Re-gearing question: 37's with 5:13 or 4:88 gears?

[Wheelin98TJ]

Someone would have to measure the tooth contact surface area to determine the strength of the gear set.

I’ve seen data showing deeper ratios sometimes having more contact area. This was for a D60 and not the Advantek D44, but there’s nothing unique about the D60 that causes this.

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[Duece McCracken]

Is this more, or less relevant to the gear ratios in the manual trans?

 

[kennyglm]

i am going 4.88 as advised by the jeep dealer and the performance drivetrain shop doing the job. I dont tow anything nor do i plan on it and i also watched to many videos of overheated rears and lower gas mileage from people that went 5.13 gears and had to replace them after a year due to failure.

 

[GEETCH]

Pinion strength between 5.13 and 5.38 are essentially the same. That is one argument for the 4.88s though is that they should be a little stronger, but I don't think that is much of an issue on JL/JT until you get into power adders (supercharged or V8).

im runnin 5:13s with 73s and the magnuson, so far im happy with that setup does great for the way i drive and the trails i take it on.

 

[Escape.idiocracy]

Pinion strength between 5.13 and 5.38 are essentially the same. That is one argument for the 4.88s though is that they should be a little stronger, but I don't think that is much of an issue on JL/JT until you get into power adders (supercharged or V8).

Thought was a tuned 3.0 is up there for torque 550~. (Understood the OP is 3.6… but for others out there reading.)

 

[TheRealGinjaNinja]

i am going 4.88 as advised by the jeep dealer and the performance drivetrain shop doing the job. I dont tow anything nor do i plan on it and i also watched to many videos of overheated rears and lower gas mileage from people that went 5.13 gears and had to replace them after a year due to failure.

Not that I care much about MPGs but mine has been shit since day one. All I can surmise is that the people getting upper teens and twenties haven’t seen more than an ant hill. I have a thousand feet elevation change almost every time I drive.

With regards to overheating…not saying you are wrong but in all of my research and experience this is the first I have heard of that. The pinion strength issues is largely debunked on JL/JT with the exception of a couple of guys running supercharger or hellcat.

 

[TheRealGinjaNinja]

Thought was a tuned 3.0 is up there for torque 550~. (Understood the OP is 3.6… but for others out there reading.)

Yep agree here. But nobody with a diesel will want to regear to 5.13 or 5.38 no matter how big of a tire.

 

[guarnibl]

Yep agree here. But nobody with a diesel will want to regear to 5.13 or 5.38 no matter how big of a tire.

On 42's loaded out I'd want 5.13's on a diesel.

 

[TheRealGinjaNinja]

On 42's loaded out I'd want 5.13's on a diesel.

42s with a diesel probably should have 5.13s…in one ton axles not the D44s ;-)

 

[guarnibl]

42s with a diesel probably should have 5.13s…in one ton axles not the D44s ;-)

Oh yeah, no way I'd ever run a D44 on 42's rofl. That would be a funny experiment though. I wouldn't even run them on 60's w/ the torque. Or at bare minimum, I'd have a 70 out back. We still were blowing up stuff in a 70 on occasion with my JK.

 

[Escape.idiocracy]

Yep agree here. But nobody with a diesel will want to regear to 5.13 or 5.38 no matter how big of a tire.

Man- agree with you on 5.38’s unless 40’s. I’ll be going 5.13’s

Nate @ dirtlifestyle (YouTube channel) also went 5.13’s with his “39’s”- bfg ko2’s which are basically in the ballpark of those on true 37’s/38’s.
Crawl ratio is crawl ratio…. Fuel economy isnt going to change as much as it’s made out to be. The rpm difference is not that significant and I’m not of the mantra to run 90 down the highway…

 

[TheRealGinjaNinja]

Man- agree with you on 5.38’s unless 40’s. I’ll be going 5.13’s

Nate @ dirtlifestyle (YouTube channel) also went 5.13’s with his “39’s”- bfg ko2’s which are basically in the ballpark of those on true 37’s/38’s.
Crawl ratio is crawl ratio…. Fuel economy isnt going to change as much as it’s made out to be. The rpm difference is not that significant and I’m not of the mantra to run 90 down the highway…

Fair point…Jeeps are the only thing I keep 77mph or less. But lately 70-75 is good enough for me. Fast cars give me speeding tickets with my Jeeps I just try to enjoy the drive with the knowledge I can do just about anything I could ask of a vehicle…except be fast lol

 

[JD101]

5.13 and never looked back . 1000s of miles driven from sea level to 14000' . Flat to mountains , rocks to mud and sand . I would have regretted 4.88s . There is no argument for 4.88s IMO . At least in a gladiator. 5.13s are like 4.88s with some reserve for towing , elevation , wind , ect.

If you like 4.88 that's cool too. Not bashing that choice . I like 5.13s and from my experience I haven't seen a downside .

I will add that you could go from a 37 to a 35 if ever needed with 4.88s the opposite is true for 5.13s . I was going to take the 35s off our JL and strap them on just for kicks one day .

 

[Tommyd]

i am going 4.88 as advised by the jeep dealer and the performance drivetrain shop doing the job. I dont tow anything nor do i plan on it and i also watched to many videos of overheated rears and lower gas mileage from people that went 5.13 gears and had to replace them after a year due to failure.

Is this legit? Like actual problems just from 5.13.. seems like there has been a lot of people with that gear installed.

 

[Wheelin98TJ]

i am going 4.88 as advised by the jeep dealer and the performance drivetrain shop doing the job. I dont tow anything nor do i plan on it and i also watched to many videos of overheated rears and lower gas mileage from people that went 5.13 gears and had to replace them after a year due to failure.

You watched videos of overheated rear ends and lower MPG?

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