2 speed rear axel

[chief2]

Got at a 99 F-550 that I use for personal use and towing my 38 ft. 5'r. I am looking for a way to lower the rpm's from 2500-2700 when running at 65/70 to closer to 2000. I have looked at an Overdrive Unit by Gear Vendors, but can't find one for a reasonable cost. $2,900.00 + driveshaft mod. Thinking about changing the gear ratio from 488's to something lower. What would work best for what I'm doing or is there a 2 speed rear end available for my truck and what would that cost. Any help sure would be appreciated. I get 12.5 mpg running 65/70 at 2500 to 2700 rpm, but get 14 when running 55 at 2,000 rpm. Every little bit helps!

Got a Banks Performance Pack with all the mods, so there is nothing I'm aware of to do there.

 

[jopes]

your rear diff is going to be the S135 there are lower ratios avilable for them, but I beleive you need the rear to have a ABS sensor, so going to a faster ratio might cause some problems.

 

[bigdiesel99]

with the power you are putting out you could probally put a 3.73 in if they are available you could do about 65 at 2000 rpm with that ratio.. but thte diff case will have to be changed to be able to bolt the ring gear up the last time i looked on to it they cost about $40 unless you are going to put a locker in then it doen matter just get the right locker..

 

[WD40]

Chief2, Is your F-550 a 6 speed? If so try a truck wrecking yard for a 3 speed Brownlite transmission. You would have 18 forwards and 3 Rev.
Don't know how it would work with a auto.

 

[chief2]

WD40,
No, I have a Auto 4OD.

 

[jopes]

with the power you are putting out you could probally put a 3.73 in if they are available you could do about 65 at 2000 rpm with that ratio.. but thte diff case will have to be changed to be able to bolt the ring gear up the last time i looked on to it they cost about $40 unless you are going to put a locker in then it doen matter just get the right locker..

where are you finding $40 diff cases?

 

[Hoss 350]

Chief2, Is your F-550 a 6 speed? If so try a truck wrecking yard for a 3 speed Brownlite transmission. You would have 18 forwards and 3 Rev.
Don't know how it would work with a auto.

And TWO SHIFT GEARS!!!

And the need for a body lift and suspension lift so it would fit under the truck without cutting holes in the floorpan or dragging down the road.... (unless the Brownlite is different from the classic "Brownie" box and is smaller)...

I guess if it would fit you could rig up an air shifter for it... Now THAT would be pretty cool.

 

[WD40]

I saw one at a yard in Dallas one time and have kicked my butt 100 times for not buying it. It is about the size of a 3 speed ford or chevy transmission, I could pick it up with both hands.