Speedo inaccurate....?

[FirstMK2]

My speedo reads 42 mph at 30, and the faster you go the worse it gets, at 100 it's well off the clock (only a 120 mph clock). The mileometer reads correctly though and I thought these both got the readings through the speedo cable....Help.......Please shed some light on this. The speedo has 185k on it if this makes any odds. Thanks.

[Uruk Hai]

You may have the wrong drive gear on the gearbox end of the speedo cable 

[takethefifth]

As Mr Uruk says probably someone has changed the clocks at some point but not changed speedo drive gear in the gear box.

Do a search and you should find info on checking and replacing it if necessary. 

[DarnPB]

If no luck, then you could get your speedo calibration checked. A firm called Speedy Cables can do this I think. Don't know their number. Do a Google search.

[rubjonny]

check the speedo gear in the gearbox, it should be red. Be very careful when you remove the cable though, they like to drop off the end into the gearbox!

If that checks out the speedo may have been messed with, for example does it have/has it had white dials in the past?  Remove the speedo from the clocks, then lift the speedo needle over the stop and it should rest next to an alignment mark.  If someone has refitted the needle so it rests at the stop, this will cause it to over-read.