You should be building a Rear Wheel Drive Rally Car
Like most noobs lacking experience or guidance, I wanted to build an all wheel drive car when I first set out to get behind the wheel of a stage rally car. Watching purpose-built World Rally Championship machines spewing gravel from all four tires was a serious influence on that train of thought. Another influence was my familiarity with the Diamond Star Motors platforms, so my first idea was to build a Mitsubishi Eclipse GSX or Eagle Talon TSi. In fact, I purchased a couple of these with real intentions to create a rally car. I fiddled with them a bit, but never got very far. I was in my early 20’s with a new wife, a new house, a new job, and four years’ worth of student loans.
Then I came to the realization that a two wheel drive car would be more practical as there are fewer parts to deal with, the classes are more broad, and most folks who know a thing or two about rally race driving will recommend starting with two driven wheels. The old timers will tell you that this helps develop better fundamentals. I took the advice and acquired a couple Plymouth Colt hatchbacks to begin a new rally build. However, before I got very far down that path, I saw the light.
Rear wheel drive rally is where the real fun is.
In 2011 I was given the opportunity to co-drive for Ian Seppanen in his S13 240sx rally car at Lake Superior Performance Rally. It fundamentally changed the way I looked at rally cars. I rode with Ian on a handful of occasions and I can’t tell you how many times I heard him giggling through the intercom while we were on stage. The 240sx was not only fun, it was also a solid rally car. It didn't often need much more than fuel during service. The whole experience left a vivid, lasting impression.
Photo by Scott Rains. Memed by me. Scott said it was ok. I was in the car when this picture was taken.
Front engine, rear wheel drive layouts are an even further simplification of a 2WD platform. In rally, simple can be a good thing, especially during service when you don't have much time for troubleshooting or repairs. In most cases, the entire engine is easily accessible. Transmissions are relatively easy to remove and work on. Differentials are a separate component of the drivetrain which makes it tremendously easier to modify and service as opposed to FWD and AWD. Just think about what it would take to change the final drive ratio if you wanted to. It's really easy to do that during service with a RWD car.
Aside from the subjective advantage of simplicity, RWD rally cars have objective mechanical advantages too. Tire loading tends to be more evenly spread across all four tires. FWD cars do all of the accelerating, most of the braking, and almost all of the turning on the front two tires. When the rear tires do the accelerating, it means the front tires have more capacity for braking and turning. There is only so much load a tire can handle before performance drops off. It all comes down to heat, grip, and wear - more heat means less grip and more wear. This is important because aside from fuel, tires are the most used consumable in rally. Depending on what kind of fuel and tires you use, these could also be one of the biggest expenses as well. I could probably write an entire article about rally specific tires, but I'll save it for another time.
The other mechanical advantage for RWD is that they have an inherent tendency to oversteer. In a motorsport where sliding around a corner can actually be faster, having the ability to easily rotate the car is a benefit. However, it also introduces higher risk of spinning out or crashing into a tree backwards if not used with discretion. Obviously it takes practice and experience to gain the skills required to ride that fine line of control, especially as your speed increases; but the ability to maintain a drift around a corner will yield faster times than trying to hold momentum through a corner for as long as physics will allow. It is a lot of fun and the fans really love it too.
Look, if you don’t believe that RWD is a great way to participate in rally, go strike up a conversation about rallying a Volvo on social media, and mention that you’re looking for the most smiles per dollar. You'll meet some pretty enthusiastic advocates.