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Old 10-17-2020, 01:03 PM   #1
throwback
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Default 1936 Ford rearend gear ratio and speed

I have a 1936 Ford 5 window coupe. I looked at the stamping on the banjo. It looks like 9-37 or 4:11 ratio. I feel like the max comfortable speed on the setup is 50-55 mph. What speed could I get from 3.78 gear ratio or other gear ratio if I am trying get more speed for hiway driving?

Thanks for replies!
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Old 10-17-2020, 01:40 PM   #2
johndee138
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Default Re: 1936 Ford rearend gear ratio and speed

I put a 3.78 R&P in mine. best thing EVER!
No problem from a still start and much better top speed. Don't forget the need to stop as well!
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Old 10-17-2020, 01:50 PM   #3
Kube
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Default Re: 1936 Ford rearend gear ratio and speed

Quote:
Originally Posted by throwback View Post
I have a 1936 Ford 5 window coupe. I looked at the stamping on the banjo. It looks like 9-37 or 4:11 ratio. I feel like the max comfortable speed on the setup is 50-55 mph. What speed could I get from 3.78 gear ratio or other gear ratio if I am trying get more speed for hiway driving?

Thanks for replies!
I have had numerous 1936 through 1940 Fords. My overall favorite gear ratio is the 3:78. Plenty good "off the line" and cruising at 55 or so is never an issue.
I currently have a '36 roadster with the stock 4:11.
It was very "comfortable" around 50 - 55.
I'd installed a Columbia only because I had a beautiful one "on the shelf".
I still do not exceed 55, but the difference in the entire driving experience is amazing. The car has seemed to "smooth out" beautifully.

If a Columbia is not in your future, I'm a firm believer that a swap to the 3:78 would make you one happy camper

One thing you may want to keep in the forefront of your mind is that while a higher gear set will allow the engine to run easier at higher speeds, you're still driving an 84 year old car. Faster than 55? Ya still need to stop when that jerk in a BMW pulls right in front of you and hits the breaks. Ya also need to swerve out of his way.
Good luck doing either safely at 55. At 70? Well, nice knowing you...
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Old 10-17-2020, 01:59 PM   #4
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Default Re: 1936 Ford rearend gear ratio and speed

My very stock '36 Phaeton, when we got it around 2009 with the 4.11 gearset was "done for" at about 55mph, like you are reporting. I'm pretty sure it would have handled more, I wasn't going there.

After CharlieNY supplied a rear with the 3.78 set the top end speed went up 10 to 15 mph. The car could do over 70 if I was brave enough.
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Old 10-17-2020, 02:00 PM   #5
1931 flamingo
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Default Re: 1936 Ford rearend gear ratio and speed

I get 70 to 75 out of my 3:78's on occasion, other than that I'm like Kube, 55.
Paul in CT
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Old 10-17-2020, 04:40 PM   #6
throwback
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Default Re: 1936 Ford rearend gear ratio and speed

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So should I look for a complete rear end that has 3:78 gears or change the ring and pinon gears on my existing rear end (by someone who knows what they are doing)?
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Old 10-19-2020, 07:52 AM   #7
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Default Re: 1936 Ford rearend gear ratio and speed

One of the rules I try to follow is; solve problems, don't create them. That said, trying to purchase a used 84 year old rear end in lieu of new components that are installed by a good mechanic does not make much sense.
I second Kobe's comment about a Columbia OD.. My '36 has a Columbia under it, has had since it was new. The gear ratio is 3.78 with about 25% OD. The car is very smooth running with good fuel mileage.
If you consider a Columbia you are not stuck with the mechanical shifting '36-40 unit's, the later model '46-48 units, electric over vacuum, will go right into a '36 with no modifications, using the right combination of parts. I converted the Columbia under my '36 to a '47-48 unit in 1955.
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Old 10-19-2020, 08:25 AM   #8
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Default Re: 1936 Ford rearend gear ratio and speed

Quote:
Originally Posted by throwback View Post
I have a 1936 Ford 5 window coupe. I looked at the stamping on the banjo. It looks like 9-37 or 4:11 ratio. I feel like the max comfortable speed on the setup is 50-55 mph. What speed could I get from 3.78 gear ratio or other gear ratio if I am trying get more speed for hiway driving?

