Outer Limits 4x4 Board

I'm sure most people realise that if you've got bigger tyres or different diff ratios to stock then your speedo will be out.
The usual fix seems to be to use a GPS to gauge correct speed but that won't correct your odometer.
I found this kit at Jaycar that can be used to correct an ELECTRONIC speedo (it won't work on cable speedos) for $55.
http://www.jaycar.com.au/productView.asp?ID=KC5435

This kit requires assembly (soldering) but I wouldn't say that it is a difficult build.
Below are some pics of how I fitted one to my LN106 Hilux. With 32" tyres I was reading 10% under speed on the speedo and this kit has fixed it so it's now dead on with a GPS.
You need a soldering iron but that's about it apart from some side cutters to trim the legs on the components.

The kit ready to assemble


Instructions are very clear - I only found two items that were hard to determine where they went.


Finished assembly.


Some of the soldering is a little tight but by no means too hard for DIY.


The trusty Haynes manual had a wiring diagram for the instrument cluster.


It is possible to trace the connector without a manual.


Out comes the cluster.


Remove the speedo wire so the corrector can go in-line with the sender - cluster.


You can see the in / out for the speedo wire and the 12v / ground.


I won't try to explain how to set it up as the instructions do that and it's too hard to describe but all it involves is turning a rotary switch and moving a jumper around until the speedo moves.
You can adjust in increments of 1% or 10% so it's pretty flexible and it can do + or - depending on what you need (most 4x4 will be going + due to larger wheels).
It can be adjusted as many times as needed so if you ever need to go back to stock wheels for any reason the speedo can be adjusted again.

While these are undoubtedly required for some (if not most?) vehicles with electronic speedos, there can be alternatives.

For some models of Pajero, the speedo is driven by a replaceable gear in the transfer case. The gear comes out in under 5 minutes, and replacements are available for around $30 (less if you can identify the one you need from another vehicle).

Before investing in one of these, I suggest climb under your vehicle and check out where the speedo sender mounts - see what else is down there?

Any reason why you mounted the capacitors to sit so high and away from the PCB????

I know for gear/cable driven speedos you just change the drive gear on the gearbox but I don't think that works for the electronic ones. I assume they make this kit to overcome that problem.

The legs on the components were already spread to the correct width at that height and the box I got with it would accommodate them so I just soldered them at the height. It is a little high but doesn't matter once they are in the box.

The electronic Toyota Speedos run off a gear just like the mechanical Speedos, the electronic sender just screws ion where the cable would normally screw on.

So u can also put a mechanical reduction box between the sender and the box, which is a good option if u cbf with the electronic side of it.

Downfall is, the percentage of correction is preset and can't be changed, and is dearer than the jaycar kit, but is on par with the pre built marks kit.

ae86levin wrote:I know for gear/cable driven speedos you just change the drive gear on the gearbox but I don't think that works for the electronic ones.

It does work for some electronic ones - like my Pajero. I was told it doesn't work for cable driven Pajero speedos, but haven't checked it out myself.

There are definitely some electronic speedos that need a box like this one - but some may find there is a simpler solution, if they look.

That's useful info for anyone else looking at a speedo correction. Where do you get these gears from?

I use a Marks Adaptors variable speedo ratio box on my 07 hilux.

you wire it in in series between the speedo pickup wire going to the dash from the pickup itself.

there are 2 settings so you can do one setting for daily tyres and at a flick of the switch have it set for your weekend tyres.