Can someone educate me

[DubaiMarauder]

I have a stock '23 JLURD and am considering a small lift and 35's on bead locks, but I also have the added concern of the extra front-end weight of the diesel, which limits which lift kits I can get. I am also trying to understand if I absolutely need to regear, as answers tend to be a mixed bag as the 35's fall right in between the stock 3.73 gears and the next step up to 4.10's. (3.73 gears x 35" tires / 33" tires = 3.95 gearing). The problem is, there is no 3.95 gearing, and I'm concerned about retaining 8th gear and fuel econ as I do ALOT of road miles as my DD, but still want to be able to wheel it on the weekends. I'm not a huge rock crawler or mudhole fan, more into overlanding, but want to marginally step up the capability of my rig without sacrificing it as a daily as I don't have a secondary vehicle. I've heard that a 4.10 regear is not necessary at 35" tires with the diesel due to the higher HP and Torque, but I don't want to put unnecessary strain on it if I can avoid it. How true is this?

Can anybody give me concise info to help me out here? My main questions/concerns are:

-Retaining similar RPMs and fuel econ/MPG's as stock
-What gearing gives mechanical advantage to the motor and how is that determined?
-What option would be better for the motor, mechanical advantage etc...
-What are the pro's/con's of 3.73 v 4.10 or staying stock v regearing?
-Improving ride quality over stock RUBI suspension for longer road trips
-Improving road manners and handling on those long road trips
-Will the lift require leveling to prevent rear end sag?
-How will this lift affect rare trailering? (No bigger than a maxed out 5x8 U-Haul).
-Will gearing to 4.10's be better for towing with 35's?
-With 35's should I go with 12.5 or 13.5 width?
-What is a good offset to maintain at least equal flex to stock if not a marginal improvement?
-Are wheel spacers an option or are they just for mall crawlers and not advisable for wheelers?

As I will likely be doing the install myself, I'm looking for factual technical answers to educate me please, not the "Go big or go home / It's your rig, do what you feel you like."

I'm currently leaning toward the TeraFlex lift system with Falcon shocks and steering stabilizer, but I have not determined what size yet, likely no more than 2-3.5" as I have no desire to go up to 37s or bigger. I know I've asked a lot, so thanks for taking the time to explain it.

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[Grayhound]

TLDR: but from what I did gather I can tell you I’m running 315/70/17 on stock rims and suspension.

I notice no rubbing and I’ve flexed it out pretty well.

I did not re gear just updated the computer with j scan.

I lost about 2-3mpg other than that everything feels the same!

 

[Ryan long]

I have a stock '23 JLURD and am considering a small lift and 35's on bead locks, but I also have the added concern of the extra front-end weight of the diesel, which limits which lift kits I can get. I am also trying to understand if I absolutely need to regear, as answers tend to be a mixed bag as the 35's fall right in between the stock 3.73 gears and the next step up to 4.10's. (3.73 gears x 35" tires / 33" tires = 3.95 gearing). The problem is, there is no 3.95 gearing, and I'm concerned about retaining 8th gear and fuel econ as I do ALOT of road miles as my DD, but still want to be able to wheel it on the weekends. I'm not a huge rock crawler or mudhole fan, more into overlanding, but want to marginally step up the capability of my rig without sacrificing it as a daily as I don't have a secondary vehicle. I've heard that a 4.10 regear is not necessary at 35" tires with the diesel due to the higher HP and Torque, but I don't want to put unnecessary strain on it if I can avoid it. How true is this?

Can anybody give me concise info to help me out here? My main questions/concerns are:

-Retaining similar RPMs and fuel econ/MPG's as stock
-What gearing gives mechanical advantage to the motor and how is that determined?
-What option would be better for the motor, mechanical advantage etc...
-What are the pro's/con's of 3.73 v 4.10 or staying stock v regearing?
-Improving ride quality over stock RUBI suspension for longer road trips
-Improving road manners and handling on those long road trips
-Will the lift require leveling to prevent rear end sag?
-How will this lift affect rare trailering? (No bigger than a maxed out 5x8 U-Haul).
-Will gearing to 4.10's be better for towing with 35's?
-With 35's should I go with 12.5 or 13.5 width?
-What is a good offset to maintain at least equal flex to stock if not a marginal improvement?
-Are wheel spacers an option or are they just for mall crawlers and not advisable for wheelers?

As I will likely be doing the install myself, I'm looking for factual technical answers to educate me please, not the "Go big or go home / It's your rig, do what you feel you like."

