Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[cockneyboy100]

hi  my speedo is out by 5 mph, my tom tom displays 90 and speedo reads 85.

is this a commomn problem, can you get speedo calibrated.

 

[JonArgraig]

its normaly the other way round.

You got the right wheel / tyre rolling size ?

[cockneyboy100]

standard 16 wheels, i agree its normally other way round

 

[Entwood]

Tomtom will only be accurate on straight and level road, whilst at CONSTANT speed.

If you are cornering, climbing/descending, or accelerating/decelerating a GPS will NOT give a true speed.

The reason for this is very simple, it uses the time taken to travel between 2 points in space that are ASSUMED to be a straight line.

[cockneyboy100]

was on motorway doing 90 on cruise, nice and flat and very straight, i know my tom tom is correct, cause i use it in my lorry,

 

[Big_Roger]

Hi,
It is possible to get speedo heads calibrated, I had one done for a Rover many years ago, but I dont know where now.

However, I also voluntary drive a charity minibus, and that had to go to have the tachograph calibrated, whilst it was on rolling road set up for that, operator said speedo was out by 7 mph. He wouldn't fix it, but said if I wanted to do it I could, so took out unit moved hand forward by that amount and put back, although he had calibrated tacho, he put back on rolling road and checked speedo and it was spot on.

So, If you can find commercial vehicle tacho specialist who is not too busy and talk nicely to them you might get lucky and they will tell you how far out your speedo is and you can adjust it.

Roger

[Taxi_Driver]

The speedos in Omegas are electronic and usually read 3mph higher than actual speed.....across the range......so actual 30mph will show 33mph.....actual 70mph will show 73mph.

The speedo can be controlled by a real TECH2......ie with engine turned off a tech2 can set to show ie 70mph.....and the speedo will move around to 73mph (normally).

Not sure if a real tech2 can adjust what the speedo says......tho it could do......question for MDTM or TB me thinks  

[TheBoy]

If its that far out, its either faulty, or has wrong config on it.  1998 ones are programmable via Tech2, but not possible to calibrate via Tech2.