6-Speed JLUR with 35s vs 37s (no re-gear)

jdubya421

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I have the gears but I haven't done it yet on my Rubi with 37s. I stalled a couple times where with 33s I couldn't get my Jeep to stall if I tried. It is usable, but man I want to re-gear so bad. Just saving up a little more money first.





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On my JLUR I had about 10,000 miles stock, 10,000 miles on 37s, and 8,000 miles on 37s with a Centerforce clutch.

1st off, you won't regret running 37s. Ride is smoother (KO2s), handling and braking is far better than I thought it would be. Stalling was not any worse than with the stock tires, and in 4Lo and 1st you have gobs of gearing, you could probably crawl with 44" boggers without stalling.

Stock, I rarely could use 6th, and on 37s, 5th happened rarely. In most cases, mpg was equal or even better in 4th vs 5th. I average 15-17 mpg over the last 20,000 miles.

On the centerforce clutch, my JLUR was transformed. It went from gutless to torquey, very difficult to stall. Even on stock gears and 37s, and in 2-hi, you can climb ledges (tall curb sized) without feeding any throttle to the engine, just feather the clutch and it grabs and pulls.
On the downside, the motor is definitely less responsive with the Centerforce and slower to accelerate. Rev hang is also worse as you have more weight spinning at high rpm. Those sacrifices are well worth the gains.
 

jdubya421

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On my JLUR I had about 10,000 miles stock, 10,000 miles on 37s, and 8,000 miles on 37s with a Centerforce clutch.

1st off, you won't regret running 37s. Ride is smoother (KO2s), handling and braking is far better than I thought it would be. Stalling was not any worse than with the stock tires, and in 4Lo and 1st you have gobs of gearing, you could probably crawl with 44" boggers without stalling.

Stock, I rarely could use 6th, and on 37s, 5th happened rarely. In most cases, mpg was equal or even better in 4th vs 5th. I average 15-17 mpg over the last 20,000 miles.

On the centerforce clutch, my JLUR was transformed. It went from gutless to torquey, very difficult to stall. Even on stock gears and 37s, and in 2-hi, you can climb ledges (tall curb sized) without feeding any throttle to the engine, just feather the clutch and it grabs and pulls.
On the downside, the motor is definitely less responsive with the Centerforce and slower to accelerate. Rev hang is also worse as you have more weight spinning at high rpm. Those sacrifices are well worth the gains.
You and I had very different experiences. Stock I would put it in 6th and be able to run all the way down to like 55 without shifting down. I couldn't get it to stall in 4LO if I tried in stock form, but with 37s if I'm not on the gas it stalls very easily. On the highway now with 37s and stock gears 5th is the same way and I can use it from like 55mph up.
 

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How is acceleration when merging when you need to get up to speed on the highway or passing compared to stock (assuming you drove stock before)?

My biggest concern is loss of power and I’m trying to understand how much of a loss am I going to experience when compared to stock or even better, when compared to 35s.

I’m expecting less power/acceleration due to added weight. I’m not looking for a race car either. Where I live people drive aggressively and I need to be able to keep up in some scenarios (i.e. merging onto the highway). Will it be like driving a slow pinto?

Thanks again!
Been deep down this road over 2+ years with a jlu 6 speed, driving 28k miles and wheeling alot:

35s with 4:10s + 4:1 transfer case: Aceptable and crawled pretty good idling up everything except the steepest obstacles where it started noticeably lugging the motor....6th gear would only hold speed on flat hwy at 70+mph. Very daily driveable...did it for a year without issues.

37s with 4.10s + 4:1 transfer case:
You lose 6th gear and 5th only holds speed on flat hwy at 70+mph. I'm in 4th up to 70mph and then sometimes 5th if it's flat and not windy. I've wheeled this setup 10+ times for almost a year and it's very doable...I have stalled several times in 4wd low 1st gear trying to idle up steep obstacles with ledges. Give it a little skinny pedal on steep stuff in 4wd low 1st gear. With that said, 4.88s would defintely be a gamechanger on 37s and I'm trying to save up for a regear. 37s + 4.10s is completely doable for daily driving, forest roads and light wheelin.

For some context, on this climb I have stalled trying to idle up...but gave it skinny pedal here and it was fine:
 

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My personal JL was a 6 speed on 37s. I would stick to 35s if you don’t want to regear or get the auto. I went 6 speed because I didn’t love the JK auto and the 8 speed was relatively new and unproven the the JL. I’m a believer now and have the 8 speed now. To me with stock gearing and 37s it wasn’t fun to drive.

brett
Even with 35s it's not very good. I drove mine for a couple of months to decide if I wanted to re-gear. My suggestion is re-gear to 4.88 for 35s or 5.13 with 37s.
 

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Even with 35s it's not very good. I drove mine for a couple of months to decide if I wanted to re-gear. My suggestion is re-gear to 4.88 for 35s or 5.13 with 37s.
What did you regear with?

My JLUR drives just fine on 4:10s but I do plan to regear to 5:13 or 5:38 at some point. Not because it needs it, but just because it's more fun to row through six gears than it is four...
 
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Been deep down this road over 2+ years with a jlu 6 speed, driving 28k miles and wheeling alot:

35s with 4:10s + 4:1 transfer case: Aceptable and crawled pretty good idling up everything except the steepest obstacles where it started noticeably lugging the motor....6th gear would only hold speed on flat hwy at 70+mph. Very daily driveable...did it for a year without issues.

