1982 Cabover

Here is what I posted on another thread on how to determing axle ratio:

To find out the ratio of the rears, chock wheels so the truck won't roll, release brakes and place transmission out of gear. Jack up one side of the rear axle until that set of tires are off the ground. Place a mark on the tires for a refrence, and also place a mark on the driveshaft that aligns up with something so you will be able to refrence each revolution, and where the mark will stop in relation to where it started.

Now, turn the wheel two complete revolutions, stopping with the mark on the tires at the same place it started. At the same time watch the mark on the driveshaft, and count how many revolutions it turns. As an example, if the drivesahft turns 3 3/4 revolutions per 2 revolutions of the wheel, then you have a 3.70 ratio. This is a very accurate way to check rear ratios.

 

Probably a 4.56, I believe that was a gear option for them.

 

A 4.56 rear, which Eaton list on their calculator, with an overdrive transmission with an OD ratio of .73, with the engine turning 2400, which is the low end of specs for a regular VT 903, and around tops for the Formula 903, running 11X24.5 tires, is putting the truck at 74.4 mph.

You would need a shift tower for a Freightliner cabover for the trans. The shift tower is the part that fits on top of the trans. The parts in the truck will still work.

I guess you could put in a 10 speed od Spicer, and the existing shift tower may work.

 

Had a 903 in a77 cab over. Bought it as a basket case. Put it back as a vtt903 675. Had 3.55 gears in it. Fun ride! Playing with CPL numbers is fun.

 

The CPL I used was for a marine app. But yes it was a twin turbo (vtt) the TT was for twin turbo.