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

Toycrusher

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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.
It's just math. Engine rpm x transmission ratio x t-case ratio x axle ratio x tire circumference = ground speed.

You can mix and match a variety of transmission ratios, axle ratios, and tire circumferences and still end up with exact same rpm-to-ground-speed ratio. The engine has no clue and honestly doesn't care how you get to that ratio.





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It's just math. Engine rpm x transmission ratio x t-case ratio x axle ratio x tire circumference = ground speed.

You can mix and match a variety of transmission ratios, axle ratios, and tire circumferences and still end up with exact same rpm-to-ground-speed ratio. The engine has no clue and honestly doesn't care how you get to that ratio.
Well weight may also factor into a vehicle’s get-up too, right?
 

rustyshakelford

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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
Heres make take and please don’t take it in any negative light. What leaves my shop is what I consider right. I wouldnt be happy with delivering you your Jeep with only 4-5 gears available out of 6. more times than not, we even regear the 8 speed. If not, it can compensate significantly better. You’re paying 55kish for a brand new Jeep only to have it's drivability reduced. That’s your decision 100% and you’re not my customer.

Im planning on picking up a 2dr rubicon with 37s and a 6 speed tomorrow. It’s getting 5.13 gears and will have full use of all the gears. Doing it’s twin again when the lift comes in in a few weeks too.

Theres trade off of a manual are the ratios and available gears. If you’re a hard core MT guy then the money saved on the auto can be put towards the gears and you’re money ahead. Its discouraging to see people accept or justify poor performance and drivability and blame it on “it’s a Jeep thing” or “it drives like a Jeep“ Not saying you are but I get it all the time. Case in point is poor quality lifts and the jeeps all over the road. Customer tells me it just drives like a Jeep and it’s to be expected. Well add some controls arms and its night and day difference and they can’t believe it.

Many years ago there was some truth to that, now with these JL, stock they are great but when done right, can be improved upon greatly with ride, comfort and performance.

consider talking to the dealership about a regear. As long as they are getting paid, they tend to cover up a lot of mods fca wouldn’t be ok with.

brett
 

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Well weight may also factor into a vehicle’s get-up too, right?
Absolutely. Unsprung weight has an effect on ride, overall weight has an effect on handling, and rotational weight has an effect on braking.

I've found 37" KO2s to be minimal in all of those areas. A set of Super Swamper Boggers might be a different story.
 

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I grew up driving three speed manuals so a four speed is ok with me lol. LOVE the super low first gear in the manual. That in itself helps you get large tires moving and once momentum takes over the other three gears are all I need. The manual is a double overdrive trans anyway. If I ever need to drive over 80mph I'd use the overdrives.

Give me another gear between 1-4.


Gear Ratios:
  • 1st - 5.13.
  • 2nd - 2.63 (would have preferred a 3.15 or something)
  • 3rd - 1.53 (2.00 would have been great)
  • 4th - 1.00 (1.50) then 1.00 5th
  • 5th - 0.81.
  • 6th - 0.72.
  • Reverse - 4.49.
  • Final Drive ratio - 3.45 standard, 3.73 optional (4.10 Rubicon)
 
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Rodeoflyer

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Auto trans ratios... I'll take the 4.49 reverse over the autos 3.53


Gear Ratios:

  • 1st - 4.71
  • 2nd - 3.13
  • 3rd - 2.10
  • 4th - 1.67
  • 5th - 1.28
  • 6th - 1.00
  • 7th - 0.84
  • 8th - 0.67
  • Reverse - 3.53
 

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Okay thanks, and with the 35s it was still fun to drive?

I don’t plan to re-gear because that would 100% eliminate my Mopar warranty on almost everything.
35's are fine, and lots of fun. I find 6th gear useable above 60, but really above 65 is better. It is fine in all the other gears and is still pretty quick. If I did 37's, I would regear with probably 4.56 or 4.88 ratio, or, like others have said, go with the auto. That auto is phenomenal, but to me, just not nearly as fun or engaging. Every time I get thoughts of re-gearing, it is sitting at a computer. When drivng it, I'm reminded why I don't. Just no need.

I've not found any struggle off-road keeping up with my friends with 37's. Most of them have the same Mopar lift, so the difference is 1" of ground clearance, give or take a quarter inch or so from brand to brand. My Jeep handles great on twisty roads, too. I'm running 315/70/17 KO2's. They ride great, too, and perform well off road.
 

