The Real Deal on Speedo Accuracy (Should say INaccuracy)

[LazyBastard]

Oh, another thing I forgot to add into the thought...

*over 3 days*... that includes constant low speeds, breaking in skids, down hills, etc., which can give you REVERSE slippage, thus causing it to read LOW.



Now as for adding the slip factor into the odo, thats easy. On the test mule, hold a GPS, run 5000 miles, check real distance vs. odo reading.

 

[LazyBastard]

First, don't waste your time arguing with Dr. Bastard. I'm starting to wonder just what kind of drugs he's on. Secondly, this is old news. At full speed, Yamaha digital speedos have been approximately 14 mph off for several years now. Nothing new here. Two weeks ago, my 127 indicated was 113 on radar, exactly 14 mph.

I got 125 gauge vs 113 gun. Thats 10.62% slip. The scratch marks were 1/4 inch long (ie 0.25" scratches, 2.5" pitch = 10%).

 

[QCRider]

Oh, another thing I forgot to add into the thought...

*over 3 days*... that includes constant low speeds, breaking in skids, down hills, etc., which can give you REVERSE slippage, thus causing it to read LOW.



Now as for adding the slip factor into the odo, thats easy. On the test mule, hold a GPS, run 5000 miles, check real distance vs. odo reading.

You are a complete and total piece of work. I know you're not stupid, but I'll be damned if you don't say the STUPIDEST things.

What would be the reason for them to do this, and yet leave the speedo inaccurate? WHY would they do it? Not HOW? Why?

From the other perspective it makes MUCH more sense WHY they would make the speedo read high compared to the odmoeter.

Go measure some more scratches in the ice for me. Here is another way in which I disproved your argument. While riding along at speed, I let off the throttle slightly. I'll be damned if the speedo and the GPS weren't 12% off on the way DOWN as well. By your argument they should be more accurate or maybe even the speedo should read LOW since it is slipping backwards, right? It doesn't matter what you do, or how you do it, they are off by 12%. Any speed, accelerating or decelerating, 12%. Get over it LB, you are wrong about this one.

 

[QCRider]

I got 125 gauge vs 113 gun. Thats 10.62% slip. The scratch marks were 1/4 inch long (ie 0.25" scratches, 2.5" pitch = 10%).

Actually genius that is about .7% slip.

How long would that scratch be if you had 100% slip? I'm thinking something around 3 feet!! Certainly not 2.5 inches!! If the track was spinning completely and the sled not moving there would be a scratch from the front of the skid to the rear. So, .25 inches is .7% of (admittedly a guess here) the 3 feet of contact that the track makes with the ice.

How many more ways do I need to shoot down this BS track slippage theory of yours before you admit you are wrong?

 

[LazyBastard]

Do this:

Go 60 MPH, slam on your brakes as hard as you can. What speed does the gauge read?


ZERO!!!


And you're going to be STILL MOVING FORWARD, so your GPS will be STILL RECORDING forward motion.






Now as for WHY...

SIMPLE:
I already explained why.

ITS IMPOSSIBLE to show an accurate ground speed, so they show an accurate TRACK speed.

IF they adjust the ODO, which I am now not at all convinced that they do since there is NO EVIDENCE of it, then it would be to give a *BALLPARK* IDEA of about how far you've gone.

 

[LazyBastard]

I got 125 gauge vs 113 gun. Thats 10.62% slip. The scratch marks were 1/4 inch long (ie 0.25" scratches, 2.5" pitch = 10%).

Actually genius that is about .7% slip.

How long would that scratch be if you had 100% slip? I'm thinking something around 3 feet!! Certainly not 2.5 inches!! If the track was spinning completely and the sled not moving there would be a scratch from the front of the skid to the rear. So, .25 inches is .7% of (admittedly a guess here) the 3 feet of contact that the track makes with the ice.

How many more ways do I need to shoot down this BS track slippage theory of yours before you admit you are wrong?

LMFAO

I know you didn't say that intentionally, 'cause thats really dumb.

A new scratch is started every 2.5 inches, 'cause thats the distance between rows of spikes.

If the scratch was 3 feet long, then it would mean... 3x12 = 36", 36 / 2.5 = 1440% (one thousand four hundred forty)...



Simpler:
For every 2.5" of registered forward motion (distance between two lugs or two spikes), there is 0.25" of slip.

