Rear Axle Identification on B-1-F

[Mavman427]

Does anybody know how to identify the rear axle gear ratio/type on the medium duty 1.5 ton trucks?  I've looked on the bottom/top of axle housing an differential carrier and didn't see anything.  I scraped and wire brushed as much crud off as I could, but it's still pretty nasty, so I could have missed something.  My trucks are 1948 & 1949 B-1-F's.

[Dozerman51]

The ratio should be stamped between the 2 carrier bolts that are parallel to the left (drivers side) axle tube. Go to the “Pilothouse Knowledge”site. Click on to the 1948-53 truck parts book. Click to the rear axle section. The photos show you where the axle ratio’s are located for all the relevant truck models.

[Merle Coggins]

[Mavman427]

Thanks, great info!!!

[Mavman427]

Both my '48 and '49 B-1-F's have the 6.285:1 rear diff's.  Gonna be slow going on the freeway, but boy those are some stump-pulling gears!

[ggdad1951]

5 hours ago, Mavman427 said:

Both my '48 and '49 B-1-F's have the 6.285:1 rear diff's.  Gonna be slow going on the freeway, but boy those are some stump-pulling gears!

 

try having a gear set that starts with a 4...

[Merle Coggins]

Yes, these trucks weren't built for high speed. But also keep in mind that your tire diameter plays a factor in overall RPM vs. Speed. Your "F" trucks have taller tires than our light duty trucks, so  higher numerical gear ratio is used to adjust for that. Although something in the high 4's or low 5's would probably offer you better cruising speed, if that's what you are after.