Talk me out of 5.13's

[bcurtman]

Gladiator Sport S Max Tow
Daily driver for 15 mile round trip commute
Occasionally will drive 50-80 miles for a doctors appt, shopping, etc
All local driving is at 55 mph with one person, empty-please keep that in mind!

Tires changed to Kanati 12.50-35-17, probably about 34" tall, 3" lift, Diamondback bed cover

Plan is to use it for weeklong / weekend trips pulling a 2 person tiny camper weighing about 1500-1800 lbs, bed loaded with camping gear, 2 people, and yes we will go to the mountains and will have to drive from central Missouri across Kansas.

In stock form with approx 31" tall tires and 4.10 gears, it should have run 70 mph at 2085 rpm.
I have to assume this is somewhat of a sweet spot and in the power band for the best mileage. No experience towing with it stock nor checking mileage much as we put the tires and lift on right away.

Math says I am now running around 1901 rpms with the new tires at 70 mph. So with only a rpm drop of 184, I am now hunting for 7th and often 6th on hills that are not at all steep. Torque curve must really drop off below 2000 rpm!! Especially true on 55 mph roads where engine would be at 1493 rpms. Dont see 8th very much here in the Ozarks.

Same scenario, 4.88's should put me at 2262 rpm, for an increase of around 177 over stock.

Is that enough of being the "same or better" to add the trailer and extra weight, or is adding 294 rpms over stock with 5.13 gears (2379 rpms) going to make me a happier camper when towing the trailer into the Kansas headwind and heading into the mountains? Only 1869 rpms at 55 mph, for what its worth 8th gear).

Looking for input from folks with actual experience vs just guesswork. Virtually no chance I would ever go to 37" tires. Might do E-lockers when I do the gears, which is immaterial I know. 4.88 seems to be the go-to. I only want to do it once and do it right. I wonder if there is a dyno torque curve available for this engine?

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[calipoontappa]

5:13s are perfect for 37s or more anything less and you should stick to 4.88.

 

[hjdca]

5:13s are perfect for 37s or more anything less and you should stick to 4.88.

Yes, I agree. I have a stick shift Rubicon with 5:13s and 37 inch tires and I think the gearing is perfect. Performance stop light to stop light is fantastic and gas mileage is great. If you have an automatic and towing with 35 inch tires, then, 4:88s should be perfect.

 

[bcurtman]

I drove the Gladiator about 75 miles one way to go out for the day Saturday with my wife, and here are my gearing observations.

It drops to 6th pretty readily on the two lane, and stayed there a lot at 70 on the interstate.

At 70 mph (with 4.10 gears and 34.69 tall tires) we were running about 2800 rpm in 6th. Math says 2790.

At 55 mph we were running about 2200 rpm in 6th. Math says 2190.

Remember that 6th gear is direct drive, or 1:1, and 8th is .67 overdrive.

So, based on those numbers and where the jeep goes rpm-wise for the power to hold speed on those inclines and situations, we could hypothetically run 6.14 gears to maintain those same rpm's in 8th.

Still think 5.13's will be too much????

 

[hjdca]

I drove the Gladiator about 75 miles one way to go out for the day Saturday with my wife, and here are my gearing observations.

It drops to 6th pretty readily on the two lane, and stayed there a lot at 70 on the interstate.

At 70 mph (with 4.10 gears and 34.69 tall tires) we were running about 2800 rpm in 6th. Math says 2790.

At 55 mph we were running about 2200 rpm in 6th. Math says 2190.

Remember that 6th gear is direct drive, or 1:1, and 8th is .67 overdrive.

So, based on those numbers and where the jeep goes rpm-wise for the power to hold speed on those inclines and situations, we could hypothetically run 6.14 gears to maintain those same rpm's in 8th.

Still think 5.13's will be too much????

For me 5:13s and 37's are perfect, but, I do not tow and many of the people I travel with go over 80 mph periodically...
Maybe something to consider --- The V6 motor doubles it's oil pressure at 3K rpm, so, my philosophy is to spend the majority of the cruising time under 3K rpm.

I have towed a lot in the past, and there is no substitute for gearing. So, I think your question is a great one. If you plan to tow a lot and do not plan to go over 70 mph in general, I can see a 5:13 geared 35" gladiator doing fantastic while towing with that gearing. You also get that tow load up to speed very quickly. The truck will be super quick. One of the main things is to keep the wheels and Tires light. Putting heavy feet on the truck will hurt your towing acceleration.

 

[Bbannongmu]

check it out. Thanks @Jt-wrx

 

[Wheelin98TJ]

I have 35s and will likely regear to 5.13.

Sorry, no actual experience, just wanted to give you support for the 5.13s.

 

[PDiddy]

I’m running 35s and 4:88 and pulling a 6k trailer with my JTR. It does well but it does rev high going up hill. Now way around that. It’s just where the power is. But it does good towing with this set up. I think you will be fine with either 4:88 or 5:13s. I still don’t use 8th hardly at all towing, but I don’t think you necessarily need to.

