37 vs 38’s and 4.88 vs 5.13

[Panthers65]

My first one had 5.13s but this one has 4.88s. Both trucks on 37s

I actually feel like the better highway gear is the 5.13s as opposed to the 4.88s, as it will allow you to use 8th more. I’m getting worse MPGs with this new one with the 4.88s than my old one with the 5.13s

THAT BEING SAID
1. This newer one has heavy MTs (Nitto Trail Grapplers) while the old one had Milestar XTs. I’m pretty sure each Milestar is 15lbs lighter than the Nittos. That alone makes a huge difference
2. A lot of people say a numerically lower (higher gear) is stronger due to pinion engagement. On the street this doesn’t matter but off road it does

All in all, I’d say the 5.13 is better for a DD which is counterintuitive

it’s not really counterintuitive, it just fits the preferences of the majority of Jeep owners and how they want their Jeep to perform. IMO from all the jeeps I’ve built with countless customers across 3 different Jeep shops, you results/preferences were by far the most common. With as much pressure as Jeep gets from the gov on fuel efficiency, they literally added a battery and developed a full auto start/stop system vs just dropping the gear ratios like mfgs use to do. I remember seeing full size 6k pickups with 3.08s just trying to artificially bump their highway MPGs to make the gov happy. They were dogs that couldn’t work for crap. Jeep took the MPG epa hit on the max tows because the deeper gears made that much of a difference.

from what remember the 4.88s and 5.13s both have the same number of pinion teeth, so the strength topic really isn’t a big deal. I’ve seen plenty of issues with the m220 bearings being issues, but if I’ve seen an actual pinion snap at the head I don’t remember. I guess you could make a case for the bearing having issues because they are spinning faster with 5.13s vs 4.88s, but that’s a stretch.

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[Zachanadandy]

the ram has a higher tow rating because of the weight, wheelbase, width, COG, and a host of other factors. If you think the only thing that factors into tow rating is HP and gearing, cameros mustangs and corvettes out there should be kicking our butts.

you were comparing factory rubicons to factory gladiators, and now that it doesn’t match your stance you have to throw “built” in there.
And the longest industry standard was to overgear the TJS even deeper than the JTs TJs were right in the time when I was in the industry and 456 on 33s for DD/488s for performance was the norm.

Keep your 37s and 4.10, you clearly drive more high-speed than the vast majority of Jeep drivers. the majority of Jeep owners and people on this form, they’ll appreciate the performance of a deeper gear set. If the Jeep engineers wanted the max tow gladiator to be at the final ratio of 4.10: and 37s, they wouldn’t have equipped it with 32s with those same 4.10s.

for a towing/trail riding/working truck:
4.10 and 32s
4.56 and 35s
4.88-5.13s for 37/38s
5.38s/axle swaps for 40s+

if you tow often/spend all your time driving around tow , go a little deeper. If you spend most all your time on the interstate and rarely tow anything more than a lawn mower trailer, gear a little higher.

Who was comparing factory? We've been talking 37s the entire time. Do you realize how much work it takes to run 37 on a TJ? Fully built and 6" of lift and you're probably still breaking out the sawzall. Sure you can put 37s on a stock JT, but most don't do that? Were you actually talking 5.13s for stock sized tires? As far as towing, of course there are other factors that go into the rating. My point was the ram with the same engine and transmission and more weight can tow the same load with much higher gearing, negating your argument that the Jeep needs deep gears to tow because you put a larger heavier tire on it. The rams 3.21 gears and 32" tires are the equivalent of 37s and 3.73s. The 4.10s will do the job no problem. I've towed an 8200lb trailer 600 miles with over 7k feet of elevation gain on 37s with 4.10s.

 

[Orange01z28]

I've heard on the YouTubes that 5.13 once you've reached highway speeds and need to over take someone, the automatic gear box will not down shift.

That’s incorrect. They must have not set the gear ratio in the computer. My old one would downshift whenever you would expect it to on 5.13s

 

[Panthers65]

Who was comparing factory? We've been talking 37s the entire time. Do you realize how much work it takes to run 37 on a TJ? Fully built and 6" of lift and you're probably still breaking out the sawzall. Sure you can put 37s on a stock JT, but most don't do that? Were you actually talking 5.13s for stock sized tires? As far as towing, of course there are other factors that go into the rating. My point was the ram with the same engine and transmission and more weight can tow the same load with much higher gearing, negating your argument that the Jeep needs deep gears to tow because you put a larger heavier tire on it. The rams 3.21 gears and 32" tires are the equivalent of 37s and 3.73s. The 4.10s will do the job no problem. I've towed an 8200lb trailer 600 miles with over 7k feet of elevation gain on 37s with 4.10s.

so your stance is gear ratio doesn’t factor into tow rating? And typically speaking deeper gears wouldn’t increase tow comps it’s all other things the same?

just because you did it and didn't screw something up doesn’t mean it was a good idea. Anyone that would pull 8k with a gladiator 600 miles imo has a serious lack of judgement, much less a gladiator on 37s.

