Setting Up Corner Weights: Scaling Your Race Car
Corner Weights
The proper scaling of your vehicle is a critical piece of the set up puzzle. This process is typically referred to as setting up the "corner weights" which creates optimal weight balance across your tires contact patches. Simple enough, right? Well, not exactly. This article covers the process rather than the physics and science of it all. First you’ll need some scales and a way to level your garage floor or trackside paddock area.
Find a level spot to set your scales. How level? The pro’s use a machinist level, which will level an object (floor, machinery, etc) to .005 an inch per 10 feet. Yes, you read that right. Remember, any variation is exaggerated by distance. So if you are off by 1/4 inch over the wheelbase of your car, your corner weights may be off by as much as 100 pounds.
So how do you level your cracked and broken garage floor or the wavy paddock area? There are a couple of options depending on your budget.

Self-adhesive floor tile. What? I don’t want to tile the bathroom, you say? No problem. You'll use the tiles as shims to level your scales. They are hard, have almost no deflection and are very durable.
Find a spot, level things up, and then mark the spots on the floor so you don’t have to do this whole process over and over. We’ve used a Smart Level and an 8 foot aluminum level to build this contraption. Believe it or not, it works. We’ve actually done this in the field at tracks as well as in the shop. 

Once you have the spots marked and level, roll your car into position, jack it up, slide the tile and scales in place, lower the car, and you are in business!

Roll Off Levelers. These are fixtures that hold the scale and have adjustment screws built in to allow for variance in the floor. Set them on the floor, lay your leveling equipment in place and start turning the adjustment screws.
Be careful as you can drive yourself crazy looking for that last hundredth of an inch! These are portable, like the floor tiles above, are built to hold your scales and can be set up on any surface. Most include a roll off pad that allow for moving the car off the scales without raising the car off the scales. This makes adjustments MUCH easier.

Scale Platforms. You’ve seen the big teams with these. Indy. ALMS. Grand Am. NASCAR. Yet, they are not so far out of reach for the amateur racer. Scale Platforms create a level place that is the exact width and wheelbase of your car.
All include roll off platforms, so moving the car around is easy, plus ramps to roll the car on and off. Sure, they take a dedicated spot in the shop or at the track, but if you are serious then it comes with the territory. These require the use of the previously mentioned machinist level. Also used are water levels, and in some cases survey equipment!
Now we need scales. There are many types of scales made for racing, but here is some sage advice. Buy more scale than you need. Inexpensive scales that have a max range of 1000 pounds per scale sounds like plenty, but all scales have an accuracy factor, usually in the .1-2% accuracy range. 

Again, that sounds great, but this error factor isn’t always over the whole range of the scale. It may be in the “sweet spot” of say 300-600 pounds. Over or under and the factor may go higher. Now, your thinking, “Geez, how can that matter, .2% is next to nothing.” If your going to this much trouble, it just makes sense to do it right. 

Also, what if in 2 years you move from racing a 1100 pound Formula Ford to a 2800 pound Grand Am Mustang? Will the scales you bought for the FF work on that Mustang? Maybe not. Buy the right thing and they can and will!

As for choosing to go with the latest trend in wireless, or the superbly cool zero deflection models, or the models with billet scale pads, or rechargeable scales that require no 110v current, this is where your fingers get to meet Mr. Google. The sky is the limit ranging in price from $1000 for basic hard wired models to $3000 or more for billet zero deflection, mirror finish rechargeable scales. In this case choice is a good thing!

In the next article we’ll look at using the scales alignment and chassis set up.

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