4.56 or 4.10 gears for 31" and dual purpose XJ?

[bobnoxious]

On my street XJ I'm running 4.10 and 30's, its not low enough for me. I did see a mpg increase in town, no change on the highway.

On my trail rig I'm running 4.88's and 35's, I have a "polished" 30 but I'm still not easy on it and I've only snapped one ring gear. 4.88 is still not low enough for me, I want 5.13

My suggestion would be go 4.56 or 4.88 and be done with it.

Curious...What about 4.10's with 30" tall rubber makes you say it's not enough for you?

 

[xjtrailrider]

Curious...What about 4.10's with 30" tall rubber makes you say it's not enough for you?

I live in the Blue Ridge Mountains, short but steep. You are either going downhill or uphill all the time.

 

[chris420]

I am at 2500rpm with 4.10 and 32 bfg at's. It also depends on what brand tire you are going to run. Some 32 inch tires are smaller than others. The weight of the tire can also make a difference. Toyo tires are very heavy and will take more hp to turn were as bfg tires are lighter and dont take as much hp to turn. Consider everything.

 

[bobnoxious]

I live in the Blue Ridge Mountains, short but steep. You are either going downhill or uphill all the time.

Sounds like you need more HP, not more gearing.

 

[Boost_Retard]

i bought my gears from RWK haus supply.
i chose 4.11 gearing to run with my 31" tire setup, should come out slightly underdriven from where i was stock with the 3.55, like 5%. but i figure the extra weight of the tires and overall increase in drag from the lift, i should feel pretty much stock when driving on road. MY goal was to end up with a jeep that i can drive for 12 hours straight to get to premium hunting areas and still be able to go hunting in it when i get there..so being close to stock was what i was aiming for for road manners..4.56 could be for you depending on how you plan to drive.

i ran 4.56 gears with 31x12.50 boggers on my previous samurai and in high range on the road i always thought it was a little over geared for a 31" tire..i actually liked the 4.11 gears i ran previous to the 4.56's better overall. i did however have a stupid low transfercase that would make up for any gearing you chose in your diffs once shifted into low range, unlike my jeep.

the choice is yours! but i would go 4.11 arty:

 

[kastein]

4.10 if you are going to stay on 31s.

4.56 if you are saying you are going to stay on 31s, but have your eyes on 33s anyways.

 

[imm/ou812]

Yeah I'm gonna go with 4.10's. If I ever go larger, I'll have to change a few things anyways and it'll be a ways down the road. By then I may change front and rearends anyway...who knows.

Thanks to everyone for pitchin' their thoughts! I'll post pics when it's done. Hopefully that will be the first of Jan. Then it's off to whippin' up on Otay!! ha ha!

 

[djlarroc]

let us know how you like it.. i wont be doing anything til spring so i can enjoy my stock xj during winter.

i will say, on my last xj, i grabbed an 8.8 w/4:10 and just regeared the front. i was running 34x10.50 judging by the charts that it would still be "in range". IT WAS AN ABSOLUTE DOG. i hated driving that stupid thing. engine ran perfect, but 4:10s was not even close imo. that makes me lean towards 4:56 on 31/32", but ive never driven a rig like that, so not sure.

 

[fallacist]

so what i've gathered is that 4.10's on 31's will net you better mpg, but 4.56 on 31's will net you more giddyup?

living out in SW CO, there happens to be a few hills around here. Would I loose out on any mpg benefit of running 4.10's b/c of downshifting on inclines?

 

[imm/ou812]

Well, looks like I might do a HP30 and go with 4.56 gears...so much for knowing what I want to do.
I'll let you guys know what I think about them with the 31's.
Brian

 

[WaXJ_Skier]

4.56 and don't look back. If you are driving 70 fuel economy isn't your concern anyway. That said it's not far off from 4.88 and 33s and you get great mileage with that combo.

 

[Kevin108]

I can't tell any difference in power between 235s and 31s. Gears to me would be an unnecessary expense with that slight of a change from stock.

 

[WaXJ_Skier]

I can't tell any difference in power between 235s and 31s. Gears to me would be an unnecessary expense with that slight of a change from stock.

Sent from my DROIDX using Tapatalk

I bet if you looked at your fuel costs you would notice a difference.

 

[FunkRider]

Don't you have a Low Pinion D30 now anyway? If you want 4.10's get a set of factory 4.10's and get a high pinion dana 30 at the same time?

 

[TRCM]

I am at 2500rpm with 4.10 and 32 bfg at's. It also depends on what brand tire you are going to run. Some 32 inch tires are smaller than others. The weight of the tire can also make a difference. Toyo tires are very heavy and will take more hp to turn were as bfg tires are lighter and dont take as much hp to turn. Consider everything.

2500 rpm w/32'as & 4.10's @ what speed ????????? What trans ???


Something there don't sound right...only way I can see that RPM is if you have a 3 speed trans. That's even high for a 4 spd trans with no lockup convertor.



I'm looking at 4.56's w/31's and even then it won't be but 2200-2250 rpm @ 60.

 

[Kevin108]

I bet if you looked at your fuel costs you would notice a difference.

From what I've seen so far, it would take quite some time to potentially recuperate the costs of gears with fuel.

 

[bobnoxious]

For you guys that live in the mountains and want more oomph for hills...elevation is robbing your power, and gearing will only help so much. The power is still missing.

 

[MT Mike]

For you guys that live in the mountains and want more oomph for hills...elevation is robbing your power, and gearing will only help so much. The power is still missing.

:doh: You can't be serious.

 

[Talyn]

Running 245/75-16 (30.5x10) and 4.11 gears I get 3000 rpm at 80mph.

 

[WaXJ_Skier]

Running 245/75-16 (30.5x10) and 4.11 gears I get 3000 rpm at 80mph.

If you are driving 80mph in an XJ it really shouldn't matter, the drag at that speed will kill any sort of fuel economy.