What if.... I don't?

[Tommyd]

I don't agree that it will suck on big hills, even towing a trailer. Outside of 1st gear the regear does nothing that a downshift doesn't. Unless you're driving up a vehicle cliff at 30mph or less it's never going to downshift to 1st gear. Even pulling an 8200lb trailer up grades it maintained 65mph without issue even climbing a grade that gains 4k feet of elevation in 20 miles. It never shifted below 4th. All a regear would have done is had it downshift to 5th instead of 4th. No gain in torque, no extra mechanical advantage.

King of anti regear.

Sponsored

 

[Sandman 4x4]

Hey Team,
Time to swap tires. 2021, Sport S, Tow Package, 4.10 gearing, 2.5" RE lift. Have a friend that is swapping his 37's for 40's. 37's (KO2's) are still fresh and shiny. For the sake of argument, If I were to strap the hand me down 37's on mine and NOT regear right now, what are the ramifications/consequences in your mind?
This is a money now money later argument.
Thoughts? and Many Thanks,
JP

First off nice choice and setup! Now I’m of the mindset to leave well enough alone, however with that said I am not you. That all depends upon how you drive each day? Do you want to be in front all the time, or relax and enjoy your ride, while getting the best mileage you can? Do you live in a hilly area and like to use cruise control or adaptive cruise control if you have it like I do and use all the time. That will cause you to drive around in the lowest gear it tells itself to than higher gear. Do you ever shift manually? Like I do half the time, that helps me stay in 8 th on the highway and at 45 and above, that’s a huge help in obtaining over 25 mpg on every highway trip. That’s of course with stock Sport S trim with the 17” alloy wheels and 245/75-17 Bridgestone Dueler HT’s at 40 psi, that’s gives a nice smooth quiet ride for the wife and I, on our trips to the beaches, where we have a great time and no issues at 15 psi in the deepest sands. Good luck, have fun and stay safe and healthy.

 

[Zachanadandy]

King of anti regear.

Math is hard and nobody seems to undertand that the 8 speed auto is supposed to shift a lot. 7th and 8th are both overdrives. That's why a JLU sport or sahara comes with 3.45s and 32" tires. And they are within 400lbs of the JT equipped the same. That's the equivalent ratio of 4.10s and 38s. No you don't gain power or need 5.13s to run 37s. That's just not how it works.

 

[bleda2002]

Math is hard and nobody seems to undertand that the 8 speed auto is supposed to shift a lot. 7th and 8th are both overdrives. That's why a JLU sport or sahara comes with 3.45s and 32" tires. And they are within 400lbs of the JT equipped the same. That's the equivalent ratio of 4.10s and 38s. No you don't gain power or need 5.13s to run 37s. That's just not how it works.

That's not true, you gain more power at the wheels for any given ratio thanks to the final drive ratio. If all you look at is top speed or towing at highway speeds, you're 100% right, the 8 speed can compensate mostly by grabbing a lower gear. What you don't get by not regearing is the low end grunt that people love, especially in the 0-30 range coming from stops. What you lose is the top end ratios for higher speeds. Just depends on what you find more important and if you value the 0-30 speeds or not. If you can live with the stock gears off the line, then don't bother, if you want more then regear.

It's also why jeep puts 4.56 on 35s which is the same as 4.88s and 37s.

 

[RubiNewbCB]

My MY22 JTRD is governed at 97mph. When I added the lift and 37s, the truck was capable of exceeding the governed speed limit (verified with GPS) prior to recalibrating the Speedo. My setup handles well at Speed on 17s and 37s. However, I'm ok with it being limited at 97mph, as I have a heavy foot and a need for speed. I'll save that for runs in my mustang.

 

[Zachanadandy]

That's not true, you gain more power at the wheels for any given ratio thanks to the final drive ratio. If all you look at is top speed or towing at highway speeds, you're 100% right, the 8 speed can compensate mostly by grabbing a lower gear. What you don't get by not regearing is the low end grunt that people love, especially in the 0-30 range coming from stops. What you lose is the top end ratios for higher speeds. Just depends on what you find more important and if you value the 0-30 speeds or not. If you can live with the stock gears off the line, then don't bother, if you want more then regear.

It's also why jeep puts 4.56 on 35s which is the same as 4.88s and 37s.

Myself and several others on the JL forums actually tested 0-60 on 37s before and after regearing. The 2.0t actually lost a half second because it had to shift an extra time to get there. The 3.6L gained .1-.2 seconds. The illusion of low end grunt because it runs through the gears faster doesn't translate to it actually having more. Under normal acceleration from a stop even on 4.10s I'm out of 1st gear by 15mph. With deeper gears you'll spend even less time in 1st gear. A tuner will do more for off the line power and 0-60 for $600 than gears do for $3k.

 

[bleda2002]

Myself and several others on the JL forums actually tested 0-60 on 37s before and after regearing. The 2.0t actually lost a half second because it had to shift an extra time to get there. The 3.6L gained .1-.2 seconds. The illusion of low end grunt because it runs through the gears faster doesn't translate to it actually having more. Under normal acceleration from a stop even on 4.10s I'm out of 1st gear by 15mph. With deeper gears you'll spend even less time in 1st gear. A tuner will do more for off the line power and 0-60 for $600 than gears do for $3k.

