The_architect
Jedi Trainee
Offline
I recently sent my Bugeye speedometer overhauled by an outfit that has a very good reputation for doing this kind of work. I had a couple of nice lengthy conversations with the lady who was going to rebuild it. She asked what size tires I was going to use, what the rear-end ratio was, how many turns the speedometer cable made when the car was pushed 50 feet and so forth, and she said she would fix it up.
Well, I got it back, put it in and went for a drive...and I thought, hmmmm. I'm only going about 45 and the speedo's a little over 70...I've driven 4 miles and the odometer is reading about 6.4. For every mile I go it's reading 1.6 miles. I have to give my Dad (79 years old and still a genius) credit for noticing that 1.6 is roughly the number you use to convert miles to kilometers.
Now, this unit was not installed in the car when I got it--it was just in a box of stuff that came with the car, so I have no idea of its condition or what its internals were...all I know is that it is a Bugeye dial and it says "miles per hour" on there.
If I understand one of the manuals about Smiths speedometers that is available on the web, the number of teeth on the gears of a KPH odometer are is different than what you would find on an MPH speedometer--this is not a matter of calibration, but the whole gearset of the KPH speedometer is different. So,you're not going to turn a screw inside there little too far to the left or right and suddenly get a 60% error.
Can anyone verify this for me? I'm suspecting internals from somebody else's gauge might have been accidentally put into mine but who knows, maybe my internals <span style="font-style: italic">were</span> from a KPH speedometer. Either way wouldn't this have been obvious when the unit was being calibrated?
Well, I got it back, put it in and went for a drive...and I thought, hmmmm. I'm only going about 45 and the speedo's a little over 70...I've driven 4 miles and the odometer is reading about 6.4. For every mile I go it's reading 1.6 miles. I have to give my Dad (79 years old and still a genius) credit for noticing that 1.6 is roughly the number you use to convert miles to kilometers.
Now, this unit was not installed in the car when I got it--it was just in a box of stuff that came with the car, so I have no idea of its condition or what its internals were...all I know is that it is a Bugeye dial and it says "miles per hour" on there.
If I understand one of the manuals about Smiths speedometers that is available on the web, the number of teeth on the gears of a KPH odometer are is different than what you would find on an MPH speedometer--this is not a matter of calibration, but the whole gearset of the KPH speedometer is different. So,you're not going to turn a screw inside there little too far to the left or right and suddenly get a 60% error.
Can anyone verify this for me? I'm suspecting internals from somebody else's gauge might have been accidentally put into mine but who knows, maybe my internals <span style="font-style: italic">were</span> from a KPH speedometer. Either way wouldn't this have been obvious when the unit was being calibrated?