Will MPG be much lower with 4.10 compared to 3.73 running stock tire size or up to 32"?

[hikernbackpacker]

Looking at a couple of different Gladiators and trying to decide which one would work best for me. One is a Sport S with max tow package and 4.10 gearing. The other is the Willys with the standard 3.73 gearing.

I rarely have a need to tow and don't think my future needs will change much from the present. I don't have a need to run 35" or greater tires either for the things I do. Most likely either stock tires or up to 32" would be as large as I would need to go. I do in-town driving, interstate driving, and some gravel/dirt roads to hiking trailheads. Planning on doing some light off roading on forest service roads but nothing intense like rock crawling and such.

I understand 4.10 gearing will degrade MPG somewhat but am not sure in my case what a reasonable reduction might be when not towing. I also think the 4.10 gearing will cause the engine RPMs to be higher during interstate driving.

Anyone have any experience or research that could help me understand what I could expect if I go with the vehicle that has the 4.10 gearing?

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[ShadowsPapa]

Can't speak to the 4.10 gearing, but I tow fine with a 3.73 ratio - 5,000 pounds. No problems.
Before I added a lot of weight and different tires I could easily get 21-22 mpg. The tire change and extra weight dropped me to 19-20 mpg in the summer, 17-18 in the winter.
Since I have an Overland - the tires stock were 32.2" with the 3.73 gearing. Does great. I changed to a slightly wider A/T tire but they are still 32.2" tires. That's what impacted the mpg as much as anything, IMO.

 

[bd100]

The 4.1 gears will allow the second overdrive more often for highway travel, so things will probably be just fine.

I will also mention that around 15K miles something in the computer changed the torque to make the engine happier at lower RPM. 3.73, 6MT. I can do 60 in the second overdrive now, and I can come out of a right turn in third, similar to my old 318 V8 pickup with 3.55 gears.

And the 4.10s make for a slightly better reverse as well.

 

[hikernbackpacker]

The 4.1 gears will allow the second overdrive more often for highway travel, so things will probably be just fine.

I will also mention that around 15K miles something in the computer changed the torque to make the engine happier at lower RPM. 3.73, 6MT. I can do 60 in the second overdrive now, and I can come out of a right turn in third, similar to my old 318 V8 pickup with 3.55 gears.

And the 4.10s make for a slightly better reverse as well.

Thanks for the good information. I am in the learning stages when it comes to gear ratios so it is all still very new to me.

 

[ShadowsPapa]

The 4.1 gears will allow the second overdrive more often for highway travel, so things will probably be just fine.

I will also mention that around 15K miles something in the computer changed the torque to make the engine happier at lower RPM. 3.73, 6MT. I can do 60 in the second overdrive now, and I can come out of a right turn in third, similar to my old 318 V8 pickup with 3.55 gears.

And the 4.10s make for a slightly better reverse as well.

Probably less difference with an automatic as it will stick to whichever gears it needs to keep up speed at the RPM it wants.
You'll either see 8th gear more or less depending on the ratio.
For a stick, I'd want the 4.10s, for the automatic, it may not matter so much. It will stay in 8th more with the 4.10s, and stick to 7th more with the 3.73s. Tire size will figure into all of that.
I only see 8th on the flats with low wind speeds.

 

[mdyucca]

The 4:10’s are a better gear set for the Gladiator. I started with 3:73’s and now have 4:10’s. My experience is if your looking for fuel economy get a small Toyota or Honda. My average fuel economy has been between 13.5 and 14.5, mostly city driving. My mileage with the 3:73 was slightly better 14.5 to 15.5. However, this was also before all the add ons and modifications; steel bumper, lift kit, winch, larger tires (33’s) and wheels, heavy duty steering/suspension components (tie rod, track bars, drag link, control arms), armor and gusset’s, steel Molle panels in the bed, Bak bed cover, air compressor, lights, mounting brackets, wireing and switches. When you add it all up the weight is significant. I still can get 20 mpg with solid 65 mph freeway driving. 20 mpg has been my best mpg with both 3:73 and 4:10’s. If I had to do it all over again I would start with a Rubicon with auxiliary switches, LED light package and tow package. I have enjoyed building my Gladiator and really enjoy off roading my rig that is as capable maybe slightly more off road capable than a stock Rubicon. In any case the Gladiator is not known to be an economy car and IMO 4:10 gears are better suited for the Gladiator.

 

[redriderjf87]

I doubt you'll see a mpg decrease at all.
4.10's will improve your city mpg, and may help your highway mpg if it reduces lugging the motor down or downshifting under load.

6th in my 3.73 manual doesn't seem to give me any mpg advantage over 5th unless I'm running 75+ (which I rarely do). Just above 2,000 rpm.

Otherwise it lugs easily and kills any mpg advantage you would've gotten from the lower rpms.

