Speedometer Calibration

[railroad]

I need some help calibrating the speedometer in my T. It has a Mooneyes Classic model gauge. The trans (C-4) has a gear driven cable to an electrical
pulse generator. I changed the driven gear on the cable and improved the reading, but am still off 4 or 5 mph.
I went to the Mooneyes site, but they do not detail any of their products.
I read somewhere that there are dip switches on the back of some speedos.
My dash is cramped on the backside and if the switches are there, I would like to know what to do, since it may involve some disassembly.
Thanks for any help.

I found a pdf calibration on the Classic site. ..., got to identify my speedo first.

 

[LOWANDRATY]

calibration

when you say you changed the gear and made it better, what tooth gear came out and what tooth gear did you put back in, how far off was it before you changed the gears, you may need 1 more or less teeth, we need more info.

 

[eyesore]

As a side note. I check my true speed with a Tom Tom now.

ISore

 

[railroad]

The speedo was way slow. I happened upon a speedo gear out of a car with a 279 rear axle. I did not count the teeth since it was a bunch less than what was in the T. It put me within 5 mph, probably 3 or 4 mph slow. I have 31 + inch tall tires on the rear. Anyway I went to Classic gauges website and found the pdf for calibrating a bunch of different models. I have to know what the speedo is showing at a true 60 mph. I will make a run with a gps and get that info before attempting to get to the back of the speedo to set the dip switches to match the error. The steering column and pedal hinge is blocking access to the back of the speedo. I appreciate you guys looking in to help me figure this out. As I may have said, Moon eyes does not list or provide this info that I can find.