Gearing

[Swegian]

So much info, so little time!
Thanks ya'll.

Went to 35's and upped the wt. 20lb with Falkins 33-MT to 35-11.5 At4w on both my diesel 3.73, lost maybe 2-3 mpg on my 2021 JLU and 3-4 mpg on 2021 JT - both Rubicons. I figure the difference is just weight.

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[Wheelin98TJ]

Being in 8th by half the speed limit is ok... with a 10 speed. Kind of eliminates the point of 2 overdrives and 8 gears if you're in the top 1 99% of the time. Why anyone is gearing the 8 speed down to the point it drives like an old 4 speed with 1 overdrive is beyond me. At altitude gearing sites nothing to compensate for the power loss. If that worked we could just use the 1st 4 gears and it would be good to go with stock gearing. The only thing that helps power loss is adding power. If you sirens a lot of time at altitude forced induction is the solution.

Why does it matter when you're in top gear?

You know what else eliminates the point of an 8 speed? Slapping bigger tires on it and crusing the highway in 6th and 7th gears.

 

[Zachanadandy]

I asked 1 because I know nothing about gears, 2 everyone on here recommends gearing. So if o went to 35s what would you recommend?

If you want to regear I'd go 4.56s for 35s. In my experience it's a little more than necessary but will also work well if you end up going to 37s later. Too much cost to just regear to 4.10s.

 

[Zachanadandy]

Why does it matter when you're in top gear?

You know what else eliminates the point of an 8 speed? Slapping bigger tires on it and crusing the highway in 6th and 7th gears.

Still see 8th under light loads and 7th is still an overdrive gear. 4.56s would be a little better in my experience... but far from $3k better which is what regears run locally. As far as why does it matter when you're in top gear, why would it matter if you were in 7th or even 6th. If it rolls in 7th any time there's increased load be it a slight incline or a head wind, it can still shift into 8th when there's less load. Conversely if you gear too deep it doesn't matter if it's down hill with a tailwind you were out of shifts before you got up the onramp. Pretending you're making better use of the trans by gearing so low it's always in 8th is wild. That's making almost 0 use of 7 gears. I could run a powerglide if I didn't want my Jeep to shift 99% of the time.

 

[Vtur]

For reference, someone need to create a poll thread regarding to whether anyone regretted regearing and such. Including different tire sizes and gears. I think this will helps for folks looking to regears.

 

[Wheelin98TJ]

Still see 8th under light loads and 7th is still an overdrive gear. 4.56s would be a little better in my experience... but far from $3k better which is what regears run locally. As far as why does it matter when you're in top gear, why would it matter if you were in 7th or even 6th. If it rolls in 7th any time there's increased load be it a slight incline or a head wind, it can still shift into 8th when there's less load. Conversely if you gear too deep it doesn't matter if it's down hill with a tailwind you were out of shifts before you got up the onramp. Pretending you're making better use of the trans by gearing so low it's always in 8th is wild. That's making almost 0 use of 7 gears. I could run a powerglide if I didn't want my Jeep to shift 99% of the time.

The same could be said against your point.

Pretending you're making better use of the trans by gearing so high it's rarely in 7th and 8th is wild.

 

[Zachanadandy]

For reference, someone need to create a poll thread regarding to whether anyone regretted regearing and such. Including different tire sizes and gears. I think this will helps for folks looking to regears.

It's exactly why I post in these threads. The guys who drive their Jeeps like they are old CLs and there's a nationwide 55mph speed limit post every time that nobody has ever regretted gearing too deep. I have and will never throw $3k away just to change which gear it rides around in at 60mph. I'm not saying 4.10s are the best combo for 37s, more that regears don't nashe enough of a diffrence to be worth the money. There was 1 guy on the JL forum who ended up regearing his heavy jlur twice because he was convinced that deeper gears would make up for power loss at elevation. Went 4.88s and wasn't happy. Went 5.13s and it wasn't any better. He ended up selling and going to a Bronco because forced induction compensates for altitude. Of course 2 regears is within $1k of the cost of supercharging the 3.6L. I'll take more wheel hp than a 5.7L hemi and low rpm cruising over more gearing any day and anyone who's driven both will do the same. My 2017 rebel with the same 8 speed, 5.7L, 35s, 3.92 axle gears, and nearly 1k pounds more weight held 8th on the freeway no problem and blew the doors of the JT. Trying to solve a power problem with gears is never going to work. Final drive ratio is all the engine sees. It doesn't know the difference between 3.45 gears in 6th, 4.10s in 7th, or 5.13s in 8th as they are all the same.