I'm currently leaning toward the TeraFlex lift system with Falcon shocks and steering stabilizer, but I have not determined what size yet, likely no more than 2-3.5" as I have no desire to go up to 37s or bigger. I know I've asked a lot, so thanks for taking the time to explain it.

I have a stock '23 JLURD and am considering a small lift and 35's on bead locks, but I also have the added concern of the extra front-end weight of the diesel, which limits which lift kits I can get. I am also trying to understand if I absolutely need to regear, as answers tend to be a mixed bag as the 35's fall right in between the stock 3.73 gears and the next step up to 4.10's. (3.73 gears x 35" tires / 33" tires = 3.95 gearing). The problem is, there is no 3.95 gearing, and I'm concerned about retaining 8th gear and fuel econ as I do ALOT of road miles as my DD, but still want to be able to wheel it on the weekends. I'm not a huge rock crawler or mudhole fan, more into overlanding, but want to marginally step up the capability of my rig without sacrificing it as a daily as I don't have a secondary vehicle. I've heard that a 4.10 regear is not necessary at 35" tires with the diesel due to the higher HP and Torque, but I don't want to put unnecessary strain on it if I can avoid it. How true is this?

Can anybody give me concise info to help me out here? My main questions/concerns are:

-Retaining similar RPMs and fuel econ/MPG's as stock
-What gearing gives mechanical advantage to the motor and how is that determined?
-What option would be better for the motor, mechanical advantage etc...
-What are the pro's/con's of 3.73 v 4.10 or staying stock v regearing?
-Improving ride quality over stock RUBI suspension for longer road trips
-Improving road manners and handling on those long road trips
-Will the lift require leveling to prevent rear end sag?
-How will this lift affect rare trailering? (No bigger than a maxed out 5x8 U-Haul).
-Will gearing to 4.10's be better for towing with 35's?
-With 35's should I go with 12.5 or 13.5 width?
-What is a good offset to maintain at least equal flex to stock if not a marginal improvement?
-Are wheel spacers an option or are they just for mall crawlers and not advisable for wheelers?

As I will likely be doing the install myself, I'm looking for factual technical answers to educate me please, not the "Go big or go home / It's your rig, do what you feel you like."

I'm currently leaning toward the TeraFlex lift system with Falcon shocks and steering stabilizer, but I have not determined what size yet, likely no more than 2-3.5" as I have no desire to go up to 37s or bigger. I know I've asked a lot, so thanks for taking the time to explain it.

I have a 23 JLRUD. I have a rubicon express 2.5 lift and fox shocks 37” tires with Icon DOT legal beadlocks. I think they are 3.5” backspace. That diesel didn’t care about those 37s. I live in California and just a 1700 mile round trip to Idaho my Jeep was packed full of gear and I got 26.6mpg and the transmission was in 8th gear going up hill. I would build your Jeep and worry about gears last. There’s not much to gain going from 3.73 to 4.10 especially if you plan on running 35s. I forgot to mention that I have heavy bumpers, winch and skid plates. That diesel and 8 speed is the best combo Jeep ever put in a wrangler

 

[word302]

The difference between 3.73s and 4.10s is so miniscule I doubt you would notice any difference and definitely not worth the cost of a regear. The diesel will handle the 35s just fine with stock gearing.

 

[DubaiMarauder]

I have a 23 JLRUD. I have a rubicon express 2.5 lift and fox shocks 37” tires with Icon DOT legal beadlocks. I think they are 3.5” backspace. That diesel didn’t care about those 37s. I live in California and just a 1700 mile round trip to Idaho my Jeep was packed full of gear and I got 26.6mpg and the transmission was in 8th gear going up hill. I would build your Jeep and worry about gears last. There’s not much to gain going from 3.73 to 4.10 especially if you plan on running 35s. I forgot to mention that I have heavy bumpers, winch and skid plates. That diesel and 8 speed is the best combo Jeep ever put in a wrangler

Thats good to know. Good to know it can handle it just fine. Thanks!

Did you recalibrate your speedo with 37's? If so, how off was it and what did you use?

 

[Ryan long]

Thats good to know. Good to know it can handle it just fine. Thanks!

Did you recalibrate your speedo with 37's? If so, how off was it and what did you use?

