Speedo over-reading? How do I check?

indyskyz · 16 May 2010 at 08:33

my micra (1995) is prety spot on 1/2mph out although my wifes Rover 400 (1997) over reads 4 mph @ 30

most phones have gps now even the cheapo nokia 5800 tube and speed apps are available on OVI store
there are hundreds on the android market

logix42p · 16 May 2010 at 09:38

what about driving past one of those signs that say your speed??

Crizzy · 16 May 2010 at 09:50

A crude but easy way of checking is to follow a mate or relative in their own car doing dead on 30, you do the same and if you gain on them your speedo is under reading. Obviously not 100% accurate but should be able to give you a good indication.

[TW]Fox · 16 May 2010 at 10:24

Crizzy said:
A crude but easy way of checking is to follow a mate or relative in their own car doing dead on 30, you do the same and if you gain on them your speedo is under reading. Obviously not 100% accurate but should be able to give you a good indication.

Haha, how did you work that out? What if your speedo was bang on but your friends speedo was under-reading?

This only works if the car in front has a calibrated speedo.

Clown · 16 May 2010 at 10:34

Fox you need to learn to read between the lines.
He was obviously implying that he needs to follow his mate who is doing dead on 30 miles per hour. His mate will be following another mate who has a calibrated speedometer.

[FnG]magnolia · 16 May 2010 at 11:23

Clown said:
Fox you need to learn to read between the lines.
He was obviously implying that he needs to follow his mate who is doing dead on 30 miles per hour. His mate will be following another mate who has a calibrated speedometer.

Speedo calibration, Benny Hill style

Hunders · 16 May 2010 at 11:31

If you get a friend with a car that isn't suspected to have a speedo problem and follow them at a predefined speed that will be fine. If theirs is reading 30 and yours is reading 30 then I'd forget about it. All speedos over read (apart from calibrated ones like police cars for all you pedants) so this isn't going to tell you if yours is completely accurate (which it wont be) but it will tell you whether it's in line with an average cars speedo.

Crizzy · 16 May 2010 at 11:54

[QUOTE='[TW]
This only works if the car in front has a calibrated speedo.[/QUOTE]

Well yeah obviously

[TW]Fox · 16 May 2010 at 11:54

Crizzy said:
Well yeah obviously

Don't say obviously like you already knew that, there is no way that 'crude method' and 'calibrated speedo' can be used in the same suggestion

Crizzy · 16 May 2010 at 11:56

The method should give you a rough indication if you think your speedo is out. But of course the car you are using to check it against has to be known to be accurate.

ScoobyDoo69 · 16 May 2010 at 16:29

You must know someone with satnav :eek:

rG-tom · 16 May 2010 at 16:39

get a new phone? I havn't had a phone for about 4 years that hasnt had a gps chip in, including the crappy blackberry curve that i have as a work phone :s

or surely you must know somebody with such a phone even if they dont have a tomtom, everyone knows someone with an iphone

Spuderoony · 16 May 2010 at 19:02

[TW]Fox;16563498 said:
Haha, how did you work that out? What if your speedo was bang on but your friends speedo was under-reading?

This only works if the car in front is a Toyota

L0rdMike · 16 May 2010 at 19:09

Drive past a Gatso at 100mph and see what speed you are being done for in court?

BigglesPiP · 16 May 2010 at 21:23

Time yourself between 2 well spread land-marks while maintaining an indicated 150mph, then measure the distance on Google earth.

GravyMonster · 16 May 2010 at 21:37

Hang a high voltage wire from one side of your street to the other. Then fashion a crude 6ft hook to the boot of your car. Accelerate towards said high voltage line at a steady 87mph.

If you go back in time your speedo is overreading.

Clown · 17 May 2010 at 14:04

If his speedo is overreading at 87mph, he isn't going fast enough?

Scania · 17 May 2010 at 14:34

thepeganator said:
Go next to a lorry on the motorway?

Then you'll be going 56mph.

or 52, 50, 57, 49.... Many HGV speed limiters are set differently, then you add tyre wear and the variation is huge.

Participant · 17 May 2010 at 14:38

SlyReaper said:
Is there any good way I can check how much it is over-reading

Drive at 36mph, see if it sets it off, drive at 37, see if it sets it off...etc. No idea re calibration.

Lol at the guy above saying follow a car with a calibrated speedo.

Crizzy · 17 May 2010 at 15:38

Robbie G said:
Drive at 36mph, see if it sets it off, drive at 37, see if it sets it off...etc. No idea re calibration.

Lol at the guy above saying follow a car with a calibrated speedo.

Well I didn't think it was that bad an idea to get a rough indication

Still I think the Benny Hill idea might be a winner