Speedometer

Yeh...

Question: What is the error rate expressed in percent, if the speedometer indicates 3 miles per hour when the vehicle is actually traveling at 30 miles per hour?

Answer: 10 percent.

The error rate could be more than a couple of percent.

If you have the discrepancy documented, I'd save the documentation in case a warranty question arises near the end of the mileage allowance.

noticed

speedometers a

I used to use this method to check whether customers' speedometers needed replacement or not but it assumes the mile markers are in fact exactly 1 mile apart and that the timekeeper starts and stops the stopwach at exactly the same position, i.e, leading edge of the bumper.

With so many variables, the mile marker stop-watch thing might not get you our of a ticket but a check on a certified calibrated dyno might. Although we had a calibrated 4 wheel chassis dyno at the office, the mile marker/stop watch trick was good enough to see if speedos needed replacement or not. People used to get pissed when their replacement speedo had a sticker adding x miles on the odometer because they thought they were getting a reprieve on their odo mileage.

As an aside, I ran a fleet of Ford trucks years ago and the speedometer gears were specific to the particular tires that the truck came equipped with. There were many different part #s for the same year, make and model depending on which tire manufacturer that truck was manufactured with. Ron

Typo correction! the question should read 33 miles per hour, not 3 miles per hour.

At a 10 percent discrepancy, when the odometer reads 36,000 miles, the car would have less than 33,000 actual miles. At 1,000 miles per month, that's like a 3 month difference.

Exactly. So regardless of how far off calibration speedometers are, those with a propensity to speed will do it anyway.

Yes.

And those that drive right up to the number on the sign will never speed IF the error is such that the speedo reads 3 or 4 mph faster than the actual speed. The variation comes with buying the base model, then swapping the tires to a larger size for whatever reason. This swap will result in a speedo that reads too slow, and when the driver of this arrangement sets the needle in accordance to the sign, he will be speeding.

I hear what you are saying, but I suspect you will lose the argument if you had to press it.

I think you can take it to the bank that the mile markes are where they say they are. The variable is that many mile markers are missing ...

If you start the watch at the front bumper and stop it with the door instead of the bumper, the difference isn't going to matter. If you were timing NASCAR or any other race, this would be a critical difference, but when timing your speedo, the variance isn't going to matter.

Set the Cruise to 80, and it takes 45 seconds to go a mile. Set the Cruise to 70, and the miles fly by at the rate of one every 51.5 seconds. You can divide 3600 by the speed to arrive at the time intervals. Then, you can anticipate where the mile markers should be. To the extent the miles markers are there, the speedometer is accurate. If you go a few miles and the mile markers are nowhere to be seen at the appointed time interval, then the speedo is in error.

I didn't know there was an argument to be won or lost; in fact, I didn't know there was an argument at all.

Is the argument that the error rate for a speedometer that indicates 33 miles per hour when the vehicle's true speed is 30 miles per hour is only a couple of percent instead of 10 percent as I stated, or is it something else?

It's that you could claim the 36,000 mile warranty wasn't up yet because the odometer has an error.

Perhaps you have more experience dealing with warranty claims than me so you have a sound basis to contradict what I posted. Among my duties as a district service manager, I was responsible for warranty claim administration for only the 50 different Toyota dealerships I visited, and part of warranty administration was interpreting and explaining warranty coverage to dealer service departments and customers. How many different dealerships were you responsible for warranty administration at? Which manufacturer?

The warranty I used to interpret sates that the warranty is for x miles or y months, whichever comes first. Note that the warranty does not say "x miles indicated on the odometer," it says "x miles." If an owner can show that the odometer is overstating indicated mileage and goes to court, the owner will win. That is why I did not turn down requests for warranty assistance if the vehicle was only a few thousand miles out of warranty mileage-wise but still within warranty time-wise. Maybe I should have been turning customers down who were only 2% or even 10% over in miles?

You shouldn't turn down anybody that is within a narrow margin of the time or distance, but it happens all of the time. If the time or distance is 3 years or 36,000 miles, and it is a week shy of 3 years but the miles are

37,000, then of course you should honor the claim if for on other reason that customer good will. But we all have horror stories of being at 37 months and 37,000 miles and finding that the warranty is expired, or 35 months and 37,000 miles.

If an owner shows up and you elect to extend the service under the warranty, then fine. But if the owner shows up and wants to back date the odometer by

3,600 miles, then you would be a dick to refuse service, but within the terms of the warranty.

I don't know where the 10% figure came from, most of my cars have had errors in the range of about 3%. My BMW is so close that I don't have the tools to accurately guage the error, I am off about 1.5 mph at 90, but the speedo error and the odo error are not necessarily the same thing. My Jeep, on the other hand, has no correlation between the speedo and reality, so the error can be all over the place between different makes. I maintain that any given automaker has an error rate that is within a very narrow margin across all of its lines, and this rate will be about 4%.

You would not have a horror story if you had a Toyota and called on one of the dealers in my district!

Ironically, extended service contracts are very strict about expiration and termination of coverage. 1/10 or 1 hour over the expiration and it's done.

This is splitting hairs, but one the time and miles on the odometer are up, warranty coverage is done, period. Any repairs covered by the manufacturer after the warranty has expired is covered under a goodwill assistance program, even if the odometer if over by a tenth or time is out by an hour.

Also in the hair splitting department, if the owner asks the dealer to record a lower mileage on the repair order than is actually indicated on the odometer, he is asking the dealer to commite fraud. Most state attorneys general and manufacturers frown on dealers and customers committing fraud, and most manufacturers will decline any further requests from that customer for goodwill assistance.

If the owner comes in and claims his odometer is over-recording mileage by x perent, the dealer can jut take his word on it, record the mileage indicated on the odometer, and submit a claim for goodwill assistance or verify and document the accuracy of the odometer, record the mileage indicated on the odometer, and submit a claim for goodwill assistance.

The third scenario, and the most common one, is where the customer comes in and says come on, I'm just a little out, I'm a good customer at this dealership, what can you do? The service department knows that the customer is a regular and submits a claim for goodwill assistance.

You had mentioned an example of doing 40 in a 35 zone, which is 14.3% over. I just rounded down to 10%, which used to be toyota's spec for speedo accuracy. Besides, 10% was easier to calculate than another number.

My BMW is so close that I don't have the tools to

For the premium you pay for a BMW combined with the German mentality for exactness, the accuracy of the BMW's gauge doesn't surprise me.

My Jeep, on the

My impression of Jeep's philosophy is "exactness and accuracy doesn't matter, toughness does" so your experience with your Jeep doesn't surprise me either.

As far as whether a given automaker has a narrow error rate across all its lines and that the error rate is 4%, I don't have enough experience with non-Toyota's speedo/odometer accuracy to make a judgementso your guess is as good as mine here.

I've checked my Corolla speedo (2005) with my GPS and the two are very very close.

John