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I grew up driving three speed manuals so a four speed is ok with me lol. LOVE the super low first gear in the manual. That in itself helps you get large tires moving and once momentum takes over the other three gears are all I need. The manual is a double overdrive trans anyway. If I ever need to drive over 80mph I'd use the overdrives.

Give me another gear between 1-4.


Gear Ratios:
  • 1st - 5.13.
  • 2nd - 2.63 (would have preferred a 3.15 or something)
  • 3rd - 1.53 (2.00 would have been great)
  • 4th - 1.00 (1.50) then 1.00 5th
  • 5th - 0.81.
  • 6th - 0.72.
  • Reverse - 4.49.
  • Final Drive ratio - 3.45 standard, 3.73 optional (4.10 Rubicon)
I agree. That's why when I do regear it will be 5:13 or lower. 6th will be more like 1:1 with a tighter spread between the others.
 

Rodeoflyer

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I agree. That's why when I do regear it will be 5:13 or lower. 6th will be more like 1:1 with a tighter spread between the others.
Kinda sad though.. they could have spec'd a manual right in line with the auto. i often wonder if I should have just got the auto trans.. but man I love shifting my own gears.

Some 5.13s should make it acceptable.
 
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35's are fine, and lots of fun. I find 6th gear useable above 60, but really above 65 is better. It is fine in all the other gears and is still pretty quick. If I did 37's, I would regear with probably 4.56 or 4.88 ratio, or, like others have said, go with the auto. That auto is phenomenal, but to me, just not nearly as fun or engaging. Every time I get thoughts of re-gearing, it is sitting at a computer. When drivng it, I'm reminded why I don't. Just no need.

I've not found any struggle off-road keeping up with my friends with 37's. Most of them have the same Mopar lift, so the difference is 1" of ground clearance, give or take a quarter inch or so from brand to brand. My Jeep handles great on twisty roads, too. I'm running 315/70/17 KO2's. They ride great, too, and perform well off road.
Why didn’t you go 37s instead of 35s?
 

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Yeah I’ll prob just play it safe and go 35s until I’m ready to re-gear... with that said it can’t hurt to ask around and try to understand if going to 37s is really that much of a difference and what that difference translates into regarding performance/power/acceleration, factoring in that crawling isn’t in-scope.

The way I understand things is by asking questions and challenging what others say, not to be a D... rather, so I can understand better. There are so many people who are perfectionist or must do everything at 100 or not at all, however they don’t factor in the application (i.e. hardcore crawling) + may have unlimited $$$ and don’t care about going down the rabbit whole of mods.

I learned the hard way of cutting corners on my TJ - and $11K later realized I would have saved if I didn’t try to take short cuts. On the flip side, for my purpose I didn’t need to do everything and upgrade all components to be happy.
 

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Yeah I’ll prob just play it safe and go 35s until I’m ready to re-gear... with that said it can’t hurt to ask around and try to understand if going to 37s is really that much of a difference and what that difference translates into regarding performance/power/acceleration, factoring in that crawling isn’t in-scope.

The way I understand things is by asking questions and challenging what others say, not to be a D... rather, so I can understand better. There are so many people who are perfectionist or must do everything at 100 or not at all, however they don’t factor in the application (i.e. hardcore crawling) + may have unlimited $$$ and don’t care about going down the rabbit whole of mods.

I learned the hard way of cutting corners on my TJ - and $11K later realized I would have saved if I didn’t try to take short cuts. On the flip side, for my purpose I didn’t need to do everything and upgrade all components to be happy.
35's to 37's/38s/40s is a big deal.. you have to decide if that's what you want to deal with, and pluses/minuses.. there are many minuses..and many more pluses.. 10 years go 35's were considered HUGE, 35's and a 2 door will get you all over everything you will want to get over.
 
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35's to 37's/38s/40s is a big deal.. you have to decide if that's what you want to deal with, and pluses/minuses.. there are many minuses..and many more pluses.. 10 years go 35's were considered HUGE, 35's and a 2 door will get you all over everything you will want to get over.
Okay “many minuses” I’ll bite - besides losing the use of 6th and mostly 5th gear, what else am I losing by going from 35s to 37s?
  • Keep in mind my intention is not to rock crawling, extreme wheeling, it’s some forest roads, minor tech stuff, highways, family vacations to the beach, to visit relatives, etc.
 

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I love a good debate.. but you're not losing much.. just have to row your gears more. that's it!! Get used to 5k rpm (which this motor loves)..

Just rev your motor higher... problem solved.
 

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