Rear axle change 1931 ccpu

C

ckulchar

Senior Member
We have a 1931 ccpu. I'm sure the rear end is a 4:11. Top speed in the truck is about 35 or so with the engine racing quite high.

A friend has a spare rear end we determined to be 3:78. Would this rear end get me to about 40 to 45 without the engine racing?

There is mention of a 3:54. Is this a stock Ford rear axle ratios or aftermarket? Would the 3:54 be better choise? Mostly flat around this area.

Thanks in advance.
Charley
 
Charley, Our '31 CCPU has the 3.27 to one rear axle ratio and it is perfect for where we live. Our CCPU loafs along at 60 MPH and still has the power to pull the rolling hills that we have here in Northwest Washington. It engine was rebuilt by H & H in La Crestenta, CA. They did it as a touring engine which gives it possibly 50 HP instead of the stock 40 HP. Being that you are in Ohio with fairly level ground, I would highly recommend the 3.27 rear axle ratio. Probably the most that you would be hauling would be two people. In our 1929 Tudor, I installed the 3.54 ratio rear end. We often haul five people and that works well. Our 1929 Tudor has a model B motor so it has a little more push than a stock model A Ford. Delightful to drive. It too, cruises nicely at 60 mph. It can go a lot faster if needed.
 

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I forgot to mention. At your Ohio touring speed that you would like to tour at, if you like touring at 35 to 45 mph, the 3.78 rear axle ratio is pleasant to work with. Nothing wrong with 3.78 at those speeds. Out west, we seldom drive below 50 MPH. Often we drive at 60 mph or more, so we need the higher speed rear axle ratios, than the 3.78
 
I have a stock engined 31CCPU. It has a 3:54 rear end. It cruises nicely at 45 to 50 and pulls the Alabama/Tennessee hills with no problem.
 
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