Good afternoon all.
I am trying to calibrate my speedo at the mo and am wandering how accurate a tom toms speedo is??
I ask this for the following reason....
I am using the electronic drive on the mt75, 3.91-1 diff 205/40/17 tyres and etb gauges.
As a starting point I put in 8000 pulses per mile on my speedo and went for a little spin around the block expecting it to be a mile out on the sat nav BUT it read exactly the same as the speedo in the indy
How likely do you think it is that it is correct and within sva tollerance?
Thanks.
john.

I would say fairly accurate as its using satellite triangulation to give you a reading that i don't think they manipulate.

See here

[Edited on 12/4/07 by Tim 45]

Very accurate, most gps only give speed and possition every second.
Any faster needs some license of sorts (US at least) as they are worried about people making guided missiles!

Darren

My GPS Sat Nav box stated that it reads speed accurate to 0.1ms. Should be more than accurate to calibrate a kit car speedo.

Chris

We used TomTom to check the calibration on our speedo a long time ago, we've not been flashed by speed camera's or pulled by the plod so reading low.

Also I'm always shouting at the car in front for doing 35 in a 40 so it's not reading fast either

That'll do for me then.
Cheers guys.
john.

my sat nav consistantly reads different to the car speedo (ie 75 when the car says 81) but i trust the sat nav more that the car anyway.

My tom tom always reads lower than car dash. computers av speed display shows half way between. As a rule i always assume true speed is about half way between.

I got a ticket when using the sat nav to set my cruise control by (It was set at 80 though - unfortunately recorded speed was 92 as id just come over the brow of a hill)

i think coppers in the US use GPS speedos to get convictions, ie drive at the same speed as another car while recording GPS data and then pull them if that's over whatever the limit is. So got to be pretty accurate, and I doubt tomtom is any less so.

The Satnav speed is surprisingly accurate and I used it to calibrate my speedo. Mr SVA said it was spot on, in fact it was TOO accurate and needed to be tweaked to read a little faster.

The sat nav is quite accurate.

The three we use are very close to each other.
The two we use on the boat have saved our skins a few times sailing at night in fog
I checked Tom Tom against our handheld garmin and it was dead on

In fact the sat nav is so dam accurate we almost sailed into one of our way points
Its a three ton outfall marker
so the marks are dead on.

The speedo on the Smartie is ten out

quote:

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Originally posted by mangogrooveworkshop
In fact the sat nav is so dam accurate we almost sailed into one of our way points
Its a three ton outfall marker
so the marks are dead on.

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Thanks for that all.
I'll go with the tom tom for speedo calibration if it's as acurate as people say.
thanks again.
john.


p.s. Ill post my sva results on speedo once i've got them.

john.

I suppose it depends on your Tom Tom setup and how steady you can hold the Throttle.

I've got a PDA with Bluetooth and a Buletooth GPS.. I'd say its extremely accurate but it doesn't respond as fast as the Astra Digi Dash does. With a Needle dial this may not be so obvious but it should get you close enough for setting the Speedo for SVA etc.