My '50 F-1 came with a Dana 41 rear axle with a ratio tag that reads W 51/13 which works out to 3.92.
According to the shop manual for 49-50-51 the ratios available were 47/11=4.27 or 47/12=3.92. Has anyone seen a setup like this before or have any idea about what type of vehicle the rear end might have come out of?
Very interesting. I own 4 dana 41's (only 2 are attached to a truck). All 4 have the following: "W 41/11" (3.73). One is a 49. One is a 50. Other 2 are unknown year. I wil say this, mtflat pointed out that the shop manual had a misprint and should have said 3.73. But that doesn't explain this particular rear end.
Very unusual... Be interested to see how this turns out! Any signs the perches were re-welded in their present position? I'm also curious about that "W"; my tag doesn't have anything but the numbers.
PS -- have you counted teeth?
I don't see any indication that the perches were re-welded or anything else that suggests that this wasn't the stock rear end when the truck was built. According to the firewall numbers, the build date is August, 1950 so I thought it might have something to do with the changeover to the 1951 models (it has the later flat panel bed) but the manual shows the same ratios available for 1951.
I haven't counted the teeth but I took it to Chuck Mantiglia to get the bearings and seals replaced and he agreed that it appears to be 51/13. He also commented that the ring gear was thinner than usual.
Ross, or Albuq F1 is the guy that put me onto the shop manual 'misprint' - maybe it wasn't a misprint after all. It might just reflect the fact that later trucks used a different ratio than early F1s since it was printed after '52.
I just did a little research. In the 1948-50 Chassis Parts Catalogue, dated July 1950, there are all three ratios listed. The 0M-4209 (a 1950 Mercury car part #) is listed as 3.92 ratio, and only fits 1950. There is no mention of the 1M-4209-A or -B (1951 Mercury car #'s), which would be for the 44.
In the 1948-51 Chassis Parts Catalogue, dated January 1951, all of the numbers show up, and the 1M #'s are listed for 1950-51.
So, apparently the 3.92 ratio got installed in some trucks with model 41's before the switch to the 44! It's interesting to note that no 1950 part numbers were ever assigned to the parts for the 44 rear, even though many of them were installed in 1950 trucks.
As thin as that ring gear is in the picture, I'd bet it was weak and a transitional effort. Note the differences in tooth counts for the 48-50 3.92 and the 51-52 3.92 -- 51/13 vs 47/11. It's strange they would use the bigger pinion and such a thin ring gear. They must have been "stuck" with using a carrier that was for much smaller pinions (higher ratios) but were scabbing the R&P from the car lineup?
Does all this mean that Dana 44 gear sets will bolt into Dana 41 axles?
That question is always on my mind! I looked up the carrier bearings in the parts catalog; the 48-50 (D-41) and 51-52 (D-44) use the same piece (and it's a real common wheel bearing). That's just one thing that has to be checked but the most obvious.
I don't know enough about these to answer this question; all the carriers on eBay say they are for specific spline-counts. How many splines are our axles? 19 comes to mind, can someone confirm? And what difference does it make as far as the carrier? Can we just put our spider gears in a carrier for lower ratios?