anyone have any exp. with gear change to increase fuel milage and lower rpm....running 4.10 w/turbo and getting 15 mpg at best...3200 @ 70mph....considering change rear gears to 3.08 or probably 3.55 also runs terrific but use a quart to 1000 miles...how about a reply someone thanks

 

I changed my 87 F250 6.9 with ATS turbo from 4.10 locker to 3.54 locker, I now turn 2900 rmps at 75 mph. I have 215 75R 16 DRW tires on it. It help my fuel mileage a little, but I am still trying to make it better. My problem is I like to keep it up there on speed. With the other gear ratio, the engine struggled to keep up on highway speeds. I now have no problem cruising at 80

Dave

<a href="http://members.aol.com/deleontow/auto/index.htm">http://members.aol.com/deleontow/auto/index.htm</a>

 

 

Hi, I have an 86 6.9 fourwheel drive with 3.73 lockers and I get about 19 mpg and the truck will run 80 all day long
John (fatforty)

 

Don't forget if you have a good shop change the gears it's going to be $800 to $1000(or more for 4wd) for parts and labor. How long will that take to pay off for 3 or 4 MPG?