Golvach
Member
- Joined
- Nov 10, 2020
- Threads
- 1
- Messages
- 8
- Reaction score
- 69
- Location
- Dallas, TX
- Vehicle(s)
- 2021 Gladiator Overland
- Thread starter
- #1
Several people asked me to post my experience with 4.56 gears, so here it is. I've got a 2021 Gladiator Overland, 3.6L V6 with manual transmission, which came with the 3.73 gears. A couple of months ago I added a Mopar 2" lift and 35 inch mud terrain tires. Last week, I had the gears swapped to 4.56. My goal for my build was to get a perfect blend between (1) a pretty darn nice daily driver truck (I came from a F150) and (2) a respectably offroad capable real Jeep. I think I have now achieved exactly that and I absolutely love the way it turned out:
Why I regeared: As soon as I added the lift and bigger tires, while still running the 3.73 gears, my truck felt severely under-powered. My gas mileage dropped from 17 mpg city/20 mpg highway to about 12 mpg no matter where I was driving. First gear starts became WAY more prone to stalling and felt very sluggish. On the highway, 5th and 6th gear became nearly useless--no power, no ability to maintain speed or pass in 5th or 6th, and constant downshifting. At 70 mph I was hitting about 2,000 rpm in 6th gear. If I hit even the slightest incline or wind, I could have the throttle completely opened up and would still be losing speed. I drive across Texas a lot, and through the Hill Country here in particular, so this was just intolerable for me.
Why I chose 4.56: I first thought about 4.10s. I talked to several "jeep people" online and in person, and everyone said regearing to 4.10 would be a waste of time and that I should be considering 4.56 or 4.88. So then I went back and forth between 4.56 and 4.88 a lot--reading forums about different experiences with each (mainly on the JL platform though--not as much info out there on the manual trans JTs), etc. I even changed my regear order back and forth a couple of times.
My main focus was increasing the RPMs in top gear back into the natural power band of the 3.6L V6 and restoring the fuel efficiency, but I also wanted a little more offroad performance vs my stock setup. The offroad shop that did the work estimated that with 4.56 gears in 6th gear at 75 mph, I would hit 2400-2500 RPM, and that would increase to 2600-2700 RPMs with 4.88s. The 4.88 option sounded like I would be running the engine a little harder than I wanted, but really would have been fine for the vehicle, and it would definitely have a lot of power. But first gear also would probably be really short with the 4.88s, and a lot of JL folks said their rides just felt a little too "tall" with the 4.88s and 35s.
Ultimately I went with the 4.56, which I determined would be just slightly over-geared compared to a stock Rubicon or Max Tow Sport (both have 4.10s) and would get the RPMs in a really good sweet spot on the highway... which sounded like exactly what I was going for.
After the regear: I just finished my 500-mile, grandma-driving break-in period on the new gears and had the gear oil drained and refilled. Now that I can drive normally again, my gas mileage has improved noticeably--roughly 17-18 mpg in the city and I've gotten similar results on short highway drives. Additionally, throughout 1st-6th gear there is significantly more power. My truck is noticeably peppier than stock off the line, and starts are much easier... let out the clutch and the truck does most of the work. 1st is quick and full of torque, but not so much that it feels like I'm driving a tractor... feels more like the power you'd get in a V8 full-size truck off the line. 5th and 6th gear maintain speed on the highway with absolutely no problem, even in hills and wind.. with no downshifting needed so far. I can accelerate to pass in 6th (which I could barely do even before the lift & tires). I'm at exactly 2,500 rpms at 75mph which feels perfect on this engine. It will be so nice to have functional cruise control in this thing now!
I'm taking it to Moab pretty soon and will report back on the long-drive and offroad experience, but so far the 4.56 seems to be the absolute sweet spot.... a little sportier feeling than a stock rubicon, but not so much that it feels like a weekend-only vehicle. Fuel efficiency is respectable so far, and it's very responsive and powerful through all gears. Feels to me like 4.88s would have been a little too much for what I was going for, and so far couldn't be happier with the pairing of 4.56s on 35 inch tires.
Why I regeared: As soon as I added the lift and bigger tires, while still running the 3.73 gears, my truck felt severely under-powered. My gas mileage dropped from 17 mpg city/20 mpg highway to about 12 mpg no matter where I was driving. First gear starts became WAY more prone to stalling and felt very sluggish. On the highway, 5th and 6th gear became nearly useless--no power, no ability to maintain speed or pass in 5th or 6th, and constant downshifting. At 70 mph I was hitting about 2,000 rpm in 6th gear. If I hit even the slightest incline or wind, I could have the throttle completely opened up and would still be losing speed. I drive across Texas a lot, and through the Hill Country here in particular, so this was just intolerable for me.
Why I chose 4.56: I first thought about 4.10s. I talked to several "jeep people" online and in person, and everyone said regearing to 4.10 would be a waste of time and that I should be considering 4.56 or 4.88. So then I went back and forth between 4.56 and 4.88 a lot--reading forums about different experiences with each (mainly on the JL platform though--not as much info out there on the manual trans JTs), etc. I even changed my regear order back and forth a couple of times.
My main focus was increasing the RPMs in top gear back into the natural power band of the 3.6L V6 and restoring the fuel efficiency, but I also wanted a little more offroad performance vs my stock setup. The offroad shop that did the work estimated that with 4.56 gears in 6th gear at 75 mph, I would hit 2400-2500 RPM, and that would increase to 2600-2700 RPMs with 4.88s. The 4.88 option sounded like I would be running the engine a little harder than I wanted, but really would have been fine for the vehicle, and it would definitely have a lot of power. But first gear also would probably be really short with the 4.88s, and a lot of JL folks said their rides just felt a little too "tall" with the 4.88s and 35s.
Ultimately I went with the 4.56, which I determined would be just slightly over-geared compared to a stock Rubicon or Max Tow Sport (both have 4.10s) and would get the RPMs in a really good sweet spot on the highway... which sounded like exactly what I was going for.
After the regear: I just finished my 500-mile, grandma-driving break-in period on the new gears and had the gear oil drained and refilled. Now that I can drive normally again, my gas mileage has improved noticeably--roughly 17-18 mpg in the city and I've gotten similar results on short highway drives. Additionally, throughout 1st-6th gear there is significantly more power. My truck is noticeably peppier than stock off the line, and starts are much easier... let out the clutch and the truck does most of the work. 1st is quick and full of torque, but not so much that it feels like I'm driving a tractor... feels more like the power you'd get in a V8 full-size truck off the line. 5th and 6th gear maintain speed on the highway with absolutely no problem, even in hills and wind.. with no downshifting needed so far. I can accelerate to pass in 6th (which I could barely do even before the lift & tires). I'm at exactly 2,500 rpms at 75mph which feels perfect on this engine. It will be so nice to have functional cruise control in this thing now!
I'm taking it to Moab pretty soon and will report back on the long-drive and offroad experience, but so far the 4.56 seems to be the absolute sweet spot.... a little sportier feeling than a stock rubicon, but not so much that it feels like a weekend-only vehicle. Fuel efficiency is respectable so far, and it's very responsive and powerful through all gears. Feels to me like 4.88s would have been a little too much for what I was going for, and so far couldn't be happier with the pairing of 4.56s on 35 inch tires.
Sponsored
