Joined
·
33,379 Posts
When I bought my 1993 Daytona in June 2009, it came with crusty/rusty 15-inch rims and worn-out tires. The factory door jamb decal said it was built with 14-inch rims. You can't trust that, because my 92 Daytona came new with 14-inch, and the decal said 15-inch.
I swapped in my 14-inch rims and good tires from my 1992 Daytona, which I was preparing to scrap.
The speed sensor gear that came with the car was the 19-tooth yellow gear. I was getting an error, so I swapped in the 20-tooth blue gear from the 92 Daytona, and this gave me a -0.5% odometer error, which was good.
But then the 14-inch rims developed pinhole air leaks from rust, so I bought all new 15-inch aluminum alloy wheels (N/A in 14-inch) and new 15-inch tires. Since then, I've had an odometer error of -2.2%, with the speedometer error being zero (as measured with GPS and by timing mile markers while driving at indicated 60 mph).
Hoping to reduce the odometer error, I put the 19-tooth yellow gear back in yesterday. Today I drove the car with GPS and got the following: +2.8% odometer error and +7.7% speedometer error.
OK, I can understand that the odometer will err the other way. But what I don't get is how the speedometer error does not proportionately track the change in odometer error. The speedo was dead on with the 20-tooth, and with the 19-tooth, it's reading 40 mph at actual 37, and 70 mph at actual 65. This is confirmed by GPS and by comparing known tachometer readings for a given speed.
It looks like I should just put the 20-tooth gear back in and cut my losses. But does anyone have any thoughts as to how the speedometer error does not track the change in odometer error? Both get their input from the Hall effect sensor triggered by the same gear turning in the transaxle. The speedometer uses the digital pulse converted to analog for the analog gauge. The D/A error should be constant and very small.
I guess the best I can do is the -2.2% odometer error and the accurate speedometer that I have with the 20-tooth gear.
I swapped in my 14-inch rims and good tires from my 1992 Daytona, which I was preparing to scrap.
The speed sensor gear that came with the car was the 19-tooth yellow gear. I was getting an error, so I swapped in the 20-tooth blue gear from the 92 Daytona, and this gave me a -0.5% odometer error, which was good.
But then the 14-inch rims developed pinhole air leaks from rust, so I bought all new 15-inch aluminum alloy wheels (N/A in 14-inch) and new 15-inch tires. Since then, I've had an odometer error of -2.2%, with the speedometer error being zero (as measured with GPS and by timing mile markers while driving at indicated 60 mph).
Hoping to reduce the odometer error, I put the 19-tooth yellow gear back in yesterday. Today I drove the car with GPS and got the following: +2.8% odometer error and +7.7% speedometer error.
OK, I can understand that the odometer will err the other way. But what I don't get is how the speedometer error does not proportionately track the change in odometer error. The speedo was dead on with the 20-tooth, and with the 19-tooth, it's reading 40 mph at actual 37, and 70 mph at actual 65. This is confirmed by GPS and by comparing known tachometer readings for a given speed.
It looks like I should just put the 20-tooth gear back in and cut my losses. But does anyone have any thoughts as to how the speedometer error does not track the change in odometer error? Both get their input from the Hall effect sensor triggered by the same gear turning in the transaxle. The speedometer uses the digital pulse converted to analog for the analog gauge. The D/A error should be constant and very small.
I guess the best I can do is the -2.2% odometer error and the accurate speedometer that I have with the 20-tooth gear.