Speedometer 4-5 mph under actual speed

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#21

11-13-2006, 11:27 AM

ag4ever

Dazed and Confused

Join Date: Oct 2006

Posts: 732

Re: Speedometer 4-5 mph under actual speed

A dynometer is not a scan tool. It is a device that the car's drive wheels are placed on a large drum or sometimes two small drums. the drums spin with the wheels, and the speed of the turning drums shows the real ground speed of the tires. They are very accurate is calibrated correctly. You might look in the yellow pages for a radio shop that does speedometer work. They usually have the same type of dynometers to check vehicle speed. Then if the dealer's and the independent shops numbers match, case closed, if not you can get a certified copy from the speedo shop to use against the dealer.

#22

11-13-2006, 06:53 PM

ken1784

Pretty Darn Active Enthusiast

Join Date: Mar 2004

Location: Yokohama, JAPAN

Posts: 499

Re: Speedometer 4-5 mph over actual speed

Quote:

Originally Posted by wallpad

That ECE spec looked very European though. Is it what Toyota uses for American cars also? If yes, then I think I am done with this issue, dissatisfying though it may be.

Yes, the main members are in Europe, but Japan, Australia and New Zealand are also the members.
A regulation is discussed at World Forum for Harmonization of Vehicles Regulations(WP.29) and the US and Canada also attending the forum.
http://www.unece.org/trans/main/welcwp29.htm

I don't know how the US government is treating this, but there is no good reason to against the regulations.
I believe it is nice to set such standard regulations worldwide.

Ken@Japan

#23

11-17-2006, 03:52 PM

scottzorch

Enthusiast

Join Date: Nov 2006

Location: Los Angeles

Posts: 11

Re: Speedometer 4-5 mph under actual speed

Quote:

Originally Posted by wallpad

Around my neighborhood we have speed limit signs with radar guns built into them. They tell you how fast you are going along with the actual speed limit.

The speed indicated on these devices is consistently 4-5 mph lower than what my speedometer shows.

I know that most car speedometers show mph a couple miles below actual, but 4-5 mph seems too much.

Is anyone else's TCH speedometer this far off?

Paul

I know that the thread is basically over, but I thought I'd add two data points. I have about a 3mph difference between GPS and speedometer on my TCH. On my previous car (2003 Corolla CE) the divergence was about 2mph.