aftermarket electric speedo

[Tiapan]

hey guys to pass the pits the stupid guy wants my speedo to be in kmph and not mph...the thing is my digital speedo is great cuz it reads to 999mph and also can tell you your top speed all-time record, 1/4 mile times and 0-60mph times.

now the thing is, when calibrating the speedo you mesure out 2 miles, push your little speedo calibrate button and then drive the 2 miles and push the button, my electric sender pulses a set amount of times over the 2 mile distance and this number is used to calculate speed, quite simple really.

NOW i was thinking if i traveled a SHORTER distance (calculated by using km and miles) then i would be able to trick my speedo into thinking i was going faster and therfore reading a higher mph, if the distance was calculated correctly i would be able to make the speedo THINK its reading in high MPH but acctually read in kmph...........can it be done?

P.S i have already brought an autometer gauge in kph just incase and set me back almost $400 :(

[trick_xd]

Im lost by your post Tiapan ??
What is the question ?

[Yellow_Festiva]

Ok sorta off topic, well kinda.

Hmmm I had an older car that had an equally old original speedo in mph that jumped all over the place and was not entirely accurate to say the least. I then upped the wheel and tyre size to fill out the gaurds which made it even more out than before.

A copied a novel idea from another guy at the car club, I went out and bought a digital pedal bike speedo for $30 that had a top speed of around 150km/h and was able to enter the diameter of the wheel to the nearest mm.

30 minutes passing a few wires, aralditing the sensors to the wheel and the brake caliper and attaching the screen to the dash and hey presto, a digital speedo that was near on 100% accurate and even had basic trip computer, top speed and other basic functions.

Simple yet effective.

[GXL078]

In England the speed limits are in Km/h and the distances are in miles. So the dash of my brother in law's UK spec Volvo has Km/h speedo and the odometer is in miles

[dansedgli]

1mph is 1.6ish kms so if you drove 3.2 kms then pushed the button it should be close I think.

[Rollin]

Dan if he drove 3.2kms that would be 2 miles and the speedo would still read in miles!

I think it needs to be the other way around - work out how far 2kms is then push the button at the start and finish, it should read correctly then

[dansedgli]

haha oops. Dont do what I said.


2kms = 1.25miles.

[Neeek]

Originally Posted by xcgxl

In England the speed limits are in Km/h and the distances are in miles. So the dash of my brother in law's UK spec Volvo has Km/h speedo and the odometer is in miles

They are? Not last time I was there (which admittedly was 3 years ago, but I am a Pom and spent quite a lot of time there!)... 30 in town, 60 on A-roads and 70 on motorways... that's not km/h.

And Volvos are a law undo themselves! All my old cars had speedos in mph (with little km/h markers, presumably for use on the continent) and the odometers were also in miles rather than kilometres...

[Tiapan]

i think the 1.25 miles is correct, spose i will just have to go do some R&D

[thestig]

Originally Posted by Tiapan

i think the 1.25 miles is correct, spose i will just have to go do some R&D

Yeah that's right.

If you drive at 60 mph over 2 miles your time will be (2/60)=0.0333333etc hrs or 2min.

if you drive at 60 mph over 1.25 miles (2km) your time will be (1.25/60)=0.02083hrs (1.25 min)

if you take 1.25min (0.0208 hrs) to cover what your car thinks is 2 miles your speedo will think you are doing (2/0.0208)=96 mph

60 mph x 1.6 = 96 kmh.

Trust me, I'm a mathematician lol

[Piotr]

Trust me, I'm a mathematician lol
Last edited by thestig : Today at 01:16 AM. Reason: mathematical error

lol

[thestig]

Originally Posted by Piotr

Trust me, I'm a mathematician lol
Last edited by thestig : Today at 01:16 AM. Reason: mathematical error

lol

Yeah ok u got me lol, but in my defence it was 1:16 AM

[garth04]

Put the autometer one in to pass, then fit the digital one after.

[Interceptor]

umm.... possibly a stupid suggestion, but how about just driving 2km instead of 2 miles? that way instead of the speedo recognising X pulses=2 miles, it will recognise the new number of pulses as being 2 miles, and you just read the speed as being in km/h.....

[Interceptor]

what? no other suggestions?

[5tumpy]

thats what he wants to do... But he needs to know how many miles is in 2 kms....

[Interceptor]

*sigh* he doesnt need to know

the speedo he has recognises that, say, 300 pulses=2 miles, so all he has to do is drive 2 kilometers, then it will think 482 pulses=2 miles...... it will still display as MPH, but 60mph will actually be 60km/h..... does that make sense now?

[Tiapan]

YES! i think your on to something fellas...sounds simpler then i thought...hmmm the threads which require thinking are not the most popular lol, i went out and got the KPH speedo calibrated and now that i have a needle (the mph one was digital display and always read wrong) i realise why i THOUGHT my brakes were crappy.....i have been traveling at MUCH faster speeds then i thought lol,

i thought it took a long time to stop after traveling estimated 100kph but my estimations were about 60kph too low :P my god i need to get a video of the needle snapping from '0' to pointing straight down! i already have made a short driving vid but its not a good idea to post it up....pm me for a link

[Tiapan]

Originally Posted by Interceptor

*sigh* he doesnt need to know

the speedo he has recognises that, say, 300 pulses=2 miles, so all he has to do is drive 2 kilometers, then it will think 482 pulses=2 miles...... it will still display as MPH, but 60mph will actually be 60km/h..... does that make sense now?

wait a minute...wouldnt it be a smaller amount of pulses for 2 kilometers