Re: [VAC] Tow Vehicles

["Dr. Gerald N. Johnson" <geraldj@xxxxxxxx>]

Watch out for "economy" rear axles on Ford pickups with the 300 I6
engine. They shipped some with a 2.79 rear axle and an weak overdrive
transmission in the 80s. I drove one once where I could feel the
individual power strokes at 65 mph. All engines get more power out at
higher RPM.

I've run through the first tank of gas on my '98 with the small V-8 and
5 speed transmission after changing the rear axle ratio from 3.08 to
4.10. It really drives nice, has great throttle response, I've not yet
put it under trailer load. Need to do that soon. The lightly loaded gas
mileage for the first tank after the change was 16.77 MPG, essentially
the same as with the 3.08 gears. Now the engine is not lugging while
cruising. And according to my computations this rates the truck at 4700
pounds trailer instead of the factory rating of 2200 pounds.

I drove a friend's 300I6 with the modern 5 speed and 3.08 axle a few
times. It badly needed this 4.10 axle gears. The change cost $490 at the
local hotrod shop. I still need to change the speedometer gear. My gas
mileage computation included correction for the original speedometer
gear.

Gerald J.