14.8 SUSPENSION
A. Ride height may only be altered by suspension adjustments, the use of spacing blocks, leaf spring shackles, torsion bar levers, or change or modification of springs or coil spring perches. This does not allow the use of spacers that alter suspension geometry, such as those between the hub carrier and lower suspension arm. Springs must be of the same type as the original (e.g., coil, leaf, torsion bar, bellows) unless noted below and except as noted herein, must use the original spring attachment points. This permits multiple springs, as long as they use the original mount locations. Coil spring perches may be changed or altered and their position may be adjustable. Spacers are allowed above or below the spring. Coil springs may incorporate spring rubbers. Suspension bump stops may be altered or removed. For cars originally equipped with transverse leaf springs, spring type may be changed to a coil spring. Spring perches may be added to shock absorbers for mounting coil springs in a "coilover" configuration.
B. Suspension bushings may be replaced with bushings of any materials as long as they fit in the original location. Offset bushings may be used. This does not authorize a change in type of bushing (e.g., ball and socket replacing a cylindrical bushing) or use of a bushing with an angled hole whose direction differs from that of the original bushing. If the standard bushing accommodated multi-axis motion via compliance of the component material(s), the replacement bushing may not be changed to accommodate such motion via a change in bushing type, for example to a spherical bearing or similar component involving internal moving parts. Pins or keys may be used to prevent the rotation of alternate bushings but may serve no other purpose than that of retaining the bushing in the desired position.
C. The following allowances apply to strut-type suspensions. Adjustable camber plates may be installed at the top of the strut and the original upper mounting holes may be slotted. The drilling of holes in order to perform the installation is permitted. The center clearance hole may not be modified. Any type of bearing or bushing may be used in the adjustable camber plate attachment to the strut. The installation may incorporate an alternate upper spring perch/seat and/or mounting block (bearing mount). Any ride height change resulting from installation of camber plates is allowed. Caster changes resulting from the use of camber plates are permitted.
D. Differential mount bushings may be replaced but must attach in the standard location(s) without additional modification or changes. Differential position may not be changed. Solid metal bushings are specifically prohibited.
E. Steering rack bushings may be replaced but must attach in the factory location(s) without additional modification or changes. Steering rack position may not be changed. The amount of metal in a replacement bushing may not be increased relative to the amount of metal found in a standard bushing for the particular application. Solid metal bushings are specifically prohibited. This does NOT allow shimming or otherwise relocating the steering rack.
F. Camber bolts may be installed providing these parts use the original, unmodified mounting points and meet the restrictions specified in Section 14.5.B. Caster changes resulting from the use of camber bolts are permitted.
G. Solid axle rear wheel drive (RWD) suspension allowances:
1. Addition or replacement of suspension stabilizers (linkage connecting the axle housing or DeDion to the chassis, which controls lateral suspension location) is permitted.
2. Traction bars or torque arms may be added or replaced.
3. A Panhard rod may be added or replaced.
4. The upper arm(s) may be removed, replaced, or modified and the upper pickup points on the rear axle housing may be relocated.
5. The lower arms may be replaced or modified and the lower pickup points on the rear axle housing may be relocated.
6. Differential covers and attaching hardware may be replaced.
7. Methods of attachment and attachment points are unrestricted but may serve no other purpose (e.g., chassis stiffening). This does not authorize removal of a welded on part of a subframe to accommodate the installation.
H. Camber kits (also known as camber compensators) may be installed. These kits consist of either adjustable length arms or arm mounts (including ball joints) that provide a lateral adjustment to the effective length of a control arm. Alignment outside the factory specifications is allowed. The following restrictions apply:
1. On double/unequal arm (e.g., wishbone, a-arm) suspensions, only the upper arms OR lower arms may be modified or replaced, but not both.
2. On arm-and-strut (MacPherson/Chapman) suspensions, the lower arms may be modified/replaced OR other methods of camber adjustment as allowed by Sections 14.8.B, C, or F may be used, but NOT both.
3. On swing or trailing arm suspensions, the main arms may not be modified or replaced, but lateral locating links/arms may be modified or replaced.
4. Front wheel drive (FWD) cars with rear beam axles may use shims between the rear axle and hubs.
5. The replacement arms or mounts must attach to the original standard mounting points. All bushings must meet the requirements of Section 14.8.B. Intermediate mounting points (e.g., shock/spring mounts) may not be moved or relocated on the arm, except as incidental to the camber adjustment. The knuckle/bearing housing/ spindle assembly cannot be modified or replaced.
6. Changes in suspension geometry are not allowed except as incidental to the effective arm length change.
7. On multi-link suspensions only one lateral link or arm per corner may be modified or replaced. Non-integral longitudinal arms that primarily control fore/aft wheel movement (e.g., trailing arm(s) or link(s)) may not be replaced, changed, or modified." Note:
Many modern suspension designs known by other names, actually function as double A-arm designs. These include the rear suspensions on 1988-on Honda Civic/Integra, Chrysler/Plymouth/Dodge Neon, BMW E36, and most "multi-link" and are covered by Section 14.8.H.1.
I. On strut-equipped cars, the strut’s lower integral mounting bracket, for attachment to the upright or spindle, is unrestricted provided it attaches to the standard location. Any resulting change to the position of the strut centerline is allowed. Such brackets shall serve no other purpose. This does not allow for changes to the integral steering arm on cars that have the steering arm integrated with the strut body.
J. Changes in alignment parameters that result directly from the use of the allowed components are permitted. For example, the dimensional changes resulting from the use of a cylindrical offset bushing that meets the restrictions of Section 14.8.B are allowed, including those resulting from a change in the pivoting action to:
- About the mounting bolt, or - About the bushing itself.
K. Subframe mount bushings may be replaced, but must attach in the standard location(s) without additional modification or changes. Subframe position may not be changed. Solid metal bushings are specifically prohibited.