I'm about to pull the trigger on ordering a set of UD60 for my JKU project and was wondering which gearing was best suited if I'm ultimately planning on an LS swap/6L80 down the line? I'll be running 40's and the factory TC (non-rubi). I was under the impression that the 4:88 was ideal but I've also read of some people with a similar setup, happy with the 5:38 gearing. Thoughts? What are you LS guys running?

Since UD's only come with two options, I would go with the 4.88s. Although I have yet to drive mine with the 5.38s still installed, future planning says I should be at a 4.56 with the 37s. As soon as I get my steering box back and exhaust installed, I will report back on both 5.38 and 4.56.

If you scroll through RPM's Gen IV thread, Jon lists out the RPMs the LS runs with different gearing.

I"m still on 44's , but very soon will be installing 60"s , I'm in a 2 door an very lite as far as weight is concerned .
I wish that Dana offered more selection for ratios , 4:56 would be the ratio that I would prefer .
My 44"s are geared 5:13 and are way too deep .
I think that tire diameter at 40 in your case considering available ratios that you will probably be 4:88 , 4:10 would in my opinion be too high , and 5:38 would make your first couple of gears entirely useless except for climbing walls .

4:30 gears really would be optimal but I don't think that ratio will ever be available in the crate format .
I believe I will be ordering 4:88"s , but anything below that you would be spinning your engine at excessive rpm like I am currently .
Wishing they would include more choices , but that would only make it harder to choose .

Which LS are you considering ?

I rode in a 6.2 ls 4 door this weekend at Motech, it had 3.73 gears and 37's and threw you back in the seat when you stepped on the gas. 70 mph in half a block. The 5.3 LS may be better suited for the 4.88 gears. They say they are getting more power out of the 5.3 then they did with the 6.0.

Only came The Ultimate Dana 60? Axles | Crate Axle 3.73 and 4.10 are now available although I wouldnt recommend them for 40s.

I went with 4.88 in my UD60s in anticipation of an LS swap but that hasnt happened yet. A buddy did the same with his 6.0 LS and told me he would have liked 5.38s for additional pep. We are at altitude so power output is lower up here.

I dont have real world results as I havent done the LS swap yet but there is only a 200 rpm difference at 70 mph between 4.88 and 5.38 which has me second guessing myself

Need more information. Which engine? You mention the 6l80 transmission which is a great transmission; however, so now is the 8 speed which requires different gearing.

Where are you driving, sea level in Florida or 8,000 feet in Utah?

Do you crawl or just run trails? Heavy trailer?

The 6.0 and 6.2's require different gearing than the 5.3. The Gen V LT engines are different yet.

My experience is most guys gear too steep and loose mpg, there's nothing wrong dropping into 5th occasionally.

Our online instructions have a gear section for reference.

For general use, off-road and highway:

35's 4:10
37's 4:56
40's 5:13

But again the weight, drag, lift, trailer, altitude.... all come into play.

Nice! Learn something new everyday

answers in quote.

Not the same tire size as op but for reference. I am running 35's with 4.10's. I have a JKU, 6.0, 6l80e. Live in Kansas. Recently went to Texas and got 16 mpg's. It will kick out of 6th gear if we are having our 30-40 mph head winds that we have on occasions and a slight hill (overpass).
At 75 mph I am turning 1950 rpm's. Generally I can cruise with cruise on and it never downshifts and will put you back in the seat if and when you are feeling froggy . I have not towed anything yet but hope to get a small camper in the near future and will see how it does.

I'm looking to do a 5.3 GenV with 8spd. Mine is a 2DR and I'm staying light with Artec aluminum skids and my ORFab bumpers are going to be replaced with lighter bumpers. My current tire of choice measures a true 36.8" but i may in time go with a true 40" tire. What gearing would you recommend for me in 1 tons?

I curse on the highway at 60-65mph and only do 70mph when passing. Majority of the time will be in Florida and Texas, but make regular trips to the Rausch Creek area of PA. No trailer and trails and crawling.

Please tell me about this. I have 4.56 in my axles right now. After consulting with Robbie, I understood that would be good with tires around 37-38 inches.

My question is more about the motor. I have a 2016. so am between the 5.3 or the 6.2 to be emissions legal. So serious question, Is the 6.2 just overkill in a JKU? Was the 6.2 you were in stock?

It is another $5k for the 6.2 over the 5.3. Which is decent money, but once you are writing the check might as well do it right.

My current setup is the 6.2L with 4.88 gears on 37's. The engine is from a denali and has amazing low end. I'm running quite light as of late with a bfh up front and no rear bumper or spare.

Off the line it pushes you back in your seat only pressing the pedal down a 1/4 of the way. Being in CA with the mountains, it downshifts from 6 to 5 on uphill climbs but the tap to shift makes all that super easy.

Personally, I plan on going to 4d's this year and keepin the 4.88s. Hope that helps Z-OR and the op.

I have a '09 4 door with a 6.0LS and a 6l80. Running 4.88's and they are the perfect balance of power and mpg. Switched from 5.38's and love it. Gained about 2 mpg. But I'm also running a fully armored jku that's heavy and am at 6500 ft.

The Gen V engines are changing the game, especially with the 8 speed transmission.

With many Gen V's on the road now I'm really excited. I can say the Gen V 5.3 impressed me. All the Gen V' s I have driven have great low and mid range torque.

With CVVT and high compression these engine just pull wherever your at in the RPM range, this affects tire size and gear selection.

The Gen V 5.3 feels strong, revs freely and pulls the hills well.

You need to gear up to take advantage of these engines. With a 4.6 first gear the 8 speed is over 10% lower than a 6 speed and worlds different than the pathetic 4 and 5 speeds.

I'm excited about the Gen V in a JK. After road testing several it is the future. I've had L86's consistantly best Hemi' s and LS3's. We geared up an L86 6.2 and are getting excellent mpg.

With OE harnesses, billet brackets and proper CAN interface these Swaps will be easier and as reliable as ever.

The Gen V in a Pentstar JK is simplicity itself. It is so well Integrated I'm excited, not just because it works but because it works so well. Nothing out there can compare IMO.

Were gearing up to produce 50 install kits at a time. This includes virtually plug and play OE harnesses, bolt on billet brackets putting the accessories where they belong. No mod A.C. and PS lines. And running OR hardware and software means emissions compliance.

It's an exciting time, by summer you will see some very exciting products that will offer the best running JK ever.

I curse on the highway too, I'm from LA

On a light 2 door with 38's cruising below 70 mph 4:56's should work well. Someone mentioned 4:30's I wish we had that option.

I've been driving a heavy 4 door JK with an L86 on 37's and it rips the tires loose off the line but 80 mph is just over 2,000 rpm and so relaxed it's like being in your living room. The L86 will hold 4 cylinder mode at 80 mph.

The 5.3 is only 1.5 liters larger than the 3.8. The Gen IV 5.3 is a great engine but has it's limitations in a heavy JK. The Gen V 5.3 has less limitations with the higher cylinder pressures. I feel the Gen V 5.3 is enough to haul most JK's around, if you must have a muscle car JK get the 6.2.

Sweet....



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