Rearend Ratios

[kevinanderson]

So the rearend ratio is stamped near the filler tube, right? Does this hold true for a '48 and a '54? I pulled a '54 Savoy 2dr w/OD home and was wondering about the rearend ratios. Thanx guys. Kevin

[kevinanderson]

OOpps, I mean filler plug.

[Andydodge]

Kevin, my references say that an overdrive trans should have a 4.10:1 rear end, the other ratio available is supposed to be 3.73 for a normal 3 speed and 3.73 for the Hy-Drive.........trust this helps, andyd

[Andydodge]

Kevin, the above post was for the 1954 model, for 1946-48 P15 my 1946 to 1954 Plymouth Service Manual lists P15's having 3.9 diff but it doesn't list anything under Overdrive or Hy-Drive for the P15(?), for the 1949-1952 P18,P20,P23 it lists 3.9 as standard with 4.1 optional for Mts & hilly country, and 4.3:1 for the Overdrive, again nothing is listed for the Hy-Drive for these yrs.......and the info I posted for the 1954 model should have included the 1949-1954.....P17,P19,P22,P24 & P25 models.....now you should be completely confused........I am.....andyd

[Tony WestOZ]

3.9 was an option in Australia.

not that that really helps much.

[Plymouthy Adams]

yes is marked just below and forward of the filler plug..could easily be the 3.9 or the 3.73..very doubtful you got the rare 3.54 but you never know...

I know this because I also have a 54 Plymouth and it is clearly stamped in this location

[billwillard]

He is asking if the ratio is stamped on the rear. I think so but am not sure.

[billwillard]

I am slower then you Tim

[Plymouthy Adams]

That's ok Bill...at least we be on top of this ..good morning to you...

[kevinanderson]

This car has a 5 blade fan and shroud. Radiator is missing. The generator looks like it has a larger pulley and blades behind the pulley. This astute observation was made looking w/ a light at 11 o'clock last night. Is this H.D. or just thet way this model is? First time around w/ a '54.

[BobT-47P15]

Answers to questions about rear end ratios and lots of other things can be found in this manual. It is not all inclusive, but has quite a bit of useful

info. Originals and/or reprints can be found on ebay.

I'm thinking the ratio numbers on the pumpkin were on the front side of the

thing, not the rear side. Usually have to do a little wire brushing to remove

the crud to find those numbers.

A 54 wiring diagram as found in the book.

Photo of fan, shroud and radiator.

[kevinanderson]

thanx bob. looks like same set up i have. haven't cracked the manual open.

[Dodgeb4ya]

I think most OD cars built 1952-4 were 4.3 ratio from the factory unless ordered otherwise. I`ll look check in the data books. My 52 Belvedere came factory W/ 4.3 ratio and I have parted a couple as the same.

Bob

[Plymouthy Adams]

Most of them I understood from the factory were 4.1 Standard was 3.9 for a standard tranny and then the automatic (1954) came with a 3.73 even though some advertised it was the 3.54. Now come a direct slap in the face toward written specs and this clinker could very well confuse a number of figures. When the OD was introduced in 1952, it was also made available in kit form to the dealers for retrofitting into earlier models and to enhance sales of floor inventory.

[Dodgeb4ya]

This OverDrive info is out of the 1952 Plymouth Salesman`s data book.

[Plymouthy Adams]

While that may be nice reading...I have to say by personal experience I have had two of these cars with factory OD and both had 3.9 ratio rear gears...so...only thing I can add there is maybe in the southern region outside of hills and such..this was norm..area of sales dictated ration in all other cars so would not think factory OD to be an exception..

[Dodgeb4ya]

Factory Data books and sales brochures are great reading! I have parted out quite a few OD cars just for the transmissions over the past 30 years and most all had the 4.3 rear ends. I junked most of those 4.3`s because I agree a 3.9 is better W/ the overdrive on todays freeways. Try driving over the Cascade mountains W/ a 3.9-- I`ve done it-back to 2nd/3rd gear all the way. I`m sure a lot of dealer installed OD kits were put in a car leaving the existing rear ends if they thought the car and terrain were compatible. I`ve run a 3.7 W/ od thats not good at all around here where I live- The great Northwest. 3.9 is good W/od.

Bob

[Plymouthy Adams]

Area of sales did dictate ratio and in my factory book it says that 1942-52 P18, 20 and 23 got the 3.9 as standard with optional gears of 4.1 for hilly area and if OD equipted..got the 4.3. The P17,19,22 24 and 25 got 3.73 gears as standard, 4.1 optional for hilly area and OD and the Hy-Drive got the 3.73 standard..while you live in the Northwest and have parted these out with 4.3 ratio and my experience in the south with the 3.9's and like your next question, where is the 4.1? can't say..I did verify those ratios though..I also read that the 54's with the automatic all came with 3.54's..again that is not true either...really am not sure there is anything written in stone on these old cars..