Mpg Increase After Ratio Change !!
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Senior User
Joined: Mar 2003
Posts: 194
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From: Stafford Springs,Ct
Mpg Increase After Ratio Change !!
Ok it's its been long enough for me to belive its for real. The ratio change was removing the stock3.55s to 4.10s. the milage went from 10 to 13 right away. I did the change in the cold weather, so I knew that the milage would be effected buy my desire to get into a warm truck. Those morning warm up do take there toll on gas. Just filled up today and checked it and to my suprise it was 15.2 mpg. I have been watching it all along and it was going up steady. starting 13 thenthru the 13s then the14s and so on. I very little highway driving with it. I drive about 18to 20 miles to work, itis mostly open road couple red lights and stop signs. Up and down hills 25 mph to 55 mph. Sometimes faster and I don't baby it. Fast take offs foot to the floor and sometimes a little rubber burning. 
I think a lot to do with the mpg increase is do to the use of overdrive. With the 3.55s where I drive OD was very seldom used. I am happy with the turn out 
I think a lot to do with the mpg increase is do to the use of overdrive. With the 3.55s where I drive OD was very seldom used. I am happy with the turn out
Post Fiend
Joined: Mar 2005
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From: Louisiana
With those 4.10 you don't have to strain the engine as much to get up to speed quicker than with those stock 3.55s, and OD always help.
Wish I could drive like I wanted and get 15 mpg. I have to baby my truck to get 15 or 16 MPG.
Wish I could drive like I wanted and get 15 mpg. I have to baby my truck to get 15 or 16 MPG.
Senior User
Joined: Jan 2004
Posts: 153
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From: NW Ohio
Had the same thing with my 94 - originally with 265/15 tires and 3.55s, got about 14-15 around town, 18-20 highway. Went to 33x12.50x15, 8-10mpg town, 13-14 highway. Installed 4.10s, now about 13-14 around town, 17-18 highway. A good tuneup should get me back to the original mileage even with the bigger tires and lift.
Posting Guru
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From: Longview, TX
To confirm everything, if you can find an Interstate where you will not get run over, put it on 60 mph and look at your odometer when you pass a mile marker. Drive it for 10 miles and see if the odometer moved exactly 10 miles. In the process, time your miles with your watch. Of course, it should take you 60 seconds to travel the mile. That will test both your speedometer and odometer. Make notes as soon as you stop and if you have a lake model your can recalibrate if needed with just a jumper wire and your notes.
Post Fiend
Joined: Mar 2005
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From: Louisiana
Some shops are different, but your looking at $50-60 labor an hour, and it takes about 6 hours from what I understand, b/c I have to pay $300 for one diff at $50/hr. After labor basically for a 1/2 ton truck, gears will be about $150, and a master install kit is about $90-100, and if you want a locker, it can run from $250-500.
I've seen how to regear a truck, read how to do it, have been told countless times how to do it, but I'm still not confidant enough to do it my self.
I've seen how to regear a truck, read how to do it, have been told countless times how to do it, but I'm still not confidant enough to do it my self.
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Senior User
Joined: Jan 2004
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From: NW Ohio
I couldn't find a shop in the area that would even quote a price on regearing mine and installing the lockers, so decided to do it myself. I spent 3 or 4 days assembling, disassembling, measuring, and looking at gear patterns. Came out OK, but I don't think I would do it again.
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Joined: Jun 2004
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From: Houston
OK guys, I'm not too smart about regearing but I've always thought that higher ratio gearing resulted in lower gasoline mileage. However, I do understand what MBBFord is saying as I seem to have to accelerate harder with my Bronco as compared to my Excursion to get up to speed. I also notice that I have to hit the accelerator harder to increase speed (even 5 mph) on the interstate. Are you guys saying that I can get better gas mileage going to a higher gear ratio (4.10) because of the gear ratio or because the higher ratio changes the way you have to drive your vehicle?
Post Fiend
Joined: Mar 2005
Posts: 8,542
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From: Louisiana
okst1, what size tires are your running?
If you have 30 or 31s, then 3.50 gears would be fine if you travled on the interstate and highways alot. But if you have those same size tires and drive in town all the time, and don't get above 45MPH often, the 3.73-4.10 gears are good, b/c you don't have to strain your engine as much to get up to speed, and the only time a low(numatically)gear ratio will give you better gas is when you travle highway speeds alot and then they keep the RPMs low(giveing you good gas mileage).
