Thurbs
|
| posted on 21/3/11 at 12:55 PM |
|
|
Speedo calibration
Hi all,
IVA on wednesday and I'm bricking it keep finding little things I'm not happy with !!!
Anyway I'm trying to calibrate my speedo ( Koso DB02r) I've got it pretty close just need to ask
to reduce to MPH do I have to reduce or increase the wheel diameter figure.
I know I've read it somewhere but a week of nightshift and IVA stress my brain is minced.
I've been trying by trial and error but don't want to push my luck and get nicked keep going up the road annoying the neighbours.
Thanks in advance
Andy
|
|
|
|
|
rb968
|
| posted on 21/3/11 at 03:03 PM |
|
|
OK so i'll stick my neck out and have a go!
I have a Koso RX1n so assuming it is the same you input the circumference of the wheel and tyre, so the distance it covers on the ground through one
full rotation. You tell it how many magnets you are using so it knows how many to count as a full rotation.
The greater the circumference the further the wheel travels in a rotation. If you input a circumference greater than the actual it will read as a
higher speed as it thinks the wheel has covered more ground for a rotation than it actually has. i.e. the wheel really covers 900mm but
you input 1000mm so it will read a higher miles per hour.
So I "think" it depends on whether your current setting is more or less than the actual circumference as to which way you adjust. My
understanding is you want the speedo to overread by a % or 2 as that is what Mr VOSA is after. Spot on accurate I understand will not pass.
I stand to be corrected! (and probably will be ) 
Rich
|
|
|
rb968
|
| posted on 21/3/11 at 03:52 PM |
|
|
Just realised I didn't actually answer the question.
If its reading over actual speed reduce the circumference figure.
My way of working it out:
Actual tyre circumference = 900mm
10 rotations in 1 sec = distance covered 9000mm = 20.132 mph
You input 1000mm
10 rotations/sec = 10000mm = 22.369mph (so speedo shows higher than actual = reduce circumference)
You input 800mm
10 rotations/sec = 8000mm = 17.895mph (so speedo under reads = increase circumference)
So by my thinking you should enter a circumference a % or 2 higher than actual to have it over read by a bit.
Rich
|
|
|
