The odometer in my '56 with light duty 3-speed is remarkably accurate- within 2%. However, the speedometer reads 7 mph slow. The needle points to zero at rest. I have a 19 tooth gear on the cable. Anybody know how to calibrate the needle?

 

Is that 7mph slow at all speeds?

 

Yes. Across the board.

 

So does the needle not move until you're above 7mph. If it needed a gear change on the trans it would not be a linear 7mph everywhere.

 

United Speedometer or a similar shop can fix that. There is a hairspring on the needle that gets adjusted to fix calibration, plus perhaps a good cleaning. I suspect the cost may be close to what a replacement costs.

 

Thanks guys-
Kinda figured the gear was correct based on the accurate odometer.
For as long as I've owned the truck, the at rest needle was never visible- dropping below the "0" mark at a standstill. I recently fixed that easily enough Here and thought it would be fixed. No such luck. I can continue to add 7mph as I've always done I suppose!

 

Because of changed rear gears, mine is off. The odo is consistently 10% low, and the speedo is until about 45 (indicated) mph, then it becomes exponential. 47 = 55, 51 = 60, and so on. I'd love to get an electronic conversion, but for now I just use the tach, which is dead on.

 

I use a GPS speedo and avoid all those problems. Totally accurate unless driving in a tunnel or parking garage.

 

I've been looking at GPS speedometers, what kind do you have?

 

I have Speed Hut gauges. I like that you can pick from an array of different combinations of design and colors. The GPS also tells you elevation and will tell you your quarter mile time if so desired. They are also very helpful and in my opinion reasonable. I fried my wiring when a friend of mine tried hooking them up and he hooked a ground to a hot by accident. I sent the gauges back in case they were fried along with the wiring harness that came with the gauges. They sent me a new harness and replaced the board that got fried. They charged me $15 total! I will always be their customer.
BTW, they are made in the US too.

 

Yes I like theirs too. They seem to fit price wise between the Chinese units and the Autometer units. I've looked at them all, the chinese units for $100-$150 are tempting and quite a bit cheaper than the Speedhut units starting at $260, but I do like the made in USA part. Did you get the plain model, or one with the turn indicators and high beam, one with the tach?

 

Here is a picture I took a few months ago. Note the holes in the dash from the PO. Sorry for the poor quality of the pic, but the speedo has a small tach.

 

Ok, is that the 4" set and if so did you have to alter the original holes for them to fit? Is that the antenna on the dash above?

 

Take your speedometer out of the dash. Clean and lightly oil the visible moving parts. There is probably a small cap or cup over the bushing that your speedometer cable drives, oil the wick or remove the cup and put a drop of oil in the hole. Do not get any oil in the end of the cup that drives the speedometer needle.

Now you need to calibrate the speedometer. You need a short length of speedometer drive cable, or equivalent, and a variable speed drill. Assemble the drive cable into the drill and speedometer. Run the speedometer at exactly 60 miles per hour. You should go exactly one mile in one minute. If you went less than a mile, reduce spring tension on the speedometer needle and try again. If you went more than a mile, add tension. Repeat until the speedometer is calibrated with itself. Reinstall and smile.

 

Interesting.....is this method only for slight adjustments or how far can you go? My COE speedo is off by about 15-20 mph at 60 (reads 75-80).
The speedo is from a '49 Ford car...