I think it was reading about 10 mph slow. I used the tazer mini to recalibrate and disable the ESS. These Rubicon’s with the high line fenders don’t need much lift. I drove mine for a week on 37’s and no lift. Like I said I have 2.5” lift and it doesn’t rub. I don’t like how they wonder around on the highway so I didn’t go crazy with my lift I could set my caster at 8 deg and a Hellwig rear sway bar and mine is one finger on the wheel at 80 mph all day. I’ll try to figure out how to send you a picture of mine

 

[Ryan long]

I think it was reading about 10 mph slow. I used the tazer mini to recalibrate and disable the ESS. These Rubicon’s with the high line fenders don’t need much lift. I drove mine for a week on 37’s and no lift. Like I said I have 2.5” lift and it doesn’t rub. I don’t like how they wonder around on the highway so I didn’t go crazy with my lift I could set my caster at 8 deg and a Hellwig rear sway bar and mine is one finger on the wheel at 80 mph all day. I’ll try to figure out how to send you a picture of mine

 

[GATORB8]

Thats good to know. Good to know it can handle it just fine. Thanks!

Did you recalibrate your speedo with 37's? If so, how off was it and what did you use?

Speedo mis-calibration is always a percentage, in general you can use the diameter change as a guideline:

33 -> 37 = 37/33 = 1.12, so 12% off. You'll be going 28 when it shows 25 and 78 when it shows 70.

JScan or Tazer are common ways to correct the data point in the computer to recalibrate. You also want to lower your TPMS trigger as you'll normally run less air pressure in the larger tires.

 

[AcesandEights]

Retaining similar RPMs and fuel econ/MPG's as stock
-You will have to regear to retain rpms; however, the difference between 3.73 and 4.10 is only 10%. I don't think it's worth it.


What gearing gives mechanical advantage to the motor and how is that determined?
-Gearing is a "multiplier", multiplying torque. Any "lower" gearing will provide a mechanical advantage, so 4.10 will be better than 3.73 and 4.56 will be better than 4.10.

What option would be better for the motor, mechanical advantage etc...
-If you have the money to do the work, save it. Make the modifications you "want", then determine what you "need". If you lift the vehicle and go to 35" tires, you'll likely need nothing, but if you do, do the modifications then. You will also have the opportunity to realize how you are really using the Jeep, and then the modifications you originally planned may change.

What are the pro's/con's of 3.73 v 4.10 or staying stock v regearing?
-Torque multiplication. Slower off road, with more torque. More "power" to pass on the freeway.

Improving ride quality over stock RUBI suspension for longer road trips
Improving road manners and handling on those long road trips
Will the lift require leveling to prevent rear end sag?
-If you're loaded up? Think of it this way, springs hold up the vehicle at any given weight (ride height). Shocks provide damping (ride quality). If you add weight, then obviously the springs will sag further. You determine the sag by how much weight you add. Measure the ride height unloaded. Measure the ride height loaded. The difference is the amount of spring height (lift) you need to maintain the stock height when loaded. Buy a spring with that, plus any additional height you want to clear tires.

How will this lift affect rare trailering? (No bigger than a maxed out 5x8 U-Haul).
-It will raise your center of gravity (the overall height of everything sitting above the springs). This will cause more sway; although, it will likely be minimal if towing such a small trailer.

Will gearing to 4.10's be better for towing with 35's?
-Absolutely it will be "better", but only marginally. So, the answer is an absolute, yes, (black and white answer), but the benefit won't be worth the cost to regear.

With 35's should I go with 12.5 or 13.5 width?
-Depends on the terrain and how often you're off road. 12.5 will ride nicer 99.9% of the time. 13.5 will only have an infinitesimal benefit in sand (which you may drive in in Texas), one time out of a million.

What is a good offset to maintain at least equal flex to stock if not a marginal improvement?
-Dunno. I'd probably get the narrowest tire I could find and put it on a stock wheel.

Are wheel spacers an option or are they just for mall crawlers and not advisable for wheelers?
-They are an option, but increase wear (marginally) on steering and suspension components.

 

[DubaiMarauder]

Retaining similar RPMs and fuel econ/MPG's as stock
-You will have to regear to retain rpms; however, the difference between 3.73 and 4.10 is only 10%. I don't think it's worth it.


What gearing gives mechanical advantage to the motor and how is that determined?
-Gearing is a "multiplier", multiplying torque. Any "lower" gearing will provide a mechanical advantage, so 4.10 will be better than 3.73 and 4.56 will be better than 4.10.

What option would be better for the motor, mechanical advantage etc...
-If you have the money to do the work, save it. Make the modifications you "want", then determine what you "need". If you lift the vehicle and go to 35" tires, you'll likely need nothing, but if you do, do the modifications then. You will also have the opportunity to realize how you are really using the Jeep, and then the modifications you originally planned may change.

What are the pro's/con's of 3.73 v 4.10 or staying stock v regearing?
-Torque multiplication. Slower off road, with more torque. More "power" to pass on the freeway.

