| Author | Message | ||
     Graham Griffiths Experienced User Username: cineprojectorman Post Number: 12 Registered: 5-2017 |
I noted when the car was traveling at 70 MPH my Garmin SatNav said 62 MPH a nearly 13% error. Members may be interested in the latest update to my web site of how to calibrate the speedometer of a SZ spirit [not sure which other models use this speedo?] http://35de8ignitionrepair.eu5.net/rolls-royce-silver-spirit-repairs-and-fixes.html#Calibration http://35de8ignitionrepair.eu5.net/rolls-royce-silver-spirit-repairs-and-fixes-mobile-view.html#Calibration Regards Graham | ||
| Kevin Deasy Experienced User Username: kevin1946 Post Number: 38 Registered: 1-2017 |
All that was very interesting to read,thanks for sharing it | ||
| Robert J. Sprauer Grand Master Username: wraithman Post Number: 302 Registered: 11-2017 |
Do you have the original "profile" tyres on the car? | ||
| richard george yeaman Grand Master Username: richyrich Post Number: 1070 Registered: 4-2012 |
I wonder what the Police speed trap cameras digital read out would be, I think I would trust my cars speedo, Richard. | ||
| Graham Griffiths Experienced User Username: cineprojectorman Post Number: 13 Registered: 5-2017 |
My tyres are 235/70HR/15, which I believe are standard equipment. Since I've recalibrated the speedo on the bench, as they would do in the Smiths/Jaeger factory, my speedo and satnav GPS MPH tally. Badly worn tyres may make a difference, for example if the car speedo says 70MPH the satnav would show a slightly lower reading because the tyres are not travelling so far/fast and the odometer would read slightly more. Conversely larger tyres would produce the opposite effect I.E. the satnav would show a higher speed to that of the car speedo. [Would anybody fit larger wheels to a SZ Rolls Royce?] Such a lot of talk on the internet of wheel size, final drive gear ratio, transducer etc. I see this as irrelevant because the electronic speedo has been bench calibrated. For 1 MPH, 8000 pulses mile * 1 mile hr/3600 sec = 2.222 Hz. E.G 8000*70/3600 = 155.5Hz I could be wrong of course Regards Graham | ||
| michael vass Grand Master Username: mikebentleyturbo2 Post Number: 552 Registered: 7-2015 |
Good work Graham! No wonder everybody was passing me lol Cheers Mike |
