Reality Check Needed

[aldo98229]

16 MPG on 37s sounds like an accomplishment!

I’m getting 13 MPG on 35s at the moment, with 3.45 gears. Hope regearing to 4.88 will bring me back to the mid teens...

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[JEEP4U]

Lionel....... Repeated prolonged gear hunting would be hard on any transmission. If you are experiencing this utilize manual mode....... Regearing for 37" tires and reprogramming your transmission will cure this problem.

 

[Lionel Hutz]

Lionel....... Repeated prolonged gear hunting would be hard on any transmission. If you are experiencing this utilize manual mode. Regearing for 37" tires and reprogramming your transmission will cure this problem.

I don't know why I didn't think of manual mode. I'll do that next time. The Jeep is programmed for the 4.56s, speedo corrected, etc.

I've never driven in such windy conditions in the Jeep and had a lot of time to overthink on the drive. It's why I titled the thread reality check.

 

[zouch]

good on you for not pushing it past where you felt it was safe given conditions! too many goofballs think they need to do every bit of the speed limit and then some, no matter what's actually going on.

considering everything (and assuming you've actually got the speedo reprogrammed to deal with your actual gearing and tire up-sizing), i think you did OK MPG-wise. probably still on winter fuel, even!

don't worry about that trans; it ain't your daddys 4-speed+locking overdrive. if you started with 33s on 4.10s, you're already pretty close to stock final drive ratio. (if you're running the typically undersized BFGs, you're probably actually even closer.)
it might be a little bit happier if you were regeared to get things a tiny bit below the original Final Drive Ratio and i probably would have gone to 4.88s (if they're available for your axle) just for the slight performance aspect, but at this point it's probably not worth the cost/energy/fuss.

I kept it right around 70-73. Any faster and it didn't feel safe. The stretch of 75 has speed limit of 75, but it didn't feel like I could comfortably keep up with traffic. Winter mileage is usually in the 16s and during the summer I can get closer to 18 with easy driving.

My first thought about the transmission is that it can't be good for it to keep shifting between 7 and 8 so often.

 

[Lionel Hutz]

good on you for not pushing it past where you felt it was safe given conditions! too many goofballs think they need to do every bit of the speed limit and then some, no matter what's actually going on.

considering everything (and assuming you've actually got the speedo reprogrammed to deal with your actual gearing and tire up-sizing), i think you did OK MPG-wise. probably still on winter fuel, even!

don't worry about that trans; it ain't your daddys 4-speed+locking overdrive. if you started with 33s on 4.10s, you're already pretty close to stock final drive ratio. (if you're running the typically undersized BFGs, you're probably actually even closer.)
it might be a little bit happier if you were regeared to get things a tiny bit below the original Final Drive Ratio and i probably would have gone to 4.88s (if they're available for your axle) just for the slight performance aspect, but at this point it's probably not worth the cost/energy/fuss.

Nailed the specs and winter fuel. I am running KO2s.

I think I'm paranoid about the transmission because my '92 YJ I had in college gave up the ghost when the 5-speed bombed out and it was too expensive to fix. I know, lots of time and R&D between the two, but the flashbacks are real.

 

[blnewt]

Nailed the specs and winter fuel. I am running KO2s.

I think I'm paranoid about the transmission because my '92 YJ I had in college gave up the ghost when the 5-speed bombed out and it was too expensive to fix. I know, lots of time and R&D between the two, but the flashbacks are real.

Kinda similar to weed, I thought the current stuff would be similar to the 90s, damn was I wrong, now I'm having a different kind of flashback

 

[No IFS]

37 inch tire with an eight speed automatic transmission needs a 5.13 gear ratio. I suggest you find somebody to test drive with, you’ll love it. 488 is not enough gear. 392 wrangler comes with 456s and 35 inch tires. you need gear or motor. It’s physics its math it’s pretty simple

 

[zouch]

depends on what you're trying to do, right?

assuming everything the OP listed, 4.88s get him closer to stock than 5.13s. it's just math, right?
if you're doing more crawling than highway 5.13s might be OK, but they're not going to be ideal for everyone.

37 inch tire with an eight speed automatic transmission needs a 5.13 gear ratio. I suggest you find somebody to test drive with, you’ll love it. 488 is not enough gear. 392 wrangler comes with 456s and 35 inch tires. you need gear or motor. It’s physics its math it’s pretty simple

 

[SanMan15]

When its windy I always put my sky one touch top up as a sail and get 60 mpg.....doesn't everyone?

 

[4xFUN]

Sudden gusts of wind can make for a very interesting drive...Last year I was in my 19' Ram Longhorn 4x4 which is bone stock (has the factory off road package that sits about an inch higher than standard) except for one size larger tires and all the sudden got caught in microburst that literally shoved me into the next lane-thankfully no one was next to and I wasn't in the high speed lane next to the concrete divider! My very first thoughts were thank God I was not driving my Rubi-2 door! That would have a been white knuckle adventure for sure...

 

[Wbino]

Hold My Beer: I used to drive MCI buses across the VZ Bridge in blizzard conditions with 50 passengers at 5am in the morning, rear tires spinning in snow on the uphill of the bridge. Whitewash conditions and city slick tires.
Wind gusts at times closed the bridge and you had semis alongside with you in the wind.
Why didn't you lock it in 6 or 7 and just cruise?

 

[Lionel Hutz]

Hold My Beer: I used to drive MCI buses across the VZ Bridge in blizzard conditions with 50 passengers at 5am in the morning, rear tires spinning in snow on the uphill of the bridge. Whitewash conditions and city slick tires.
Wind gusts at times closed the bridge and you had semis alongside with you in the wind.
Why didn't you lock it in 6 or 7 and just cruise?

I’m not sure. I’ve only used manual mode a few times and each time was off road. Just didn’t think of it.

 

[blnewt]

I guess it really depends what you're after. If you want to just drive it as is there won't be a problem running your 4.56 gears w/ your 37s. With this setup you won't hit 8th gear often but you still have a damn good 7 speed AT If you want to regear to a lower set just be prepared to shell out 2k to 2.5k and you may run into warranty concerns. If it were me I'd just let my AT work a bit harder when things get a bit adverse. Like mentioned, if you plan on being a rock hound, then yeah, those 5.13s start to look much more appealing.

 

[RFR JLR 2.0]

Sounds about right. I'm running 35" tires with a 2.5" lift on stock 4:10 gears and rarely see 8th gear in a head wind. Take the top and doors off and they cut through the wind like butter. You may freeze to death but you'll stay in your lane.

 

[OldJupiter]

I don't know why I didn't think of manual mode. I'll do that next time. The Jeep is programmed for the 4.56s, speedo corrected, etc.

I've never driven in such windy conditions in the Jeep and had a lot of time to overthink on the drive. It's why I titled the thread reality check.

I have 3.45 gears + 2.0T and 37's recalibrated and such on my 2 door. Sounds like the same ride I get in 50-60mph winds. I average 19-20 mpg regularly, but it will dip exactly down to 16 mpg just as you described. If you hadn't posted this I would have never had the energy to detail it how well you did. It does hunt for gears, but I hit 8th gear without much issue. What PSI were you running? Lately it's been so cold I've been running 36 PSI warm. In the Spring and Summer I run 33 PSI warm.

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