1949 Mercury differential ratios?

The first of the mid century Mercs had the Dana 41. They had a 3.91:1 for standard shift models and those with overdrive. They were also available with 4.27:1 & 4.55:1 ratios for mountainous regions and those that wanted to pull a trailer. Ratios changed with the change over to the Dana 44 in mid 1950 and for the Merc-O-Matic transmission that also came along in mid to late 1950.

Some new stuff is available for the 19-spline Dana rear axles but a person would have to contact Randy's Ring & Pinion to see what can be done there.
 
I find it hard to believe that 3 speed standard cars with and without overdrive used a 3.91:1 read end ratio. Sounds like the ratio for overdrive only if anything to me.

Sal
 
scicala said:
I find it hard to believe that 3 speed standard cars with and without overdrive used a 3.91:1 read end ratio. Sounds like the ratio for overdrive only if anything to me.

Sal
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The standard non-od 3:73 Ford car ratio results in engine rpm very close to the Merc's 3:91 with the larger OD Merc tires.
 
The F-1 pickup with the Dana 41 came with 3.73:1 but the Mercs didn't. When the automatics came out they had two lower ratios for the Dana 44 that was in use at the time.
 
My 49 F1 has a Dana 41 4.27:1 (47:11) that I have just swapped to a 3.55:1 (39:11). New seals and bearings from Early Ford V8, including NOS planetary gears. Motive Gear Performance ring and pinion HC-4209-HS fitted.
 
49r said:
My 49 F1 has a Dana 41 4.27:1 (47:11) that I have just swapped to a 3.55:1 (39:11). New seals and bearings from Early Ford V8, including NOS planetary gears. Motive Gear Performance ring and pinion HC-4209-HS fitted.
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That new 3.55 gear set, did it fit straight on to your original (4.27) carrier?
Martin.
 
I checked Motive Gear and they have the gears for the 6 5/8 bolt circle ring gear (8.5"carrier) with 10-bolts. It's under their P/N D44-354 for a Dana 44 carrier. They list nothing for the D41 axle under that part number. The only thing I could find and Early Ford V8 Sales was P/N 8C-4209-HS for 48 thru 50 Dana 41 which has the 5 5/8" carrier of the D41. I'm not sure if they are new reproduction or old stock since it doesn't say on their site. Maybe Motive Gear made them for suppliers but they don't list them on line. It may be that they are a limited supply too.

The D41 has the 5 5/8 bolt circle carrier and I don't think it will fit a 6 5/8" D44 carrier due to the size of the main case being different. Spider and side gears are all the same for all the 19-spline axle assemblies but I think a person has to find good used or NOS parts if needed since none of the later D44 axles had 19-spline. Randy's Worldwide has carriers to fit all the available D44 axles and gear sets that work for the early D44 Axle with 19-spline. I don't know if the pinion spline for the U-joint flange is the same though. It's likely different.
 
info mercury rear ratio from factory overdrive trans is 427 ratio...without overdrive 392 was provided and optional ratios 427 and 455 was available....special ratios were available at extra cost and limited choice
 
The gear ratio was 3.91 (D41)or 3.92:1 (D44) standard unless the buyer placing the order was living in a flat or mountainous region. It just depends on where the order was placed from and what assembly plant put them together. Both of my 1951 cars have the 3.92:1 Dana 44 rear axle and both were assembled less than a month apart at the Saint Louis plant. The 4.55:1 ratio was for pulling the Long Long Trailer.

The 1951 automatic transmission cars had either 3:31 or 3:54:1 depending on flat country or mountainous.
 
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Not to hijack a thread, but I'm in need of help. I have a 1950 Ford rear in my roadster, it came from a 1950 OD car. It was gearset (B5A-4209-C) 4.11 to one, way too slow. I found a (B5A-4209-B) 3.89 gears from a 51 automatic, still way to slow. I have acquired a (B5A-4209-A) 3.30 gears, but they are not adjusting right. The 3.30 gears are advertised for 51 thru 56 differentials. My question, is there any difference in a 1950 and a 1951 differential housing. Any knowledge would be greatly appreciated. I have been always told the 1949 thru 1951 cars have the same differential housing.
Thanks
John
 
All the Ford cars with exception to station wagons and police cars have that early precursor to the 9-inch with replaceable third member. The 49 thru 51 cars with the Ford axle may be more narrow than the 52 thru 56 cars but I'm not that familiar with them to know for sure. There may also have been running changes in those early production years. I don't have access to my Hollander interchange manual so I'll have to check it later to see what it reflects. The 1951 with Ford-O-Matic would likely have a higher speed ratio rear axle but the manual trans cars don't. There may also be a different carrier involved but I don't know that either. I'll just have to see what the parts books & interchange manual list.

Are you a Harley 45 owner? The reason I ask is your forum ID and I'm a flathead HD owner with a 1948 model WL, 45 Solo.
 
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I have a 51 Merc rear with 3.3, New brakes and drums emergency brake cables. I'd let go cheap. PM me.
 
My Hollander Interchange states that the 49 & 50 are the same. The 1951 housing changed to use rubber pads for the springs but will interchange with the early types as long as they are padded or not padded appropriately. The 1952 thru 1954 are same. The 1955 and 1956 are both a one year only but I don't know what's different between them. They did share with the Thunderbird in 1955 but not in 1956 so that might be a difference.

3rd Members/Hogs Heads
The parts book lists two different carriers for 49 & 50. One P/N 8A-4200-B is stamped 11/41 for the 3.73:1 ratio. The other 8A-4200-D is stamped 10/41 for the 4.10:1 ratio. In 1951 there were three ratios. available. The 4.10:1 as mentioned previously and the 1A-4200-A stamped 13/43 for 3.31:1 and the 1A-4200-B stamped 11/39 for 3.54:1 ratio. The 1952 & 53 axles shared the 3.31:1 and 3.54:1 with 1951 and added a 3.90:1 P/N AB-4200-A stamped 10/39. The ring & pinion kits list the ring gear & pinion as a set along with shims & spacers by P/N but the shims & spacers are all the same part numbers. The other check I made was just the carrier itself. There were two. The 8A-4205 for 1949 thru 53 is to be used with all the 3rd member sets except the 1A-4200-A. The P/N 1A-4205 is to be used with P/N 1A-4200-A only and that is the 3.31:1 set so that might be what you are up against.

Where it gets real confusing is when you look in a 1955 or later parts books and it starts referring to part numbers that supersede the early ones but the ratios are sometimes different. I imagine that you are not the only person to find that stuff doesn't work right together. With all that and the Mercury car/Ford pickup/station wagon, etc. Dana 41 & 44 thrown into the mix, it gets even more confusing. It's easy to tell the Dana from the Ford though visually but it can leave you scratching your head in some of the Ford part numbers.
 
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