Yesterday I pulled the center section on the rear end from my 1955 Fairlane Club Sedan to check ratio and condition.  I was expecting a 3.89:1 as it is an 8 cylinder car with manual transmission. This is what I found on the ring gear.  AG-4210 -B-"C"  Ford  10X37.  This would be 3.70:1.  My confusion is that neither the shop manual for '55 or the 1949-1959 Car Parts Catalog list a 3.70:1 differential.  The 4210 is confusing as the parts catalog shows the number for the Ring and Pinion as 4209 (unless 4210 is the ring gear alone).  Also etched on the ring gear in hand writing is 8536 although the 8 looks like a S with a diagonal line.  The differential case looks like the '55-56 model although I understand the earlier cases are the same. The parts catalog lists a 3.70:1 but only for the '57.  I believe this would be a 9" rear end.  Anybody know what I have here?  Also I feel the 3.70 gears would work well with the T5 transmission.  I can get a 3.89 center section What do you think?




Mark

1956 Mercury M100
1955 Ford Fairlane Club Sedan
Delta, British Columbia

If you pulled the center section out, You have an 8 or 9'' rear end. the 55/56 would open from the rear with a cover. Send us a photo. 

Frank/Rebop

Bristol, In ( by Elkhart) 

My understanding is that the 55/56 sedans had a rear that the chuck pulled out like a 8 or 9 inch.  The wagons had a Dana, which had the opening at the rear of the housing.  However, the 55/56 sedan rear was not the same as the later 8 inch or 9 inch and parts are not inter-changeable.  Danas were also used in 55/56 Birds.





54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Mark: If I recall correctly (it was many years ago) my '55 club sedan, 272 c/w std trans, was a 3.73 ratio..however it might have been 3.70.  As  I understand it, those design rear ends were used in all '55-'56 sedans. I read somewhere that the 3.89 ratio was the higher option (lower #) for the O.D. trans. The correct description of that rear axle escapes me at the moment. The heavier Dana units were found in wagons, sedan deliveries & early T. Birds.  I seem to recall that Bruce Young at Y-Blk magazine wrote an item, a long time back, about that 4210 designation you posted, but the details I don't remember unfortunately..    


Paul

Thanks Paul and Paul 2748 you are right.  I have the Dana 44 in my pickup and its the same rear end as the T birds, Country Squire, Country Sedan, Ranch Wagon Courier and Interceptor models.  My shop manual refers to the rear end I have as Banjo Housing Hypoid Rear Axle.  The Dana 44 is termed Integral Housing Hypoid Rear Axle.  The manual lists the ratios available for the Banjo axle as :  35 Drive,9 pinion 3.89:1 for standard and OD 6 and 8 cylinder; 33 Drive 10 Pinion 3.30:1 Fordomatic 6 and 8 cylinders; 32 Drive 9 Pinion, 3.56:1 Fordomatic 6 and 8 cylinders; 37 Drive 9 Pinion 4.11:1, OD 6 cylinder; 34 Drive 9 Pinion, 3.78:1 standard 8 Cylinder. Does not show  37 Drive 10 pinion, 3.70:1. but the ring gear has this inscribed on it right beside the Ford insignia.  The 1949-59 Parts catalog lists a number of other ratios but also no 3.70:1.

Paul Arcande the 1949 -59 parts catalog lists a 3.73:1 but it is for a Thunderbird or Police Interceptor so it would have been a Dana 44.

My wife (who knows how to drive a car and that's about it for automobiles) walked by as I was staring at this center section, so I asked her why there is a 3.70:1 ratio on the ring gear but no listing for it.  She said in an asking kind of way "Because its a Mercury?"  which got me thinking. Wonder what they put in Monarchs and Meteors, maybe its Canadian eh?  Makes me wonder even what year it is.  I have been told that the '55 '56 Banjo rear ends were not heavy duty.  Well after pulling the center section out from under the car it may not be duty but it certainly is heavy.  Also there is supposed to be a difference between the '55 '56 and the '49 '54 version but in the parts catalog they look eerily identical.  Just curious where it comes from.


Mark

1956 Mercury M100
1955 Ford Fairlane Club Sedan
Delta, British Columbia

Mark: Now that you mention it, what I thought was 3.73 was likely 3.78. If you aren't too heavy footed it should be o.k. for street use. A lot of young drivers years ago would break rear axles and differentials doing stupid stuff, like spinning one wheel in the gravel until it hit the pavement, resulting in breakage of one sort or another, and then blame the manufacturer for a weak product..   


Paul

3.89 was 3 speed o/drive, 3,.70  was 3 spds manual.




  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

A photo would help id it.

Thanks Aussie, although I am still baffled as to why there is no listing in the Shop manual or the '49-'59 Parts catalog.  Perhaps the 3.70:1 replaced the 3.78:1 ratio (listed in my references as for the 3 spd. manual) in Canadian/Australian Fords.
For those that requested photos here are some.



Mark

1956 Mercury M100
1955 Ford Fairlane Club Sedan
Delta, British Columbia

This center section case has AF 4025 C and 10-8-54 cast into it.  Assuming month day year - October 8, 1954.  Reasonable I guess for a 1955 car?


Mark

1956 Mercury M100
1955 Ford Fairlane Club Sedan
Delta, British Columbia