Inaccurate speedo

Why are speedo inaccurate at high speed? I heard that the maker did it intentionally. I don't know why or if it is true. Can somebody fill me in?

Well, what kind of car are you talking about?

The simplest error to introduce into a speedometer, using the wrong size tires, will result in speed error that grows proportionally to speed. This is true regardless of what kind of car you have.

Some manufacturing defects (depending on kind of speedo) can have a similar effect.

I'm talking about Honda accord 1995. My friend didn't do anything to his car (change tires etc.) and it showed that 135 mph is his top speed on the freeway which confirmed that his speedo is wrong. I heard honda did it intentionally. I can't confirm it but if you can plz do.

All speedos get innaccurate at high speeds. Equations and wheel sizes are fine in ideal situations, but the real world isn't ideal at all. There's too many variables to accurately tell speed over such a broad range.

And i know for a fact that Honda is electronically limited to 112 mph by gearing and rev limiters.

And i know for a fact that Honda is electronically limited to 112 mph by gearing and rev limiters

oh yeah? which honda?

elaborate plz. Limit to 112? you mean accord can only go 112 mph?

do you have those retarded dayton gold spoke wheels on your car?

do you have those retarded dayton gold spoke wheels on your car?
???

Originally posted by 454Casull

???

http://www.aaawheels.com/RWD%20WHEELS/DAYTON%20WIRE%20GOLD.JPG These wheels kill wheel bearings and totally fry the accuracy of speedometers.

No, actually, there was a section in a popular car mag (C&D or R&T or something like that) about speedo inaccuracy, with BMW as the one with screwiest speedo, and GM with the least.

Originally posted by ivymike1031 Originally posted by 911GT2
And i know for a fact that Honda is electronically limited to 112 mph by gearing and rev limiters.
oh yeah? which honda?
And which is it? Gearing or Rev Limiters? (Or drag?)

That seems to be an interesting fact you have there... :confused:

Know anything about honda accord and the inaccuracy of its speedo?

nope, I know nothing about the accord

my 97 civic consistently read about 8% too high after I installed indiglo gauge faces (checked w/ gps, estimated gps error 0.8%). I never noticed the problem before buying the faces (didn't have the gps then) and I never took the faces back off to compare.

My '88 civic with the factory gauge faces reads spot-on with the gps.

(enginerd)These wheels kill wheel bearings and totally fry the accuracy of speedometers.
I'll take your word for it on the wheel bearings (large offset wheels, I guess?). I'd like you to go into a bit more detail on how you expect the wheels to affect the speedo accuracy, if possible (were you assuming a smaller OD tire to accompany the clown wheels?).

Originally posted by ivymike1031
nope, I know nothing about the accord

my 97 civic consistently read about 8% too high after I installed indiglo gauge faces (checked w/ gps, estimated gps error 0.8%). I never noticed the problem before buying the faces (didn't have the gps then) and I never took the faces back off to compare.

My '88 civic with the factory gauge faces reads spot-on with the gps.


I'll take your word for it on the wheel bearings (large offset wheels, I guess?). I'd like you to go into a bit more detail on how you expect the wheels to affect the speedo accuracy, if possible (were you assuming a smaller OD tire to accompany the clown wheels?).

It's been my experience that the od of these wheels (wheels are smaller in diameter than stock; even with tires) is smaller vs. stock sizes. They are offset about 3-4", thus greatly leveraging the weight of the vehicle against the wheel bearings. I've made a fair amount of income from replacing wheel bearings/ hubs on cars equipped with these wheels. I'm am sour about them because one such car had an owner who drove off after having new beaings installed and crashed into another car. Keep in mind these wheels skew caster and camber angles and the steering wheel will not self-center when released. The owner of the car decided to sue my boss and I had to go testify in court. The car owner lost the case, but after that, any employee touching a car equipped with those wheels was immediatly terminated. The smaller diameter wheels indicated a higher speed than actual.

Originally posted by ivymike1031


oh yeah? which honda?

Every one. Limited by the Japanese government in the original case, they don't change the computer for NA. About 185 kph. And yes, it is impossible to go over 112 mph in any Honda recently made (meaning the last 10-15 years). And it is a combination, a rev limiter in fifth gear keeps you from reaching any speed over 112. And yes, that includes the Accord.

And mike, you seem to be challenging me in ever post...challenging the new guy??? Not that i mind....i like a challenge ;)

Do you have a source with that fact? It is not that I don't beleive you, it just that i'm trying to prove my friend wrong. He said he went 135 on his accord.

Originally posted by 911GT2
Every one. Limited by the Japanese government in the original case, they don't change the computer for NA. About 185 kph. And yes, it is impossible to go over 112 mph in any Honda recently made (meaning the last 10-15 years). And it is a combination, a rev limiter in fifth gear keeps you from reaching any speed over 112. And yes, that includes the Accord.Source?

Every one. Limited by the Japanese government in the original case, they don't change the computer for NA. About 185 kph. And yes, it is impossible to go over 112 mph in any Honda recently made (meaning the last 10-15 years). And it is a combination, a rev limiter in fifth gear keeps you from reaching any speed over 112. And yes, that includes the Accord.

And mike, you seem to be challenging me in ever post...challenging the new guy??? Not that i mind....i like a challenge ;) [/B]

To be more accurate, I'm challenging the "wrong" guy. My personal experience directly contradicts your statement about the max speed of Honda vehicles.

It's a Japanese government regulation. Just like the rule that high powered cars must be rated at 276 hp, no matter what they actually dyno at. And for the guy who said he went 135 mph in his Honda, it's entirely speedometer innacuracy. I also have a friend who went 195 kph in his Civic when it's actually limited to 179. Speedometers are made so that at legal speeds, you can accurately tell your speed to avoid ticket problems. That's all.

