What Tuners Need to Know About the 2017 Ford Focus RS

From Road & Track

If there were ever a car made for enthusiasts, it's the 2017 Ford Focus RS. As I covered in my review of the RS, it's absolutely fantastic. And it just loves going sideways. But during the engineering presentation, and then on my drive, a couple red flags made me wonder if this car would end up being quite the tuner toy we'd all hoped.

First, as Ford explained during the pre-drive presentation for the RS, the car's driveline was optimized for 350 horsepower and 350 lb-ft of torque. That means the driveline is as light as possible to improve performance while still being able to reliably put down power-especially under Launch Control. But that also means the driveline is quickly approaching its limit for handling more power.

According to Ford, any increase in power would be split four ways to each of the wheels. The RS has the ability to transfer 70 percent of the power to the rear wheels, so a 100-hp increase only loads each rear wheel by an additional 35 hp, implying there might be a little wiggle room. Not a lot, though.

The other concern is regarding Ford's excellent Torque Vectoring Rear Drive Module (RDM), which combines a differential and two hydraulically activated clutches to control the power distribution to the rear wheels. I've seen plenty of people speculate that the Rear Drive Module could be the car's weak spot, and they might be right. While doing hot laps on the Circuito de la Comunitat Valenciana Ricardo Tomo, I managed to shut down the AWD system. Admittedly, I wasn't driving normally, but it's still worth noting.

Here's what happened: I put the car into Drift Mode and was forcing it to slide from one corner to the next in third and fourth gear. After a few laps, something started whining in the back of the car as I slid through the apexes. A few corners later the sound was gone . . . along with my all-wheel drive. The rear differential had suddenly just stopped working. The car was much better in front-wheel drive than I expected, but there was a lot of wheel spin exiting the corners while aggressively putting power down.

I jumped in a new car, switched back to Track Mode, and never had another problem. Ford told us the AWD system comes with built-in thermal safeguards to prevent damage to the driveline, and I'm willing to bet I overheated something by driving the car too aggressively. At least the car was smart enough to turn off the rear diff to prevent any damage. Again, it's important to note that I was driving the RS hard. We spent hours drifting the cars in circles at lower speed and never had an issue.

Part of the point of the thermal safeguards is to ensure the clutches in the rear differential are "lifetime" parts. When you overdrive the car, it remembers and assigns a value to your punishment. When the points add up high enough, the car tells you to change the differential fluid. There is a cooler for the front Power Distribution Unit, so maybe Ford will offer a rear-differential cooler through their Performance Parts catalog, so you can drift for hours at high speed without having to worry about the rear diff.

As for the brakes, they are outstanding, and it's doubtful many tuners will change the factory setup. The suspension can be upgraded like any car, but then you would lose the 40 percent increase in dampening rate when you select Sport Mode. It would be great if Ford worked with Tenneco to also offer a set of aftermarket shocks for Sport Mode and up that could handle the stiffer spring rates needed for hard track driving.

That just leaves horsepower, and as we've seen with Ford's other turbo products, there is a lot of room to increase power by increasing turbo boost. The intercooler is massive on the RS for a production car, and should be able to cool the extra pressure. The only question is whether the RS driveline, specifically the rear differential, will be able to handle it.