 

[exfil offroad]

Gladiator Sport S Max Tow
Daily driver for 15 mile round trip commute
Occasionally will drive 50-80 miles for a doctors appt, shopping, etc
All local driving is at 55 mph with one person, empty-please keep that in mind!

Tires changed to Kanati 12.50-35-17, probably about 34" tall, 3" lift, Diamondback bed cover

Plan is to use it for weeklong / weekend trips pulling a 2 person tiny camper weighing about 1500-1800 lbs, bed loaded with camping gear, 2 people, and yes we will go to the mountains and will have to drive from central Missouri across Kansas.

In stock form with approx 31" tall tires and 4.10 gears, it should have run 70 mph at 2085 rpm.
I have to assume this is somewhat of a sweet spot and in the power band for the best mileage. No experience towing with it stock nor checking mileage much as we put the tires and lift on right away.

Math says I am now running around 1901 rpms with the new tires at 70 mph. So with only a rpm drop of 184, I am now hunting for 7th and often 6th on hills that are not at all steep. Torque curve must really drop off below 2000 rpm!! Especially true on 55 mph roads where engine would be at 1493 rpms. Dont see 8th very much here in the Ozarks.

Same scenario, 4.88's should put me at 2262 rpm, for an increase of around 177 over stock.

Is that enough of being the "same or better" to add the trailer and extra weight, or is adding 294 rpms over stock with 5.13 gears (2379 rpms) going to make me a happier camper when towing the trailer into the Kansas headwind and heading into the mountains? Only 1869 rpms at 55 mph, for what its worth 8th gear).

Looking for input from folks with actual experience vs just guesswork. Virtually no chance I would ever go to 37" tires. Might do E-lockers when I do the gears, which is immaterial I know. 4.88 seems to be the go-to. I only want to do it once and do it right. I wonder if there is a dyno torque curve available for this engine?

ive had 5.13s with my 35s for the last several months, I dont regret at all, pick up is insane. I do plan to go to 37s, but honestly even if you plan to tow, you wont regret 5.13s. Its the same price point for any gear change, so why not go up, heck you might change your mind down the road and your covered.

 

[LostWoods]

The only downside to short gears is cruise so if you want to see if you can handle 5.13s, 7th gear on a Rubicon or Max Tow is the equivalent gear change to what 8th will be with 5.13s. Personally, I find that a little too short with 35s but our freeway speeds are frequently 80 or better.

 

[jsalbre]

I’ll add a comment counter to a lot of the others. I’m on 35s with 4.10s and towing 4500 lbs. it does just fine, even in the mountains. I get into 8th gear on flat ground occasionally. It does rev up pretty high on climbs, but even gearing isn’t going to fix that. Gas engines rev for power. Even my Ram 2500 with 410 HP revved up high for steep climbs.

Obviously you’re going to see an improvement in power with a gear change, but I’m not sure it’s enough to be worth the cost, especially with as light of a trailer as you’re pulling and with only going to 34s.

 

[exfil offroad]

The only downside to short gears is cruise so if you want to see if you can handle 5.13s, 7th gear on a Rubicon or Max Tow is the equivalent gear change to what 8th will be with 5.13s. Personally, I find that a little too short with 35s but our freeway speeds are frequently 80 or better.

holly crap your driving over 80 on the highway in a jeep? man enjoy the ride...

 

[jsalbre]

holly crap your driving over 80 on the highway in a jeep? man enjoy the ride...

If you’ve got a modern Jeep and it’s not comfortable to dive at over 80 then someone has jacked something up with the suspension. It’s going to inhale gas at that speed, but there shouldn’t be any ride concerns. We covered half of Idaho with 80 MPH speed limits at about 5 over because of a time crunch and it was as easy as doing 60, though admittedly there was a bit more wind noise.

 

[exfil offroad]

If you’ve got a modern Jeep and it’s not comfortable to dive at over 80 then someone has jacked something up with the suspension. It’s going to inhale gas at that speed, but there shouldn’t be any ride concerns. We covered half of Idaho with 80 MPH speed limits at about 5 over because of a time crunch and it was as easy as doing 60, though admittedly there was a bit more wind noise.

not uncomfortable, just dont drive over 80, like ever, not in a twin turbo, not in a jeep, just dont need to drive that fast. to be honest i also think people underestimate the lethality of a car wreck.

 

[Aonarch]

holly crap your driving over 80 on the highway in a jeep? man enjoy the ride...

I split my time in Montana, and speed limits out there and a few neighboring states are 80 or 85 MPH.

The soft top cannot go above 85 mph without buffeting itself to death.

Back on topic:

To me 5.13s are aggressive.

For 35s, 4.56 is the closest match to factory 4.10s with 33s (Rubicon spec). That is why the Xtreme Recon comes with 4.56 gears.

Personally I'd go 4.56 even for 37s, but for you I'd recommend 4.88.

It's a nice compromise between cruising and acceleration for 37s.

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