I was wondering if anyone out there has changed the rear end gear ratio from 4.10 to let's say 3.55 or 3.08. The truck is great but gas mileage stinks for long distance highway trips. I only use 4 wheel drive in the winter and once in a while putting a small sail boat in the lake. I called Torsen direct and they said it should be able to be done but their advise stopped there! I'm not a mechanic so I'll need layman terms to pass on to the Ford guys at the dealership.
Thanks in advance.
Dale

 

ok if you change the rear ration you have to change the front.


ok my truck came with 3.27s and 235 tires its super high and i got 19 mpg on the highway and i drove an 80 miles a day round trip to work. then i put 31s on my truck and i got around 18 mpg and drive around town sucked ***. I also towed with my truck and it also sucked. then i swapped my truck to 3.73 gears with 31s and i was getting around 20-21 mpg on the high way and it was nice to drive around town. now im running 30s and 3.73s and my truck is a blast to drive has power and gets decent gas mileage.


if you want better high way mileage i would get a 32 inch tire it will be like putting high gears in your truck and lower your high way RPMs you should be able to get around 20-23 mpg on the highway. i think shane said he got his best mileage with 4.10s and 32s. also it will be much cheaper to buy new tires then to put in new gears. also if you want to go back its simply changing the tires.

 

It is a waste of money.
The 4.0L is geared with 4.10 gears in that application to keep the engine in it's power range on the highway. Re-gearing both diffs is going to run $1200-2000 and you will be lucky if you see a small improvement in mileage, plus you will lose a lot of performance. The truck isn't going to get good mileage by running lower (numerically) gears. If you are truly getting poor gas mileage, look elsewhere for the cause.

 

I get about 15 to 16 miles per gallon at 60 mph. I guess I could have the dealer check it out next oil change but I'm sure that's all it will get. The truck runs very smooth and starts first try winter or summer. $1200.00 to 2k is a lot for a few less gallons of gas.

 

My 2005 Sport Trac (same frame but more overall weight), with 4x4, 4.0L auto, 4.10 gears and 30" tires got 18mpg on the highway completely stock, for what it's worth.
15-16 mpg isn't far off from where it should be anyway. Part of the crappy thing about a ranger is getting full size economy with mid size performance.

 

What year is your truck?

You are better off replacing the fuel filter/ spark plugs/ engine oil/ and if you have an auto gettting a programmer for the truck.

I had an '03 fx4 level 3 and got 20 mpg on the freeway at 60 with an K&N Intake, flowmaster exhaust and a programmer for better shift points.

 

the truck is a 2009 and only has 11000 miles. the plugs should be ok.

 

Are you gauging the gallons consumed from fill up to fill up or just what the fuel guage says? Have you done any modifications to the truck?

 

fill up to fill up. truck is stock. I call it the gas guzzler!

 

You just have to deal with it man...if your auto, get a programmer, thats the best option.

 

I paid 2k for 4.88 Yukon gear swap front and rear, all new bearings, rear end posi rebuilt, two new CV Half Shafts, a few other parts, fluid, seals AND labor charge. That was at Randy's Ring and Pinion I went from 3.73 to 4.88 with was a HUGE improvement, and well worth the money. I couldn't see paying that much to downgrade like that to a point where you couldn't ever run a bigger tire, at all.

 

Its been said, your best bet is to run slightly larger tires. Either 32's or 33's. This will lower your RPMS by a bit. Best thing about that is in a couple thousand miles you can get new tires with a different size.

 

He is in Canada so it is going to cost more up there.


Bigger tires will decrease the final drive, but then he is adding more drag, more weight, adding height, using more power to get the tires moving, etc.

 

Thats true but your trying to find a happy medium. I don't think going from 31's to 32's or 33's is going to hurt performance that much. I have a 3.0L and I mean you can feel the difference between tire sizes but on the highway. (if its not a lot of hills) I'd much rather have had my 3.73's but the 4.10's allow me to have the get up and go I require. He has a 4.0L with 4.10's already so 33's aren't going to stress that truck much more. He may feel the difference from a stand still but cruising he'll notice the lower rpms and thus better gas mileage.

 

brian, i disagree about lower numerically getting better milage. i kno i'm getting better milage then someone with 4:10s and stock. it's gonna help keep the rpms lower.
OP what is your engine speed at 100kms mine with 3:73s is 2500rpms? i'm guessing that his is 3000 or just over. so right there i'm saving fuel. his truck is stock and no different then mine. the only thing he has going against him is the fact his motor is newer and not as broken in as mine.

i do agree with the whole bigger tire lower rpms comment tho. as long as he finds a happy medium. 32's would probably be his best bet since stock is 30. not too much more weight and drag added, but stil larger so the tire rpms will be less then stock.

i also agree that changing tires is cheaper then new gears.

 

The SOHC 4.0L needs higher revs to make power, and runs a lot different than the old 3.0L and 4.0L OHV engines. 3.73s and 31's on my 98 4.0L OHV was perfect, and 4.10s on 31s in the newer 4.0L SOHC worked equally well.

Like I said, with a heavier sport trac with 4.10 gears and 30" tires I was getting 18mpg on the highway.
I was even getting 14mpg higher with a 3" lift, 4.88 gears and 33x12.50 tires, with a roof basket and 33" tire on top. I really don't think he is going to benefit much, if any from going to a larger tire. And with 11k miles I bet buying tires is the last thing on his mind. lol

 

i edited before you posted. hell at 37,000 tires are the last thing on my mind for purchasing. i keep my rpms low, if i need that extra boost or passing power, i downshift. i'm not sure if the OP can do that since he didn't psot if he's got a manual or an auto.

 

i bet hes auto with those numbers

 

Downey you are right I have an automatic. But the poster who asked what my truck revs at 100 kms/ph must have a different set up, mine revs at 2300 at 100k. I got a call from the local Ford dealer while at work this afternoon so couldn't talk. They are ready to quote on parts for front and rear differential gears. I'm going to call tomorrow am and see what they say. Called about tires already, just one place and they had 32 inch light truck tires for $200.00. Those 32 inch tires are 265-70 16's in metric.

 

you sure? I've driven a 4.0L SOHC and it did not need anything like the RPMS that my 3.0L needs.

 

dude you are going to hate your truck if you drop it to 3.55 gears just get some 32s and call it good

 

truck seems to have lots of power. I'll call the dealer for a quote but imagine it will be more than I can afford for what will probably only be a few miles per g difference. Probably wear these tires off and buy taller ones!!!

 

good

 

willard, i asked about the rpms at 100. you have an auto and i have a manual. your rev's are close to mine. can anyone clear this up? two different gearings, two different trans. what am i missing?

i agree with downey, just get tires, it's cheaper and if you ever want to lift and go larger in the tire size, you might not have to regear. if you swap to 3:55s your gonna have to reswap to 4:10s or larger just to get back to where you were. the tires you want are not too much larger then the stock ones.

use this to imput the two tire sizes and you can see the difference.

Tire size calculator

 

Morris, I have overdrive on my transmission maybe that is the difference.