Gear ratio poll for 37” tires on 17” wheels 3.6 gasser

[Panthers65]

96% of jeep owners will never regear, I mean if we are just pulling numbers out if thin air and stating them like actual facts. The difference being I'm probably 90% closer to the actual reality.

You can think that all you want, and I would agree a majority of Jeep owners won't regear, but the ones that do understand and go deeper a vast majority of the time.

the 95% in here either have regears or will regear, the 100's of gear swaps I did when I was in the industry all regeared.

and I didn't pull any numbers out of thin air. You said you didn't want to be running 3000 RPM at 85mph, I did the math and showed you wouldn't be running 3K at 85 on 37's. The math don't lie, the calculator is right there.

Sponsored

 

[Zachanadandy]

You can think that all you want, and I would agree a majority of Jeep owners won't regear, but the ones that do understand and go deeper a vast majority of the time.

the 95% in here either have regears or will regear, the 100's of gear swaps I did when I was in the industry all regeared.

and I didn't pull any numbers out of thin air. You said you didn't want to be running 3000 RPM at 85mph, I did the math and showed you wouldn't be running 3K at 85 on 37's. The math don't lie, the calculator is right there.

The hundreds of regears...on transmissions with half the 1st gear ratio? Apples and potatoes. Even on stock gears this 8 speed is nothing like taking off in 2nd or 3rd as you eluded to. Show me the 1 JK or TJ that you regeared to 7.5 to 1... and that just gets you to the stock 4.10s. If you fix the math in your calculator using actual tire diameter of 36.25" (which is still generous for most 37s) you're just over 2700rpm, which is way more than I want to be turning rolling downhill at almost no load with 2 overdrives. Under 2400 rpms like factory works for me and returns better fuel economy. You don't need to be into the peak power under no load and I (and the engineers) would argue you don't want to be.

 

[WILDHOBO]

I see 8th in my mojave on the freeway with 4.10s. And at 85mph it's about 2150rpms. We have a JLUR for rock crawling, and it's only geared 4.56 on 39s. I'd argue 85-1 crawl ratio in an automatic is enough gearing for crawling on 50" tires but that's just my experience. Hell the XJ only had a 32-1 crawl ratio with its auto and 4.10s and never had any issues crawling on the Rubicon or fordyce on 35x14.50s. This trans has more than enough gearing.

I’ve compared mine to others while on the same trail. I can definitely see the difference in ratios adding to my control. But I’m slow on the faster stretches in low range than everyone else. 10mph is 8th gear. Oh well. Tradeoffs.

 

[WILDHOBO]

Go with 5.13's- if you're like 96% of jeep owners, you'll be very happy with those.

85MPH with 37's and 5.13's puts you at 2650 RPM, right on the bottom end of the peak power curve for the 3.6 Pentstar. Understand that there isn't a gearing available that will get you decent mileage at 85 in a gladiator on 37's.

Totally agree.

 

[Zachanadandy]

I’ve compared mine to others while on the same trail. I can definitely see the difference in ratios adding to my control. But I’m slow on the faster stretches in low range than everyone else. 10mph is 8th gear. Oh well. Tradeoffs.

The Rubicon transfer case gives more than enough control with stock gears. That's still a 77-1 crawl ratio...in an auto. If you can't control that I'd argue it is a driver finesse issue. I've run the Rubicon in XJs with their 32-1 crawl ratio, there it could use more gearing. And again I'm arguing for a more freeway friendly 4.56 axle gear. That 85-1 crawl ratio is plenty control in the JLUR on 39s. I'd even argue that going to 96-1 will just make 1st gear in 4LO less useful as it's so slow you'll only use it in the midst technical sections of a trail like the rubicon. The vast majority of that 18 miles I'm doing more than 1 mile per hour.

 

[Pismo61]

Yep Ive learned to go one step higher than you think.So 4.88 sound right,then Id go 5.13s.

 

[Minty JL]

Yep Ive learned to go one step higher than you think.So 4.88 sound right,then Id go 5.13s.

^^^ I like that mindset.........oh I want 35s........so I bought 37s LOL

 

[WILDHOBO]

The Rubicon transfer case gives more than enough control with stock gears. That's still a 77-1 crawl ratio...in an auto. If you can't control that I'd argue it is a driver finesse issue. I've run the Rubicon in XJs with their 32-1 crawl ratio, there it could use more gearing. And again I'm arguing for a more freeway friendly 4.56 axle gear. That 85-1 crawl ratio is plenty control in the JLUR on 39s. I'd even argue that going to 96-1 will just make 1st gear in 4LO less useful as it's so slow you'll only use it in the midst technical sections of a trail like the rubicon. The vast majority of that 18 miles I'm doing more than 1 mile per hour.

I love it when driving skills get questioned. As if I couldn’t do it without 5.13’s because I somehow lack control of my vehicle. Maybe I’d prefer it to be nicer. It doesn’t mean I can’t drive with less gearing.

