3.78? Rear end

[ivoryjohn]

What is the most likely rear end ratio in a late production, stock, 1929 Briggs Fordor? What else do I need to know before ordering a Mitcheal Overdrive?

 

[Jordan]

3.78 generally. Could have had a 4.11 by order.

Why would this affect your order of a Mitchell?

if i were guessing it would be so he knows what ratio overdrive to order since mitchell has a variety of ratios.

but yes, it is most likely a 3.78.

 

[Barry B./ Ma.]

The standard mitchell overdrive is a 26% reduction. My coupe has the std. 3:78 rear with a std. Mitchell 26%. This seems to be a perfect combination for the Model A and mine has a Snyders 5.5 head and touring cam. In my opinion a 3:54 rear would be too much for the overdrive and you would be running it in low range most of the time in a hilly area.

 

[Charlie Stephens]

Put a chalk mark on the tire and count the number of turns of the engine required to make one revolution. If the ratio is already 3.54 you probably don't need an overdrive and installing one would lug the engine. It is probably 3.78 or 4.11 currently. Is your speedometer accurate and what is the number on the speedometer turtle?

Charlie Stephens

 

[Tom Wesenberg]

That would certainly be a guess.
It would/should be the same ratio OD choice for 3.78 or 4.11.

Many people seem the think more OD ratio is better.
It is not.
23% to 26% is about as much as you should go or need.
Want more OD ratio? Better stock-up on horsepower first.

Here's what I want for Christmas. Anyone got one for sale?

Ruckstell Dual High Transmission on Ford Garage

Yep, I want one too.
Now, why didn't Henry think of this?
Someone should repro this overdrive ******.

 

[H. L. Chauvin]

Maybe Interesting:

1. With fuel in the fuel tank, with water in the radiator, with a few tools & jack under the front seat, a spare tire, & few light traveling items in the trunk, a Model A of different styles with four (4) doors vs. a Model A of different styles with two (2) doors will have approximately (220) pounds of different approximate weights.

2. If four (4) equal weight passengers are in the four (4) door, & four (4) equal weight passengers are in the two (2) door, (i.e., two (2) in the rumble seat of the Model A with (2) doors), the approximate vehicle weight difference appears to be about (220) pounds more in the Model A with four (4) doors; again, assuming that all passengers are of the "exact" same weight & all have the same weight of tools & accessories.

3. Now if each passenger in the coupe weighs about 28 pounds more, & each passenger in the (4) door weighs just 28 pounds less, (which is not uncommon), both engines are pushing approximately the same total vehicle weight.

4. Appears that the 220 pound vehicle weight difference of just these two (2) vehicles, (without passengers), is not quite as crucial for gear ratios as is the selection of passengers riding in the vehicle.

5. Maybe something to consider.