Mavman427 Posted December 4, 2018 Report Share Posted December 4, 2018 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. Quote Link to comment Share on other sites More sharing options...
Dozerman51 Posted December 5, 2018 Report Share Posted December 5, 2018 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. Quote Link to comment Share on other sites More sharing options...
Merle Coggins Posted December 5, 2018 Report Share Posted December 5, 2018 1 Quote Link to comment Share on other sites More sharing options...
Mavman427 Posted December 6, 2018 Author Report Share Posted December 6, 2018 Thanks, great info!!! Quote Link to comment Share on other sites More sharing options...
Mavman427 Posted December 10, 2018 Author Report Share Posted December 10, 2018 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! Quote Link to comment Share on other sites More sharing options...
ggdad1951 Posted December 10, 2018 Report Share Posted December 10, 2018 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... Quote Link to comment Share on other sites More sharing options...
Merle Coggins Posted December 10, 2018 Report Share Posted December 10, 2018 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. Quote Link to comment Share on other sites More sharing options...
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