Checking speed

[Burner]

How do most of you check your speed? I have seen much about the Predator and how it will "correct" you speed'O but not an actual conformation. I know that the math is correct in the configuration program...but I have not seen actual data on the results. :rolleyes:

A couple of weeks ago I went to Atlanta. On the way home I hooked up my Garmin etrex vista to find out what the actual difference was. I rest my truck and the GPS and drove 100 miles on the truck OD. The Garmin showed close to 103.4 or 104.3 in the 100 miles. That does not correspond with what the numbers say, I don't know why? The road from Atlanta to Birmingham is virtually flat. I don't think that 200 or 300 ft elevation change would make a difference.

Who has checked their speed'O with a GPS unit?


Burner-----> :D :D

[mackin]

The Predator in real time date will report actual speed ... Mine is accurate to 80 ...After that at 100 actual speed'o reading yielded an actual 96 on the Predator screen ...


Mac ;)

[sdaver]

gps over several miles..... plugged in the predator set the cruise to exactly 55 on the pred screen(which is reading directly from ecm) and compared it to gps.....mine is within .5 mph :D dave

[Burner]

I guess it could have something to do with how much the tire is flexing. Say you had 4 32" tires @ 60psi and the truck weighed 8,000 lbs, your tires would not be 32", perhaps 31" or 30" tall. That may have somthing to do with my speedo and GPS being within 3% instead of 6%. :rolleyes: Sometimes I just don't think......
David, what are you doing? Lets take the kids to the lake. :D


Burner-----> :D

[sdaver]

been on the lake all day..lets get the calendars together......dave

[Applecore]

I know that mile markers are not always exact, but they are very close. So, to check your speedometer, clock in seconds, the time between mile markers. Divide the seconds into 3600, the answer is the miles per hour you are traveling. Example (simple) 3600/60sec = 60mph. Another example, If it takes 55 seconds to travel the mile then 3600/55=65.45.... mph.

[sdaver]

or drive ten miles according to the mile markers and check your odometer....if it shows ten then your correct......if it shows 9.5 then you are off 5%.........slow........I did this to correct my speedometer on my jeep w/38's had a gear drive corrector made for my mechanical speedo.........gps is easier

[RWTD]

Dave, ever noticed how these Alabama mile markers are put about wherever them workers want them to be? Especially after a hard night out on Sunday, lol. ;)