Fifty years ago, the original muscle car wars were just beginning to heat up. Back then, suspension components did little to aid in any type of performance. Factory suspension components for just about all the muscle cars were basically the same: stamped steel with rubber bushings. Hey, that was high technology in the ’60s and ’70s (and it’s still the winning factory formula in many of today’s performance cars). But today the automotive performance aftermarket has much better components, and technology allows us the ability to make a classic muscle car handle well in the corners while maintaining a comfortable ride quality when cruising down the highway.
While each aspect of a classic muscle car project carries a certain level of importance, the suspension can make or break it. Whether it’s a street cruiser or an all-out race car, the right suspension components can make all the difference. While it sounds simple, the suspension is responsible for some critical aspects of the final product. Handling ability, traction, ride quality, and NVH (noise, vibration, and harshness) are all determined by the suspension components you choose.
When it comes to suspension parts, how the car will be used should dictate what options to choose. One of the biggest choices to make is what bushings to use. “Bushings are the direct connection between the suspension link and either the chassis or the differential (rear), or front tires and the chassis (front),” explains Brett Rockey, BMR Product Design Manager. “Though this seems like an obvious and almost insignificant fact, the bushings do a lot more than you may think. Most importantly, torque is transferred through the drivetrain and the bushings are the first pieces of the suspension that sees the forces of that energy.”
When it came to the rear suspension of this 1967 Chevelle street/strip project, we wanted a lot of adjustability and as little deflection as possible. NVH was not a concern so we decided to use as many solid links as possible. By solid mounting the control arms, you greatly reduce the amount of power that is absorbed as it transfers through the chassis. This means more power gets to the tires. Another benefit is more consistency in your wheel alignment.
All of the rear suspension components came from BMR Suspension in Seffner, Florida. With more drag race time than street time on this A-body’s horizon, parts were selected with that in mind. Fully adjustable upper and lower control arms with spherical bearing and rod ends replace the stamped-steel factory arms with soft rubber bushings. This will add the ability to fine-tune the suspension and dial in the alignment, ensuring the car goes as straight as possible on every pass. The upper and lower control arm mounts are linked together by BMR’s Control Arm Reinforcement Braces (PN RB001). These are designed to strengthen the control arm mounts and reduce deflection under load.
The last piece of the puzzle was BMR’s Xtreme Anti-Roll Bar. The heavy-duty sway bar is designed to be extremely stiff and keep body roll in check during hard launches. And with solid links there won’t be any wasted power, and we should see big improvements in our 60-foot times.
01. BMR Suspension’s drag race components for 1964-’72 GM A-bodies are designed to provide loads of strength and adjustability, allowing you took hook up at the track with almost any power level.
02. The stock upper and lower rear control arms on our ’67 Chevelle are made from flimsy stamped steel. While this design is fine for stock or mildly modified vehicles, the addition of any real power or hard-core drag use will cause deflection, resulting in erratic handling and inconsistent traction.
03. BMR’s adjustable upper rear control arms (PN UTCA024) feature a 1 1/8-inch, heavy-duty center adjuster that allows for on-car pinion angle adjustability. These also use a spherical bearing instead of bushings, giving you bind-free articulation without absorbing power. The solid bearings transfer every bit of power, resulting in better throttle response and acceleration.
04. BMR’s Control Arm Reinforcement Braces (PN RB001) tie the upper and lower rear control arm mounts together, adding strength to each mount. This brace reduced flex seen in the chassis in high-power/high-traction situations.
05. The factory upper control arms simply unbolt from the chassis and differential housing.
06. The stamped-steel design of the factory links does little for performance. This design allows for considerable amounts of twist and deflection in high-horsepower applications.
07. The stock rubber bushings are great at minimizing NVH, but they eventually rot, deflect, and absorb power, making them less than desirable for a racing or performance application.
08. BMR’s upper rear control arms simply install in the factory location. As a starting point, the arms are set to factory length. This is also when the reinforcement braces are installed on the upper mounts.
09. The stock lower rear control arms are designed just like the uppers. In a drag race application, the stockers are not optimal.
10. BMR’s double-adjustable lower rear control arms (PN TCA038) feature a rod end design with billet aluminum spacers for the correct offset. These arms allow you to dial in wheelbase and thrust angle, ensuring the rear wheels are pointed in the right direction.
11. The disassembly of the lowers is as simple as removing the stock bolts.
12. It’s easy to see the differences between the stock and BMR lower rear control arms when looking at them side-by-side. The BMR arm is considerably smaller in design, but offers significantly more strength. The soft rubber stock bushings are replaced with rod ends and custom billet spacers. This ensures no power is wasted as it is transferred to the tires.
13. Installation is as simple as the removal of the stock arms, and the adjustable BMR control arms are set to the factory length. Longer bolts are used on the body side to allow the reinforcement braces to attach.
14. With the uppers, lowers, and reinforcement braces installed, it’s easy to see how everything works as a system. The adjustable links will allow us to fine-tune the suspension and alignment once the tire choice and ride height is set.
15. If you’ve raced or seen a stock A-body at the dragstrip, then you know how much body roll there is. It’s not uncommon to see the left front wheel a few inches in the air and the right front firmly planted on the ground. This twisting is nothing but wasted energy and motion. Fortunately, BMR has a rear sway bar designed to correct this. BMR’s Xtreme Anti-Roll Bar (PN XSB006) is a bolt-on antiroll bar that is equally at home on the street or on the track.
16. BMR supplies heavy-duty fabricated, bolt-together axle clamps that the sway bar mounts to. At this point in the installation do not tighten them completely; wait until the sway bar is installed. This will allow for easy centering of the bar. BMR’s axle clamps are designed for specific size axletubes. Different size clamps are available, so no matter what rearend is in your A-body, BMR has a kit for you.
17. Next, the sway bar was installed to the axle clamps. Prior to bolting it on, coat the inside of the bushings with grease and install them on the bar. The supplied billet-aluminum mounts bolt to the axle clamps. With everything loose, center the sway bar and mounts on the rearend housing and tighten everything down.
18. The only fabrication required during the installation is drilling four holes in the chassis to mount the L-brackets for the sway bar endlinks. With the endlink bolted to the L-brackets and attached to the sway bar, hold the assembly to the chassis and mark the locations for the holes. The endlink should be mounted as close to straight up and down as possible.
19. The L-brackets bolt on with supplied hardware …
20. …and the endlinks are attached to complete the installation.
21. Once the suspension alignment is complete, the antiroll bar can be set. The bar should be set parallel to the ground with the driver (or the weight of the driver) in the driver’s seat. The bar should be set neutral with no preload on either side as a starting point. Preload can be added to either side based on the attitude of the car when launched.