4.88 or 5.13?

[rustyshakelford]

Ill agree that the pinion head is a little bit smaller but it sure seems stout enough. To make this driveable and have a better crawl ratio I don’t think gear swaps can be denied. If I do destroy the pinion I’ll replace it back with 5.13s

Brett

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[intentsrig]

We saw that problem with the FJ Cruisers... 4.88s would fail before 4.56 or even OE. However, I wonder how much meat you are giving up on the 44? Is the pinion head that much smaller with the lower (higher) gears? So much so that you are giving up actual durability?

There is a video on YouTube of the JL experience One of them is running 5.38’s with 40” tires on stock axles. Breaks a Ujoint and later the ring and pinion.

However, he was facing down a steep ledge AND trying to reverse up while bound up. Reversing is the weakest point for the gears in that front axle. So I’d stay with 5.13’s or numerically lower. 4.88’s etc. With what he was doing with those stock axles and 40’s I wouldn’t have been surprised if the stock gears had let go.

 

[fat_head]

There is a video on YouTube of the JL experience One of them is running 5.38’s with 40” tires on stock axles. Breaks a Ujoint and later the ring and pinion.

However, he was facing down a steep ledge AND trying to reverse up while bound up. Reversing is the weakest point for the gears in that front axle. So I’d stay with 5.13’s or numerically lower. 4.88’s etc. With what he was doing with those stock axles and 40’s I wouldn’t have been surprised if the stock gears had let go.

Here's the vid. That poor Jeep! Skip to 15:40, then to 26:40

 

[BLLFRG]

This is the direction we are going when our Jeep comes in. 5.13 on 37s with the 6 speed. I’m thinking it’ll like the slightly higher rpms on the highway too. When we test drove one, it felt almost like you were lugging it at 70

I typically don’t drive faster than 65 so hopefully it’ll be a good fit

Brett

Ok, so what size and weight tire/wheel combo do you have? Does that part even matter/factor in? I am considering a 2 door, 3.6, 6 speed, 2.5" lift, 37x13.5/18s....which will put about 115lbs on each corner.... I've debated between 4.88 and 5.13 also.

 

[rustyshakelford]

Ok, so what size and weight tire/wheel combo do you have? Does that part even matter/factor in? I am considering a 2 door, 3.6, 6 speed, 2.5" lift, 37x13.5/18s....which will put about 115lbs on each corner.... I've debated between 4.88 and 5.13 also.

We have the mopar beadlocks ans cooper STT pro 37/12.5r17. The 3.6 is pretty anemic and performs much better in the higher rpms. If you were only going 35s with an auto I’d leave it alone. 37s and up I’d do 5.13s. The 5.38s are an option to but I think you lose to much pinion strenght and with that gear you’d be running 40s typically and that’s just a recipe for d44 disaster

Brett

 

[jerseymike]

As a data point, I have a jl sport 6 speed that had 3.45 gearing and went to rubi 285/70/17 ko2's and still had a little pull in 6th gear at 70+ mph. Went to 315/70/17 ko2's on rubi wheels and 6th gear lost useful pull.(70mph @1800rpm) Switched to rubi jl d44 axles with 4.10 gearing using the sport driveshafts and 6th gear power improved and had useful pull.(70mph @ 2100 rpm) It felt similiar to driving with the 3.45 gearing and 285/70/17 tires.

thanks for the info....I have 285/70/17 now and plan to likely go 315 in the future....debating on regearing from 3.45 to either 4.10 or 4.56, sounds like either would work but maybe 4.56 is the way to go

 

[jerseymike]

Do you have a 6 speed or auto? Auto seems to pull a little better. I would definitely go to 4.56 if you're going to 35's and have funds to regear.

Good point (probably most important in regear decision), I have the manual (if I had auto I maybe wouldn’t even need to from what I have heard)

 

[intentsrig]

Ill agree that the pinion head is a little bit smaller but it sure seems stout enough. To make this driveable and have a better crawl ratio I don’t think gear swaps can be denied. If I do destroy the pinion I’ll replace it back with 5.13s

Brett

Here’s a picture I took while re gearing. It only looks so drastic because of how high the 3.45 gears are!
Roughly around the same size head as the JK 5.13, maybe a tad bigger and different design for the pinion.

Mechanic said the new 44’s are more like old school 44’s due to where the pinion rides on the ring gear.

 

[rustyshakelford]

Here’s a picture I took while re gearing. It only looks so drastic because of how high the 3.45 gears are!
Roughly around the same size head as the JK 5.13, maybe a tad bigger and different design for the pinion.

Mechanic said the new 44’s are more like old school 44’s due to where the pinion rides on the ring gear.

Mine were 4.10s swapped to 5.13s. I wish I had taken more pics. The shafts are stout.
Did you have to change the carrier up front?

Brett

 

[Zeus]

Here’s a picture I took while re gearing. It only looks so drastic because of how high the 3.45 gears are!
Roughly around the same size head as the JK 5.13, maybe a tad bigger and different design for the pinion.

Mechanic said the new 44’s are more like old school 44’s due to where the pinion rides on the ring gear.

WHOLE lot of difference in the thickness of the metal on the head of those. Be interesting to see a comparison of a 4.10 to 5.13

 

[intentsrig]

Mine were 4.10s swapped to 5.13s. I wish I had taken more pics. The shafts are stout.
Did you have to change the carrier up front?

Brett

I replaced with an Ultimate dana 44 for the JL in the front. Install tommorrow

 

[OBJLU]

Mine were 4.10s swapped to 5.13s. I wish I had taken more pics. The shafts are stout.
Did you have to change the carrier up front?

Brett

How do you like the 5.13’s, I’ve got my regear scheduled in about a week and will be going with the same gears and 37’s but now starting to worry about the rpm’s but I rarely go over 70 mph during my daily drive and cal learn to drive slower when taking trips. Would you have gone with 4.88’s, after driving it for a while?

 

[rustyshakelford]

How do you like the 5.13’s, I’ve got my regear scheduled in about a week and will be going with the same gears and 37’s but now starting to worry about the rpm’s but I rarely go over 70 mph during my daily drive and cal learn to drive slower when taking trips. Would you have gone with 4.88’s, after driving it for a while?

For the manual, I still think the 5.13s are a perfect combination. So, to answer your questions, I’d stick with the 5.13s

Brett

 

[OBJLU]

I regeared and it's awesome off-road! I don't mind the higher RPM"s on the highway - I just drive slower, no prob, leave a little earlier and I still get around 20 MPG

 

[UKCATS]

I’m getting 4.88’s installed as I type. I’m running 35’s. I think it will be perfect.

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