Gear Ratios: Misinformation at its worst.

We had one in silver with red stripes. Had an Offy dual plane with a 4bbl, big cam and headers. AMC refused to warranty the rear end after #3. So it got a Dana. Dad surprised a lot of supposedly fast cars with that little beast.

My aunt drove it 45 miles with the oil light on, on her way to pick up her Vega dad had been working on. He was not amused.

 

Have you seen any pinions out of these really tall rears? Suckers are huge, like saucer sized.

 

I was hoping it showed in this picture, but no such luck. I can hardly imagine the shock load it took to break a hunk out of a ring gear like this.

 

And both segments are chasing lower RPM at Cruise, but for different reasons.

The best BSFC numbers from a diesel occur somewhere on the lower end of the plateau of torque Peak. And they're trying to push the RPM down to lower frictional losses.

Gasoline engines in automobiles use a much smaller percentage of their total power for cruising. They are also much more efficient with larger throttle openings to reduce intake manifold vacuum. So they operate well below torque Peak in order to allow for those larger throttle openings. By going to more gears with more overdrives, they can keep their final drive ratios low to maintain acceleration while still keeping the very low Cruise RPM.