Speedo too Fast

[caymandave]

Here is a good one. Our speedometer is readingh about 5% too fast.
That means we are putting 5% more miles on the coach than is actually driven. When I talked to the Freightliner guys they told me they could do nothing about the extra miles and depreciation they caused.
Any on have any ideas?
Dave

[Flagelpater]

FWIW, About 3 months ago there was a news article about a Class Action Law Suite involving Honda, I think. The auto manufacturer had to adjust the warranty period for the actual mileage. It was about 3,000 miles in error to favor the car owner. You may want to do some research and provide it to your manufacturer. It looks like a method to cheat on the advertise MPG. Are you still using the same tires that were delivered with your rig?

[Flagelpater]

You may want to check your readings against a clock and GPS if you use one. My Buddy's coach was off by .9 miles in a 10 mile stretch! Cruise control and highway markers work pretty good. Is that how you found the error?

[wa8yxm]

There are several different types of speedo's Including the old mechanical such as I have on my towed.

This type can be accurate on millage and off on Speed, in fact mine is at low speed (long about 25MPH the needle and the GPS agree, but at 14 mph per the needle, the GPS says 10, I trust the GPS)

Most rides today, be it an analog (Needle) or digital display are digital electronic,

How the speedometer works. (Old) and new

(There is a gear weel, usually on the output of the transmission which drives a cable which drives the speedometer/odometer, there are a couple of differnet ways the meter can work, I won't go into them)

Or there is a sensor, there are several different sensors so again I won't try to describe them all, that senses the revolutions of the drive shaft (Transmission output shaft) it reports to a computer which then counts those revolutions. Multiply by the rear end ratio (or differential ratio) and the tire size and you have MPH (or KPH)

But if the tires are under (or over) inflated then the reading will be off (Under inflation means a smaller tire and a higher than actual reading, over, the other way around, though not as much)

If the tires are the wrong SIZE to start with.. Same thing

If the computer was programmed for a different differential (or tire) same thing.

And if the sensor is falsing and reporting more revolutions than happen.

You guessed it


Alas. a GPS will confirm the error

But unless it's an inflation issue, takes an EXPERT to fix it

[MrTransistor]

Hi caymandave,

Let us know what coach you have and what engine and transmission combination are used. If it’s a CAT engine, I have the 6 and 9 pin cables to connect to the CAT computer and a PALM to do the talking. It’s a simple mater to set the odometer and speedometer dead on using the CAT Pocket Tech Software. I know that this is applicable to at least the 2003 and forward CAT’s. I don’t know what year CAT switched to the current computer. I’m sure that Cummins is the same, I just don’t have the software for that engine.

Don’t let a Freightliner tech convince you that this can’t be changed. If you can’t find someone with the Pocket Tech, then take it to a CAT dealer and they can correct it for you.

If it’s the old style cable driven type speedometer, then generally, you can set the odometer to be very close (that’s the goal) but the speedometer may be off. This is done by changing the little plastic gear in the transmission in combination with the drive gear on the tail shaft (also changeable). Normally they are available with different numbers of gear teeth that allows the ratio to be changed. As and example, 17, 18, 19, 20, 21 teeth against a tail shaft gear with 42 teeth would allow for about a +or- 10% correction in 5% steps. For fine correction, both gears may have to be changed like a 19/41 combination or a 20/43. (these are just example numbers, I have no idea what the teeth counts are on the older Allison or Eaton transmissions) These little gears are made by the transmission manufacturer so that the odometer can be matched to various size tires by the OEM.

Good Luck.

[caymandave]

Thanks for the information will look into it. They said they were allowed a certain amount of variance. That is total BS.

[caymandave]

I have a pretty accurate GPS so I think the thing is off by 10% not in my favor. So I will look into to your thoughts and thanks for the reply

[caymandave]

The coach is a 2007 Damon Tuscany. It has a 360 HP Cummins and an Allison 6 speed automatic all new the tires are the original factory supplied units. Freight Liner said they could correct the problem but they would do nothing about the 700 extra miles on the chassis. They said there is a federal law restricting them from turning back the Odometer but extending the factory warrenty by 700 miles is a great thought.

[lllkrob]

What the Freight-Liner dealer told you is absolutely correct. There is a federal law prohibiting the tampering with an odometer in any manner whatsoever. and the fines are very stiff. Exactly how do you know that your speedometer / odometer is off as stated. Has the unit been tested on a chassis dynometer or is this just a comparison to mile markers/ GPS readouts/ ??? Remember police speedometers are only certified accurate to + or -2%, and + or - 3% is a commercially acceptable error range for any instrument.

[Pigman]

Hit Freightliner and they'll correct it. Mine was off about 5% right out of the factory and a stop at Gaffney put it right. They're supposed to plug it into a test bench before it leaves the factory to check these things, but it seems that cat is out to lunch (in more ways than one) rather frequently. Ours is right on now when checked against 2 different GPS's.

John



John

[KC1BUD]

Quote:

Originally Posted by caymandave The coach is a 2007 Damon Tuscany. It has a 360 HP Cummins and an Allison 6 speed automatic all new the tires are the original factory supplied units. Freight Liner said they could correct the problem but they would do nothing about the 700 extra miles on the chassis. They said there is a federal law restricting them from turning back the Odometer but extending the factory warrenty by 700 miles is a great thought.

I would think having the paper work showing the problem and the fix would be all you need to convince the next owner.

[TXiceman]

Just because the speedo part is a bit off, does not mean that the odometer is off by the same amount. You can easily check both with the GPS system. On my truck, the speedo is about 2 mph faster than actual speed. The odomer is darn near dead on wit hthe current new tires on the truck.

Ken

[powerboatr]

hmmm
my 08 tuscany is 65 on the speedo but gps is 66-67.
now the dash information panel will say road speed 64, cruise 65,

and even gps is not dead on accurate, there is a time error, amongst other things, aging satellites that are not 100% on track , etc

mile marker and a stopwatch will get you real close.....however the mile marker signs are 2-3% off as well, darn gov. employees

let us know if you get friehgtshaker to extend your warranty