S60 speedo accuracy (UK)

Discussion in 'Volvo S60' started by Tim Riglar, May 17, 2004.

  1. Tim Riglar

    Tim Riglar Guest

    Took the trouble to try to calibrate the speedo in my S60 today (2.0 SE auto
    with 17" wheels and correct 45 profile tyres) - no particular reason, just
    out of interest. AIUI, UK legislation requires +0 -5% accuracy, but I'm
    overreading by about 8.5% at 60, 70 and 80 (didn't check any others). I used
    the 100m markers on the motorway, and set the cruise. The timings were
    pretty repeatable. I suppose the markers could be inaccurate, but it doesn't
    seem very likely. Interestingly I measured 16 posts to an indicated mile,
    which would seem to indicate that the odometer is pretty accurate (and
    confirms that they are at 100m, not 100yd intervals).

    Has anyone else tried this? It's disappointing that the error is this large
    and (strictly speaking) illegal.

    Tim
     
    Tim Riglar, May 17, 2004
    #1
  2. I confess.

    Yes, my name is Stewart, and I, too, am a marker post counter.

    Not on a regular basis, you understand, but once, out curiosity, I
    counted the posts over an indicated mile on my trip meter.

    16. Exactly.

    To confirm this, I counted them over 10 miles.

    160. Exactly. My oddometer seems very accurate, too.

    You are obviously much younger than me; I realised straight away that
    they were at half furlong intervals. There are 8 furlongs (220 yards)
    to a mile. An odd unit these days, but it equates to the length of a
    cricket pitch, and one furlong by one furlong is ten acres.

    So, half a furlong is 110 yards, which is slightly over 100 meters.

    I would hazard a guess that your accuracy with the throttle, with
    reading the meter while driving, and with the time taken for the meter
    to respond may all contribute to the extra 3.5% error.
    --

    Stewart Hargrave


    For email, replace 'SpamOnlyToHere' with my name
     
    Stewart Hargrave, May 18, 2004
    #2
  3. Stewart Hargrave wrote:

    So, who noticed my (ahem) deliberate mistake?

    A *chain* (22 yards) is the length of a cricket pitch - a chain is a
    tenth of a furlong.
    --

    Stewart Hargrave


    For email, replace 'SpamOnlyToHere' with my name
     
    Stewart Hargrave, May 18, 2004
    #3
  4. Tim Riglar

    Rob Guenther Guest

    The furlong... the "chain" - I am so glad we are taught metric in Canada.

    I wonder how many hectometers per unit decalitre my car is getting?
     
    Rob Guenther, May 18, 2004
    #4
  5. Tim Riglar

    Nobody Guest

    Come to Melbourne (or anywhere in Victoria for that matter)Australia. The
    money hungry incompetents in Spring Street as well as the tunnel visioned
    Police here allow you a 1-3% leniency on your speed. Pretty much every car -
    including new ones are out by more than that. And they try to convince us it
    is in our own interests.....

    How did we get idiots like this?
     
    Nobody, May 18, 2004
    #5
  6. Tim Riglar

    David Taylor Guest

    out of interest. AIUI, UK legislation requires +0 -5% accuracy, but I'm

    My understanding was that the speedo cannot under read (obviously) but
    can over read by up to 10% at speeds above 10mph. Therefore, by that
    your speedo is within tolerance.

    David.
     
    David Taylor, May 18, 2004
    #6
  7. Tim Riglar

    Tim Riglar Guest

    I used to quote this 10% rule, too, then I'm sure I discovered it was 5%
    (don't think I dreamt it, anything's possible). However, the Statutory
    Instrument 1996 No. 3013 (The Motor Vehicles (Approval) Regulations 1996)
    which I looked up this morning, actually states:

    "For all true speeds of between 25 mph and 70 mph (or the maximum design
    speed if lower), the difference between the indicated speed and the true
    speed shall not exceed V/10 + 6.25 mph (where V = the true speed of the
    vehicle in mph)"

    which puts a different perspective on things, and seems to suggest that at
    at true 60, the speedo could read 72.25mph, which is more like a 20%
    allowance. Interesting that "10%" seems to be lodged in the mind of most
    people.

    Looks like my error is well within range, but still disappointing in a
    modern car in my view.

    Tim
     
    Tim Riglar, May 18, 2004
    #7
  8. Tim Riglar

    David Taylor Guest

    (don't think I dreamt it, anything's possible). However, the Statutory
    I was looking for the right one but it wasn't turning up. Well done!
    Well, the point is to stop people speeding, driving at an indicated 70
    and finding your doing much less isn't much of a problem. I have to say
    that my Saab compares well between the speedo and a GPS, no more than a
    couple of mph out by my reckoning (and ability to accurately read the
    speedo).

    David.
     
    David Taylor, May 18, 2004
    #8
  9. Tim Riglar

    Mike F Guest

    Not that this helps much, but a few years ago on a cruise in my '98 V70
    to Montreal (500 km away) on the highway which has kilometer markers I
    tested my accuracy. To get to a true 120 km/hr I had to set the speedo
    to read 123. At this speed (cruise control) the average speed indicator
    in the trip computer read exactly 120 after resetting. Also, over 200
    km my odometer didn't even vary 0.1 km!

    --
    Mike F.
    Thornhill (near Toronto), Ont.

    NOTE: new address!!
    Replace tt with t (twice!) and remove parentheses to email me directly.
    (But I check the newsgroup more often than this email address.)
     
    Mike F, May 18, 2004
    #9

  10. No, metric is a daft system.

    25.4 mm to an inch
    39.37 inches to a meter.

    Madness.
    --

    Stewart Hargrave


    For email, replace 'SpamOnlyToHere' with my name
     
    Stewart Hargrave, May 18, 2004
    #10
  11. Tim Riglar

    Rob Guenther Guest

    Reminds me of a quote I can't quite remember fully, from the television
    show: The Simpsons

    "Bah!! Metric, thats the tool of the devil, my car gets 28 rods to the hogs
    head, and that's the way I likes it!" - Abe Simpson
     
    Rob Guenther, May 19, 2004
    #11
Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.