37s with 4.10s + 4:1 transfer case:
You lose 6th gear and 5th only holds speed on flat hwy at 70+mph. I'm in 4th up to 70mph and then sometimes 5th if it's flat and not windy. I've wheeled this setup 10+ times for almost a year and it's very doable...I have stalled several times in 4wd low 1st gear trying to idle up steep obstacles with ledges. Give it a little skinny pedal on steep stuff in 4wd low 1st gear. With that said, 4.88s would defintely be a gamechanger on 37s and I'm trying to save up for a regear. 37s + 4.10s is completely doable for daily driving, forest roads and light wheelin.

For some context, on this climb I have stalled trying to idle up...but gave it skinny pedal here and it was fine:
By not having 5th and 6th gear, are you losing anything beyond better gas mileage?

I’m asking is because if the Jeep is still quick enough to merge onto a highway with other drivers zipping by and you don’t feel like you’re driving a small beat down pinto without any zip, then what’s the actual trade-off and why wouldn’t everyone (who isn’t into rock crawling) just do 37s instead of 35s?

It’s too bad there aren’t more 6-speed lifted JLs at my local dealerships here in MD so I could find out for myself what the difference really feels like.
 

jdubya421

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By not having 5th and 6th gear, are you losing anything beyond better gas mileage?

I’m asking is because if the Jeep is still quick enough to merge onto a highway with other drivers zipping by and you don’t feel like you’re driving a small beat down pinto without any zip, then what’s the actual trade-off and why wouldn’t everyone (who isn’t into rock crawling) just do 37s instead of 35s?

It’s too bad there aren’t more 6-speed lifted JLs at my local dealerships here in MD so I could find out for myself what the difference really feels like.
You still have plenty of power in your non-overdrive gears (1-4). I personally skipped 35s and went straight to 37s because I really don't see the point in 35s. I guess overall there might be less wear on items like bushings, wheel bearings, ball joints, and steering, but oh well.
 
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You and I had very different experiences. Stock I would put it in 6th and be able to run all the way down to like 55 without shifting down. I couldn't get it to stall in 4LO if I tried in stock form, but with 37s if I'm not on the gas it stalls very easily. On the highway now with 37s and stock gears 5th is the same way and I can use it from like 55mph up.
I skipped over this post. So even with 37s you’re able to use 5th gear? What tire/wheel package do you run?

I’m looking to do Nitto Ridge Grapplers; however BFG ATs are lighter and more like 36.5”, which may make more sense -I just wasn’t a fan of BFG ATs on my TJ back in the day, even though I know so many love them.
 

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I agree with all of the responses above. I have Toyo MT 35's (E rated, *very* heavy tires). I could go with a 37'' D rated and only gain about 7 lbs of weight, however the taller tire will be the main issue w/ stock 4.10 gears. I can still mount a 35'' Toyo MT in the stock spare location w/o a relocation kit or adapter. If I go to 37's I'll probably get some kind of internal tire carrier, but will cross that road when I come to it. I can do 90% of Colorado trails with 35's, 2'' lift/winch, and a bevy of under body skid plates.

I rarely use 5th or 6th gear. I use my manual trans like a 4 speed. The 3.6l likes that 2.5k-5k rpm torque curve so that's where I keep it. I can do 80mph in 4th gear and only be turning 3200rpm. I rarely drive over 80mph if I'm not traveling.

I wouldn't want to to go to a heavy 37'' mud terrain tire w/o at least 4.88's but would go 5.13's if I do gears. That would keep me in that 2.5-5k rpm range where I like to drive. Then I'd also have the spare tire issue mounting expense, etc...
 

jdubya421

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I skipped over this post. So even with 37s you’re able to use 5th gear? What tire/wheel package do you run?

I’m looking to do Nitto Ridge Grapplers; however BFG ATs are lighter and more like 36.5”, which may make more sense -I just wasn’t a fan of BFG ATs on my TJ back in the day, even though I know so many love them.
Yes, absolutely. It is exactly like when I had a sport and put 33s on it. 6th is gone, but 5th is my new 6th. I have 37" milestar patagonias and I have procomp 7032 wheels. I also have a 3" teraflex lift if that makes any difference with my Jeep being taller and having more drag.

My 33s were ridge grapplers and the only "issue" I had with them was that they got significantly louder on the highway as time went on.
 

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Even with 35s it's not very good. I drove mine for a couple of months to decide if I wanted to re-gear. My suggestion is re-gear to 4.88 for 35s or 5.13 with 37s.
I agree. Trying not to stay somewhat positive. It’s doable, just not ideal. I’m right there with you on the ratios.

brett
 
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I agree. Trying not to stay somewhat positive. It’s doable, just not ideal. I’m right there with you on the ratios.

brett
And I 100% agree it won’t be “ideal” - but then again is any lifted Wrangler ever ideal, unless you got crazy $$$ and can do a complete custom suspension, with everything across the board - I mean even a V6 vs. V8 Isn’t ideal...

For some reason on the forum in similar threads, I’ve read people suggesting no larger than 35s without re-gearing. If the only loss is 6th and even 5th gear, why would you advise against it - again, keeping in mind that the scope doesn’t = rock crawling or extreme wheeling. Eventually if I do that level of off-road, I’ll 100% re-gear.
  • for now I just want to be able to drive as fast as I could when it was stock (same level of zip) and do forest roads, minor tech stuff + have a killer looking JLUR

 

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