1950 f1 rear

35 coupe

35 coupe

Senior Member
Just got a 50 f1 and trying to figure out what rear it has. there is a tag on it that has W 51 over 13 on it. 51/13 does that mean anything. the only other markings are pat. #. THANKS.
 
Divide the 13 into 54 and you get 3.92 which is the gear ratio of the rear end. I have read that 1951 Merc rears were also used in the early 1950's Ford pick-ups. Specifically, the 1951 Merc rear was a Dana 44 and was offered with the 3.92 option. So, your rear may be a Dana 44. Very strong rear. If possible , please post a phto of it. Here's a photo of a 1951 Merc rear. The inside dia. of the drums is 11 in. Bolt pattern is 5 x 5 1/2. The width of the rear from WMS to WMS is 61 1/4 in. Click on photo to enlarge. Here is a posting that the rear may be a Dana 41.
http://www.jalopyjournal.com/forum/showthread.php?t=326549 Also be sure and read this info. http://www.ford-trucks.com/forums/893241-1951-f1-rear-diff.html
 

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If you still have the plate that is attached to the inside of the glove box door it will also give you the rearend ratio.( providing it is the original rear end).
 
TJ said:
If you still have the plate that is attached to the inside of the glove box door it will also give you the rearend ratio.( providing it is the original rear end).
Click to expand...


Not for those models.

ASSUMING that it is indeed a Dana 44 and is the original rear end, I am kind of surprised. The Dana 44's with the 3.92 weren't really used until 51-52.
 
49 Mercury and 49 F-1 rear ends appear identical except for the spring brackets which are on top of the housing on the F-1 and under the housing on the Merc. My Merc has the 3.91 gear without overdrive. My F-1 has a 3.73 which is about right for the 6 cylinder.
 
Dick Webber said:
49 Mercury and 49 F-1 rear ends appear identical except for the spring brackets which are on top of the housing on the F-1 and under the housing on the Merc. My Merc has the 3.91 gear without overdrive. My F-1 has a 3.73 which is about right for the 6 cylinder.
Click to expand...

48-50 F-1 rear ends are primarily Dana 41's with 3.73 ratios. I have four of them. One is behind an original flatty. It does well. I never have understood why Ford went to the 3.92 in 51 and 52. I guess the old farmers wanted even more tree stump pulling power. Speed was never a concern to them. There are some visual differences between the Dana 41 and the Dana 44, especially in the rear cover area.
 
I checked the rear housing and there is a 41 on it, and the plate in the glooove box has model 9rc and the serial number on it.
 
35 coupe said:
I checked the rear housing and there is a 41 on it, and the plate in the glooove box has model 9rc and the serial number on it.
Click to expand...

That's a Dana 41 (which was the standard rear end of 1948-50 for these trucks). The curious thing about yours is the tag you found. Now I'm curious. The stock Dana 41's usually had a tag that said "W 41/11" indicating a 3.73 rear end. It honestly would be worth a look for you to remove the back cover and actually check it out.

The "9RC" is just the model number they used (you'll see that a lot on the titles to these trucks). If the serial number is 98RC______, that means it was a half-ton F-1 with a flathead eight cylinder.
 
I'd like to pick up a 3.9 rear for an F1 at a reasonable price some where near Vermont. Foe a future project. I have a 51 Merc rear with 3.23?? now.
 
I just bought a '50 F1 and I am doing my research and this thread sparked my interest.....

My truck has the 41 stamped with a W 51/13 tag. I also have a 4 speed transmission which hasn't been mentioned before.
Will swapping to a 3 speed help me a little or are you still convinced that a rear or gear change is necessary?

Thanks.
 
Our '51 F-1 has a Dana 44 with 3.52 ratio, I'm running a '53 Merc, basically stock, backed up to the original three speed and the truck is an excellent highway cruiser.
 
Falcon320 said:
I just bought a '50 F1 and I am doing my research and this thread sparked my interest.....

My truck has the 41 stamped with a W 51/13 tag. I also have a 4 speed transmission which hasn't been mentioned before.
Will swapping to a 3 speed help me a little or are you still convinced that a rear or gear change is necessary?

Thanks.
Click to expand...

The 4-sp is the spur gear, no-synchro unit? A swap to a 3-sp won't change top-gear ratio, both are 1:1. But the 3-sp is synchro on 2nd and 3rd.

Interestingly, the '51-'52 3.92 axle uses 47 / 12 ring and pinion; the carriers are different between the D-41 and D-44.
 
The 3-speed is a better highway ratio set and you won't have to double clutch every shift like the old stump puller. The 4-speed's 1st gear is almost a granny but not quite. You have to shift real quick to 2nd with a double clutch or grind em. I'd go for a 3-speed any day unless you have an F2 or F3 and plan on hauling heavy loads.
 
I changed from the crash box 4 speed to the regular 3 speed in my '48 F-1. What a difference in drivability!! If you go down this route be aware that the driveshaft, rear support and u-joint are different. Everything is readily available from the usual vendors except the driveshaft and yoke. I found mine (with yoke!) leaning against a barn in Maine!!
 
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