Thanks for replies!
You can run the numbers and get a fairly good estimate. What people are normally concerned about is the engine rpms.

rpms = (axle ratio x mph x 336) / tire diameter

To determine the mph at a given rpm just rearrange the equation.

mph = (rpm x tire diameter) / (axle ratio x 336)
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Old 10-19-2020, 09:43 AM   #9
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Default Re: 1936 Ford rearend gear ratio and speed

Throwback I am rambling again LOL. Most all vehicles were 4:11 4:56 whatever. So I
time travel and lucky I saw and drove yes a 36 ford here most roads were gravel even
into high school early 60s in which 45 mph was speeding. So you go for parts or food in
the city and you are lucky to get to 3rd speed. those days were tire chains and stay in
a rut. so these were made for that time and for most times lasted into the early 50's. There are no super hy ways yet. Now . my car has 3:78s all vehicles I ever drove has sweet spot so this car with foot just resting on the gas pedal kind of likes 55 with
no noise no over revs I have punched it to 80 but shame I'm too old. My boy has a 1950 4 dr. this is like day and night 65-70 silent so I suspect 3:54s ? You have a closed drive shaft so its either columbia if you take a loan out or Mitchel over drive. The Mitchel maybe the best option. again I'm ramblin with hey fever....sam
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Old 10-19-2020, 10:30 AM   #10
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Default Re: 1936 Ford rearend gear ratio and speed

This didn’t copy well but still decipherable.....

1935 Ford 85hp @ 3800 rpm
Std Ratio Columbia Std Ratio Columbia
Speed3.78 2.7 4.11 2.7
45 2041 1460 2221 1587
50 2268 1621 2467 1764
55 2494 1783 2714 1940
60 2721 1945 2961 2117
65 2947 2107 3207 2293
70 3174 2269 3454 2469
77 3799
84 3809
100 3242 3528
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Old 10-19-2020, 12:42 PM   #11
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Default Re: 1936 Ford rearend gear ratio and speed

I cleaned up the rows and columns.
Attached Images
File Type: jpg RPM Chart.jpg (47.0 KB, 48 views)
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Old 10-19-2020, 01:40 PM   #12
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Default Re: 1936 Ford rearend gear ratio and speed

Engine revs isn't the only consideration.
Engine noise may be reduced but road noise, tyre noise, wind noise, road/tyre induced harshness (vibrations) will not be. You need to consider the brake performance too higher speeds demand better brakes, especially if in and amongst modern traffic. Tyres, too. A tyre that is perfectly happy at 55 mph might not be too happy at 70 plus.

Generally, though, a taller axle ratio will make for a more comfortable ride, but won't necessarily make the cruising speed much higher.

It just makes it more comfortable at any given speed, providing the motor has the torque to pull that speed.

Mart.
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Old 10-19-2020, 02:05 PM   #13
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Default Re: 1936 Ford rearend gear ratio and speed

Using a Mark Williams gear ratio computer the RPM reduction you will see at 60 MPH going from the 411 to the 378 would be 200 RPM. Now if you go to the 354 ratio the RPM is now 2400 RPM lowering 200 more RPM for a total of 400 RPM less when compared to the 411 gear. The calculation I used was based of a 30 inch tall tire. Making a decision to change the rear gear considering the time and expense involved giving some thought to going to the next step which would improve economy a lot might be a wise decision. Any stock flathead would have the torque needed if the 354 gear ratio is being used.
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Old 10-19-2020, 02:23 PM   #14
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Default Re: 1936 Ford rearend gear ratio and speed

In my 36 I am building I am using a 3.25 ratio, BUT I am also using the 29 tooth transmission cluster which in my opinion is the trick ticket with a 3.54 or 3.25 especially if you live near hills like me.

Of course a Columbia with a 3.78 is a dream but also lots of $$
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