 

[Sled Dog]

How can a gps account for uphill or downhill runs. You will be going faster than the GPS will record as all it sees is lateral movement.

 

[LazyBastard]

Thats an interesting point.

Actually, a GPS *does* account for 3 dimensional motion...


But that wasn't really what I had in mind... more the concept of *sliding* down a hill.

 

[QCRider]

A new scratch is started every 2.5 inches, 'cause thats the distance between rows of spikes.

If the scratch was 3 feet long, then it would mean... 3x12 = 36", 36 / 2.5 = 1440% (one thousand four hundred forty)...

Let's talk for a second about what 100% slippage would mean LB. What is it in your world? In mine it means that the track is spinning, but the sled is not moving. Any argument with that? If that is the case, exactly HOW LONG WILL THE SCRATCH BE? 2.5 inches? Are you HIGH? How could it be only 2.5 inches and the sled NOT move? Please do share your thoughts there?

So, if the speedo reads 100 MPH at 100% slippage and the sled is NOT moving (can we agree that at 100% slippage it is truly NOT moving?), and the scratch mark is 36" long. Here is the hard part, it requires math. How long would the scratch mark be if the sled was moving at 50 MPH when the speedo reads 100? 18 Inches, YOU'RE RIGHT!!!. And how long would it be if the sled was moving 90 MPH when the speedo said 100? THAT'S RIGHT, 3.6 INCHES!!! RIGHT AGAIN. But certainly NOT 1/4 inch.

You are wrong. Wrong wrong wrong wrong wrong....

 

[Sasquatch]

1\4 inch scratch could be caused simply by the stud gaining speed as it rounds the rear idler. As pressure is released on the ice the stud which was bent slightly forward now springs back causing 1\4inch scratches.

Just adding fuel to the fire.

My speedo is out at all speeds. I say speedo error, others may disagree.

 

[QCRider]

How can a gps account for uphill or downhill runs. You will be going faster than the GPS will record as all it sees is lateral movement.

Good point, and probably only adds to my argument. So, the 3% difference in the Odometer reading means that the track was actually slipping much LESS than 3%, because much of my trip was up and down hills where the sled would put on more mileage than the GPS would recognize. So the Odometer is even more accurate than I thought.

However, the speed tests were on long flat surfaces, rivers, rail beds, fields, etc. Not hills, and the speedo error was about 12%.

 

[QCRider]

1\4 inch scratch could be caused simply by the stud gaining speed as it rounds the rear idler. As pressure is released on the ice the stud which was bent slightly forward now springs back causing 1\4inch scratches.

Just adding fuel to the fire.

My speedo is out at all speeds. I say speedo error, others may disagree.

I totally agree. 1/4" scratch is meaningless.

 

[Buckeye]

Yes, but how many people cut the speedo gear to make the reading accurate. Not many. People like to believe they are going that fast.

:ORC

 

[Sled Dog]

A new scratch is started every 2.5 inches, 'cause thats the distance between rows of spikes.

If the scratch was 3 feet long, then it would mean... 3x12 = 36", 36 / 2.5 = 1440% (one thousand four hundred forty)...

Let's talk for a second about what 100% slippage would mean LB. What is it in your world? In mine it means that the track is spinning, but the sled is not moving. Any argument with that? If that is the case, exactly HOW LONG WILL THE SCRATCH BE? 2.5 inches? Are you HIGH? How could it be only 2.5 inches and the sled NOT move? Please do share your thoughts there?

So, if the speedo reads 100 MPH at 100% slippage and the sled is NOT moving (can we agree that at 100% slippage it is truly NOT moving?), and the scratch mark is 36" long. Here is the hard part, it requires math. How long would the scratch mark be if the sled was moving at 50 MPH when the speedo reads 100? 18 Inches, YOU'RE RIGHT!!!. And how long would it be if the sled was moving 90 MPH when the speedo said 100? THAT'S RIGHT, 3.6 INCHES!!! RIGHT AGAIN. But certainly NOT 1/4 inch.

You are wrong. Wrong wrong wrong wrong wrong....

Realistically if your track is reading 100 mph and your ground speed is 50 mph I would say your scratch is going to be full length.

 

[QCRider]

Exactly Buckeye. And that is why I say the OEM's do it on purpose. It is not track slippage, it is intentional.