Speedo under-read..20% !!

Ok..anyone elses speedo reading way out? I shall use a gps for accuracy tomorrow but i drove through 3 of those digital 'Your speed is'' signs today..

The sign said 40mph when my speedo said 35mph (12%)
50mph 42mph (16%)
60mph 50mph (20%)

Now I dont know if this is just my speedo or a combination of the non-standard wheels/tyres and the speedo..or whether these digital signs over-read to slow you down a bit..

I must admit, the speedo never gets above 65mph, which is a bit odd as i have the 200tdi with the defender box/disco transfer..it certainly feels faster than 60mph when i settle on the motorway..much quicker than the old N/A..

All a bit odd really..

maybe it was more happy bein baby blue

there are several drive units available to fit to transfer box to correct it

Would you care to point me in their direction oh lord of the open flys...

Cheers!

mine reads similair - under reads, so always use gps for speed reading though not needed here as no cameras to bother you, only for when in spain/france and uk

I would guess it's the disco box that does it. My speedo on my 200 used to read over but now with the big wheels, it's pretty much right most of the time.
Oh and maybe this helps but there's one of those speed signs across from where I live and it goes off on every car. It's supposed to be at 30mph and the sat nav said 28 and it went off. Doesn't tell you your speed though like others it just flashes up 30.

Combination of ratio's the link describes it

fanatic said:

Combination of ratio's the link describes it

Click to expand...

Yeps, just trawled thru it..reckon i need the blue one (why they name them after a colour is beyond me) for a 20 tooth drive..part no FRC3310, only a tenner from craddocks..paddocks dont recognise the part number..

Speedo drive gears - LR4x4 - The Land Rover Forum

90/110 speedo drive gears
frc3310 blue --------- 20 teeth
frc3311 green ------- 21
frc3312 yellow ------ 22
frc3313 red ---------- 24

Discovery 1 [200Tdi/V8]
frc3310 blue ------- 20----diesel
frc9339 ------------- 23----[see note]

frc3310 blue ------- 20 ---- V8 efi
frc9339 ------------- 23 ---- V8 twin carb

Note frc9339 diesel for gulf states vehicles,no colour code listed, auto trans Tdi vehicles

my 200Tdi 110 runs a blue 20t frc3310 on 255/85r16 tyres, speedo is nearly spot on with my gps- less than 4 mph difference, hope that helps

Click to expand...

Should sort out just about all combinations