SLROC Forum

The speedo on my S3 is drastically out it seems.. Indicated 70mph but in actual fact was doing 59mph.

This is probably due to the tyres on it. Is there any way I can make the speedo right? or should I just learn where 30,40,50,60 and 70 are?

Thomas

Given that you're 109 isn't standard, you can't be sure what the speedo is fitted as there are a number of different ones depending on original tyre size, or what drive is in the gearbox etc. 

It's probably easier to get a passenger to sit in with a sat nav while you're driving and when it reaches 30, 40, 50 etc they could place those sticky dot things on the face of the speedo.  You might be a couple of mph out either way, but it'll give you a near enough reading for road use.     Given it's also ex military, you could check that the speedo head isn't in km/ph instead of MPH.

Duncan

On the dial of the speedo there is a small four digit number written somewhere.  This is the number of revolutions that equate to one mile.  On series motors the SWB and LWB had different speedos to cover the different tyre sizes.  You need to check if your speedo is the right one for your LR.  Using a LWB speedo in a SWB was a common modification to correct the error introduced when 750 tyres were fitted in place of the standard 600's

ZD 

You can send your speedo away for refurbishment. Costs around 70quid.
I think they need tyre sizes and number of revolutions counted off somewhere.
Richmond Speedographs or similar