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Speedo Correction - Disco 1


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Howdy all,

OK, so I've searched through the forum and found all the info I could on different speedo driven gears applicable to RRC/Disco1 and collated it and attached it here for ease of reference... There's some really good info there, so thanks guys :)

I've got a '94 Disco 1 V8 (3.9 EFI) so I'd have to conclude that I've got a blue 20t gear (FRC3310) factory fitted. With my 31" tyres, the speedo is pretty much dead-on (error of <1%) - GPS verified. I'm about to fit 4.10:1 diff gears (to replace the standard 3.54:1 gears), so that'll increase the speedo reading (and engine speed) by 15.8%. Increasing the number of teeth on the speedo gear to 23t (FRC9339) will slow down the speedo signal by 15.0%, which should bring it all back to an overall error of around 1-2% which is perfect.

Are there any flaws to this logic that I'm not aware of? Like issues with swapping the speedo gears, or finding them, or a change to the sender/cable/housing/output shaft gear/whatever that doesn't allow this? Does anyone know the colour of the 23t gear? Apart from potentially having to replace the o-rings on the sender, are there any other "consumables" that may be required for this job? Also, where could I procure a 23t speedo gear in SE Oz? Please don't mention LR dealers, as my mortgage is already maxxed-out.

Cheers :)


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