Speedo is reading roughly 10mph to high.
 

Guy's having a bit of an issue with the cars speedo, last week I put a new set of clocks in as my LCD odometer was starting to leak LCD internally. I had the mileage done to what the old clocks where at. Everything seemed ok but I noticed that the car felt slow on the road when the speedo says 40mph. Today I went to pick some bit's up and used the Sat nav which has always been just about bang on in my other cars and it was saying I was doing 60 on the M1 when my clocks said 70mph. The speedo is roughly 10mph to high no matter what speed I'm doing. I was sold the replacement clocks as MY98 V4 UK which was what I needed. An Ideas fellas.

Strange one, as IIRC this is cable driven. Maybe the speedo needle can be removed and rotated 10mph then replaced? Do a few more GPS speed checks first though.

Hi mate, the clocks aren't cable driven for the speed they were the amongst first ones to be electronic. The needle does rest at 0 when the cars on tickover. Just wondered if the clocks I bought sold as UK ones maybe import, would that affect the speed. Is there an easy way to check this at all.

Bump, any ideas guys.

What size wheels and tyres?

The speedo is calibrated to the oe rolling road radius thingy.

Thats strange as a speedo error due to incorrect wheel/tyre size/calibration usually causes a percentage error, so the faster you go the bigger the error.

for example for a speedo that overreads by 10%:

10% @ 30mph = 3mph
10% @ 60mph = 6mph
10% @ 100mph = 10mph

(inccidentally my Golf overreads by 10%)

So to be out constantly by 10mph would mean the problem is in the speedo itself IMO as the drive signal (sensors, and actual wheel speeds etc) are increasing in a linear and proportional fashion.

Has the needles/dials been messed with? Such as changing the face colours or changing from km/h to MPH etc.

Hi mate, yes when they reprogrammed the mileage on the new clocks to what the old ones said they had to take the speedo needle off to get behind to the chip. Thanks for trying to help answer this for me.

Bump still looking for help with this guys.

Bit off hassle, but if you have the old clocks, put them back in. You should be able to remove the LCD part of the speedo, and swap it out with your working clocks.
As Ali mentioned, they may have re-located the needle incorrectly when programming the chip. Where does it sit when car is idle?

It surely must be the case of the speed needle being replaced in the wrong place. Will have a careful fiddle with it this weekend mate. Handy knowing I could possibly swap the lcd over to fella cheers for that.