Improving ride quality over stock RUBI suspension for longer road trips
Improving road manners and handling on those long road trips
Will the lift require leveling to prevent rear end sag?
-If you're loaded up? Think of it this way, springs hold up the vehicle at any given weight (ride height). Shocks provide damping (ride quality). If you add weight, then obviously the springs will sag further. You determine the sag by how much weight you add. Measure the ride height unloaded. Measure the ride height loaded. The difference is the amount of spring height (lift) you need to maintain the stock height when loaded. Buy a spring with that, plus any additional height you want to clear tires.

How will this lift affect rare trailering? (No bigger than a maxed out 5x8 U-Haul).
-It will raise your center of gravity (the overall height of everything sitting above the springs). This will cause more sway; although, it will likely be minimal if towing such a small trailer.

Will gearing to 4.10's be better for towing with 35's?
-Absolutely it will be "better", but only marginally. So, the answer is an absolute, yes, (black and white answer), but the benefit won't be worth the cost to regear.

With 35's should I go with 12.5 or 13.5 width?
-Depends on the terrain and how often you're off road. 12.5 will ride nicer 99.9% of the time. 13.5 will only have an infinitesimal benefit in sand (which you may drive in in Texas), one time out of a million.

What is a good offset to maintain at least equal flex to stock if not a marginal improvement?
-Dunno. I'd probably get the narrowest tire I could find and put it on a stock wheel.

Are wheel spacers an option or are they just for mall crawlers and not advisable for wheelers?
-They are an option, but increase wear (marginally) on steering and suspension components.

Thank you so much for taking the time to give me this very helpful answer. This makes my decision making process much easier.

 

[Eischman]

I have a 23 JLRUD. I have a rubicon express 2.5 lift and fox shocks 37” tires with Icon DOT legal beadlocks. I think they are 3.5” backspace. That diesel didn’t care about those 37s. I live in California and just a 1700 mile round trip to Idaho my Jeep was packed full of gear and I got 26.6mpg and the transmission was in 8th gear going up hill. I would build your Jeep and worry about gears last. There’s not much to gain going from 3.73 to 4.10 especially if you plan on running 35s. I forgot to mention that I have heavy bumpers, winch and skid plates. That diesel and 8 speed is the best combo Jeep ever put in a wrangler

Thats odd, mine is always downshifting into 7th gear going up a small hill even when I'm going 60mph, most of the time I just put it in manual 8th so it won't do it. (running 35")

 

[Deleted User 38384]

I have a stock '23 JLURD and am considering a small lift and 35's on bead locks, but I also have the added concern of the extra front-end weight of the diesel, which limits which lift kits I can get.

I've been wondering this for a minute myself.

The weight of the EcoDiesel isn't enough to actually matter.
-2021 Jeep Wrangler Unlimited Rubicon curb weight: 4,160 lbs
-2021 Jeep Wrangler Unlimited Rubicon EcoDiesel curb weight: 4,449 lbs

300 lbs isn't enough of a difference to matter. I mean if it did, I wouldn't have been able to upgrade to my old steel front bumper, and winch over the factory plastic one I had before. I will say, it did create a slightly positive rake, but something I end up fixing with coil spacers. BIG WHOOP!

So I ask, is there anything other than 300 extra pounds up front that would actually stop someone from installing a non-diesel lift on their EcoDiesel Wrangler?


If the only difference would be upgraded coils in the front, it wouldn't massively open the amount of options out there for EcoDiesel Wranglers!!

 

[DubaiMarauder]

I've been wondering this for a minute myself.

The weight of the EcoDiesel isn't enough to actually matter.
-2021 Jeep Wrangler Unlimited Rubicon curb weight: 4,160 lbs
-2021 Jeep Wrangler Unlimited Rubicon EcoDiesel curb weight: 4,449 lbs

300 lbs isn't enough of a difference to matter. I mean if it did, I wouldn't have been able to upgrade to my old steel front bumper, and winch over the factory plastic one I had before. I will say, it did create a slightly positive rake, but something I end up fixing with coil spacers. BIG WHOOP!

So I ask, is there anything other than 300 extra pounds up front that would actually stop someone from installing a non-diesel lift on their EcoDiesel Wrangler?


If the only difference would be upgraded coils in the front, it wouldn't massively open the amount of options out there for EcoDiesel Wranglers!!

I've got the Rubi steel bumper and the Badland Apex 12S winch up front as well, after swapping out the crappy plastic bumper, so yea, I've got a bit of the positive rake as well. I just added 35s, to stock suspension, and it's ok. I'm considering the Teraflex STI 1.5" spacer lift for $300, but that's not really gonna add anything to the flex, just picks it up a bit. It should (according to their website) fix the rake.

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