Wheel Camber and Handling Performance
Written by Jeff Ireland Tuesday, 13 September 2005
Of the many factors that can affect the handling of your '02, wheel camber is one of the most important. You can spend a large amount of money on tires, wheels, shocks and springs, and sit back and wonder why "lesser" cars continuously outpace you on the track. Chances are, they are just set up better, and part of this setup is getting the camber right. Negative camber is when the top of the tire tips inward, and positive is when it tips outward. Negative camber is necessary for good cornering performance. The main question is how much. When turning a corner the body rolls and the outside tire is forced to tip outward in relation to the road. This causes the tire to ride on it's outside edge and lose grip rather than being flat on the road. I refer to this as body roll positive camber.
To maintain the best grip we would like the tire tread to remain flat on the road. To compensate for body roll camber change auto manufacturers design in some negative camber. Again the question is how much is the right amount. To improve cornering performance and reduce body roll camber change most tuners (us included) increase roll stiffness via stiffer springs, sway bars and lowering the body (lower center of gravity).
Increasing negative camber is one of the most effective and inexpensive ways to improve handling but is often overlooked on street cars. Negative camber in the 2 degree range will have little effect on tire wear but can have a dramatic affect on reducing understeer. Insufficient negative camber is the reason many driver school students destroy the outside edges of their front tires. For perspective, the front suspension of race cars are usually set up with 3 to 4 degrees (or more) of negative camber. However, this much negative camber would quickly wear out the tires of a street driven car that spends most of it's time going straight.
Increasing Negative Camber Options:
We at Ireland Engineering offer several types of camber plates. Fixed plates are usually the best choice for performance street cars. These add a fixed amount of negative camber and use the factory upper strut bearing. These are an economical path to upgraded performance without affecting ride quality. However, customers who want more aggressive performance and/or use their cars for driver schools, track days, or autocross usually use adjustable camber plates, or a combination of plates and having their strut tubes bent for additional initial negative camber (more on this a bit below).
Fixed Camber Plates - installed top view
The adjustable plates allow you to have "street" and "track" settings and to fine tune the handling. These are available in several styles:
Race cars use camber plates with spherical bearings and solid slotted mounts. These offer no compliance but locate the suspension most accurately. We don't recommend these for street cars but some customers use them anyway, as we do on our dual purpose cars. With the racing plates you can expect increased vibration and noise.
Slotted Adjustable Racing Plates
We also offer the KMac type adjustable camber plates which are similar to the factory upper strut bearing except they have a stiff urethane bushing instead of rubber. The KMac plates are made up of 3 plates which allow the center piece containing the strut bearing to be adjusted for both camber and caster and then clamped in place when the bolts are tightened. We now offer a new type of camber plate that is exclusive to Ireland Engineering that allows the use of the factory upper strut bearing and allows up to 1.25 degrees of additional negative camber. This plate also offers up to .5 degree of positive camber for cars that are radically lowered or to correct damaged suspensions.
Please note that the amount of camber available is limited by the size of the stock top spring "hat" which hits the inner fender at around 1deg. of negative camber (or less). In order to make best use of ANY adjustable camber plate, we recommend the use of coilovers, which have a much smaller top spring "hat" which allows for more adjustability. It is also possible to get additional clearance with a little creative grinding!
K-Mac Adjustable Plates
Beyond the bolt-in options above, it is also possible to have your existing strut tubes heated up and bent to provide a fixed amount of additional negative offset dialed in. From there, you can just use stock strut top bearings, or additional racing or KMac-style adjustable plates to dial in more or less camber from that initial "hard" setting. This would allow you to have a total negative setting on track day of far more negative camber than would be possible with only using plates, then still allow for adjustment back closer to the stock setting for the drive home, etc. Easy method to measure camber:
You will need a carpenter's square and a tape measure. With the car on relatively flat surface, place the carpenters square on the ground and against the tire. The square will be touching the side wall near the ground. Measure the distance from the same point on the side wall near the top of the tire to the square. Also measure the distance between the two data points. The tangent of one degree is .017. Therefore 1 degree of camber is .017" per inch. An example is: If the two points are 20" apart , then one degree is 20 x .017" = .340". There is a slight error due to the lower side wall bulging for the weight of the car, but you can easily estimate this.
If you have any questions don't hesitate to post them to the Message Board!