I have changed the speedometer calibration 5 times but it does not seem to change. I'm comparing speedometer to gps using track addict and it seems to 5 to 7 mph off each time. Am i missing something ? The buggy is a 16 RGR900 with 32s and 13 % reduction in trans
Did you figure it out?
My 2016 Ranger is almost the same. 32 Terminators, with Highlifter Reverse chain and reduction in transmission.
I am sure there is a formula for this I just have not had the time to figure it out. I was able to get it real close by switching Override Cal to Calibration and Cal Value to 150ft.
It probably has to due with tire rollout and the number of teeth on the tone ring.
Still have not been able to get it but currently have 155in. And I swear it doesn't seem like it's changed anything . I will try your suggestion and see what happens.
Tried the 150 ft and it was almost dead on . Thanks for the suggestion!
Happy to help.
I think this is how it works but, I have not swapped tires to verify and maybe someone else can confirm.
The spur gear has 53 teeth and the sensor picks up on that. So there is 53 pulses per tire rotation or the distance traveled for 1 pulse is the tire circumference/53. It looked to me that this number was off by a factor of 1000 so I came up with this.
Diameter*PI/53*1000/12 = cal factor in feet.
I suspect that 158.06755 feet is the theoretical number for 32 inch tires. I say theoretical because tires usually don't measure advertised size and then add a little squat to them with weight and the roll out (the distance traveled for one revolution) is shorter.
I have bigger tires and can possibly test here soon. Waiting for the logging issue to be fixed, so it's currently back on DynoJet, but I can swap over to test.
- Jason
www.jaztuning.com
That math worked for me . I actually went and measured my tires ( kanati mongrels) and they measure 32.5 at 12psi. This is all still a learning process to me and new so all info is much appreciated.
Jazztuning I sent you a pm
I am having a very similar issue. I have made some major changes in the calibration value but only minor changes happen on the speedo.Originally Posted by whothe
I have a 18 RZR 1K XP Highlifter with 36" tires and 45% reduction portals. I think the key here is my portals reduction making my speedo faster than I am actually going, even with the larger tires. I believe most others have a slow speedo because of installing larger tires which this calibration would solve.
I have tried everything from 48m down to 0.7m. The closest I can get to being accurate is at the 0.7m and even then the speedo is about 30% too high. And it almost appears the calibration is just an offset. And I need it to go negative, but the acceptable values show to be 0-202m
Try 257.84770 feet.
Thanks for the response Archer. So that comes out close to 78m and I just now tried it. Here are the results I have had with the settings I have tried
tests are with speedo showing 20mph.
78m = ~9mph actual
48m = ~10mph actual
24m = ~12mph actual
0.7m = ~13mph actual
Stock tire size was 29" so me running 36" mean speedo would have speedo read ~24% to low.
Now throw the 45% gear reduction in and makes that number now showing speedo ~20% faster than I am going if my math is right.
But any calibration value I enter just makes the reading further off...
Something else interesting is the Cal. Value that shows up on my initial read. It was 5.54324m which looks much lower than other files I had downloaded. Maybe because this is a highlifter with the much lower gearing...
Click on the m until it reads ft. Did you change Override Cal to Calibration?
Okay, I did and the 78m turns into 254ft. Yes I changed from EEPROM to Calibration. And it is actually changing my speedo readings. Just very slight changes.
Try making it the 257 number, 3 feet difference per tire revolution is a lot.
Sorry, I typo'ed there. It is set at 257.20898. That value makes the speedo read 20mph while GPS reads 10mph.
I am certain at this point, this value makes a measurable difference on my calibration. But it is very little and not going to allow me to calibrate mine. Not sure why mine is that way, but it appears so.
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