Hi all

I have an Acewell 3250 speedo

Can anyone tell me the 4 digit code to enter to calibrate the speedo

running 195/5015,3.62 diff and 4 magnets

cheers Gavin

depends on were your taking pulses from, best place is then the only calculation is the rolling circumference of the wheel. Acewell work perfectly well with just one magnet

tony

I attached my pickup to the propshaft which meant easier (ie. shorter) wiring and only involves a quick bit of arithmetic to correct for the diff ratio. I would agree with the above that only one magnet is required although I glued an M6 nut on to the opposite side of the propshaft to maintain balance.

Once you are ready just pump up your tyres to normal working pressure (eg. 18psi) and roll the car across the garage floor using a mark on the tyre (eg. a bit of masking tape with an accurate pen mark on it where the tyre meets the ground) as a reference. Then measure between where the marks hit the ground to get circumference. Now just correct for the diff ratio (if using the propshaft) by dividing by your diff ratio.

My tyre circumference was 1858mm and my diff is 3.92:1 so I entered 474 into the computer. I would caution you though, during SVA my speedo was described by the tester as the most accurate he has ever seen which was both good and bad. I was absolutely spot on at every test speed which means I was right on the edge of failure because if I had been under-reading speed by a single MPH then I would have failed SVA. Build in a safety margin of 5 or 6 percent would be my advice. That would mean entering a higher value into the computer than the actual measured amount.

If you are using 4 magnets then you will need to divide your pulse count by 4 before entering the value into the computer. I would not recommend having 4 magnets on the propshaft as you may have issues with the pulses being too fast with 4 magnets at high speed.

HTH,
Craig.