speedometer drive gears TH350

[mrloboy]

I am running a TH350 Trans in a 49 Ford with an 8" Ford diff with 3.00:1 gear ratio and 215/75R15 tires (27.5" diameter) At 60 MPH I am running between 5-10% faster than the speedometer is registering. Currently the drive gear is black and the driven is green.
In the past I have seen a chart with the different driven and drive gears listed and what to use to fine tune the registration. Anyone out there have this information? Thanks, Rick

[reborn55]

try www.wallaceracing.com

[Crosley.In.AZ]

Watch the diameter of the drive gear.

A t-350 gear from a chevy is larger (slightly)...   than a t-350 for a Buick - Pontiac - caddy - Olds

[Learpilot]

I am running a TH350 Trans in a 49 Ford with an 8" Ford diff with 3.00:1 gear ratio and 215/75R15 tires (27.5" diameter) At 60 MPH I am running between 5-10% faster than the speedometer is registering. Currently the drive gear is black and the driven is green.
In the past I have seen a chart with the different driven and drive gears listed and what to use to fine tune the registration. Anyone out there have this information? Thanks, Rick

Rick, I had the same problem. Chevy did not have a rear end ratio of 3.00 so I know of no combination of stock GM gears that will work.
I did find in the Street Scene mag a Speedometer co. Rowand Speedometer Co. 727-410-6352. They sell a gear ratio adapter. I don't know how mush it cost.
My solution was to get a programmable Speedo. You pull up to a mile marker push the button, drive to the next mile marker, push the button again and the speedo is programmed. If you decide to change gear ratio just re-calibrate and you have a correct speedo.


Rick


Rick

[reborn55]

http://chevelleengineer.home.comcast.net/~chevelleengineer/speedo.htm

Here is another place that I have used