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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Speedometer Accuracey /cgi-bin/YaBB.pl?num=1332125205 Message started by Cavie on 03/18/12 at 19:46:45 |
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Title: Speedometer Accuracey Post by Cavie on 03/18/12 at 19:46:45 I know the speedometer on my Volusia is 5 MPH slow. They all are 5-8 mph off. How about the S-40. Are they accurate? |
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Title: Re: Speedometer Accuracey Post by verslagen1 on 03/18/12 at 19:52:35 about the same till you put a 140/90-15 on, then it's about right. |
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Title: Re: Speedometer Accuracey Post by ralfyguy on 03/18/12 at 21:10:03 Mine shows about the same speed as my GPS phone app with stock tire size. |
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Title: Re: Speedometer Accuracey Post by justin_o_guy2 on 03/18/12 at 22:38:16 I know the speedometer on my Volusia is 5 MPH slow. Shows -5 at a stop? 5 mph at 10? 65 WHEN RUNNIN 70? 95 when runnin 100? |
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Title: Re: Speedometer Accuracey Post by 12Bravo on 03/19/12 at 06:22:06 4F5C4B4A55585E5C5708390 wrote:
+1 This has been discussed a lot on BurgmanUSA.com. The Suzuki Burgman 650 speedometer reads 9-10% faster than actual speed. Most vehicles will read faster than actual speed. Speedometers can read up to 10% faster than actual speed but not slower. |
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Title: Re: Speedometer Accuracey Post by verslagen1 on 03/19/12 at 07:14:32 It's typical of all vehicle mfr's. The last thing they want is for a customer to sue them for a number of speeding tickets and a documented incorrect speedo. |
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Title: Re: Speedometer Accuracey Post by Cavie on 03/19/12 at 09:21:08 405F595E43447545754D5F53182A0 wrote:
Vol shows 5-7 mph faster at all speeds using roads side (Your speed) radar signs. Sits at 0. |
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Title: Re: Speedometer Accuracey Post by Serowbot on 03/19/12 at 09:48:12 FYI... from the department of odd facts... Speedometers aren't actually gear driven, as many people believe... The needle indicator is not physically attached to speedo cable at all.. It's position is varied by an electromagnetic force called an eddy current... The end of the speedo cable rotates a magnet within a thingy called a speedcup that the needle is attached to, and as the magnetic field increases, the needle moves... Oh,.. the weirdness!... No, don't thank me... I'm just a fount of useless information... ;D... Why did I post this?... Because I have no other useful reason for storing such a stupid little factiod... :-?... |
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Title: Re: Speedometer Accuracey Post by spacepirates on 03/19/12 at 11:17:43 4F594E534B5E53483C0 wrote:
This interested me, so I looked it up: http://en.wikipedia.org/wiki/Speedometer#Eddy_current Seems like post 1980's they switched to electronic operation, though the fact still stands that there isn't a physical-drive connection in either method. neat-o. |
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Title: Re: Speedometer Accuracey Post by Boofer on 03/20/12 at 14:22:34 Serow, A day on Mars is 24 hours, 35 minutes, 22.7 seconds, I think. I learned that in school and can't forget it. Now I'm just goofy, but you is uncommon smart. ;D |
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Title: Re: Speedometer Accuracey Post by Savage_Rob on 03/20/12 at 14:28:13 5457464442574E5546534254270 wrote:
This interested me, so I looked it up: http://en.wikipedia.org/wiki/Speedometer#Eddy_current Seems like post 1980's they switched to electronic operation, though the fact still stands that there isn't a physical-drive connection in either method. neat-o. [/quote] If the rest of the world just switched to electronics in the 80's, our thumpers are likely still using magnets. They would be cheap since nobody else wanted them anymore. I like less electronics anyway, so I hope they use magnets. |
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Title: Re: Speedometer Accuracey Post by Serowbot on 03/20/12 at 16:27:07 5361766167655F526F62000 wrote:
I think,.. by "electric",.. they are referring to digtal LCD type speedo's... Most cars and some bikes have them,... we don't... Our's is old fashioned eddy current manual... ;)... 0B26262F2C3B490 wrote:
No wonder the Martians are so far ahead of us... :-?... |
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Title: Re: Speedometer Accuracey Post by J C Stokes on 06/07/12 at 03:54:46 Hmm, I just put a 140/90 15 on. Nice to know the speedo should be accurate. |
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Title: Re: Speedometer Accuracey Post by 360k+ on 06/07/12 at 07:58:58 52415657484543414A15240 wrote:
If this is the case, wouldn't the mfrs want to the speedo to read too fast, instead of too slow? A speedo that reads too slow will GET you tickets (i.e., you think you're going 65, but really doing 70). Also if your speedo reads too slow (compared to real speed), then going to a larger aspect ratio tire will make it even slower, because the tire RPM will be lower for any given real speed. The speedo reading is directly proportional to tire RPM, but varies with tire diameter when compared to real speed. In other words, the overall final ratio will change with the tire size/mfr and also as the tire wears out (it rotates faster, or more times for a given distance). It is pretty easy to calculate the theoretical speedo reading based on various tire diameters. In another thread think I calculated 4 to 5% decrease in tire RPM going from an 80 to a 90 aspect ratio tire (assuming 140 width). By the same token you can measure tread depth when the tire is new and figure out how much smaller the tire will become as it wears out. This will give you a speedo reading delta: new vs worn out. |
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Title: Re: Speedometer Accuracey Post by sjaskow on 06/07/12 at 09:57:14 I have a 140/90-15 D404 on the back of my 06. The speedometer now seems to be accurate but my odometer is now 1/10 of a mile short per mile. This means for every actual mile I drive, I only record 9/10 of one. |
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Title: Re: Speedometer Accuracey Post by Savage_Rob on 06/07/12 at 10:18:29 61787361797D65120 wrote:
Hmmm, I have the same on mine (Dunlop 491 instead of 404, comparable) and found my speedo to be accurate but never paid any attention to the odometer. |
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Title: Re: Speedometer Accuracey Post by Greg on 06/07/12 at 10:44:11 I have a Dunlop K555 140/80-15. The speed reads correctly when I pass the radar things. I never verified the speed or distance with my GPS though. |
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Title: Re: Speedometer Accuracey Post by 360k+ on 06/07/12 at 11:51:55 59404B5941455D2A0 wrote:
As Serowbot pointed out, the speedo itself is current induced; called a d'arsonval movement. It's very similar to that used in volt and amp meters before the digital age. However, the odometer is usually gear or worm screw driven. Since it's mechanically coupled, it's probably more accurate than the speedo (to rear wheel RPM, not true speed). In any case, you need an external accurate distance measurement (or GPS) to see how truly accurate one or both readings actually is (like mile markers on some interstates). For instance, if you could find a 10 mile stretch of straight interstate and run steady at 60 mph, it should take 10 minutes (1 mile/minute). The amount of difference can be used to calculate true speed and speedo error. |
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Title: Re: Speedometer Accuracey Post by rfw2003 on 06/07/12 at 23:46:04 Before I put the 140/90 15 on mine was accurate according to GPS and someone following me in a car. Now with the 90 series tire it's off by about 3 to 4 MPH R.F. |
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Title: Re: Speedometer Accuracey Post by J C Stokes on 06/08/12 at 03:37:45 Must be better if and when you sell it |
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Title: Re: Speedometer Accuracey Post by Savage_Rob on 06/08/12 at 13:50:59 5A776D6C7776716C7D180 wrote:
Shouldn't be a problem if you ride it 'til the rear tire is almost bald! |
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