Need Some General MPG/Driver Feel information

[WNY964x4]

last night i bought a 98 Explorer XLT , 4.0 SOHC , 5R55E , unsure of the t-case , and it has 3.55 gears , here is what i am looking for , i plant to swap the 31's off my 96 onto the 98 and i need answers to these 2 questions in relation to swapping on the 31's with no gear change

1. What kind of mileage do you get with running 31's with an auto and 3.55 gears ?

2. Have you noticed a lack of power after installing the 31's ?

the Explorer they are currently on has 3.73's , came factory with 235's , this one has 3.55's and came with 235's , thanks for any input

here is a pic of the new ride , paid $1000 at the auction , after fees , tax , title , registration , inspection and a new battery i am looking at $1350 roughly , has 134k and about 1 dozen spots of slight surface rust , all just need touch up work

 

[gribly]

I have a '91 Navajo with 3.55's and 31's and it drives fine. I have a manual though, and first gear is a little tall. Yes, there is definitely a drop in power over the 235's. It's also tire width, compound, and tread that affects this, but I went from being able to do a brake stand in 2nd gear to only being able to do it in 1st.

 

[WNY964x4]

thanks for the info gribly , i run a set of Kuhmo Road Venture KL78's , just the basic all terrain , nothing too agressive

 

[CraigK]

Probably not directly comparable, but here's some info on my 94 4.0 Explorer Sport w/ 3.55's, 235's and an AT.

I am getting about 16.2 to 16.5 mpg all-around driving (actual mileage data during extended 1500-2000 mile intervals) which includes a mix of town (not city), country road and interstate driving. I have done a couple of tests of using the Overdrive vs. no Overdrive, and mileage is about the same. I mention this as when using Overdrive, this gearing is TOO TALL for most highway driving. If there is even a moderate incline, the motor tends to bog and load-up, and a kick-down into 3rd is required. Also, I have to run a can of Seafoam through the tank each few tankfuls to keep the engine from loading up a bit.

Why not just keep running with no OD? I am noticing that the motor is using 1 quart of oil (Mobil-1 synthetic) every 800 miles. The motor is A-OK, 126,000 miles, no blue smoke etc., oil consumption seems to be just from running the motor at higher revs on the highway without the OD.

So, although I have no direct experience with either your motor or with 31's (I won't go there with this truck), I suspect that you will find the 3.55 gearing problematic using AT using the OD, and might have an oil use issue without using the OD.

Testing continues . . .

CraigK

 

[WNY964x4]

Probably not directly comparable, but here's some info on my 94 4.0 Explorer Sport w/ 3.55's, 235's and an AT.

I am getting about 16.2 to 16.5 mpg all-around driving (actual mileage data during extended 1500-2000 mile intervals) which includes a mix of town (not city), country road and interstate driving. I have done a couple of tests of using the Overdrive vs. no Overdrive, and mileage is about the same. I mention this as when using Overdrive, this gearing is TOO TALL for most highway driving. If there is even a moderate incline, the motor tends to bog and load-up, and a kick-down into 3rd is required. Also, I have to run a can of Seafoam through the tank each few tankfuls to keep the engine from loading up a bit.

Why not just keep running with no OD? I am noticing that the motor is using 1 quart of oil (Mobil-1 synthetic) every 800 miles. The motor is A-OK, 126,000 miles, no blue smoke etc., oil consumption seems to be just from running the motor at higher revs on the highway without the OD.

So, although I have no direct experience with either your motor or with 31's (I won't go there with this truck), I suspect that you will find the 3.55 gearing problematic using AT using the OD, and might have an oil use issue without using the OD.

Testing continues . . .

CraigK

the only difference i can see between our trucks is yours is a 4 speed , mine is a 5 speed , and mine had the higher output 4.0 207vs160 for HP and 238vs225 for torque

 

[85_Ranger4x4]

Probably not directly comparable, but here's some info on my 94 4.0 Explorer Sport w/ 3.55's, 235's and an AT.

I am getting about 16.2 to 16.5 mpg all-around driving (actual mileage data during extended 1500-2000 mile intervals) which includes a mix of town (not city), country road and interstate driving. I have done a couple of tests of using the Overdrive vs. no Overdrive, and mileage is about the same. I mention this as when using Overdrive, this gearing is TOO TALL for most highway driving. If there is even a moderate incline, the motor tends to bog and load-up, and a kick-down into 3rd is required. Also, I have to run a can of Seafoam through the tank each few tankfuls to keep the engine from loading up a bit.

Why not just keep running with no OD? I am noticing that the motor is using 1 quart of oil (Mobil-1 synthetic) every 800 miles. The motor is A-OK, 126,000 miles, no blue smoke etc., oil consumption seems to be just from running the motor at higher revs on the highway without the OD.

So, although I have no direct experience with either your motor or with 31's (I won't go there with this truck), I suspect that you will find the 3.55 gearing problematic using AT using the OD, and might have an oil use issue without using the OD.

Testing continues . . .

CraigK

My parents had a '94 too, factory 235's.. with 3.27's. It would sit there and bounce around through the gears on hills and averaged about 15-16mpg. 180k when they traded it and never had to touch the trans either. Their '02 can get close to 20 if it feels like it, usually high teens on the highway.

In my experiance, don't deviate too far from stock tire size unless you plan on regearing. I pretty much turned my F-150 from one of the county's best stump pullers to a turd by swapping from 235/70-16's to 255/75-17's. Told myself at the time I would just regear it. $500 for just gears and a lot of time fixing something that really isn't broke is a lot of messing around just to look cool after I got to checking into it and thinking about it... and even then the milage wouldn't be what it was before.

My Ranger has 3.73's and 31's. Gets around very well around town and NEVER downshifts for a hill... but then it has a three speed

 

[gribly]

Oops, forgot. I still get 20mpg. Used to pull 22-24. Yes, I am doing the math correctly. I just have maintained my engine very well, and I clean the MAF regularly and all that jazz. I get as little as 10 sometimes, though, but that is tanks when I go wheeling..