by Jim Kerr
Good ideas never die. Chrysler is building rear wheel drive cars in volume again. True, rear wheel drive has always been around in trucks and high performance cars, but most car models have been redesigned with front wheel drive. With the Chrysler 300 slated for sale in April and the Dodge Magnum coming later this year, we are seeing the resurgence of rear wheel drive in what I predict will be two fairly high volume production cars.
2005 Chrysler 300. Photo: Paul Williams
Why do I think these vehicles will be high volume? Because they are well-built, perform exceptionally well, offer excellent ride, have ample room for cargo and passengers and are priced right. But why rear wheel drive? Isn’t front wheel drive supposed to keep costs low and put the weight over the drive wheels for superior traction? Yes, that may be partially true but let’s look at what current technology allows us to do with rear wheel drive.
Traction. Putting the weight over the drive wheels in front wheel drive cars makes a lot of sense but there is more to traction than straight-line performance. Tires can only provide a finite amount of grip. This grip must be divided between acceleration, braking and cornering. Whenever some grip is used for accelerating, there is less grip available for cornering traction. With front wheel drive cars, the majority of cornering traction and all acceleration traction must be carried by the front tires. Try to accelerate too hard on a corner and the car will understeer – the front end tries to push straight ahead. Rear wheel drive helps balance the forces on the tires. The front tires are used for cornering traction while the rear tires handle the acceleration loads. Traction improves and tire wear decreases.
Even on all-wheel-drive vehicles, the torque is usually split by the transfer case to provide a majority of power to the rear tires and balance the load on the tires. All-wheel-drive does offer superior traction and handling because it maximizes the load on all the tires. Perhaps that is why performance-oriented vehicle manufacturers like Porsche and BMW offer AWD on select models and Subaru on all its models. The Chrysler 300 and Dodge Magnum will be available as all-wheel-drive models later in the year too.
2005 Dodge Magnum. Photo: Paul Williams
Electronics now enable us to control rear wheel drive traction and keep vehicles stable. When manufacturers switched to front wheel drive, we didn’t have the benefits of traction control or electronic stability systems available. Even during full throttle acceleration on slippery roads, these systems can intervene to keep rear wheel drive cars safely under control. The response time of the electronics is much faster than the driver could react, to control it even better.
Handling. Balance is the key. Balanced weight distribution, balanced traction. Rear wheel drive cars place mechanical components at the rear for more equal weight distribution. Front wheel drive cars are front heavy. Manufacturers have helped balance the weight by moving batteries to the rear, moving engines toward the back of engine compartments and reducing front overhangs. Suspension design has also changed to counter the handling effects of front-heavy vehicles. Manufacturers such as Acura and Honda have done very well in providing balanced handling but when pushed to the limits, rear wheel drive still wins out.
Cost. Combining the transmission and final drive into one unit for front wheel drive should save the manufacturers money. There are fewer castings, less mechanical parts such as driveshafts, universal joints and seals, and assembly into the vehicle requires less time. While front wheel drive would appear to have won the cost battle, there is more to cost than just building the vehicle. There are long term costs. Vehicle down time, repair costs, customer satisfaction. These must all enter into the cost equation.
When a mechanical problem develops in the driveline of a rear wheel drive vehicle, the labour it takes to remove and install components is usually much less because of easier mechanical access. Repair parts often cost less too. Have a transmission problem? It doesn’t affect the final drive. Warranty costs are lower which translate into lower vehicle costs. Customer satisfaction with lower repair bills? Priceless!
Chrysler is not alone in building rear wheel drive cars. BMW, Mercedes and Porsche have been building them all along. Other manufacturers offer rear wheel drive on some models; Honda’s S2000 or Nissan’s 350Z for example. Manufacturers such as Cadillac and Infiniti, are building rear wheel drive vehicles again.
Chrysler has taken the lead by offering rear wheel drive in vehicles that will be plentiful on our roads. Will drivers be doubtful about going back to rear wheel drive? I don’t think so. Traction, handling and lower repair costs are benefits they can enjoy.