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  #1  
Old 07-26-2010, 06:46 PM
BerniniCaCO3 BerniniCaCO3 is offline
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Default differential swap?

Hi!

I have a 1999 ford ranger, regular cab, 6' bed.
So, I've been only getting 16mpg mixed fuel economy lately. I'm not sure how that breaks down between highway/city, but that's a fair number highway... and lower than I used to get.

About a month ago a check engine light went on for just a little while, then went off. Pulled the code and it was an O2 sensor; accidentally erased the code and couldn't find out which. Wondering if I might just replace them all, to be proactive...

But anyway, I digress.
My other thought is that even before I had reason to wonder about an O2 sensor, the fuel economy is not fantastic. I only very infrequently haul heavy loads, and never ever tow a trailer.

I'm wondering if a permanent way to significantly improve fuel economy, would be to switch out for a different gear ratio with a new differential?


Has anyone done this?

I don't actually know what the standard, stock ratio is; but someone here probably does know. Are there any other vehicles that ford built on the same chassis, that have a compatible differential, that would offer less torque but better fuel economy? I'm not really taking advantage of the torque/ hauling capabilities anyway: more of a daily highway cruiser.



thanks!
-Bernard
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  #2  
Old 07-27-2010, 01:58 AM
STL STL is offline
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Default Re: differential swap?

Click This -->http://www.fordrangerforum.com/drive...xle-codes.html

Swapping rear axles is not hard if you have help. I highly doubt your fuel economy is a result of the rear axle. You may need to service the vehicle. Change fuel filter clean air filter.

What size tire do you have on the truck?
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Old 07-27-2010, 03:20 AM
BerniniCaCO3 BerniniCaCO3 is offline
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Default Re: differential swap?

Good idea-- air filter should be good, but I have no idea how long it's been since the fuel filter was done. Probably too long.

I guess I was wondering that even its original fuel economy wasn't great, and if I might not swap out for a (lower?) gear ratio?
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Old 07-27-2010, 03:23 AM
01_ranger_4x4 01_ranger_4x4 is offline
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Default Re: differential swap?

what motor do you have? if its either of the V6's 16 mixed driving is about the norm for mileage. if you were getting better and now your not its not the gear ratio thats the problem, its something else. either it needs a tune up like STL suggested or maybe you changed your driving habits slightly.

ps, i moved this to the appropriate section.
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-Headers
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-SCT X-Cal2 and some small exterior mods

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Old 07-27-2010, 03:37 AM
STL STL is offline
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Default Re: differential swap?

I can get roughly 18mpg In my 05 with the 4.0 that is city driving.
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Old 07-27-2010, 09:07 AM
BerniniCaCO3 BerniniCaCO3 is offline
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Default Re: differential swap?

It's the 3.0L v6 vulcan.

Yeah, I should look at the fuel filter and the O2 sensors. Maybe do spark plugs just because.

But what I'm really asking: it was never all that high, maybe 2-3mpg better,
so for a SIGNIFICANT improvement in fuel economy, is swapping out the rear differential an option?

If so, how do I go about locating a lower-geared one that will swap into place?

I realize of course that I'd lose some 'get-up-and-go,' but that's OK.

It just has whatever the standard tire size is, I'll check this evening.
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  #7  
Old 07-27-2010, 09:17 AM
01_ranger_4x4 01_ranger_4x4 is offline
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Default Re: differential swap?

Quote:
Originally Posted by BerniniCaCO3 View Post
It's the 3.0L v6 vulcan.

Yeah, I should look at the fuel filter and the O2 sensors. Maybe do spark plugs just because.

But what I'm really asking: it was never all that high, maybe 2-3mpg better,
so for a SIGNIFICANT improvement in fuel economy, is swapping out the rear differential an option?

If so, how do I go about locating a lower-geared one that will swap into place?

I realize of course that I'd lose some 'get-up-and-go,' but that's OK.

It just has whatever the standard tire size is, I'll check this evening.
no there is no ratio that will significantly increase your mileage. you can go lower and that could help with around town mileage but will most likely hurt highway and if you go with a higher ratio it will be just the opposite. these trucks come from the factory with the ideal gear ratio depending on motor and drivetrain options. changing ratios really is only a benefit when you go up or down a few tires sizes and the goal with that is to get the truck back to near stock final drive ratio. the factory has figured out what RPM range you truck is most efficient at and gears the truck accordingly. as i stated earlier your problem is not your gear ratio, from the sounds of it you need a tune up. dont expect to get any better than 18-19 mixed driving if thats what you were getting before because these trucks just dont pull that kind of mileage around town.
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2001 Ranger 4x4 Stepside
-RCD Suspension lift
-33x12.5 BFG KM2's on Mickey Thomson classic locks
-4:56 gears
-Auburn gear LS
-James Duff traction bars
-Headers
-Flowmaster duals
-SCT X-Cal2 and some small exterior mods

http://www.cardomain.com/ride/2321189

2005 F-150 Lariat 4x4
-LED third brake light
-Weathertech floor liners
-Edge tuner
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  #8  
Old 07-27-2010, 10:47 AM
BerniniCaCO3 BerniniCaCO3 is offline
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Default Re: differential swap?

Just for theory, if I did go with a lower gear for better highway mileage, why would that hurt town mileage?
I'd lose my low-end torque... so acceleration would be slower, but would it necessarily take more gas?

Though... would it also be harder on the engine, since the engine would have to generate more torque (that it couldn't do through the gears)?
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  #9  
Old 07-27-2010, 05:00 PM
Areyouforcereal? Areyouforcereal? is offline
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Default Re: differential swap?

You are backwards in your thought. A lower ratio will give you better acceleration. A higher ratio will give you more speed (if you have the horsepower.) A lot of people mix these up. The bigger the number, the lower the ratio. For example. A 4.10:1 is lower than a 3.73:1. A lower gear will give you worse highway millage because you will be operating at a higher rpm to go the same speed. A higher ratio will hurt your city mpg, because it will take more Horsepower to get rolling. Hope this clears it up for you.
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