Mopar B Body Suspension Parts: Complete Description and Guide

The Mopar B-body platform includes iconic models like the Dodge Charger, Coronet, Plymouth GTX, and Road Runner from the mid-1960s through the 1970s. These cars are known for their powerful engines and classic styling, but their suspension systems also play a critical role in ride quality and handling. This article provides a thorough description of Mopar B-body suspension parts, from factory components to common aftermarket upgrades, helping you understand what each part does and what to consider for restoration or performance builds.

Front Suspension Components

The front suspension on B-body Mopars is a torsion bar independent setup, a design that was advanced for its time. Key parts include:

Control Arms

Upper and lower control arms connect the steering knuckle to the chassis. Factory arms are stamped steel and often rust or wear at the bushings. The lower control arm houses the torsion bar socket. Upgraded tubular control arms reduce weight and allow for better alignment adjustment, especially important for lowering the ride height.

Torsion Bars

Instead of coil springs, Mopars use torsion bars that twist to absorb road impacts. They run from the lower control arm to a crossmember at the rear of the engine bay. Torsion bar diameter determines spring rate; larger bars provide stiffer suspension and better handling. Common factory sizes are 0.86- to 1.06-inch, but aftermarket bars go up to 1.14-inch or more for performance applications. When replacing, ensure both bars are matched in rate.

Shocks and Struts

Front shocks are mounted between the lower control arm and the frame rail. B-body cars originally used hydraulic shocks, but modern gas-charged units offer better damping and longer life. For heavy-duty use, consider adjustable shocks or coil-over conversions that replace the upper control arm mount and allow fine tuning.

Sway Bars (Anti-Sway Bars)

The front sway bar connects both lower control arms to reduce body roll during cornering. Factory bars were about 0.94-inch diameter. Upgrading to a larger bar (around 1.25-inch) improves handling significantly. Polyurethane bushings provide crisper response than rubber.

Steering Linkage

Steering components include the steering gearbox (manual or power) and relay linkage. The steering box mounts to the frame rail; worn boxes cause play. A popular upgrade is swapping to a faster-ratio box from a late-model or aftermarket source. The pitman arm and idler arm should be checked for wear.

Rear Suspension Components

B-body cars use a live rear axle with leaf springs. The rear suspension is simpler but crucial for traction and ride.

Leaf Springs

Multi-leaf steel springs support the axle and locate it longitudinally. Over time, springs sag, affecting ride height and handling. Replace with factory-style or heavy-duty springs that include more leaves or an additional leaf. For drag racing, slapper bars or traction bars help control wheel hop.

Rear Shocks

Shocks mount between the axle tube and the frame. Like the front, upgrade to gas shocks or adjustable units. For lower cars, consider shocks with a shorter overall length.

Sway Bar (Rear)

Most B-bodies did not come with a rear sway bar, but aftermarket kits are available. A rear bar reduces understeer and creates a more balanced feel. Typical diameters range from 5/8 to 1 inch.

Control Arms (Rear Locating)

The rear axle is also located by two lower control arms (sometimes called trailing arms or rear control arms) that connect the axle to the frame. These have rubber bushings that can deflect. Aftermarket arms with polyurethane or Johnny Joints improve geometry and reduce axle wrap under acceleration.

Steering and Brakes

Power Steering Pump and Box

If your B-body has power steering, the pump can leak and the gearbox may develop slop. Rebuild kits or remanufactured units are standard. A faster ratio box (like a 16:1 instead of 18:1) reduces the number of turns lock to lock.

Steering Column and Shaft

Inspect the coupler and rag joint at the base of the steering column. Upgrade to a u-joint style shaft for a direct feel.

Brake Components

Suspension work often goes hand-in-hand with brakes. Factory discs or drums should be upgraded for safety: larger rotors, dual-piston calipers, and braided lines. A proportioning valve (adjustable) helps balance front and rear bias.

Upgrades and Considerations

Ride Height and Alignment

With torsion bars, you can adjust front ride height by turning the adjusting bolts. But significant lowering may require dropped spindles or custom lower control arms. For the rear, leaf spring shackles or lowering blocks can drop the car. After any suspension changes, a professional alignment is necessary.

Bushing Materials

Rubber bushings are compliant and isolate noise but wear quickly. Polyurethane is firmer and lasts longer but can be noisy. For a street car, rubber is acceptable; for a performance car, consider poly or spherical bearings.

Cost and Priority

Start with shocks and bushings for the biggest improvement in ride quality. Then add a larger front sway bar. For handling, focus on torsion bars and rear springs. Budget for a quality alignment after installation.

Final Recommendation

For most B-body owners, refreshing the suspension with quality replacement parts is the best first step. Use OEM-style torsion bars from reputable brands like Moog or PST. Replace control arm bushings with polyurethane for durability. Upgrade shocks to gas-adjustable units (e.g., Bilstein or KYB). Add a front sway bar if you want sharper handling. For the rear, new leaf springs and shocks will restore ride height and control. Avoid cheap, unbranded parts. If you are building a track car or g-machine, invest in tubular control arms, adjustable sway bars, and a coil-over conversion. But for a daily driver or weekend cruiser, a well-matched combination of stock-style components will keep your B-body safe and enjoyable. Always verify compatibility with your specific year and model, and consult a knowledgeable mechanic for complex installations.