And btw, i'm not including bikes in this statement, if that's what mike is talking about. And without it being chipped or having the rev limiter removed, 112.

I'm 100% sure a bone stock NSX directly out of the Tochigi plant in Japan could prove you wrong in about 15 seconds.

Too bad I can't prove it for you myself, but I don't need a third ticket. :(

Here the NSX isn't a Honda, it's an Acura. Technically, i guess you're right, but that's not your everyday Honda. Remember that this question was originally about an Accord....not exactly an NSX.

All Acuras are Hondas. You said all Hondas. I'm sure the S2000 (a truer Honda?) could do it in a little more than 15 seconds, too.

Originally posted by jay@af
All Acuras are Hondas.As soon as I said it, I bite my tounge. I know the Acura SLX was really an Isuzu. :p

Ah, true. S2000 can hit 150mph, but that's a sportscar. The fact still remains that the stock 1994-97 Accord is speed limited to 112 mph.

Source? http://www.vmrintl.com/Usedcars/Car%20%20Reviews/Honda%20Accord%2094-97.htm

And when i say Honda, i mean cars badged as Honda. Acura has a more sporting image, so to limit their cars to 112 mph would be just plain stupid, especially their type S.

But please, search for yourselves, the only Hondas you will see go over 112 mph (aside from the NSX and the S2000) are modified. See for yourself.

That site showed 112 as the top speed, but didn't say why they picked that number.

S2000 is different? But I thought you said ALL hondas?

In regard to your statement about the rev limiter, consider the following:
The rev limiter in a 1997 civic is at 8000 rpm (unless my memory has failed). If the vehicle was in its top gear at 8000 rpm, and the rev limiter was limiting the vehicle speed to 112mph, then at 8000rpm in top gear the vehicle would be going 112. Using the same gear at 60mph would result in an engine speed of 4286rpm, which is WAY too high for highway cruise. For the rev limiter to restrict vehicle speed to 112 in top gear, the rev limiter would have to be set in the 'hood of 4800-5500rpm.

Check out this site:
http://www.car-videos.com/performance/top_speed.asp

or this one:
http://world.honda.com/news/2001/4010219.html

"The 2.0-liter engine of the Type-R is part of the new family of highly advanced DOHC i-VTEC engines from Honda featuring Variable Timing Control (VTC) as well as the highly renowned VTEC system. Its 200 PS (147 kW) at 7,400 rpm and torque of 196 Nm at 6,500 rpm enables the Type-R to reach 62 mph in just 6.8 seconds and go on to a top speed of 145 mph (233 km/h). "

or this one:
http://www.motorway.com/home/articles/hondacivicsi.asp

112 is just an arbitrarily selected number, just like 276 hp. I can't peer into the minds of Japanese government officials to see why, so I can't explain why. And i did say all Hondas, and i was wrong. I'll freely admit that.

And i can't really explain the technicalities. Look at quoted top speeds, they'll agree. And keep in mind that i'm talking about North America in particular, and we don't get the type R here. Besides, the Type R is made in England isn't it? Which would mean it really wouldn't have to abide by regulations.

Originally posted by 911GT2
And when i say Honda, i mean cars badged as Honda. Acura has a more sporting image, so to limit their cars to 112 mph would be just plain stupid, especially their type S.Originally posted by 911GT2
112 is just an arbitrarily selected number, just like 276 hp. I can't peer into the minds of Japanese government officials to see why, so I can't explain why. And i did say all Hondas, and i was wrong. I'll freely admit that.Badging makes no difference to Japanese regulations; there is no Acura in Japan.
Originally posted by 911GT2
And i can't really explain the technicalities. Look at quoted top speeds, they'll agree. And keep in mind that i'm talking about North America in particular, and we don't get the type R here. Besides, the Type R is made in England isn't it? Which would mean it really wouldn't have to abide by regulations. a. Why are we talking about only North America if it's a Japanese regulation?

b. All Type R cars are made in Japan. The only notable (possible? I'm not sure...) exception is the Accord Euro R, which may be assembled in the U.K. The NSX-R, both Integra Type Rs and both Civic Type Rs were made in Japan, with their engines hand-assembled in the same Tochigi plant.

c. We (the U.S.) did get the ITR for 4 of its 5 years of production. We're expected to get both the new ITR and CTR sooner or later... Since the S and Si, respectively, are selling well.

did you notice the Civic Si @ 133mph?

Originally posted by ivymike1031
did you notice the Civic Si @ 133mph? In this article you posted; 135mph:
http://www.motorway.com/home/articles/hondacivicsi.asp

:p

Well there's exceptions then. The Accord originally spoken of didn't go 135 mph, and that's my point. There's exceptions to every rule, and this example shows that there can be many. But that Accord along with Civics (aside from the Si designation) are limited to 112.

And asking me why they chose 112 is akin to me asking you why you spell your name mike as opposed to myke. Arbitrary decision.

Originally posted by 911GT2
Source? http://www.vmrintl.com/Usedcars/Car%20%20Reviews/Honda%20Accord%2094-97.htmYou know, on this very same page where it says the I4 Accord's top speed is 112 mph, it also says that the V6 Accords Top speed is 130 mph...

How many exceptions are there to this rule?

:confused: :confused: :confused: :confused: :confused: :confused: :confused:

Well shit. I guess i'm proven wrong then. No real explanation to it, i'd just thought that all Hondas were limited to 112 because of their Japanese counterparts. Sorry for any confusion. But what engine did that Accord have??

I guess i can find consolation in the fact that either way, the Accord never saw 135 huh???

for some reason, there are no solid facts of top speeds of honda accords. I searched everywhere and all the facts were different.

Likely because people posted on websites the speeds shown on the gauges or with aftermarket mods.