 

[Greg_L]

I do believe in the mechanical and mathematical reasoning for re-gearing for large tires but do not believe that everyone should do it just because. Internet groupthink is like watching a cult. It's a personal decision based on needs and wants....and budget! I get that. I don't know any of you but I trust that you all have more Jeeping experience than me, although I'd put my general automotive mechanical knowledge and experience against anyone's. My background is general daily driver repair and extreme high performance drag/circle track racing.

Having said all that, my Gladiator on 37s and 3.73s only has 6500 miles on it. While I don't think I require a re-gear for my needs, I'm open to try it because I am very capable of doing the work. If I can set up drag race and circle track differentials and they survive that kind of abuse, I can set up gears in a Jeep. It's all the same. It's a ring and pinion. The ring and pinion doesn't know the difference between doing a wheelstand or crawling over boulders. In fact, if it could talk, I bet a differential would prefer climbing boulders over doing drag race launches.

Fuck I'm sorry for rambling...my question...as I said I only have 6500 miles on my Gladys. Would doing a re-gear void my warranty?

 

[Zachanadandy]

I love it when driving skills get questioned. As if I couldn’t do it without 5.13’s because I somehow lack control of my vehicle. Maybe I’d prefer it to be nicer. It doesn’t mean I can’t drive with less gearing.

My point was the transfer case gearing makes the real difference. Going from 4.56s to 5.13s is negligible in my experience. With as low as the 1st gear is even the stock mojave 53-1 is controllable. If it's primary use was rock crawling, it would get at tcase before axle gears.

 

[Zachanadandy]

I do believe in the mechanical and mathematical reasoning for re-gearing for large tires but do not believe that everyone should do it just because. Internet groupthink is like watching a cult. It's a personal decision based on needs and wants....and budget! I get that. I don't know any of you but I trust that you all have more Jeeping experience than me, although I'd put my general automotive mechanical knowledge and experience against anyone's. My background is general daily driver repair and extreme high performance drag/circle track racing.

Having said all that, my Gladiator on 37s and 3.73s only has 6500 miles on it. While I don't think I require a re-gear for my needs, I'm open to try it because I am very capable of doing the work. If I can set up drag race and circle track differentials and they survive that kind of abuse, I can set up gears in a Jeep. It's all the same. It's a ring and pinion. The ring and pinion doesn't know the difference between doing a wheelstand or crawling over boulders. In fact, if it could talk, I bet a differential would prefer climbing boulders over doing drag race launches.

Fuck I'm sorry for rambling...my question...as I said I only have 6500 miles on my Gladys. Would doing a re-gear void my warranty?

Technically it shouldn't void warranty on anything but the gears themselves. There have been some who had warranty claims denied on lockers, axle shafts, and even transmission work though so there's definitely a risk.

 

[Greg_L]

Technically it shouldn't void warranty on anything but the gears themselves. There have been some who had warranty claims denied on lockers, axle shafts, and even transmission work though so there's definitely a risk.

That's my concern.

Change anything from stock and that gives a dealership a reason to decline related warranty repair.

I remember asking my salesman specifically..."can I mod this thing and keep it in warranty"? His response was basically, yes within reason. A 2-3 inch lift and wheels/tires won't void warranty. Basic Jeep stuff.

 

[Minty JL]

Well it got spicy in here

 

[Zachanadandy]

That's my concern.

Change anything from stock and that gives a dealership a reason to decline related warranty repair.

I remember asking my salesman specifically..."can I mod this thing and keep it in warranty"? His response was basically, yes within reason. A 2-3 inch lift and wheels/tires won't void warranty. Basic Jeep stuff.

Mines been on a 2" lift and 37s before 1100 miles. Just past 22k miles and no issues so far. It hasn't been back to the fake since the day I bought it.

 

[WILDHOBO]

I do believe in the mechanical and mathematical reasoning for re-gearing for large tires but do not believe that everyone should do it just because. Internet groupthink is like watching a cult. It's a personal decision based on needs and wants....and budget! I get that. I don't know any of you but I trust that you all have more Jeeping experience than me, although I'd put my general automotive mechanical knowledge and experience against anyone's. My background is general daily driver repair and extreme high performance drag/circle track racing.

Having said all that, my Gladiator on 37s and 3.73s only has 6500 miles on it. While I don't think I require a re-gear for my needs, I'm open to try it because I am very capable of doing the work. If I can set up drag race and circle track differentials and they survive that kind of abuse, I can set up gears in a Jeep. It's all the same. It's a ring and pinion. The ring and pinion doesn't know the difference between doing a wheelstand or crawling over boulders. In fact, if it could talk, I bet a differential would prefer climbing boulders over doing drag race launches.

Fuck I'm sorry for rambling...my question...as I said I only have 6500 miles on my Gladys. Would doing a re-gear void my warranty?

I’d just love to pick your brain and learn how to do gears. It will void the warranty for the gears. I had Jeep agree to warranty my locker sensor even though I had regeared. I didn’t take them up on it though as they were going to have it too long and I fixed it myself.

Sponsored