Been There, Done That, Never Again - trying to make a 6-cyl big truck happy on the highway
Posted Jul 18, 2012 6:52 PM
The 6-cyls are geared low because Studebaker engineers knew there wasn't enough power to pull a load without the big multiplier. Thus their max speed is about 40-45 MPH.
Raising the rear axle ratio/adding an overdrive/adding a Browning to get a higher cruising gear lessens the RPMs/raises the cruising speed on flat ground. However, when loaded like a working truck, the lack of power requires down-shifting a couple of gears at every hill, so it's crawling along with the engine screaming anyway.
Bottom line, there's no way to make the 6-cyls a working truck to haul rated loads at today's highway speeds. Either accept the slow pace or begin with the 289" V8 and 5-speed overdrive.