3.73 info

[Bklein01007]

I have a 46 WC 1/2 ton pickup and looking for a set of 3.73 rear-end gears. I have heard some 50's plymouth and dodge cars will work. I also have a junk yard locale that has some cars from that era. What year and model cars have those gears?

Thanks

Bill

46 WC

Vermont

[dpollo]

Many Desotos  46-8 and some Chryslers with the M 6 transmission, also the Plymouth business coupe 49 to 52.

 

all of these will fit but you may have to change the input flange.  Watch for different axle splines 53  to 56 but it  is possible to change the axle gears.

 

The ratio is stamped on a flat boss on the lower side of the gear housing.

[knuckleharley]

I found a NOS 3:73 ring and pinion gear for my 42 Dodge on ebay. Given the rarity of 42 anythings in junkyards,I doubt that is much help to you.

[dpollo]

that ring and pinion will fit 37 to 56  

[Bklein01007]

Thanks to all

My truck has the joint pin style u joint not the cross style used today. I would most likely take it all apart anyway and just use the ring and Pinon and replace the bearings while there what the hack I have rebuilt everything else.

[dpollo]

 The drive shaft flanges usually interchange without problems.   

[knuckleharley]

that ring and pinion will fit 37 to 56  

Thank you. Good to know.

[dale]

Anyone know where the gear ratio is stamped on a 1946-1948 Plymouth if it is ?  Otherwise I suppose you can tell by turning the driveshaft 360 degrees and count the wheel revolutions.

[Young Ed]

Anyone know where the gear ratio is stamped on a 1946-1948 Plymouth if it is ?  Otherwise I suppose you can tell by turning the driveshaft 360 degrees and count the wheel revolutions.

Typically stamped on a flat spot on the top of carrier. Hard to read while installed in the car. Try wire brushing the area well and taking a digital photo or two. You should see 3|73 for 3.73.

[Niel Hoback]

Probably 90% of p-15s are 3.9.

[DonaldSmith]

If one wheel is on the ground, the other wheel will rotate twice as much.  For a 3.7 ratio, 3.7 revolutions of the drive shaft will produce not one, but two revolutions of the free wheel.   

[CoronetGuy]

If one wheel is on the ground, the other wheel will rotate twice as much.  For a 3.7 ratio, 3.7 revolutions of the drive shaft will produce not one, but two revolutions of the free wheel.   

It wont do 2 full rotations. It will spin less than 2. A 3.90 gear rear end will spin very close to 2

[dpollo]

It is stamped, along with the date of manufacture on a flat "boss"  facing down in about the 4 o'clock position on the passenger side of the car.  It was often highlighted with yellow.   The boss surface is not machined so it may take a bit of scrubbing with a wire brush to reveal the stamping.   I was told that the axle ends were painted yellow, red or other colours to indicate the ratio but have never confirmed this.  On a 52 diff which I went out to check before writing this, the "boss" was just below the oil fill plug.  This would be different on a 48 since the fill plug is on the rear of the housing .

[Plymouthy Adams]

 I have always found that the ratio is stamped at the very top flat of the hoghead just at the sealing surface to the housing.  this area usually is first to get a bit of grease and dirt accumulation and my be easier seen when cleaned as it is better protected from wash off and eventual rust.  be prepared to see the gear teeth count and do the math...as in 11/43 for example would be a 11 tooth pinion and a 43 tooth ring for a effective ratio of  3.909

Edited April 14, 2016 by Plymouthy Adams