 

[hikernbackpacker]

Probably less difference with an automatic as it will stick to whichever gears it needs to keep up speed at the RPM it wants.
You'll either see 8th gear more or less depending on the ratio.
For a stick, I'd want the 4.10s, for the automatic, it may not matter so much. It will stay in 8th more with the 4.10s, and stick to 7th more with the 3.73s. Tire size will figure into all of that.
I only see 8th on the flats with low wind speeds.

Thanks for the informative additional information. I have driven a stick plenty, but at this point am looking at automatic as my work commute does involve a lot of start/stop/red light sitting in downtown traffic. With the information everyone has provided I don't feel as apprehensive about the different gear ratio and feel more at ease with it so I'm not ruling the Sport S that has it out of the running for potential purchase.

 

[AverageJoe]

My Willys with stock tires and an auto trans is averaging 21 mpg overall. That is combined highway and "small town" driving. Fortunately, I don't have to contend with stop-and-go city driving. I notice that it does downshift, even on slight inclines, so 4.10's would probably help you in that respect. Like ShadowsPapa said, either way, it will find the gear that keeps it in the right rpm range. If you think you will ever go to larger tires, I would opt for the 4.10's. I think 34's would be about the upper limit to "comfortably" run with 3.73 gears.

 

[MikeSalt]

I calculated that 4:10s with 33s switched to 35s (34.5) will change the ratio to 3.92. Not too bad.

 

[Jclayc]

I just went from an Overland with a 1 1/2” Teraflex level kit on the front and 33’s to a stock Rubicon. The Overland averaged around 20 mpg and on the Rubicon, I’m getting no more than 18.4 in the first 1800 miles. The 4.10s in the Rubicon don’t seem to search for gears on the highway like the Overlands 3.73 did. And like mdyucca said, if we were concerned with fuel economy, we’d all drive a prius. Although my Harley gets 47 mpg and just slightly more fun to drive than a prius.

 

[AverageJoe]

I just went from an Overland with a 1 1/2” Teraflex level kit on the front and 33’s to a stock Rubicon. The Overland averaged around 20 mpg and on the Rubicon, I’m getting no more than 18.4 in the first 1800 miles. The 4.10s in the Rubicon don’t seem to search for gears on the highway like the Overlands 3.73 did. And like mdyucca said, if we were concerned with fuel economy, we’d all drive a prius. Although my Harley gets 47 mpg and just slightly more fun to drive than a prius.

Plus, you can go to 35's easily and it won't kill your power!

 

[bleda2002]

No, unless it's forced to run in a much higher rpm than now, gearing has little effect on everyday mpg because the engine still has to put out a certain amount of power to propel the vehicle.

In something like a 1/2 ton it matters more because the V8 has enough juice to use all the gears already so you are forcing it to run higher. In the JT the v6 is barely able to use 8th anyways so you'll end up at a wash as the new gears will make 8th more accessible

 

[ShadowsPapa]

No, unless it's forced to run in a much higher rpm than now, gearing has little effect on everyday mpg because the engine still has to put out a certain amount of power to proper the vehicle.

In something like a 1/2 ton it matters more because the V8 has enough juice to use all the gears already so you are forcing it to run higher. In the JT the v6 is barely able to use 8th anyways so you'll end up at a wash as the new gears will make 8th more accessible

And if I decide on tires taller than the 32.2 A/Ts I'm running now, it would be tempting to go to 4.10s to be able to see 8th at all
As it is, with wind facing me, I've driven 25 miles and never saw it leave 7th except to drop back to 6th.
With our hills and constant wind, I'm beginning to see 8th as a luxury gear.
Our 4xe, however, says "bring it on!" and stays in 8th.

 

[hikernbackpacker]

The 4:10’s are a better gear set for the Gladiator. I started with 3:73’s and now have 4:10’s. My experience is if your looking for fuel economy get a small Toyota or Honda. My average fuel economy has been between 13.5 and 14.5, mostly city driving. My mileage with the 3:73 was slightly better 14.5 to 15.5. However, this was also before all the add ons and modifications; steel bumper, lift kit, winch, larger tires (33’s) and wheels, heavy duty steering/suspension components (tie rod, track bars, drag link, control arms), armor and gusset’s, steel Molle panels in the bed, Bak bed cover, air compressor, lights, mounting brackets, wireing and switches. When you add it all up the weight is significant. I still can get 20 mpg with solid 65 mph freeway driving. 20 mpg has been my best mpg with both 3:73 and 4:10’s. If I had to do it all over again I would start with a Rubicon with auxiliary switches, LED light package and tow package. I have enjoyed building my Gladiator and really enjoy off roading my rig that is as capable maybe slightly more off road capable than a stock Rubicon. In any case the Gladiator is not known to be an economy car and IMO 4:10 gears are better suited for the Gladiator.

Thanks for the detailed information. Your rig sounds like a great off road vehicle ready to tackle just about anything. Hope you have many adventures with it.

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