RallyCross: Must-have modifications

Image by Philip Royle

RallyCross: Must-have modifications

SCCA / SportsCar Magazine

RallyCross: Must-have modifications

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Stepping into RallyCross is easy, but there are basic car modifications to consider

If you read our last RallyCross feature, we outlined suggestions for good cars to get you started in the sport. If you’ve already purchased a vehicle for RallyCross, great! But now what? Well, before you take your car to an event, you should be sure it’s prepared for the task at hand.

Obviously, any competition car needs to be in good working order. Beyond basic maintenance, you should make sure any worn suspension bushings or components are replaced and any low-hanging parts are either moved in to a better location (perhaps pivot that exhaust clamp) or protected with a skid plate. While skid plates under the motor aren’t strictly necessary, they will give you peace of mind and keep some grime out of the engine bay, making post-event cleanup a breeze.

Once you have the car mechanically sorted and protected, what upgrades are necessary? Much of that will depend on the class you’re competing in, but my first recommendation applies to all classes: shocks and struts. The thing to remember about your suspension is that its only job is to keep the tires in contact with the ground. To that end, a fresh set of shocks is the best bang-for-your-buck investment for RallyCross vehicle upgrades (tires notwithstanding).

The great thing about RallyCross is that you don’t need $2,000 shocks to be competitive in the Stock classes; dampers like the KYB GR2 and Excel G have been the industry standard for quite a while, and the Bilstein B6 is also a great choice. Something to remember: Stock class in RallyCross does not allow for adjustable shocks – those will bump you into the Prepared category.

Be aware, the majority of “off the shelf” aftermarket coilovers are not the correct choice for a RallyCross application, either. The spring rates in these kits are usually too high and often don’t offer enough suspension travel for loose or bumpy surfaces. And, if you do decide to purchase a set of aftermarket shocks and springs, make sure they’re intended for dirt or snow.

It’s also notable that your car doesn’t need three feet of ground clearance. Many SCCA Regions see stock height Miatas, MR2s, and other low-slung sports cars that compete without constantly denting oil pans. While a little extra height via spring or tires will offer a margin of safety, most cars are fine at the stock ride height.

Image by Rupert Berrington

Tire selection is a topic unto itself so we won’t go there today, but we will discuss wheel selection. While virtually any car can compete in RallyCross, it’s a sport that can be rough on cars, and your wheels will take the brunt of the load. To that end, it turns out that the car’s original wheels are actually a great choice for competition. Factory original wheels may be heavier than their aftermarket counterparts, but they offer intense durability, which is ideal for what you’ll be putting them through. But contrary to what you might imagine, factory steel wheels may bend easier than stock aluminum ones. Now, if you can afford rally-specific wheels, those are also ideal.

On to powertrain modifications, your best investment is going to be in some type of limited slip differential. Many will say a clutch type LSD is best for loose surfaces, but helical gear differentials have also proven to be effective. Even welded diffs work great on dirt, they just require a unique driving style.

While RallyCross speeds are not great, brakes should not be overlooked. It’s important that you choose a pad compound that’s easy to modulate and is not overly aggressive. Street pads like the Hawk HPS are a popular choice, offering great modulation while not being quick to lock the tires.

With a car ready to RallyCross, soon it will be time to discover the secrets to speed. Luckily, those come easy as the RallyCross community is one of the most generous in motorsports. To that end, don’t be afraid to ask competitors for advice – you’ll certainly learn a thing or two, and you’ll undoubtedly make a new friend.

This featured appeared in the August 2019 issue of SportsCar magazine.

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