perfect and quiet now.

 

[Scratch]

I'll admit I haven't read through all 20 pages....
I have changed gears on several jeeps and know how to select gears and 4.88s or 5.13 w 37s would be great for our vehicles.
My question is specific to user experiences. Those of you that are running the 8 speed trans 4.88s or 5.13's did anyone retain downshifting to 4th for passing? I have heard that 5.13 definitely looses downshifting to 4th but recently heard that 4.88s and 37s also loose shifting to 4th to pass.
I live at 5,000 ft and do tow from time to time but I don't think Im willing to give up the downshift. The little 3.6 does its best work at higher rpm.
Thanks
Scratch

 

[duvinclunk]

I'll admit I haven't read through all 20 pages....
I have changed gears on several jeeps and know how to select gears and 4.88s or 5.13 w 37s would be great for our vehicles.
My question is specific to user experiences. Those of you that are running the 8 speed trans 4.88s or 5.13's did anyone retain downshifting to 4th for passing? I have heard that 5.13 definitely looses downshifting to 4th but recently heard that 4.88s and 37s also loose shifting to 4th to pass.
I live at 5,000 ft and do tow from time to time but I don't think Im willing to give up the downshift. The little 3.6 does its best work at higher rpm.
Thanks
Scratch

That depends on the speed and RPM that you're traveling at when you are attempting the pass. With my 5.13s, I have seen 4th for passing but I'm also at a lower speed. As I increase speed the vehicle can't downshift to 4th as it would essentially be right near redline so the truck won't go there. I live about 4.2k in elevation and travel to and from Moab and southern Utah and haven't had an issue passing. The only time I feel the truck lug is going up really steep grades into the canyons or over mountain passes.

 

[NCLife]

I’ve now had 37’s on my Mojave for over a month. I live in Charlotte, so it’s relatively flat. I do use a Pedal Commander. I don’t tow anything. I do have a lift, front steel bumper, armor underneath and a winch. I don’t see any reason to change the gears. I may struggle when I head to the mountains a few times a year, but otherwise I really didn’t notice much difference. I still find 8th gear on my auto. Just my two cents. I think the Pedal Commander is the key...and no I don’t work for them.

 

[Jeeperjamie]

I’ve now had 37’s on my Mojave for over a month. I live in Charlotte, so it’s relatively flat. I do use a Pedal Commander. I don’t tow anything. I do have a lift, front steel bumper, armor underneath and a winch. I don’t see any reason to change the gears. I may struggle when I head to the mountains a few times a year, but otherwise I really didn’t notice much difference. I still find 8th gear on my auto. Just my two cents. I think the Pedal Commander is the key...and no I don’t work for them.

I'm in the Charlotte NC area as well and still get 8th gear in my max tow. Stock gears, nothing else done to mine. I average around 17.2 mpgs, got 18.3 on the way to the beach and back.

Had 37's on since February

 

[Deleted member 30519]

I ordered the yukon 5.13 gears for my M/T with 38s. I didn't realize how long it takes to get into a really good shop. I have to wait until late July!

 

[cmb396]

I'll admit I haven't read through all 20 pages....
I have changed gears on several jeeps and know how to select gears and 4.88s or 5.13 w 37s would be great for our vehicles.
My question is specific to user experiences. Those of you that are running the 8 speed trans 4.88s or 5.13's did anyone retain downshifting to 4th for passing? I have heard that 5.13 definitely looses downshifting to 4th but recently heard that 4.88s and 37s also loose shifting to 4th to pass.
I live at 5,000 ft and do tow from time to time but I don't think Im willing to give up the downshift. The little 3.6 does its best work at higher rpm.
Thanks
Scratch

I have 513 in our JLUR with 37's, and was leary of the same thing until I got them. Like mentioned above, depends on kickdown speed whether its hits 4th or 5th. With that said, I have had zero issue with passing someone whether I'm going 70, or 80 when I go to pass someone. I wouldn't worry about that at all if I were you. I live in WV, not as much elevation as you, but def a mountainous area and commute.
Picking up my JTR in a couple of weeks with 37s and I will be doing 513 immediately. Wish I would have done it 2 years ago in our JLUR.

 

[Scratch]

I have 513 in our JLUR with 37's, and was leary of the same thing until I got them. Like mentioned above, depends on kickdown speed whether its hits 4th or 5th. With that said, I have had zero issue with passing someone whether I'm going 70, or 80 when I go to pass someone. I wouldn't worry about that at all if I were you. I live in WV, not as much elevation as you, but def a mountainous area and commute.
Picking up my JTR in a couple of weeks with 37s and I will be doing 513 immediately. Wish I would have done it 2 years ago in our JLUR.

Thank sir for taking the time for the thorough reply.

 

[WhatExit?]

I’ve now had 37’s on my Mojave for over a month. I live in Charlotte, so it’s relatively flat. I do use a Pedal Commander. I don’t tow anything. I do have a lift, front steel bumper, armor underneath and a winch. I don’t see any reason to change the gears. I may struggle when I head to the mountains a few times a year, but otherwise I really didn’t notice much difference. I still find 8th gear on my auto. Just my two cents. I think the Pedal Commander is the key...and no I don’t work for them.

37's and a lift on a Mojave

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