Speedo Wrong by 7mph - Page 4

HarryM1BYT · 26th May 2014, 15:28

Quote:

Originally Posted by SD1too

And just so that I'm clear on this; the digital display does not repeat the over-reading on the speedometer dial?

Simon

If that was intended as a question, the digital display is a true reading of speed, or rather exactly what the IPK calculates the speed to be, from the ABS pulses. The entire IPK uses this speed directly, except for it being adjusted to a higher value (+5%) for the analogue speed display.

As said if anyone has an ex- emergency service 75, which has a true reading analogue display, comparing it to another 75 should show which byte is different. Thus allowing us all to have a true reading in the analogue speedo.

SD1too · 26th May 2014, 15:46

Quote:

Originally Posted by HarryM1BYT

If that was intended as a question ...

As the intonation in my voice failed to be transmitted over the e-mail system Harry, I added a question mark to confirm my intention!

Quote:

The entire IPK uses this speed directly, except for it being adjusted to a higher value (+5%) for the analogue speed display.

Thanks for this. You'll be interested to know that in my case the error seems to be about 10%.

Quote:

As said if anyone has an ex- emergency service 75 ..

James Taylor's book mentions attempts to sell the ZT-T to police forces, but with no declaration of success. He does say that two were sold to the West Midlands and Shropshire Ambulance Service. Yes, two! There's a photograph of one of them in his book but the registration number is not known to DVLA.

Do we actually have any evidence that any emergency service cars still exist?

Simon

okenora · 26th May 2014, 16:05

the PSNI had a ZT traffic car, COLIN_NI might have info on it's whereabouts now.....

HarryM1BYT · 26th May 2014, 16:13

Quote:

Originally Posted by SD1too

Thanks for this. You'll be interested to know that in my case the error seems to be about 10%.

There has to be a reason why your is so different to everyone else, I wonder what?

I'm calling 65mph at a true 70 5% but actually its a bit more than that, but I don't do percentages on a bank holiday.

klarzy · 26th May 2014, 16:24

Quote:

Originally Posted by HarryM1BYT

There has to be a reason why your is so different to everyone else, I wonder what?

I'm calling 65mph at a true 70 5% but actually its a bit more than that, but I don't do percentages on a bank holiday.

You were moaning at me for not using them earlier..

Union Wheels · 26th May 2014, 16:49

Harry, you seem to have got it backwards "65mph at a true 70" would mean the speedo under reading.

klarzy · 26th May 2014, 16:54

Quote:

Originally Posted by Union Wheels

Harry, you seem to have got it backwards "65mph at a true 70" would mean the speedo under reading.

They do under read, that's the point bud..

kaiser · 26th May 2014, 16:55

klarzy · 26th May 2014, 16:56

Quote:

Originally Posted by kaiser

????

Your speedo is set up to read slower than you are actually going, this is to prevent manufacturers from getting sued if you get a ticket..

okenora · 26th May 2014, 16:58

Quote:

Originally Posted by klarzy

They do under read, that's the point bud..

illegal to manufacture a car that does that, if yours is doing that you have a fault somewhere.....

edit, just seen your reply, what you describe is "under reading" and is illegal. All cars by default (and law) over read or are 100% accurate. At 70mph real speed your speedo will indicate 75mph for example, but the reason you give for it is correct

26th May 2014, 16:49	#36
Union Wheels Loves to post Honda Accord Tourer i dtec Join Date: Jul 2011 Location: Wakefield Posts: 331 Thanks: 56 Thanked 90 Times in 75 Posts	Harry, you seem to have got it backwards "65mph at a true 70" would mean the speedo under reading. __________________ [SIGPIC][/SIGPIC] How to Retrofit Diesel Cruise Control + Loom http://www.the75andztclub.co.uk/foru...87&postcount=1 How to Modify a 3 Speed Fan for CDT & V6 into a 2 Speed with a Resistor. http://www.the75andztclub.co.uk/foru...d.php?t=209920 CDT now gone to new owner, but still on forum

26th May 2014, 16:05	#33
okenora Posted a thing or two Rover 75 Conn CDT SE + intelligence pack Join Date: Jun 2013 Location: Enniskillen Posts: 1,094 Thanks: 6 Thanked 141 Times in 128 Posts	the PSNI had a ZT traffic car, COLIN_NI might have info on it's whereabouts now.....

26th May 2014, 16:55	#38
kaiser This is my second home 75 Tourer 2.5 Auto, 1.8T, 75V8ZT Join Date: Jun 2007 Location: Johannesburg ZA Posts: 6,200 Thanks: 1 Thanked 859 Times in 613 Posts	????