Changing the wheels on your car is probably one of the most common modifications that people do Thats right but it CAN stop your speedo from reading accurately because of the change in diameter and that means you could be inadvertently speeding without even realising it and that means you could lose your license, and then the only way you can get to work is by walking to a JDM meet and stealing a rusty tricycle of the roof racks of a volkswagon so today we’re going to show you how to fix it, on Mighty Car Mods. Intro Sequence Moog: so we’re using a tyre size calculator on the internet and based on this we’ve entered in the stock tyre information, and then we’ve put on the new tyre and rim information which is bigger.
Now based on that its come back and calculated that the speedometer reading with the non-stock tyre is actually going to be reading 7.3% too slow. So that means if the speedo reads 60km/hour you’re actually going 64.4km/h and that is enough to get you a ticket. We’re taking the blue turd out for a quick drive to see just how far out the speedo really is compared to GPS tracking. The tyre calculator is spot on, its reading about 5km too slow.
Marty: so there’s are the tools you’re going to need. A screwdriver, a socket set, pliers and trim removal tools you’re going to need a multimeter to find the signal wires, power and earth.. and you’re going to need a soldering iron and solder to put together the speedo corrector kit. Moog: make sure you read and understand the instructions before you begin. Troubleshooting circuits like this can be a real pain in the balls (or your equivalent) Marty: now these kits can seem daunting at first, but all you need to put them together is a soldering iron some solder and a stand which you can get for around $20.
The kits are alot cheaper than buying off the shelf parts so lets put it togther. Moog: used a find tip soldering iron, and keep the tip clean, wiping it regularly on a wet cloth or sponge. (that sounds really wrong) but anyway that will help you make good solid joints. Avoid breathing the smoke from the solder because its got lead in it and lead is nasty. Okay so the kits finished and now its time to jack up your car. yes you actually need to jack up your car. So the wheels with drive are in the air. If you’ve got a mad AWD car, you’re going to have to raise the whole thing. Axle stands are particularly important because the wheels are going to be spinning,. Moog: remove the instrument cluster, and unplug the wires from the back of it Marty: now this kit is only going work on cars that have an electronic speedo so if its mechanical, you’re going to have to find gears and do it a totally different way. The other thing is, we’re only changing the speed that we’re seeing, even though the ECU often wants to know how fast the car is going, the small change we’re going to make isn’t going to effect that, but it IS going to effect how fast we see on here.
Moog: the kit can figure out how to modify the signal, we just have to find it and feed it into the input of the circuit. Moog: so probably the most challenging part of this build is working out which wire is coming from the ECU carrying the speed signal to the cluster of the car. Now if you’ve got a wiring diagram or you can get that off the internet, obviously thats the easiest way. Because we don’t we’re gonna use a multimeter and we’re gonna find out which one of these wires is carrying the signal, once we know that, we’re going to hack in this kit and it’s gonna take the speed signal from the ECU and allow us to modify it and thats going allow us to adjust what we see on the cluster. Moog: in order to find the fluctuating signal, the car has to be in gear with the wheels spinning. Moog: a really good tip if you’re looking for pins inside these plugs and you can get the end of the multimeter in then you can wrap a little bit of wire or a little bit of solder, and that will give a much thinner piece that can get into tighter places.
Set your multimeter to volts and probe each wire, the signal will be low range and will fluctuate with road speed, try each pin and give the car a rev while in gear 4th gear worked best for us, as we could get a variety of road speeds at low revs. Moog: okay so we’ve just found the right pin it’s the second one from the top right, and we can see that as we accellerate, the voltage is going up, and the way that we can prove this is right is that we put clutch in and put the brake on, you’ll see that voltage will stop Cause now we’re going down to 0km per hour and you’lls see as i acellerate again, and let the clutch out, it goes up.
So THAT is the wire that we need to splice our kit into, for some mad cluster adjustment. Marty: okay so we’re going to double check that we’ve got the right wire, we’ve plugged the cluster back in we’re gonna turn the car on. I’m gonna put it in gear, the speedo should start to climb okay, I’m going to cut the wire that Moog found and if it’s right, the speedo should drop, what a legend. Did something exceptionally useful. Moog: strip back each end of the signal wire and then grab some hookup wire Moog: why do you still have that in your car? Seriously. We spoke about this, that’s the previous owners head slime. Marty: you know why its because if that wasn’t there and people keep seeing the car and it dissapears they’ll think i’ve swapped cars, because we do sneaky stuff like that swap a total blue turd with the same K3VE conversion and dashboard and everything and if i don’t leave that, there’s no way of actually proving this is the original blue turd.
Moog: but that is scum off someone elses head… DON’T LICK IT!! DON’T.. DUDE… DON’T!. That’s my job. Moog: okay its time to connect the kit up into the cluster Solder hookup wires to both ends of the sigal wire and use heatshrink so you don’t short anything out. Marty: okay so we’ve spliced in the signal wire that goes into our kit, all we’ve got left to do is connect up the power and earth we’re gonna leave these on long wires so we can adjust it once we’ve found the right settings we’ll shorten up the wires and stick it up under the dash.
Moog: the kit takes the signal from the ECU, modifies it, and sends it back to the cluster. It also needs a power and ground, which you can find using your multimeter use a switched 12v that comes on when the key is in the on position. Moog: soldering is easy to learn and really cheap to get into, and its something that every car enthusiast should know how to do. Marty: okay so its installed, now its time to set it up. There’s a few different configurations. depending on what kind of speedo you’ve got. We’re gonna put it in 4th gear so we get a good range of speed Moog: it’s not moving yet martin. Marty: Not yet. it can take a couple of seconds. There it goes. alright so the speedo’s working as it would have originally. So adjustments are on this second dial so at idle its going to sit at just under 40km/h we adjust this, in a few seconds we’ll see the change. So that bumps it up 10ks an hour, 5ks an hour there we go. So we’ve got a coarse and a fine adjustment now its time to take it for a proper trip on the road, with a GPS and adjust our speedo so its perfect.
Moog: drop your car off the jack and hit the highway or footpath, depending on how many zombies there are. Moog: have the passenger adjust the settings while you hold a constant speed and then cross reference the speed reading from a GPS Obviously you want the reading from the GPS to be exactly the same as the reading thats on the cluster. You can put the circuit in a box, and hide it up under the dash its a accurate and easy way to adjust in the future if you ever change your wheels. Moog: so that is a properly nerdy mod, but nerdy and practical just like the blur turd Marty: thats right now if you want to get your car engineered you actually have to have a properly calibrated speedo. Moog: thats right, now if you are c hanging your wheel size to bigger than stock, and you want to get that made legal and engineered, you ave to do this mod, it is not an option is mandatory BUT if you’ve got a newer car, you may be able to make these adjustments directly with the ECU so do some research first.
Marty: if you’re rocking something, then chances are the whole speedo system going to be mechanical so obviously thats changed a whole different way. Moog: now we’ve got Mighty Car Mods Lanyards available now on the MCM which are available at shop.mightycarmods.co and we are giving you guys 20% off plus free shipping anywhere in the world, so just go to shop.mightycarmods.com Hello Martin. Seeya Mate. Seeya later mate. End Im hungry. Moog: me too. I could eat the contents of the anus of a low flying pterodactly Laughs Moog: be all like dinosaur food thats gone through a pterodactyl’s butt hole and straight into my mouth.
With a glass of dinosaur piss to wash it down. Marty: why don’t we just eat a pizza instead?.