Could this be the reason some Camaros sit higher on one side than the other?

[Mr. Anderson]

CAMARO/FIREBIRD STRUT TOWER DIMENSIONING

I just found this. Sorry for the long read. This seems to make sense. What do you think?

In order to meet safety, performance and design standards, General Motors vehicles adhere to strict tolerances during the manufacturing process. These same tolerances must be met by repair specialists whenever they perform structural repair or body work on GM vehicles.

The topic of this document is the upper strut tower mounting hole locations on the Chevrolet Camaro/Pontiac Firebird. These holes provide the upper mounting location for the shock absorber/spring assembly on the
Camaro/Firebird SLA (Short Arm/Long Arm) front suspension systems. The intention of this information is to explain the manufacturing process used to locate the upper strut tower mounting holes, and to minimize
confusion concerning proper measurement procedures required during collision repair.

UPPER STRUT TOWER HOLE LOCATING
During manufacturing the upper shock absorber/spring assembly mounting holes are located using a process called “form and pierce.” During this process the forming and piercing equipment positions itself in relation to
the datum and center line. By allowing the equipment to accommodate the slight variations within vehicle build tolerance, the strut tower holes are always located at the same height from the datum. The forming and piercing equipment reads each vehicle’s position and performs its function accordingly, regardless of whether the strut towers are slightly high or slightly low in relation to the vehicle. As mentioned, the forming and piercing equipment has the ability to always place the strut
mounting holes at the same height from datum.
However, because each strut tower mounting surface is pitched inward and slightly rearward, the holes will not necessarily have the same width measurements.
The length measurements are virtually unaffected by this process.

Example #1: The “Perfect” Position In this example, the vehicle is in perfect position for forming and piercing
because the strut towers are perfectly level and square relative to the datum and center lines of the vehicle. As the piercing equipment drops into place, it will locate the strut tower holes the same distance from the center line.


Example #2: High Left, Level Right In this example, the strut tower is slightly high to the vehicle on the left
(driver's) side, but not enough to be out of build tolerance. As the piercing equipment comes into position, it will encounter the left strut tower closer to the centerline on the inboard slope. As a result, the holes on the left side
tower will be more inboard than those on the right. Likewise, the point-topoint measurement for these holes will be different from the vehicle in example #1, however, the holes remain equal in height from datum.

Example #3: High Left, Low Right In this example, the strut towers are slightly high on the left (driver's) side, and slightly low on the right (passenger's) side of the vehicle, but not enough to be out of build tolerance. As the piercing equipment comes into position, it will encounter the right strut tower farther outboard from centerline and the left strut tower closer to the center line. As a result, the
holes on the left side tower will be more inboard than those on the right. However, as before, the height of the holes from the datum remains the same.

PERFORMING MEASUREMENTS ON THE F CAR The set of variables described in these three examples is repeated over and over again as vehicles undergo the piercing process. The result is that some vehicles may have strut tower hole measurements that are out of range of the
published tolerances.

In reality, the hole measurements are correct in the most critical area: height from the datum plane. This measurement is critical to ensure proper vehicle attitude and curb height. Holes that are too high or too low from the datum would cause a misalignment of the suspension and steering systems.

Because the strut tower hole locations may vary slightly in terms of their inboard/outboard positions (0–13mm overall width variance), accurate tram measurements cannot be taken from the strut tower holes to other locations
on the vehicle. Three-dimensional measuring systems should be used on these vehicles. Notice the intersection points of the solid lines in example 3. They intersect the strut tower the same distance from the centerline and the same height from the datum, while the dotted lines measure a different width from the centerline and yet retain the same height from the datum.