 

[Zachanadandy]

so your stance is gear ratio doesn’t factor into tow rating? And typically speaking deeper gears wouldn’t increase tow comps it’s all other things the same?

just because you did it and didn't screw something up doesn’t mean it was a good idea. Anyone that would pull 8k with a gladiator 600 miles imo has a serious lack of judgement, much less a gladiator on 37s.

If gearing was the limiting factor, but the ram proves the Jeep isn't limited by gearing even with 4.10s and 37s. If you didn't have enough gearing to get the trailer going then it's a gearing problem. That's clearly not the case as the ram will do it with the same weight as a JT on 37s with 3.21s. That's a fact you can't ignore or argue. You have the gearing to do the work with 4.10s.

 

[Orange01z28]

If gearing was the limiting factor, but the ram proves the Jeep isn't limited by gearing even with 4.10s and 37s. If you didn't have enough gearing to get the trailer going then it's a gearing problem. That's clearly not the case as the ram will do it with the same weight as a JT on 37s with 3.21s. That's a fact you can't ignore or argue. You have the gearing to do the work with 4.10s.

What size tires are on the Ram and the Jeep?

Tire diameter affects overall gear ratio

 

[Zachanadandy]

My first one had 5.13s but this one has 4.88s. Both trucks on 37s

I actually feel like the better highway gear is the 5.13s as opposed to the 4.88s, as it will allow you to use 8th more. I’m getting worse MPGs with this new one with the 4.88s than my old one with the 5.13s

THAT BEING SAID
1. This newer one has heavy MTs (Nitto Trail Grapplers) while the old one had Milestar XTs. I’m pretty sure each Milestar is 15lbs lighter than the Nittos. That alone makes a huge difference
2. A lot of people say a numerically lower (higher gear) is stronger due to pinion engagement. On the street this doesn’t matter but off road it does

All in all, I’d say the 5.13 is better for a DD which is counterintuitive

Or you proved that ATs are the better tire for a DD and the MTs are making the 4.88s appear worse? Id argue your 2 very different tires would make more of a diffrence than the gears when you're talking 4.88s vs 5.13s. As far as mpg if the new one is brand new that's also contributing to worse fuel economy.

 

[Orange01z28]

Or you proved that ATs are the better tire for a DD and the MTs are making the 4.88s appear worse? Id argue your 2 very different tires would make more of a diffrence than the gears when you're talking 4.88s vs 5.13s. As far as mpg if the new one is brand new that's also contributing to worse fuel economy.

The new one is used. And yeah, my conclusion is the weight of the MTs is making the 4.88s appear worse

 

[Zachanadandy]

What size tires are on the Ram and the Jeep?

Tire diameter affects overall gear ratio

The ram and the Jeep come with the same sized tires outside of the Rubicon and mojave trims. And even if you do the math for 37s that mashed the effective ratio just 3.73s to match up to 3.21s and 32s. Not saying that's optimal, especially for a Jeep that gets wheeled on 37s but the argument that it needs more gearing to tow is just false.

 

[Panthers65]

If you didn't have enough gearing to get the trailer going then it's a gearing problem.

really?

That's clearly not the case as the ram will do it with the same weight as a JT on 37s with 3.21s. That's a fact you can't ignore or argue. You have the gearing to do the work with 4.10s.

What fact? Is the fact in the room with you right now?

I said gearing was one of SEVERAL factors that contribute to a tow rating. That the gladiator lacks in other factors it has to make up in gearing. Deeper gears is one of several things a mfg will do to contribute to a higher tow rating.

Either way, I’m done. Anyone that thinks it’s a good idea to pull an 8k trailer 600 miles with any gladiator, much less a modified one, isn’t someone that should be giving any sort of advise out. Your are the epitome of poor information on the internet.

 

[Zachanadandy]

really?



What fact? Is the fact in the room with you right now?

I said gearing was one of SEVERAL factors that contribute to a tow rating. That the gladiator lacks in other factors it has to make up in gearing. Deeper gears is one of several things a mfg will do to contribute to a higher tow rating.

