One of the first indications...
One of the first indications of a car that has poor alignment of the four tires is that it takes a whole crew to push. Not that this is the case with this car, but most teams will say that the easier a car rolls, the better it seems to run. High rolling resistance is detrimental to peak performance and can be holding your program back.
Top teams and many manufacturers of race cars have discovered the importance of alignment. There's a long history of how alignment was established by the car builders and how that might have facilitated setup trends. There was even some manipulation of the chassis alignment to attempt to cure handling ills. Those days are mostly gone now and there's good information and many different tools available to use to establish proper alignment.
Of all of the setup parameters, including moment center location and setup balance, alignment ranks at the very beginning of the list. Why? Because when your alignment is not what it should be, nothing will compensate for it. The alignment package has a tremendous influence on the way a race car handles.
Along with the knowledge of the importance of alignment has come better equipment that we can use to check and adjust our race car so that it's aligned perfectly. The reason for the onslaught of interest in this issue is because car builders have finally bought into the importance of roll centers, setup balance, Ackermann issues, and alignment. The manufacturers of race car parts have now included in their inventory tools that help us align our race cars more accurately and quickly. We're going to show you some advanced systems available for the short-track racer.
In the past it was common...
In the past it was common to string a car by making marks on the floor. This is a good method for checking rearend square and can be used to line up the right-side tires. It's a little slower to do than the raised string method but can be more accurate due to the process of dropping points down to the floor with a plumb bob and then making direct measurements to the rearend. The numbers relate to the sequence of making the lines.
The Elements of Proper AlignmentA. Toe Settings We need to set the proper toe at the front and the rear. A set of tires that isn't toed correctly will create a lot of drag, much like applying the brakes, and sometimes more efficiently than the actual brakes. The standard of the circle track industry is to toe the front out 1/16 to 1/8 inch for asphalt cars and more, up to 1/2 inch, for dirt cars. The rear wheels are tobe straight ahead and parallel to each other, having no toe at all.
B. Front-to-Rear Tracking The tire contact patches must track straight ahead from front to rear and, in most cases, we need to line up the right-side tire contact patches. Our final alignment will show the right-side patches are in line with one another with the rearend being perpendicular to that line.
C. Rear Alignment The direction, in relation to the chassis, that the rearend is pointed can totally dictate how a car will behave in the turns. For example, on turn entry, if the rearend is pointed to the right of the chassis centerline, no amount of setup tuning will prevent the car from being loose. That looseness will stay with the car throughout the turns, especially ruining the turn exit. If the rearend is pointed to the left of the centerline of the chassis, the car will be tight through the middle and off the corner.
For many procedures, we would...
For many procedures, we would want better access to some of the components used for adjusting alignment, so removal of the wheels is necessary. When measuring with the wheels off the car, it's a common practice to use solid links in place of shocks or coilovers to position the rearend and front spindles where they would be in relation to the chassis at ride height.
There should never be any reason to misalign the rearend. It should always be perpendicular to the centerline of the chassis and to the right-side tire contact patches, which are themselves inline.
D. Ackermann Adjusted The last alignment priority, and one of the most important, is making sure you have very little Ackermann, which is the creation of additional front toe as the wheels are turned. On most - to -mile racetracks, we need very little Ackermann to make sure the wheels are tracking inline with the radius of the turn for each wheel.
Calculations show that for circle tracks with fairly large radii (much more than was used to design our passenger cars for turning the corner at the stop sign) a very small amount of added toe is needed to properly align the front wheels to their individual radii.