UK-POLOS.NET - THE VW Polo Forum

Can anyone answer this question for me?

Since I fitted a new MK2 Speedo in my Polo (The dials with Speedo on the left/Rev counter on the right and digital clock in the middle) I am not 100% sure as to what speed I am doing anymore!

The dials on my old speedo go from 0 round to 100mph if I remember rightly whereas the new dial (which I think is from a Golf) goes from 0 - 120mph (there's a 20mph difference). Should this cause a problem when fitted in my car?

I ask this because I've driven behind the wife in her car while she was doing 30mph and my dial read 40mph. And when I'm doing 70, it read more like 90mph!!!!

I've also noticed that the milage counter is a few miles out too (For every 10 miles I travel it counts about 13!)

Is this because I've taken dials from a faster car and put them into a slower car or shouldn't this matter and it's actually a faulty set of dials that I've got?

Nothing's faulty. Those dials juast aren't meant to be fitted in that car.

there is a number on the speedo, usually 1578 on a polo 100mph speedo and 1540 on a golf. This equates to the number of speedo drive revolutions per mile, so 1540rpm at 60mph. Which means that at 60mph, your speedo drive it doing 1578rpm, which makes your speedo read 62mph. Another thing that makes a differece is tyre size, golf have higher profile tyres than polos, so smaller tyres will make the speedo give a high reading.

Why did you use the 120 speedo by the way? Its possible to swap the speedos around. This will also mean you can retain the correct mileage.

i have a 120 speedo in my car and never had any troubles and my car still goes off the clock

this has only happened on the rollers

I was having problems with my original speedo - the pointer kept sticking at the 10mph (home) position and it also looked as if they'd cleaned the clear plastic cover with a brillo pad!! On my previous Polo the dials were a speedo on the left and clock on the right so I posted on here about changing the clocks and got a few replies telling me what would fit and so on. I saw some clocks on ebay and I decided I'd have a go at changing them. No one told me about the difference in speedo calibration though!