Speedometer problem

[ranchhopper]

I bought a 1009 from the nebraska federal property div this spring.This was a colorado national guard headquarters truck and by far the best one I have had to date.I have a somewhat perplexing problem with the speedometer.The speedo reads ten MPH slow I have checked with numerous people following me at given speeds and all radar speed detectors read it as 10 MPH slower than what shows on the speedometer.The odometer however is right on the money as checked by mile markers on the freeway.I would think with the speedometer reading 10 MPH slow the miles on the odometer would read as longer than they should be.The truck is stock with stock tires and rims any ideas?

 

[AJMBLAZER]

Considering they get their input from the same speedo cable then they should be reading correct. Perhaps at some point the speedo was damaged or failed?

At what speed is it 10mph off?

 

[ranchhopper]

It is consistantly slow at all speeds thats what is a little puzzling it should be off on both the speedo and odometer.

 

[AJMBLAZER]

So it gets progressively more and more inaccurate as you go faster?

2mph off at 10mph indicated, 5mph off at 20mph indicated, 10mph off at 30mph indicated, etc etc?

 

[ranchhopper]

It stays 10 MPH slow whether Im going 20 or 50.

 

[AJMBLAZER]

Hrmmmm...that's weird. If it was a speedo gear or cable issue then it would get progressively worse as you went faster.

So when you're just sitting still, what does it read?

 

[ranchhopper]

It goes right down to zero.

 

[319]

From out in left field, the needle can be adjusted on the shaft, try that.

 

[AJMBLAZER]

Yeah. Was starting to wonder if the needle somehow slipped or something?

 

[SmokeyDod]

The cable from the gear in the tranny is direct to the adaptor on back of your odometer, so as long as nobody has changed the gears with wrong ratio, your odometer (not speedometer) should be good as you say.
The speedometer is operated much different. It kinda works off I believe a magnetic type arangement where by the faster the cable turns-the more pull is put on the speedometer very light wt. hand. Just take one off and spin it with your fingers and you will get what I'm saying.