Summary
More cars are sold with front-wheel-drive (FWD) than any other driveline configuration. However, for handling, FWD has cornering disadvantages over rear-wheel-drive (RWD) and all-wheel-drive (AWD). The issue is that a tire can develop maximum force longways (traction and braking) or sideways (cornering) — but it can’t do both at the same time. And with FWD, asking the front tires to develop strong cornering and acceleration/braking forces is exactly what is happening during cornering!
Making The Rear Tires Do More Work
The key FWD handling trick, then, is to get the rear tires doing as much of the cornering as possible.
Increasing Rear Roll Stiffness With A Stiffer Sway Bar Or Springs
So a major element of getting a FWD to handle is to make the rear tires do more work by increasing the load on the outer rear tire and reducing it on the inner rear tire. (And how do we do that? By fitting stiffer rear springs and/or a stiffer rear sway bar — more on this in a moment.)
Stability Control Allows You To Run Higher Rear Roll Stiffness
Good electronic stability control is the perfect parachute to (automatically) deploy if you set a FWD up for a moderate amount of oversteer, and then the driver is ham-fisted or you’re carrying a larger rear load. I am prepared to go stiffer in rear roll in FWD cars with stability control than I am in cars not so-equipped. However, either with or without stability control, when setting up rear roll stiffness, do lots of testing on slippery surfaces and with large rear loads.
Using Zero Rear Toe Or Even Toe-Out
In addition to increasing rear roll stiffness (and/or reducing front roll stiffness) to change the understeer/oversteer balance, you can alter the rear alignment. Nearly all FWDs run rear toe-in. This means that the heavily-loaded outer wheel faces a little towards the car’s centerline. Thus steering the rear inwards and so giving more understeer. However, zero toe (or even toe-out) can be used, reducing understeer.
Getting The Power Down
Running a high rear roll stiffness, as described above, will also help in FWD cornering traction. That’s because the load being carried by the front tires will be more equal. And so the inner front wheel is less likely to spin. However, if inner wheelspin does still occur, one solution — unfortunately not available on all cars — is to fit a limited slip differential (LSD).
Improving Front Grip
In addition to making the rear tires work much harder in turning the car, you can reduce understeer can by improving front grip. You can achieve this by using front negative camber and more castor. Thus increasing front tire pressures and/or fitting stickier front tires.
Driving style
Whether you find the driving style of a particular car natural depends on what you’re used to driving. In a FWD, more throttle leads to more understeer; in a RWD, more throttle leads to more oversteer!
How It Works In A Tightening Corner
Now let’s look at the handling approach in a real-world scenario: A corner that unexpectedly tightens. In a well set-up FWD, the resulting greater throttle lift will give a greater cornering rotation. This means the car will turn even more. To achieve the same thing in a rear-wheel-drive, you’d need to give it a bit bootful of throttle. And also hope there was enough power to oversteer the car around the corner. Therefore, most people’s approach of lifting the throttle when something is going wrong matches the handling characteristics of a well set-up FWD.
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