Reference source for rear gear ratios for a '55 E12 with 4-speed ?

[PackardV8]

Just realized I don't have anything showing what would have been the standard fitment rear gear ratio for a 1955 E12 w/4-speed transmission. Anyone have a '55 Truck Shop Manual, Parts Manual or anything else which would definitively show what were the standard and optional rear axle ratios?

Also, what would have been the rear gear if the '55 E12 was equipped with the 3-speed overdrive?

TIA,

jack vines

[StudeRich]

You know it is not going to be too exciting though right Jack? They never used higher (lower numerically) than 4.09 except on Automatic Trans. which was usually 3.73.

The '57-'61 Parts Book says that in 1/2 Ton 2 wheel drives, only the 170 & 185 Sixes used a 4.88, but a 7 (V-8) 1/2 Ton can have a Conventional Axle of 3.73, 4.09, 4.27 or 4.55 and they left it up to the sales people to list the std. vs optional ratios.

So the brochures should show that info.

In a Twin Traction axle the available ratios are the same.

So that brings up an interesting question does it not?

What is the Torque Converter multiplied final drive ratio (output) IN LOW gear in a Truck Automatic vs a Truck version H.D. T-89 3 speed Overdrive in LOW direct?

The answer will/may explain the Engineers decision to choose 3.73 on Auto & not Manual Trans. Trucks!

I did deliver several new Los Angeles Water & Power '62 Champs from Inglewood, CA to downtown with V-8 Auto. (I think 259) but don't know, they could have been H.D. 289's!
All I can say is, you had to make a special effort NOT to hit the go pedal much more or EVEN half way, on startup with that LOW GEAR start Auto. not to get the attention of the LAW with the smoke and squeal of the tires and WITH TT !

[PackardV8]

Hi, Rich,

Good general info, but still doesn't answer the question with what gear ratio a '55 E12 with 4-speed would have come equipped.

The '57-61 info isn't at all applicable, because those trucks had Dana 44 and 60 rear axles. The '55 - early '56 were the only V8s with the old Timken rear axle. I can't find anything in print about the gear ratios for the 4-speed and 3-speed overdrive V8 '55 E12 models.

jack vines

[StudeRich]

Sorry, I don't have time to find the '55 Brochure. This is what I had quickly available and I totally missed that you only care about 3/4 Tons with Timkens. I only save the more common Spicer 60 and 70 rear axles.

[mbstude]

If I'm reading this right, looking in the parts book shows that an E12 could have had 3 different rear gear ratios. 4.11, 4.85, or a 5.57(!). I don't see anything about transmission variations.

[StudeRich]

That's right Matt, in post #2 it says the Brochure needs to be consulted for which AVAILABLE axle ratio was used for what, that includes Transmission type. I had to mention the Automatic ratio from memory.