audi a8 6 speed box for 17in wheel rf

[Huw Peplow]

Having chosen this option i need to know how many pulses per revolution the speedometer sensor produces to work out the pulses per mile entering the speedo

pulses per mile = revolutions per mile of wheel x pulses per revolution

pulses per mile = (12x3x1760/81) x pulses per revolution

any one know

[Brett James-McCall]

Huw,
What size rear are you running?

According to Goodyear F1 GS-DS 285/40-17 will turn 800 times per US mile.

Kuhmo Ecsta V710 state: 275/40-17 821; 295/40-17 799; 315/40-17 821

Brett

[Huw Peplow]

all I did was measure round the wheel at 81 inches which gives me782.2 rev per uk mile, pretty close to good year estimate .I am using cooper tyres on 17 inch rims , cant remember the exact size but the speedo needs 2500 pulses per mile minimum so assume rf has calculated using this speedo which means that there must be about 4 or more pulses per revolution!

[Jim c]

Huw

You will need to pull the speedo transducer out of the trans and count the amount of teeth on the chopper wheel.

EG 20 teeth per rev of wheel.
This will effect your calculations.

Jim

[Jerry]

Hi Huw,

There are four pulses per wheel revolution. With a tyre size of 255/50 16 the circumfrence is 2083mm which gives 772.6 revoloutions per mile. this works out at 3090 pulses per mile. Aim to set the speedo reading slightly high for the SVA test, as if it reads low then its a fail.

Hope this helps, Jerry

[Tobias]

So there is 4 pulses per rev on the audi box..
On a audi 01E there is no copper wheel its done by a sensor of some sort magnetic maybee?

[Huw Peplow]

the sensor is in a plastic case that attaches near the drive shafts and slides in there.on removal one can count 4 pulsed raised portions on the inner drive shaft .presume they are magnetic as dont know of any other way to transfer a pulse accross the gap.
Some chap called faraday might know!