gv@mtuxo.att.com (52341-G.VALENTINI) (10/11/88)
In article <171@leibniz.UUCP>, keithh@leibniz.UUCP (Keith Hanlan) writes: > Peter, typically the speedometer lags behind the true speed of the > vehichle. If you had just turned the corner and finished accelerating > and your speedo read 70, with error, it is not unreasonable to guess > that you were really doing 88. > I don't agree. Typically the manufacturers set the speedometers to read HIGHER than what you are actually going. So if you think you're going 70, you're really going 67mph or so. They probably do this for safety concerns. I have calibrated (used LOTS of sample points) my '86 RX7 with the mile markers on the highway and have found my speedo to read 2-3% higher than actual. My friends' results are also the same, so I have a two sample points to back my observations. Other viewpoints? -- Those that will burn in hell: 1) homicidal maniacs 2) terrorists 3) people who drive too slow in the fast lane. THE FAR SIDE cartoon by Gary Larson George Valentini att!mtuxo!gv
fiddler%concertina@Sun.COM (Steve Hix) (10/12/88)
In article <3010@mtuxo.att.com>, gv@mtuxo.att.com (52341-G.VALENTINI) writes: > > Typically the manufacturers set the speedometers > to read HIGHER than what you are actually going. > So if you think you're going 70, you're really going 67mph or so. > They probably do this for safety concerns. I don't drive a car (unless I make arrangements with my wife, since it's her car...), so this may not apply, but it is illegal in CA to sell a motorcycle whose speedometer reads less than the actual speed being ridden. Manufacturers therefore set the meters to read up to 10% high, just to be safe. (What you do in the way of adjusting them after sale is not their concern.) I assume that this is also the case with cars.
keithh@leibniz.UUCP (Keith Hanlan) (10/13/88)
In article <3010@mtuxo.att.com> gv@mtuxo.att.com (52341-G.VALENTINI) writes: >In article <171@leibniz.UUCP>, keithh@leibniz.UUCP (Keith Hanlan) writes: >> Peter, typically the speedometer lags behind the true speed of the >> vehicle. If you had just turned the corner and finished accelerating >> and your speedo read 70, with error, it is not unreasonable to guess >> that you were really doing 88. >> >I don't agree. > >Typically the manufacturers set the speedometers >to read HIGHER than what you are actually going. >... > George Valentini Sorry, I guess I didn't make myself clear. By "lag behind", I meant the speedometer's reading, *UNDER ACCELERATION*, is inaccurate. Once the car's speed stabalizes (0 delta-v), the speedometer "catches up" and becomes accurate. Note that "catches up" and "becomes" are not instantanious. Thus for "finished accelerating" read "*just* stopped accelerating". I hope that this clarifies the issue. On the subject of speedmeter inaccuracies, I agree that most read high (most notoriously Ferraris). My posting did not mean to imply anything on this topic. Both my car's and my bike's speedometers have been calibrated dead-on though so I wouldn't get in the habit of correcting your speedometer as you drive. ("But officer, I assumed that my speedo was 5% fast and that you wouldn't mind +15% so I tried to keep it at 120 in the 100 zone...") Keith