2 speed differential

[zmotorsports]

Originally Posted by Mark Kovalsky

A late '97 would have an E4OD, not a 4R100, but the overdrive ratio is the same on both of those. It's 0.71:1, not 0.69:1. So his change from the stock overdrive ratio was even less than you thought.

You are correct. It was an E4OD in his coach, the 4R100 I built for him was in his PowerStroke. But the point was still the same the ratio of the Gear Vendors was not as deep of an overdrive gear as his overdrive transmission in the coach.

Mike.

[MT4Runner]

Originally Posted by C-Leigh Racing

Wonder if it is true, that the Super C class RVs, International & Freighliner chassis are getting 12 to 14 MPG ?.
Neil

No, but 8mpg with 2-2.5x the weight we are hauling is possible.

They have a better economy of scale--fewer dollars per pound moved per mile. Our V8's and V10's are rapped out at 2,500-3,000rpm while their similar-displacement diesels are lugging at 1,600rpm. 22.5r's and 24.5r's have lower rolling resistance than 16" wheel/tire combos.

But diesels are more expensive to repair and maintain, and fuel is 1.5x more. They are noisier, have more vibrations, and stiffer suspensions.


I used to run an '89 International MDT conversion. 7-speed OD trans and the 7.3L IDI. I got 8mpg loaded at 26,000 gross with a trailer.

My 460 now gets 8mpg with no trailer, but is FAR more comfortable to drive.

[Gordon Dewald]

A two speed rear end if you can get one with an overdrive gear will reduce the torque at the rear wheels.

It may require that you run lower gears in order to maintain your desired speed. If so you may only be able to maintain speed in top gear while driving on the level, with the wind or downhill. It would be frustrating to have to change gears everytime you encountered a small rise.

[mohamer]

I am not sure what ratio the 2 speed axles are that you would find.
I drove a bus with the 460 V-8 and a 5 speed transmission with 2 speed axle in it for a while. The highest speed I had it to was about 70 mph and that was really going.
That bus got 5 mpg on a good day.

[MT4Runner]

I'm not sure what is even available in 1-ton, dually rear axles. Seems more common in old heavy trucks and farm trucks before 10- and more speed transmissions were common.