[USMA:36576] Re: Chevrolet

[Carleton MacDonald]

In my 1988 Saab 900T there was a trip reset button in the middle of the speedometer.  If you pushed it while the car was moving, a gear broke and then the odometer no longer worked.  I went on the Internet to find a replacement and a Saab parts store from Ontario had one, so I ordered it.  It was in km only (up to 240).  I installed it and was quite happy.  When the car finally died for good with a blown engine on autoroute 15 south of Montreal, the dealer that took it off my hands (Gravel Saab-Subaru-Isuzu in Brossard) wondered how a USA car with Maryland plates had a metric speedometer in it.    (They also wondered about the “Sauvez les Expos en Montreal” bumper sticker but that’s another story.)   Carleton   From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Michael Payne Sent: Sunday, April 16, 2006 16:03 To: U.S. Metric Association Subject: [USMA:36575] Re: Chevrolet   Newer cars just pick up revolutions somewhere on the transmission or drive shaft, and use that to send an electrical signal to the speedometer, which is programmed to convert the rpm pulse to distance traveled and hence to speed in either unit. I think the difference between the km and mile indications must be via some built in microchip. The rpm these days comes from a top dead center sensor that signals every revolution of the engine. The engine computer uses this to figure out when to inject fuel, etc. as well as to provide the tachometer reading, no mechanical connection these days in either. I remember there used to be a gear driven flexible drive from a wheel (in the VW beetle) or the transmission to the speedometer.  This particular Chevrolet Impala had a speedometer calibrated up to 140 in either unit. Fine in mph but easily pegged when I passed someone on a two lane road with it set to km/h.   Mike Payne ----- Original Message ----- From: Martin Vlietstra To: U.S. Metric Association Sent: Sunday, 16 April, 2006 18:49 Subject: [USMA:36574] Re: Chevrolet   Odometers usually count wheel revolutions and have two sets of gears - one for miles and the other for kilometres. ----- Original Message ----- From: Mike Millet To: U.S. Metric Association Sent: Saturday, April 15, 2006 9:37 PM Subject: [USMA:36571] Re: Chevrolet Also I'm not sure if odometers calculate internally in km or if many of them are still in miles. Mike