Speedometer gears to match 3.27 to 1 ratio axle gears?
 

I am installing 3.27 to 1 ratio axle gears into my 1931 model A pick up. My dilemma is that I haven't found anyone making speedometer drive gears to match up to my new 3.27 to one axle gears.
What have Ford Barners been doing to match up the model A speedometer to the 3.27 to one rear axle gears?
I have a balanced and very strong Model A touring motor from H & H so that I can pull these taller gears.

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

I found my answer. I must use a speedometer speed adapter. Available from Bert's Model A Parts.

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

Or a 17 tooth driven gear

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

Make sure that if you get a 17t gear you also get the turtle to go with it as the distance between the shaft and drive shaft will be closer to get the 17t to mesh right. I trimmed a 20t turtle to use a 17t and get the mesh right.

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

If I ever restore another Model A I am thinking of installing 3.27 rear ration. How do they perform. I know a strong motor is a must.

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

Contact MAFCA Tech Director Jim Cannon as he has a set in his '29 Phaeton and a few years ago he ran the Blue Ridge Pkwy mountains with ease with a bunch of Model-A guys. I think he will tell you that he loves his set.

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

See another similar recent thread . I used a Speed Ratio Adapter due to speedo 4 mph fast w/ 4 speed OD tranny. Ratio was easy to calc. and the speedo is now accurate compared to road speed indicators GPS, etc. I tried 17, 18 teeth gears with the stock 9-34 gear case to no avail and similar to post 4's experience.

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

https://parts.modelastore.com/show_Product.asp?ID=4676


Searched on 3.27

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

Got mine from PATC 1-888-201-2066 because I had special situation. Tell them how much mph over or under and they will size for you . Also, which type of fitting for cable, shaft ends, etc. Mine came with a couple of adapters, separate adapter kit not needed.

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

From rough calculations I did some time ago a 3.27:1 is the same as a 4.11:1 with a %26 overdrive?

So %15 over in all gears.

Here is a calculator for diff ratio to speed


http://www.csgnetwork.com/rgpspeedcalc.html

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

I used a speedometer speed adapter purchased from Bert's but it was geared backwards. With my 3.27 to 1 gears, it made my speedometer twice as slow as without it. I took the speedometer speed adapter apart and reversed its inner gears and now my speedometer is spot on. I had to do some brazing and filing to change the gears around to fit the cable ends. I would have been better off to find the smaller driven gear for the speedometer cable end.

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

I have a 1931 Model A pick up with a Touring Motor built by H & H in California. It puts out a lot more torque than stock and it pulls the 3.27 to 1 gears like a champ. Truly like an overdrive. At 60 MPH, the motor is loafing along being real quiet. I have upgraded a couple of other of our model A Fords to taller gears but this is the first 3.27 to 1 that I have done. From now on, I will not upgrade to anything other than 3.27 to 1. If you are using the taller gears, you need a stronger motor to survive in these Cascade Mountains here in the Northwest Washington.

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

Hi Steamer,

FWIW:

1. I have a 1930 Briggs Town Sedan that came from a car collector's 30 year collection with the B Marked Model A Police Head. (Also have a few original standard spare Model A heads that I really don't care to use unless in case of a mechanical emergency).

2. On this Town sedan, I changed out the stock Model A cam to Stipes IB330; l had the original Model A flywheel lightened and counterweights installed and balanced by Mr. Ron Kelley, (who advertises in The Restorer); have Model B distributor and Model B carburetor installed, with spare Model A distributors & carburetors in rear metal trunk which can both be swapped out in about 15 minutes); have new Coker 550-19 "Radial" tires with Coker "Radial" heavy tubes provided with (4) ounces of Dyna-Beads per tire; and have Bert's 3.27:1 speedometer adapter.

3. Been on flat land, hill country, and steep Mississippi River Bridge up ramps and bridge crossings with four (4) passengers with no problems; and average 20 miles per gallon with stop & go traffic on 55 mph maximum speed limit on rural back roads with stop signs, traffic lights, railroad crossings, and reduced speeds down to about 30 mph in small towns.

4. If you, or any Model A owner is sincerely interested in just one (1) sincere experienced opinion with a 3.27:1 rear and Bert's speedometer adapter, I also have a 1930 standard original Coupe that I have had since a teenager for 60 years .... and .... if I ever get to it, I'll do my 1930 Coupe the exact same way I did my above described Town Sedan.

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

I have ran 3:27 gear since 2001 and 2003 installed Mitchell od. check my info 31 Tudor. Have fun modelAtony tony white Lafayette, LA

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

you know you can send your speedometer to a builder like me and have him set the speed to what you need. Like if your car is reading 10 miles slow have them set the speedometer to read 10 miles faster.

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

With our model A Fords, we follow tour directions with the exact mileages between turns. We need both accurate speedometers and accurate odometers too.

Re: Speedometer gears to match 3.27 to 1 ratio axle gears?
 

What you can do run your car to a GPS and that will tell you how far it is OFF. You can check you speed and miles that way. Then go from there. You can work on the gears or have the speedometer reset. papa nick.