 

[Zachanadandy]

The same could be said against your point.

Pretending you're making better use of the trans by gearing so high it's rarely in 7th and 8th is wild.

We make the 600 mile drive to our AZ property every 4-6 weeks. It spends probably 500 of those miles in 7th. Up the larger hills might be 5th or 6th. Downhill is 8th. The JLUR with 5.38s would spend 590 of those miles in 8th. I still say my way is more efficient for my use. If you aren't seeing 7th with 4.10s and 35s you must have a magic route that's all uphill both ways and never over 55mph. It sees 7th in the dirt regularly, how slow are people driving?

 

[Darth Rubicon]

Just dropping in to soak up all the knowledge as someone who rides around on 37’s with 4.10

 

[D_JT]

Dirt Road Cred dropped this video the other day. Every tech at the shop they went to recommend 4.56 for 35"s. In the days of 4.0L Jeeps. 4.88 was absolutely the gear of choice for 35". But with more power and 8 speed transmissions. 4.88 is better for a 37" or even a 40" depending on needs and set up.

 

[Zachanadandy]

Dirt Road Cred dropped this video the other day. Every tech at the shop they went to recommend 4.56 for 35"s. In the days of 4.0L Jeeps. 4.88 was absolutely the gear of choice for 35". But with more power and 8 speed transmissions. 4.88 is better for a 37" or even a 40" depending on needs and set up.

I agree that 4.56s are plenty of gear if you're going to 35s. Of course if you already have 4.10s it is not much of a difference so you won't see much gain. Now if you started with a JLU sport with 3.45s I'd recommend a regear for 35s. If you were ordering new axles or adding lockers a regear would make sense for 35s. The other factors like warranty on your stock lockers are all the more reason to use your mod money somewhere else. Going from 4.10s to 4.56s will likely make less of a difference in drivability than a tune... which is a lot cheaper. Of course every shop that regears is going to suggest a regear... they make $0 off you if you realize the cost vs benefit doesn't make sense.

 

[Stan H]

Dirt Road Cred dropped this video the other day. Every tech at the shop they went to recommend 4.56 for 35"s. In the days of 4.0L Jeeps. 4.88 was absolutely the gear of choice for 35". But with more power and 8 speed transmissions. 4.88 is better for a 37" or even a 40" depending on needs and set up.

He said He personally went with 4.88
4.56 with 35's yes no additional weight overlanding etc.
4.88 with extras.

 

[JaysZJeep]

Just dropping in to soak up all the knowledge as someone who rides around on 37’s with 4.10

And how is it, when cruising on the highway is it hunting or happy ibuprofen a gear, how about off road?

 

[Darth Rubicon]

And how is it, when cruising on the highway is it hunting or happy ibuprofen a gear, how about off road?

I’m in Florida so I rarely see a hill to drive up. I get 8th on the highway but it hunts a bit. Off-road has been fine, although the hardest trails I’ve rode were north Georgia moderate difficulty. Feels fine around town and daily driving. When my beds loaded down is when I only catch 8th on a down hill. I do plan on regearing but it doesn’t feel like a must do right now sort of upgrade.

 

[T-Rock]

Seems like lots of opinions and variations in use, weight, geography...all of which make a diffference in gearing.
The point of hitting 8th (imo) is for highway fuel economy. No I didn't buy a Jeep for fuel economy, but yes I care because I want to avoid stopping for gas as much as I do And I want to have plenty of fuel for trails once I arrive. Since I've added a RTT to the SmartCap & Decked system I am running with roughly 700lbs without me or passengers 100% of the time. And that is also without additional camping gear, etc. when I am going on a roadtrip/overland trip. Being in Arizona I rarely drive on flat ground, even the desert has 500-1000 ft hills rolling along. Going up to 10-12K elevation is a common activity.
Constructive discussion about specific vehicle, weight, geography along with tire size seems to be most needed to clarify and not conflict with anyone. Personal preference is always present and to each his/her own so have fun and learn more.
Sounds like info from local people in your local area is the best advice guided by some practical gearing details.
Am I far off track here folks?

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