Wonky speedo!

Hi All,

i have searched, but no luck.

Vehicle is a defender 110 with Disco 3.9 v8 and the transfer box from a 200tdi disco.

Recently replaced the speedo gear in the transfer box as the other fell apart (three sides fell of the square peg hole). Took some advice from a local garage that said as it was a 110 running 235/85 i should use blue 20-tooth speedo gear. I also found through googling advice on another forum that said anything with 235/85 tyres should used this speedo gear.

However...speedo gear fitted the speed reading is way out from my GPS speedo (75 on the speedo = 65 on the gps), but the trip/ mileometer is completely accurate.

So i'm at a bit of a loss. Any ideas as to how i can make the speedo more accurate without knackering the trip reading?

Cheers in advance,
S

You can't being as they are fed by the same input (speedo cable). I would get the speedo right by increasing the teeth count on the gear (not sure what colour that is). As it is you are over-reading speed by 15% so I think you have an issue with the speedo anyway if the odometer is correct. Unless you change the speedo you have to make a choice as too which one you want to read correct.

blue speedo drive frc3310 is the one lr produce used for largest tyre size

Cheers both. I've definitely got the right gear in then. The speedo has always been optimistic. I guess it'll at least stop me from losing my license! I'm reluctant to change the speedo as it's the original one for the vehicle and i like that fact.

I might let it be, but install a gps speedo like you can get for classic cars.

my speedo is the same,there not that clever TBH