hi all. as some of you may know already my car failed on the speedo. i am using a koso rx1n and thought i had set it up correctly, however it is way off.
the tester gave me a print out of the speedo test.
it is as follows

Actual speed-------speedo speed
speed 1 008mph----------------35
speed 2 009 --------------------40
speed 3 011 --------------------50
speed 4 013 ------------------- 60
speed 5 014 --------------------70

now what have i done wrong? im using 195/50/15 tyres and entered a circumference of 1810mm and am using 4 magnets. i think my diff is 4.3:1. also the pick up is mounted on the prop. has anyone else used this type of speedo with it mounted on the prop? got my retest week tommorow.
any ideas guys?

atb

rob

[Edited on 14/7/08 by COREdevelopments]

[Edited on 14/7/08 by COREdevelopments]

[Edited on 14/7/08 by COREdevelopments]

when we set up the brother in laws electronic speedo we kept passing one of those speed detectors and adjusting the value until it matched, looks like its the circumference you have a problem with. Our startin point was based upon 2000 rpm with a car engine with a 5 speed box was between 40 and 50 mph do we jacked up the back end and got the car to the required rpm then checked the speed aginst this and adjusted then took it out on the road, the SVA tester should let u recalibrate the speedo

we mounted the sensors on the driveshaft ie after the diff

looking at those numbers I would say you need to divide the number you put into the Koso by 4 .

That would make it alot closer !

Cheers

Vorn

i had similar probs with mine,managed 225 mph on the jack,take 2 magnets off and go from there ,in top 40 mph should be about 2000 rpm as a starting point

dividing by 4 sounds like a good idea Vorn, i will try that and see what readings i get.

thanks
rob

nope
the kos has a minimum circumference of 3ocm thus putting it on the prop and telling it that the wheels are 1810 will put it way out.

either put it in thr front upright and mount the magnet (1) on the hub or similar.

or find somewhere that will be more than 30cm in circumference and change the 1810 to that measurement

easy job - i know as i had to change mine (pre sva luckily)

if you are using an r1 engine then be aware that the revs will be off if you set the pistons to 4 and the cylinders to 4 ...............
i had to play about with mine - thankfully i ride one so i could do a side by side check.

i'm still awaiting the actual resolutiojn to that problem from KOSO europe

You need to divide by your diff ratio of 4.3 surely because your on the prop not a driveshaft?

your values appear to be about 4.3 out - so multiply the circumference by 4.3 before entering. if this value is too large you can set it to 2 magnets, which will double your reading then adjust circumference to suit.

Richard - the circumference is NOT a minimum of 30cm - mine works just fine on output shaft about 7cm across. Rememeber the magnets pass at the same interval no matter the size of the object it's mounted to.

"russbot" the diff ratio has to do with it .


mark the ground and wheel with chalk

roll the car one rev of the wheel and mark the ground again

measure between the marks ( this is the number to put into the speedo unit)

if you have more than one magnet , divide the measurment by the amount of magnets ( someone said the Koso has a setting for the amount of magnets , if so don't divide the number )

the unit is looking for how far the car travels between each pulse from the magnets.

Cheers

Vaughan

[Edited on 15/7/08 by vorn]

and the correct answer is as russbot said, i divided the circumference by the diff ratio, which was 1810 divided by 4.3 which was 420.93 so put in 421 with 4 magnets and hey presto my speedo is almost spot on,
70 is 1 mph below
40 is 2 mph below

but thats good enough for me and the sva man

hope this helps anyone

rob

[Edited on 24/7/08 by COREdevelopments]