speedometer

[FlyingLow]

I got a speeding ticket and went to a local place that checks your speed for you. Mine was dead on at all speeds. You could find one of those in your area and have then check it. Well really if it is off by 8-9 MPH just cruise next to a buddy and ask him what his speed is and compare it to yours.

 

[Jeff Kehoe]

GPS- Thats the way to go to be perfect. My truck is dead on what my GPS says. At only about 7k for my system it seems to be the best way to go.

 

[Prof]

My '03 Hemi truck came factory with 17" wheels. I had them changed to 20" before I picked it up. The speedo was off because of this but the dealer fixed it in 2 seconds with a laptop.

Ron

Different trucks different technology...I am lead to believe...

 

[mauiSRT/10]

Gear changes do not effect the speedo!


patrick

 

[tidnab]

look at the bright side...

If you're clocking 52 and actually going 60 you're putting less miles on your truck... (according to the odometer anyway)

 

[TheMoparConnection]

GEAR CHANGES WILL NOT EFFECT THE SPEEDO. HOWEVER IF THE PINION FACTOR IS NOT SET FOR YOUR TIRE SIZE, IT WILL BE OFF.

 

[BigRed460]

GEAR CHANGES WILL NOT EFFECT THE SPEEDO. HOWEVER IF THE PINION FACTOR IS NOT SET FOR YOUR TIRE SIZE, IT WILL BE OFF.

How? The pcm measures the rpms a the output of the trans, If you change gears you change the final gear output. How does that not affect the speedo?

 

[BigRed460]

My '03 Hemi truck came factory with 17" wheels. I had them changed to 20" before I picked it up. The speedo was off because of this but the dealer fixed it in 2 seconds with a laptop.

Ron

Is'nt the outside diameter of the tires the same? why would rims size change affect the speed?

 

[TheMoparConnection]

How? The pcm measures the rpms a the output of the trans, If you change gears you change the final gear output. How does that not affect the speedo?

because thats not the sensor it reads. it uses the rear wheel speed sensor.

 

[rottenronnie]

Is'nt the outside diameter of the tires the same? why would rims size change affect the speed?

I think I know where you are going with this because the 20" spare our trucks have is the same diameter as the 22" low profile Scorpion Zero ..right?

But the 17" wheel and tire on the '03 was definitely lower than the 20" assembly.
Regardless, yes it is the overall diameter that affects the speedo.

Ron

 

[Black1]

hemi keller thanks but i already did that and i was of by 6 to 8 miles per hour.

Most factory speedos are calibrated to show you are going faster than you really are. ....... Unless they are police/service cars. Then the speedo is "calibrated". It will say so on the gauge itself. Usually, stock gauges are 3-5 MPH fast. 8 sounds a little excessive. :dontknow: Not sure if the dealer will warranty it or not. :dontknow:

 

[tidnab]

Most factory speedos are calibrated to show you are going faster than you really are. ....... Unless they are police/service cars. Then the speedo is "calibrated". It will say so on the gauge itself. Usually, stock gauges are 3-5 MPH fast. 8 sounds a little excessive. :dontknow: Not sure if the dealer will warranty it or not. :dontknow:

I will admit I know nothing about this topic... but I can say that if DCX knowlingly adjusts speedo's to clock 5mph faster... I consider that fraudulent.. because the ODO will be off as well... I am HIGHLY suspicious of that statement and doubt that there is any basis for it.. p.s. my speedo has been spot on <in both trucks> tested via mile markers and GPS

 

[FlyingLow]

I I am HIGHLY suspicious of that statement and doubt that there is any basis for it.. p.s. my speedo has been spot on <in both trucks> tested via mile markers and GPS

I had mine checked via some sort of dyno looking machine that is calibrated by the state. I was hoping to get out of a speeding ticket. My truck was dead on at all speeds.

 

[tidnab]

I had mine checked via some sort of dyno looking machine that is calibrated by the state. I was hoping to get out of a speeding ticket. My truck was dead on at all speeds.

of COURSE it was... DCX would assume liability if they knowingly set their speedo's to give inaccurate information

i rest my case