Tim2809 Posted February 17, 2019 Share Posted February 17, 2019 ive got a 1989 110 running 300tdi, r380 gearbox and 1.2 transfer box. speedo was reading faster than going and had 23 teeth so swapped for a blue 20 tooth drive gear. it has brought speedo closer to telling the truth but still showing 11% faster than actually travelling at and also putting 11% more miles on the clock too. any suggestions as dont think there is an alternative or do i need a new speedo head? thanks in advance Quote Link to comment Share on other sites More sharing options...
western Posted February 17, 2019 Share Posted February 17, 2019 this may help Quote Link to comment Share on other sites More sharing options...
Tim2809 Posted February 17, 2019 Author Share Posted February 17, 2019 i did have a read but im on 235/85/16 and cant find any other options as need less teeth on drive gear Quote Link to comment Share on other sites More sharing options...
landroversforever Posted February 18, 2019 Share Posted February 18, 2019 Which gear is fitted to the Puma defenders? They've got to be on the same gearing from the speedo point of view, as it's after the main gearbox. 1.2 LT230 and 235.85/16 tyres. Quote Link to comment Share on other sites More sharing options...
TSD Posted February 18, 2019 Share Posted February 18, 2019 Puma has the Blue 20T gear as well, though as it has an electronic speedo, the only reason it's the same is because there's no reason to change it. There are (I think) 5 gears available, but 20T is the limit. 11% fast sounds about normal to me. Remember they all read fast as it's illegal for it to under-read, and there is some variation from unit to unit. Easiest (but not cheap) option is to change to a Td5 speedo and reprogram it to read closer to the correct value. Quote Link to comment Share on other sites More sharing options...
miketomcat Posted February 18, 2019 Share Posted February 18, 2019 My Speedo in the ibex (standard disco 1 at the time) read 70mph actual was 57mph at the IVA test. Still a legal pass though mind only just. Mike Quote Link to comment Share on other sites More sharing options...
Tim2809 Posted February 18, 2019 Author Share Posted February 18, 2019 3 hours ago, TSD said: Puma has the Blue 20T gear as well, though as it has an electronic speedo, the only reason it's the same is because there's no reason to change it. There are (I think) 5 gears available, but 20T is the limit. 11% fast sounds about normal to me. Remember they all read fast as it's illegal for it to under-read, and there is some variation from unit to unit. Easiest (but not cheap) option is to change to a Td5 speedo and reprogram it to read closer to the correct value. do you know for a link with how to do the td5 and programming Quote Link to comment Share on other sites More sharing options...
landroversforever Posted February 18, 2019 Share Posted February 18, 2019 Have a look on retroanaconda.com James on here did a cracking write up @CwazyWabbit is the man for reprogramming it too. 1 Quote Link to comment Share on other sites More sharing options...
TSD Posted February 18, 2019 Share Posted February 18, 2019 (edited) Long thread here on reprogramming, but in short you need td5 speedo and sender unit, connectors for each, and cabling. Connect it all up and get it working as-is. Note how far out it is on the road. If you want to do it yourself, you can reprogram the speedo using a raspberry pi computer. You need to open the speedo and attach a few wires, but that's as difficult as it gets. If you're not up for that, I'm sure someone here will help out. Edited February 18, 2019 by TSD 1 Quote Link to comment Share on other sites More sharing options...
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