OOOps! you're right . I was wrong. It's actually a 3.92 in the front and a 3.90 in the rear. I told those idiots at GM not to do that, but they went ahead and did it anyway. Who knew?
This information provided to you from the 1960/61/62 ST-9 Service manual supplement for tilt cab/ 4 wheel drive/ and Powermatic transmission.Section 16-16.
I realize that I am only a wrench fetcher compared to you being a shop shark.
are we talking apples to apples or to oranges.
it apperars that you are talking meduim duty truck-(tilt cab-4 x 4-powermatic trans, which in this application would be a napco)
"
4WD high/Low (locked) forces both front tires to turn the same rotation. Thus you get axle binding when making turns (outter tire turning faster than inner tire on the same axle). Also, on some older generation 4x4's (not sure if this still applies today), the front axle has a slightly higher gear ratio than the rear axle, thus causing a bind in the transfer case. So you can imagine that you can have one or two areas where binding can occur and shorten the life of the drivetrain if you were to drive your vehicle in 4WD locked mode on normal dry surfaces. When driving in snow or wet surfaces, this allows you the drivetrain to have some slippage but still maintain traction. But this mode should only be used for short term as binding on your drivetrain components still exists. I am sure you have experienced your D doing its jerky jerky motion when trying to make a turn from a standstill. The jerky jerky motion is caused by the front tires as the inner tire is spinning same rotation as outter tire. As the inner tire has a shorter distance to travel, it is trying to outpace the outter tire."
in our trucks K10-20 the ratios for these vehicles were as listed
3.73:1 frt 3.73:1 rear
4.10:1 frt 4.11:1 rear
4.55:1 frt 4.57:1 rear
ron