If you have 30 or 31s, then 3.50 gears would be fine if you travled on the interstate and highways alot. But if you have those same size tires and drive in town all the time, and don't get above 45MPH often, the 3.73-4.10 gears are good, b/c you don't have to strain your engine as much to get up to speed, and the only time a low(numatically)gear ratio will give you better gas is when you travle highway speeds alot and then they keep the RPMs low(giveing you good gas mileage).
Elder User
Joined: Jun 2004
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From: Houston
MBBFord, I'm running 31" tires and travel about 35 miles one way to work so I'm mostly on the highway/interstate. My problem is that I have to accelerate pretty hard to get up to speed from a standstill and I always have to hit it hard to accelerate from 55+mph up 'til I get to 70. At 70 mph, it runs and accelerates just fine. I'm getting about 15 mpg. I've thought that running stock size tires or changing the rearend to 4.10 gears might take care of my acceleration problem but have yet to try anything. Thanks for responding. Any ideas are appreciated.
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Joined: Jul 2003
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From: VB. Virginia
Originally Posted by okst1
OK guys, I'm not too smart about regearing but I've always thought that higher ratio gearing resulted in lower gasoline mileage. However, I do understand what MBBFord is saying as I seem to have to accelerate harder with my Bronco as compared to my Excursion to get up to speed. I also notice that I have to hit the accelerator harder to increase speed (even 5 mph) on the interstate. Are you guys saying that I can get better gas mileage going to a higher gear ratio (4.10) because of the gear ratio or because the higher ratio changes the way you have to drive your vehicle?
Last edited by 94 XLT White/ Silver 302; Apr 29, 2006 at 06:39 PM.
Post Fiend
Joined: Mar 2005
Posts: 8,542
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From: Louisiana
Originally Posted by okst1
MBBFord, I'm running 31" tires and travel about 35 miles one way to work so I'm mostly on the highway/interstate. My problem is that I have to accelerate pretty hard to get up to speed from a standstill and I always have to hit it hard to accelerate from 55+mph up 'til I get to 70. At 70 mph, it runs and accelerates just fine. I'm getting about 15 mpg. I've thought that running stock size tires or changing the rearend to 4.10 gears might take care of my acceleration problem but have yet to try anything. Thanks for responding. Any ideas are appreciated.
You don't want to do that, trust me. If anything put stock size tires and leave the 3.50 gears.
Gears are expensive, and if you down sized tires then that would be like putting 3.73 gears in it(which would help acceleration), and take that money you were going to put into gears and buy headers and dual exhaust and a more aggresive cam wouldn't hurt.
Elder User
Joined: Jun 2004
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From: Houston
Thanks for the info guys. I think I'll buy stock size tires especially since most of my travel is on land and my off road travel is only to the deer lease which is not normally too rough.
Does anyone know of an off-the-shelf set of headers and dual exhaust I could purchase and install myself? I guess they would have to be specific to my vehicle since I have to reinstall the catalytic converter (maybe I'll have to buy another one??)and the oxygen sensors. I really don't anything loud-a nice rumble would be good.
Does anyone know of an off-the-shelf set of headers and dual exhaust I could purchase and install myself? I guess they would have to be specific to my vehicle since I have to reinstall the catalytic converter (maybe I'll have to buy another one??)and the oxygen sensors. I really don't anything loud-a nice rumble would be good.
Post Fiend
Joined: Mar 2005
Posts: 8,542
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From: Louisiana
What year is your Bronco, and what engine and tranny do you have?
Also for exhaust Bassani(I think that's how you spell it, there to expensive for me to even want to look into anyway) sells headers and exhaust systems.
I personally would run either duals (2.25" piping), or a single exhaust like stock, but w/ 3" pipeing, and have the work done by a local exhaust or mufflers shop(for usually around $200.
Also for exhaust Bassani(I think that's how you spell it, there to expensive for me to even want to look into anyway) sells headers and exhaust systems.
I personally would run either duals (2.25" piping), or a single exhaust like stock, but w/ 3" pipeing, and have the work done by a local exhaust or mufflers shop(for usually around $200.