c300g
Member
i need that speedo!
and the console, and the shifter....... damn it i need the whole car!
Calibrating a speedometer
- Thread starter c300g
- Start date
and the console, and the shifter....... damn it i need the whole car!
polara71
Old Man with a Hat
All three of mine are fairly accurate. At least compared to that radar thing the cops have on the side of the road. I am always within two mph when comparing my needle to the electronic sign, regardless of speed
fjr
New Member
I think adding an overlay would be more work than I would want to get into but that would first require that your odometer and speedometer were properly calibrated. The odometer is a mechanical counter and it is calibrated by picking the best speedometer pinion gear for your tire & axle combination.
You would have to send the speedometer out to a speedometer shop for calibration because the magnets or springs need adjusting. I think the standard is 60 mph requires 1000 rpm of the speedo cable.
When I upgraded my 65 Barracuda to LBP wheels, I had to figure out what tires and speedometer pinion I needed. I did a write up about tire upgrades on my web site and have a calculation for the speedometer pinion teeth.
You could theoretically use a smaller pinion gear to convert your speedometer & odometer to metric but only if you find one with the 1.609 times less teeth. There also speedometer cable gear adapters that would speed up your cable by 61%. Either way, you would end up with a 120 km/h (75 mph) speedometer.
I use a GPS as my speedometer because it is always accurate and I can easily switch units depending upon whether I'm travelling through Canada or the USA.
You would have to send the speedometer out to a speedometer shop for calibration because the magnets or springs need adjusting. I think the standard is 60 mph requires 1000 rpm of the speedo cable.
When I upgraded my 65 Barracuda to LBP wheels, I had to figure out what tires and speedometer pinion I needed. I did a write up about tire upgrades on my web site and have a calculation for the speedometer pinion teeth.
You could theoretically use a smaller pinion gear to convert your speedometer & odometer to metric but only if you find one with the 1.609 times less teeth. There also speedometer cable gear adapters that would speed up your cable by 61%. Either way, you would end up with a 120 km/h (75 mph) speedometer.
I use a GPS as my speedometer because it is always accurate and I can easily switch units depending upon whether I'm travelling through Canada or the USA.
65Fury440
Senior Member
Speedometer app on phone is what I use.
I'd love to have a 200 kph speedo. That's cool!
I'd love to have a 200 kph speedo. That's cool!
BillGrissom
Active Member
I am amazed the U.S. still uses English units 50 yrs after I was in high school, but we seem to be regressing in many ways. Gas stations did switch overnight to pricing in $/liter during the 1970's oil embargo, but that was to assuage their less than literate customers.
Forget the yelling across w/ Billy-Bob method. In the 1990's, I checked my 1965 Newport's speedometer after a rebuild by driving at exactly 60 mph "indicated" and timing between two mileage markers on the highway. Of course, GPS makes that easier today. There is a little arm at the bottom (where spring grounds) that I pushed back and forth until it took exactly 60 sec between mileage markers. No wasted gas, I did so during my commute. Of course, it then wasn't perfect at 30 mph, but most people need best accuracy around 60 mph. For major changes, you need to get a different speedo pickup wheel. That is usually needed if you change rear-end gear ratio, but perhaps also w/ different rear tire OD.
I have seen photos of factory pickups that mount in-line w/ the speedo cable, as part of cruise control I recall. There may also be after-market pickups that sense driveshaft rotation. If you ran that to a digital kph dash display, that would be perfect.
Forget the yelling across w/ Billy-Bob method. In the 1990's, I checked my 1965 Newport's speedometer after a rebuild by driving at exactly 60 mph "indicated" and timing between two mileage markers on the highway. Of course, GPS makes that easier today. There is a little arm at the bottom (where spring grounds) that I pushed back and forth until it took exactly 60 sec between mileage markers. No wasted gas, I did so during my commute. Of course, it then wasn't perfect at 30 mph, but most people need best accuracy around 60 mph. For major changes, you need to get a different speedo pickup wheel. That is usually needed if you change rear-end gear ratio, but perhaps also w/ different rear tire OD.
I have seen photos of factory pickups that mount in-line w/ the speedo cable, as part of cruise control I recall. There may also be after-market pickups that sense driveshaft rotation. If you ran that to a digital kph dash display, that would be perfect.
Thank you thrashingcows, I was able to get good speedometer readings on a nice day, last Sunday. I called them on Monday, I got a ratio adapter in the mail today.
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