Pros & Cons: 3.54 vs. 4.44 & Mitchell OD

[Will Kimble]

I have only put a few miles on my new AV8 but I am already concerned about the 4.44 gear ratio that came in the rearend - I don't think it is gonna work for even a short highway trip. I always figured I would switch to a 3.54 and keep things simple, but...

But the car is a hoot to drive around town with the 4.44 rearend. I am starting to think a 4.44 rear with a Mitchell overdrive would be really handy, almost like a four speed. Use 1-3 in town and pull it onto overdrive when you want to go 65.

So I am evaluating the options and looking for input on pros & cons. I don't want to go any faster than 65, but I would like to be able to run 65 from Cincinnati to Columbus, Dayton, Indianapolis or Louisville. My car is pretty light, but is a 221 with a stock cam & heads, dual 97s and headers. And a '39 transmission. I know what goes into a rear gear swap, but have never worked with a Mitchell before - although their product reputation is superb. My only concern would be getting the right size overdrive for my car, since it isn't a stock piece - a '37-40 rearend that has been shortened to fit a '32 chassis and has the short '46-48 rear radius rods.

I guess the big question is should I keep it simple (3.54) or would the extra planning and expense of the overdrive be worth it?

Here's a shot of the car for reference:



Thanks for your thoughts,
Will Kimble
www.kimblemandolins.com

[blucar]

Reviewing your picture I would say that you have a rear tire that is around 600x16. A later model differential, '33-34 would most likely not be to wide for your body, 3.54 would work very well. The overdrives, Columbia and/or Mitchell work very well.... The Columbia's look better under a street rod... If you use an overdrive, a 3.78 would work better with your tire size.
For my point of view, if you intend to drive the car on the highway at 65 mph, you had better plan on doing a lot of suspension improvements to the chassis.

[Human Fly]

I dont know what the price of the Mitchell, but what about a quick change. I bought a New Zealand one and its a very nice item. Not sure what price it would be in USD.

[JWL]

In my experience with Mitchell I found you can describe the dimensions of your radius rod mount and get the lengths and locations you specify. I have 3.78 & Mitchell and have considered 3.54 plus Mitchell. The 4.44 would be great if pulling a heavy trailer.

[flatmotor40]

I have a Mitchell in my 40 conv and would not change a thing it works great got the 36% OD from them.Whwn you need the 4.44 you still have it and when you need to cruise push in on the cable and go in any gear.I did opped for the cable because I didn't want any hole in the floor

[Will Kimble]

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Thanks guys, getting some good input.

Blucar, sorry, that is important info - the rear tires are 7.00X16s.

And thanks JWL, that is helpful to know I could give them the measurements and get what I need.

Will

[oldford2]

Do 7:00-16 tires work on stock 6:00 -16rims? If so, what is the diameter increase? Thanks John

[Will Kimble]

I have run the 7.00s on '35 Ford wire wheels and they worked great. These wheels are from a '47 Ford. According to Coker the tires are 30.4" diameter. I will measure them as a double check and report if they are significantly different.

I see quite a few hotrodders running 7.50s on these wheels but that is beyond my comfort zone.

Will

[BrianCT]

Originally Posted by oldford2

Do 7:00-16 tires work on stock 6:00 -16rims? If so, what is the diameter increase? Thanks John

I have looked at that and concluded you gain 2 or 3 % at best.

[blucar]

A quick change rear end would be all right for racing and/or bragging rights, however, for daily driving use it would not be practical...
Opps, hill ahead, time to get out the tools and re-gear the diff...

[flatmotor40]

change the rear gear and you lose the stump puller go with OD

[Kahuna]

Will, you've got a great, well thought out car. If it were mine, I'd replace the rear axle gears with 3.78 or 4.11. Then go with either a Mitchell or Volvo type overdrive. To me, the Volvo would be best
Great car
Jim

[HotRodmicky]

use 3.54 r&p

Easy and simple.....no od to hook up etc.

I ran a 3.25 in my `33 Sedan with a 221ci engine.
Later i used a 255ci.
Was the perfect combo.

So 3.54 with a 221ci is fine (and 7.00x16)

[flatmotor40]

with OD when you hit freeway and you push OD on engine RPM goes like a new car saves wear and tear on flathead

[Tim]

I can only speak from my current situation. 3:54 gears, 7:50-16's and a 28 tooth V8 gearbox all powered by the tough little Banger A motor. I can cruise comfortably all day long at 65-68. The 28 tooth V8 box is the key though as you still have a low 1st. Do the 3:54 and save lots of $. A '36 rear is only 1" overall wider and makes the tires just right in the Rear.


Tim

[38 coupe]

A 4.44 axle with the 36% overdrive gives you a final drive of 2.84. The same 4.44 axle with 26% overdrive will get you a final drive of 3.29. For hot rod use I think if you are enjoying the 4.44 around town, don't mess that up. Put a Mitchel in and go.

[Will Kimble]

Thanks for the input everybody, I really appreciate it. The Mitchell is tempting and makes a lot of sense, but I think for the sake of simplicity I will proceed with the 3.54. I had it in my last car (Model A roadster pickup with B engine) and was satisfied, I expect I will like it even better with the V8.

Best wishes for the holidays,
Will Kimble