Either way, I’m done. Anyone that thinks it’s a good idea to pull an 8k trailer 600 miles with any gladiator, much less a modified one, isn’t someone that should be giving any sort of advise out. Your are the epitome of poor information on the internet.

You use words like physics until it doesn't remotely fit your argument. Gearing is used to make up for wheelbase and width? It's sounds even dumber when I type it than when I read it. The Jeep needs more gearing to do the same work with the same powertrain because of wheelbase? You can't be serious.

 

[Panthers65]

You use words like physics until it doesn't remotely fit your argument. Gearing is used to make up for wheelbase and width? It's sounds even dumber when I type it than when I read it. The Jeep needs more gearing to do the same work with the same powertrain because of wheelbase? You can't be serious.

Go tow 8k with a mid-size 6cyl truck on 37s. Puts words in my mouth I didn’t say all you want, you’ve showed your knowledge on the subject and it’s no longer worth my time. Your posts should come with a disclaimer.

 

[mtudb24]

My gladiator started life at 0 miles on true size 35's and is a max tow with 4:10's. So i never knew what driving on stock tires was like. What I can tell you from my previous JK Rubicon on stock 33's and upgrading finally to 35's with the 3.8L, and a 4 speed auto trans, and 4:10 gears, the JT with the 35's/ 37's and a 8 speed trans is so much better daily driver.

Then going from the 35's to a smaller 37's (36.5 overall tire height) 4 months ago, i've not seen a appreciable difference in performance at all. I still hit 8th gear while running the freeway.

For what I use my gladiator for (Occasional logging mud trails in the UP, silver lake sand dunes, and towing a 5500lb boat 2-4 times a year) I'm perfectly fine with the 4:10 gears.

I'd rather spend my money on a Eaton front locker or limited slip then to pay the money for re-gearing.

Just my opinion on how to use my gladiator. Others with other uses may have a different opinion.

 

[Hemy5587]

"Prove to me exactly what I want exactly how I want it while standing on 1 foot, rubbing your belly, and saying the pledge of allegience"

I'd rather just....not. You seem to think I care more than I do. I'm getting 18+ on 37's and 5.13's. Stubby bumper and flat fenders. Typically no traffic in the morning but at least 10-15 minutes of sitting in traffic in the afternoon. Believe me or not, don't really care. My jeep is actually fun to drive again with the 5.13's. It doesn't drop gear every time I hit a hill, it pulls my boat substantially better than it did with the 4.10's, and there's plenty of gear left on the highway. Do I drive 90+ on the interstate? No, but I'm not an acne covered 19 year old with daddy's credit card paying for my gas. Buying a Jeep to drive fast is like paying a prostitute to take home to your parents, It might work but we all know it's a stupid decision. 5.13 is a 125% jump from 4.10. Meaning in first gear when I'm trying to get moving, I have 125% (excluding inefficiency) more than I would have had with 4.10's. That's not some backwoods test, that's basic physics and math, and it works.

And it's not hard to calculate RPMs on the interstate. a 10 second google search will pull up our final drive ratio and multiple RPM Calculators

.67:1 overdrive, 5.13 gears, and 35.6" tall BFG's gives you a ROME of 2270.8 at 70mph. 2300 RPM is peak efficiency for our motors. This matches what I see every morning and every afternoon on the interstate. I'm not a tool bag, I don't play on my phone while driving down the interstate.

Again- quite happy with my choice.

As long as you're happy, that is all that matters as it is your rig. Just surprising to hear especially with the all idling factored in but after another 10 second google search you are not alone although the minority with that efficiency and similar set ups. Makes me second guess what I would gain with my setup, I went with an air intake, ported throttle body, afe Y pipe and pulsar but if I add gears on top of it all... might just be icing on the cake.

 

[Panthers65]

As long as you're happy, that is all that matters as it is your rig. Just surprising to hear especially with the all idling factored in but after another 10 second google search you are not alone although the minority with that efficiency and similar set ups. Makes me second guess what I would gain with my setup, I went with an air intake, ported throttle body, afe Y pipe and pulsar but if I add gears on top of it all... might just be icing on the cake.

It’s the same mentality people have when looking at full size trucks. “If I get a 6cyl instead of an 8cyl I’ll get better MPGs”. That rarely works because they have to work the 6cyl 25% harder to get the same result, so the mileage gains end up being minimal.

Now if you drive that 6cyl like a little old woman, yea you might get close to the higher mileage, but with real world activities it just doesn’t often work out that way.

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