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July 24, 2007

VRPerformance Open Track Day at Grattan Raceway

What a great way to spend a day— at the race track in the company of great cars and like minded people. Better still, you’re driving those cars at their limit on the track without a care for police or drivers on cell phones or little children suddenly running out in front of you. And with sunny skies and temperatures in the mid 70s, the day was darn near perfect.

Our mission at VRPerformance is to make cars perform better. Many times the upgrades we do to a car cannot be completely experienced on the road. The value of a tighter suspension, bigger brakes or free flowing exhausts truly come out only when the car is driven closer to its limit than is possible on Main Street. And that’s why we sponsor open track day events like this one at Grattan Raceway in Belding, Michigan (near Grand Rapids). It’s a chance to have some safe fun while learning more about the car and its capabilities.

All told, we had 26 cars ranging from sporty to super fast. We had a few new track drivers and plenty of experts. And everybody kept in on the track for the most part. To capture the on track action as well as the mood in the paddock, for the first time we had a photographer on hand. Cody Hanson took the stunning photos you see here.

Brand new Mercedes-Benz CLK 63 AMG Black Series

Classic E30 M3

Waiting to get onto the track

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Porsche GT3

BMW E46 M3

Ghostly Lotus

A classic Porsche 930 in action


Blitzin' Blue STi

Big v. Small

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Track Star

Watching the action at the "jump"

Thanks to all those who came out and made the day a fun--and safe-- one.

July 12, 2007

Getting into Balance: Corner Balance Basics

In the world of automotive performance, the term “corner balance” is one that is often used but seldom understood. It is a further derivative of weight distribution and refers to the amount of weight or force that each individual wheel exerts on the road. By “corner balancing”, one shifts the weight carried by each wheel towards the optimal value for that car.

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At the most basic level, think of your car as a table with four legs. If the table top is 100 pounds and perfectly balanced, each leg holds 25 pounds—or exerts 25 lbs of force on the floor. Now let’s extend one leg, say the left front. All of a sudden that one extended left front leg and the leg at the opposite corner, or the right rear leg, are carrying 50 pounds each. The table will teeter on those two legs. The key to this example is to understand the relationship between the legs. In other words when you adjust a leg, the opposite corner leg is affected.

Since a car has a suspension and not stiff legs, the load is not transferred so absolutely, but it is transferred nonetheless.

The basic equations for corner balance are as follows:

fig 1) LF/LR = RF/RR -or- fig 2) LF + RR = RF + LR

LF = left front
LR = left rear
RF = right front
RR = right rear

The goal of corner balancing is to have equal front to rear weight ratios (fig 1) for both the left and right sides.

Street cars are less susceptible to corner imbalance since they run springs that are relatively soft. Performance and race cars that run spring rates higher than 300 lbs/in really benefit the most from a properly aligned and balanced suspension (think back to the stiff legs of a table example above).

In order to adjust the corner balance of a car, we need to be able to adjust the corners individually by raising or lowering the spring height (and to a lesser degree tire pressure—but that’s a whole other topic). This can only be done using adjustable spring perches such as are found on coil-over suspensions. And you thought that the fancy coil-over kit you bought was only good for ride height!

The process to corner balance a car takes a bit of trial and error. The first step is to get some initial corner weights and plug the numbers into the corner balance equation. The actual corner balance will never be as perfect as the above examples, but there are acceptable ranges. Starting with the initial readings the technician will adjust the spring heights and re-measure the corner weights, fine tune, re-measure… until the equation gets into that acceptable range. This can be a long and tedious operation, but for the track enthusiast or race car driver it is worth the effort. A properly balanced car will handle the same in left and right corners and the tire contact patches will be maximized at all four corners. The car will be more predictable and simply easier to handle.

If you have a height adjustable suspension, it only makes sense to have the car corner balanced.