How to calibrate your speedometer to agree with your GPS speed

[Bfromla]

Interesting. That's one thing that BRP have stuffed up - the speedo. On some days the difference between my GPS, the digital display and the "analogue style display can be as much as 20k. Coming home from a weekend away with the chief cook on the back travelling alone one of our freeways, the GPs showed 110, Digital 117, "analogue" 125 ish.

In this day and age it takes real incompetence to stuff this kind of system up - well done BRP - please never make altimeters for planes

:bbq: hopefully sometimes its just to see if (or help) you are paying attention.

 

[DickB]

I just recalibrated the speedo on my 2014 RSS.

Holding the cursor over the Speed Calibration box shows that the formula is
Speed_new = Speed_old * (1 + CalConst/65536).

Solving for CalConst,
CalConst = ((Speed_new/Speed_old) - 1) / 65536.

My speedo read 72 mph at 70 mph GPS, so ((70/72) -1) * 65536 = -1820, but I found that -350 got the speedo matching my GPS at test speeds up to 70 mph. -500 was just slightly over GPS (GPS reading 70, with 69 every once in a while).

I got a free Megatech 7-day trial license here: https://diag-systems.net/shop/41/desc/license_key_megatech_for_buds to do this.