I gained a full second 0-60 on 5.13s and 39s than 4.10s and 39s. Averaged over 10 runs 5 in each direction. You have the same number of shifts 0-30 on 4.10s and 5.13s so there is no loss there. Physics don't lie in this case and the extra torque in the 2 gears makes a huge difference.

Did you manually shift or did you let the tranny do it? All my best runs were manually shifted to let it run up to red line and minimize shifts.

 

[Zachanadandy]

I gained a full second 0-60 on 5.13s and 39s than 4.10s and 39s. Averaged over 10 runs 5 in each direction. You have the same number of shifts 0-30 on 4.10s and 5.13s so there is no loss there. Physics don't lie in this case and the extra torque in the 2 gears makes a huge difference.

Did you manually shift or did you let the tranny do it? All my best runs were manually shifted to let it run up to red line and minimize shifts.

Let the tranny do it for consistency. Manual shifting has too much human error. When you lower the speed significantly at which the 1-2 shift happens you actually lose power until you get to the point the talker geared rig shifts. If the 5.13s don't shift until you're beyond the 30mph mark then they should have an advantage there. If they soft at 30 the 4.10s won't shift until nearly 40 mph. The 1-2 shift has the biggest gap in the trans which is why it's really only 1st where you gain much in daily driving in my experience and unless you're doing full throttle pulls to redline you barely spend any time in 1st anyway.

 

[Chasm]

Since we're now drag racing our Gladiators I finally have some relevant knowledge!
Bigger gears help you at the front end of the track and hurt you at the far end.
Bigger tires hurt you on the front end and help on the back.
All other things being equal of course.
The only times increasing one helps on both ends of the track is that you were set up wrong to start with.
And that's where my knowledge hits the Gladiator wall. I would bet they are not set up "right" for maximum acceleration. So either side might be right in this argument!

 

[bleda2002]

Let the tranny do it for consistency. Manual shifting has too much human error. When you lower the speed significantly at which the 1-2 shift happens you actually lose power until you get to the point the talker geared rig shifts. If the 5.13s don't shift until you're beyond the 30mph mark then they should have an advantage there. If they soft at 30 the 4.10s won't shift until nearly 40 mph. The 1-2 shift has the biggest gap in the trans which is why it's really only 1st where you gain much in daily driving in my experience and unless you're doing full throttle pulls to redline you barely spend any time in 1st anyway.

That explains the discrepancy. The computer straight sucks at actual acceleration unless you are towing then it will hold that straight to redline in my experience. If you're letting the computer do it it'll just short shift you everywhere.

As I really mentioned before I only did gears for 2 specific reasons that I sadly deal with often enough to care. And that's towing heavy and big cliffs. Daily driving I honestly thought the 8 speed did just fine.

 

[Zachanadandy]

That explains the discrepancy. The computer straight sucks at actual acceleration unless you are towing then it will hold that straight to redline in my experience. If you're letting the computer do it it'll just short shift you everywhere.

As I really mentioned before I only did gears for 2 specific reasons that I sadly deal with often enough to care. And that's towing heavy and big cliffs. Daily driving I honestly thought the 8 speed did just fine.

That's why I caution people and counter the guys who are convinced you need more gear to run 35s and that nobody has ever regretted a regear. Biggest waste of $3k I've ever spent on a Jeep. But we do a lot of roadtrips at 80-85mph. In my experience across multiple JLs and a JT from 35-39s and 4.10s to 5.38s, 4 56s and 37s was the best combo. Next would be 4.56s and 39s. Followed by 4.10s and 37s. The 4.56s with 35s even felt slightly over geared at freeway speed. Even 4.10s and 38s was better in my opinion than the 5.38s and 38s. Over gearing is worse than under gearing especially on a Rubicon with the 4-1 transfer case. Over geared 4LO is almost useless.

 

[Chasm]

Over geared 4LO is almost useless.

Aw, but "granny low" was always entertaining. Rarely useful, but entertaining.

 

[Zachanadandy]

Aw, but "granny low" was always entertaining. Rarely useful, but entertaining.

It's already stupid low for an auto. 77-1 crawl ratio plus the torque multiplication from the torque converter is plenty for 50" tires. Before the 8 speed nothing was anywhere near that in an auto unless they were running 2 transfer cases. The xj, tj, early jk autos had a 2.84-1 first gear. Even with 5.38s and a 4-1 transfer case they only had a 66-1 crawl ratio. If it was an xj or non-rubicon they would have a whopping 42-1. And yet we all built and wheeled them back then on 35s and even 37s. Drove fine on the street although geared that low they topped out about 60mph. Crawled great on the Rubicon, the dusy, fordyce, or wherever. People just ignore how deep this 1st gear is and assume they need the same gears they did in their previous Jeep... because math is hard. With the 2nd overdrive you can get away with deeper than necessary gears but I saw no benefit in it and if you drive western freeway speeds that start with an 8 you lose more than you gain. I agree that slightly deeper gears are better than 4.10s and 37s, but they aren't enough better to justify the cost. If you want more power, add power. If you want significantly more power spend double what the gears cost on a supercharger and you'll never once think you need more gears when you have ~140 more whp.

Sponsored