1930 common rear axle ratio

[coup34]

like to know the most common rear axle ratio.
THANKS

[Vic in E-TN]

3.78 is the most common. Others - 4.11 and 3.54 were available from dealers usually. Sometimes you could get parted out rear ends with these.



Vic

[coup34]

Thanks

[Terry, NJ]

I believe 3.78 is the most common. However, with today's road conditions, cost of gas, etc I would have no problem with 3.54 in it. If your engine is really strong or you live in flatlands, I would recommend the 3.25/27. I put 3.54s in my two coupes and i can't imagine what Henry was thinking of when he used the 3.78s. But it can be expensive (About $700 ) and a lot of work. Good Luck!
Terry

[Synchro909]

Originally Posted by Terry, NJ

I believe 3.78 is the most common. However, with today's road conditions, cost of gas, etc I would have no problem with 3.54 in it. If your engine is really strong or you live in flatlands, I would recommend the 3.25/27. I put 3.54s in my two coupes and i can't imagine what Henry was thinking of when he used the 3.78s. But it can be expensive (About $700 ) and a lot of work. Good Luck!
Terry

I think these days, many of us forget that in Model A days, cars shared the road with horses and the speed limit on the best highways was 40mph.

[Big hammer]

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Originally Posted by Synchro909

I think these days, many of us forget that in Model A days, cars shared the road with horses and the speed limit on the best highways was 40mph.

Yep muddy roads deep snow and the hills where steeper, they spent a lot of time in second gear

[nkaminar]

3.78 with an overdrive and high compression head (6.0:1) = 20 mpg.

[Bob Bidonde]

This is a list of all I could find:

[BRENT in 10-uh-C]

Originally Posted by Vic in E-TN

3.78 is the most common. Others - 4.11 and 3.54 were available from dealers usually. Sometimes you could get parted out rear ends with these.

Hey Vic, I hear that you are out of the hospital now and hopefully you are feeling better.

Not sure if you are suggesting the 3.54 ratio was available from the Ford Agency (dealership) or a reproduction parts dealer, but I have heard this stated many times that Ford offered the 3.54 back in the day. I am curious if you, -or anyone has any proof of this. The reason I ask is I have researched it at the archives and know there was a pre-production experimental gear set that was a 3.54 however it was superseded in production by the 3.70. Outside of that, I have never seen any print or literature that has shown the 3.54 ratio for a Model-A. Does anyone have anything to confirm it was indeed available back then??

Originally Posted by Bob Bidonde

This is a list of all I could find:

Bob, to muddy up the waters and add another ratio or two to the mix, in early 1932 all V8 powered vehicles came standard with a 4.33 gear ratio (-which interchanges with the Model-A R&P). Then, there is a 4.56 gear ratio that was offered in the AF models along with a 4.88 gear set that was manufactured by Power King to use in their Economy Tractors that used cut down Model-A rear axle assemblies.

[fundytides]

In my Ford (Canada) parts catalog, dated 1938, only the 3:78 and 4:111 matched sets are listed as available for 1928-32 A, B and 18. The only 3:54 - high speed- set is listed for 1935-36 Model 48, 50. 67 and 68.

[Tom Endy]

During Model A production three ring & pinion ratios were used. The early 28's used a 370 ratio. The majority of cars used a 378 ratio. Pick-up trucks, station wagons, and some town sedans used a 411 ratio. The 354 ratio was introduced as an after market some years later when the country's roads improved.

Here is a list of the ratios available today:
370 - 37\10
411 - 37\9
378 - 34\9
354 - 39\11
327 - 36\11
433 - 39\9 (1932)
Divide the smaller number into the larger for the ratio. The numbers are the tooth count on the gears.

The attached article describes the the early ring & pinion.

http://www.santaanitaas.org/wp-conte...ing-Pinion.pdf

Tom Endy

[jeepguy1948]

Just in case you are considering swapping to a 3:54 gear you should know that a Model A motor (Even modified) won’t pull a 3:54 and an overdrive and you lose “parade gear” first

[Terry, NJ]

Originally Posted by jeepguy1948

Just in case you are considering swapping to a 3:54 gear you should know that a Model A motor (Even modified) won’t pull a 3:54 and an overdrive and you lose “parade gear” first

I am impressed at how good the 3.54 reargears pull the hills around here. I live in Rock Hill townsp, Bucks co, Pa. They don't call it "Rock Hill" for nothing. Many of the smaller roads going up and down have switchbacks. Portions of some of the roads are just too steep to go straight up or down. I've never had the head off the engine, but I suspect it's a Snyder 5.2. The engine also has a "B" carb. with a bored out manifold. I was so convinced of the superiority of this rear and engine set up, i'm making another one.
Terry