Variable-camber suspension for steering
If you've read the wheel and tyre bible, you'll know that camber is the lateral tilt of the suspension (and hence the wheel and the tyre) to the road surface. Proper camber (along with toe and caster) make sure that the tyre tread surface is as flat as possible on the road surface. The problem with regular fixed-geometry suspension is that the camber is set up to be ideal when driving straight. This means that however much you dislike the idea, when you corner, less of the tyre's tread is in contact with the road surface because the tyre has to tilt slightly when the steering is turned. In 2006, OnCamber LLC patented their variable camber steering system which they launched at SEMA in Las Vegas. Matthew Kim, OnCamber's founder and president was kind enough to send some pictures of their development system which you can see here. The idea is simple - as the steering wheel is turned, the steering input shifts the top mounts of a McPherson strut type suspension system laterally. In other words, the top of the strut is no longer solidly bolted to the strut tower. When the top mount point is moved, the camber of the suspension system changes. Turn to the left, and the mounting points shift to the left tilting the wheels over to the left giving a larger contact patch whilst cornering. ie. the inside wheel tilts and goes into positive camber(almost parallel to the outside wheel), which in turn contributes to the overall grip of the car. The variable camber action also gives even tyre wear. Pyrometer readings during testing have shown that the inside, mid, and outside tyre tread temperatures are all within 2° of each other. With regular fixed-camber steering, the inside of the tyre was 20° higher. OnCamber's development car is an RSX although they have designs on the table for double-wishbone variants of their system too. On the RSX testbed the camber plates are attached together by linear guides which permits them to move freely. The top connecting rods are mechanically connected to the steering rack. The degree of camber applied with steering is adjustable by varying the distance of the rods from the pivot point. ie: when the rods are mounted closer to pivot point you get more camber with less steering input. On track, this system has shaved 3 seconds off the development vehicle's lap times in race conditions. Whether this sytem will trickle down into consumer level cars is debatable. It's doubtful that a manufacturer would add this as standard but the racing and aftermarket scenes will undoubtedly welcome this development with open arms. 3 seconds off your lap time for a change of suspension components? Why wouldn't you? The images below show a camber plate at the top of one of the strut towers, and the mechanical steering linkage.
Anti-roll Bars & Strut Braces
Strut Braces
If you're serious about your car's handling performance, you will first be looking at lowering the suspension. In most cases, unless you're a complete petrolhead, this will be more than adequate. However, if you are a keen driver, you will be able to get far better handling out of your car by fitting a couple of other accessories to it. The first thing you should look at is a strut brace. When you corner, the whole car's chassis is twisting slightly. In the front (and perhaps at the back, but not so often) the suspension pillars will be moving relative to each other because there's no direct physical link between them. They are connected via the car body, which can flex depending on its stiffness. A strut brace bolts across the top of the engine to the tops of the two suspension posts and makes that direct physical contact. The result is that the whole front suspension setup becomes a lot more rigid and there will be virtually no movement relative to each side. In effect, you're adding the fourth side to the open box created by the subframe and the two suspension pillars.
Anti-roll Bars (Sway Bars/Stabilizers)
No, these aren't the things that are bolted inside the car in case you turn it over - those are rollover cages. Anti-roll bars do precisely what their name implies - they combat the roll of a car on it's suspension as it corners. They're also known as sway-bars or anti-sway-bars. Almost all cars have them fitted as standard, and if you're a boy-racer, all have scope for improvement. From the factory they are biased towards ride comfort. Stiffer aftermarket items will increase the road-holding but you'll get reduced comfort because of it. It's a catch-22 situation. Fiddling with your roll stiffness distribution can make a car uncomfortable to ride in and extremely hard to handle if you get it wrong. The anti-roll bar is usually connected to the front, lower edge of the bottom suspension joint. It passes through two pivot points under the chassis, usually on the subframe and is attached to the same point on the opposite suspension setup. Effectively, it joins the bottom of the suspension parts together. When you head into a corner, the car begins to roll out of the corner. For example, if you're cornering to the left, the car body rolls to the right. In doing this, it's compressing the suspension on the right hand side. With a good anti-roll bar, as the lower part of the suspension moves upward relative to the car chassis, it transfers some of that movement to the same component on the other side. In effect, it tries to lift the left suspension component by the same amount. Because this isn't physically possible, the left suspension effectively becomes a fixed point and the anti-roll bar twists along its length because the other end is effectively anchored in place. It's this twisting that provides the resistance to the suspension movement.
If you're loaded, you can buy cars with active anti-roll technology now. These sense the roll of the car into a corner and deflate the relevant suspension leg accordingly by pumping fluid in and out of the shock absorber. It's a high-tech, super expensive version of the good old mechanical anti-roll bar. You can buy anti-roll bars as an aftermarket add-on. They're relatively easy to fit because most cars have anti-roll bars already. Take the old one off and fit the new one. In the case of rear suspension, the fittings will probably already be there even if the anti-roll bar isn't.
Typical anti-roll bar (swaybar) kits include the uprated bar, a set of new mounting clamps with polyurethane bushes, rose joints for the ends which connect to the suspension components, and all the bolts etc that will be needed.
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Suspension bushes
These are the rubber grommets which separate most of the parts of your suspension from each other. They're used at the link of an A-Arm with the subframe. They're used on anti-roll bar links and mountings. They're used all over the place, and from the factory, I can almost guarantee they're made of rubber. Rubber doesn't last. It perishes in the cold and splits in the heat. Perished, split rubber was what brought the Challenger space shuttle down. This is one of those little parts which hardly anyone pays any attention to, but it's vitally important for your car's handling, as well as your own safety, that these little things are in good condition. My advice? Replace them with polyurethane or polygraphite bushes - they are hard-wearing and last a heck of a lot longer. And, if you're into presenting your car at shows, they look better than the naff little black rubber jobs. Like all suspension-related items though, bushes are a tradeoff between performance and comfort. The harder the bush compound, the less comfort in the cabin. You pays your money and makes your choice.
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The Ins and Outs of complex suspension units.
Generally speaking, this section will be more relevant to you if you ride a motorbike, but you can get high-end spring / shock combos for cars that have all these features on them. The thing to realise is that if you're going to start messing with all these adjustments, for God's sake take a digital photo of the unit first, or somehow mark where it all started out. It's a slippery slope and you can very quickly bugger up the ride quality of your vehicle. If you don't know what the "stock" setting was, you'll never get it back.
