If you have an STI transmission or even an STI that has a Driver Controlled Center Differential (DCCD), the question might come up of whether or not you need an aftermarket DCCD controller.
There are two scenarios where an aftermarket DCCD Controller makes sense, but the most common and obvious one is if you are installing an STI transmission into a WRX that doesn’t have the wiring, etc. to allow the DCCD to work. In this case, you would want to install a DCCD controller to be able to make use of that DCCD and to get the maximum benefit to the handling of the car for having put the STI transmission into your car.
I will say that you can run an STI transmission with no power going to the DCCD. It won’t harm the transmission, and in that configuration, the DCCD is basically in full open mode. What that means is that your transmission is in its maximum rear bias setting, so most of your power is going to the rear wheels. This can make a WRX feel more like a rear wheel drive car than an all-wheel drive car, and in some circumstances when driving on slick surfaces like snow and ice, the drive force going to the front wheels can be almost zero.
While you may like the way car feels sometimes with all the power going to the rear, with no controller, if you are ever in a situation where you need to move more drive to the front, you won’t have that option.
Beyond that, one of the reasons that an STI feels like it has so much traction does have a lot to do with how the DCCD is working. With a good aftermarket controller like the MAP DCCD, you can get that same feeling that the car is sending power exactly where it needs to even in your swap.
This brings me to the second scenario where a stand alone DCCD controller may be an advantage over the factory installed one. If you want to be able to not just put the DCCD into auto mode, but to be able to actually pick a specific way that the DCCD behaves, or to even tune the way that the DCCD behaves and reacts, then you would want an aftermarket controller.
This could be the case if you have an STI that you are turning into a rally car, or track car, just as much as if you are swapping an STI transmission into a WRX rally car or track car, etc.
We have been using the MAP DCCD Controller in both our WRX Rally Car and WRX Pikes Peak car for a while now because of the ability that gives us to tune how the drivetrain will respond. The MAP DCCD Controller comes with 10 pre-built maps to allow you to find one that gets the car to respond the way that the driver wants it to. For instance, there are 4 different tarmac maps, all with slightly different behaviors tuned in ranging from the most aggressive locking which sends more power to the front, to the least aggressive locking which keeps the majority of the power going to the rear. Because the DCCD is literally in in the center of the drivetrain, having this level of control will let you set up the way that the car handles and uses the available traction in a way that nothing else will.
And with a controller like the MAP DCCD, if you want to adjust the map that is closest to what you want to make it even better, you can do exactly that. The variety of the pre-built maps, and the total ability to customize the behavior of the DCCD is what we love about the MAP DCCD.
In short, a good DCCD controller will give you complete control over the way that the drivetrain responds, and that is a huge advantage.
- Jon Cooley