Gear Ratio


drifter22

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I have a 2003 Ford Ranger with a 4.0, automatic, extended cab and 4 wheel dr. I get terrible gas mileage, 15 or16 mpg. The door jam tag says it has R7 differential, which 4:10, something you would need in a log truck! Has anyone ever changed the ring and pinion gears? I have been looking and I can not find any lower than 3:08. I would like to get it better, Rock Auto has a 2:73, but it's for a 7.5 ring gear and mine is a 8.8 inch.

Any Ideas, Gene
 


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Dirtman

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If you try to put 3.08 or smaller gears in that truck youll need a calendar to time how fast it takes to get to 60... 3.54 is as small as I would consider going. And unless your doing 100% highway driving your mileage will most likely drop even worse.
 

ericbphoto

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What size tires are you running? That's a major factor in gear calculations. Have you looked at this chart in the How To Tech section?
 

fastpakr

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There's nothing wrong with 4.10 gears in an OHC truck.

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adsm08

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I hate to break it to you, those things seem to top out at 17 MPG or so. You will probably get more bang for your buck out of a tune up than a re-gear.
 

scotts90ranger

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Yeah, auto 4.0L is going to be around 17 tops, all highway I got ALMOST 20mpg with my manual trans explorer...

I'm with them though on tire size as well, while you were looking at the door tag, what size tires did it say it came with? what's that compare to what's on it now? If you have bigger tires on it now than it came with you are going further per revolution than indicated moving your mileage up...

I'm running 5.13:1 gears, gearing goes with tire size and overall vehicle setup, the '91 explorer I mentioned above came with 3.55 gears, I swapped it to 3.73 gears and a limited slip axle and with 235 75 15 tires from the 225's or whatever that thing came with, was a perfect combo, I think it cruised at 2000rpm at 60? don't remember exactly it's been 6 years...
 

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High teens are about it for a 4.0L. And yes, tire size will play a huge roll in determining gear ratio. 3.08's might be ok for something still rocking tires for 14" rims.

8.8's do go down to 2.72 (sometimes listed as 2.73), but there's not a lot of aftermarket in that ratio.
 

drifter22

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If you try to put 3.08 or smaller gears in that truck youll need a calendar to time how fast it takes to get to 60... 3.54 is as small as I would consider going. And unless your doing 100% highway driving your mileage will most likely drop even worse.
How much do you think 3:08 gears would help? I had a 1995 Ranger XLT and it had 2:73 differentials and I got a lot better mileage with it and took NO time to get to 70 mph. I pulled a lot of heavy trailers with it and had no problems. Both had 265-70-16 tires. The 1995 was the same as this one except it was a 5 speed. If Ford could have made it so you could bleed the brake master cylinder, I would still have it!! I got a lot of 23 and 24 mpg and once in Colorado in the mountains, I got 27.8 with Texaco gas!
 

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You added 2.73 gears to it?
 

kimcrwbr1

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Your gas mileage is in direct relation to foot feed and the 4.0 is not a power plant. If you go with a 4.56 you will increase towing torque and it will be easier on the skinny pedal. You know you need to change both diffs to match?
 

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How much do you think 3:08 gears would help? I had a 1995 Ranger XLT and it had 2:73 differentials and I got a lot better mileage with it and took NO time to get to 70 mph. I pulled a lot of heavy trailers with it and had no problems. Both had 265-70-16 tires. The 1995 was the same as this one except it was a 5 speed. If Ford could have made it so you could bleed the brake master cylinder, I would still have it!! I got a lot of 23 and 24 mpg and once in Colorado in the mountains, I got 27.8 with Texaco gas!
273 gears front and rear with a ranger and 265 16 tires?....31 inch tires?



you swapped in old school dana axles....and
you had a 454 big block and turbo 400 transmission too?



with 31 inch tires that cammer will get its best all around economy with 4.10 gears. 308 gears and 31 inch tires will ruin it.
 

Dirtman

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With 2.73 gears and 265/70r16 tires and a 5r55e trans you would be doing about 1,350 rpm at 65 mph. :icon_rofl:
 

drifter22

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What size tires are you running? That's a major factor in gear calculations. Have you looked at this chart in the How To Tech section?
I have 265-70-16, I dose call for 245-70-16 on the door jam sticker. I looked it up and what I found was the 265's were 8 inches longer in circumference. I don't know how much that helps; don't seem like much. I have too many projects going now. Thanks, everyone for your help!

Gene
 

ericbphoto

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Ok. Your original tires had a 29.5" diameter and the tires you are currently running have a 30.6" diameter.

4.10 gears shouldn't be too bad for those 265/70 r16's. You might get slightly better mileage with 3.73 gears. But the truck will seem a bit more sluggish on acceleration. I would leave it as it is.

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