If you've already tackled the front suspension in part one of this series, you know that a well-sorted chassis makes all the difference in how your second-gen F-body drives. Now it's time to address the rear end. The factory leaf-spring setup on these cars was adequate for cruising in the 1970s, but it leaves a lot to be desired in terms of handling, stability, and adjustability. In this part, we'll cover the most effective upgrades for the rear suspension of a 1970-1981 Camaro or Firebird, from simple bolt-on improvements to full race-oriented conversions.
Understanding the Factory Setup
Second-gen F-bodies came with a Hotchkiss-style rear suspension using semi-elliptical leaf springs and a solid rear axle. The springs serve dual roles: they support the vehicle's weight and locate the axle laterally. While simple and durable, this design has inherent compromises. Under hard acceleration, the springs wind up, causing axle hop and poor traction. During cornering, the axle moves sideways, leading to unpredictable handling. The stock rubber bushings also allow excessive deflection, which dulls response.
Common Weak Points
- Thin, multi-leaf springs that sag over time and offer inconsistent spring rates.
- Soft rubber bushings at the spring eyes and shackles.
- No dedicated lateral locating device – the leaf springs do all the work.
- Weak shock absorbers with limited damping control.
Step 1: Upgrade the Leaf Springs
The simplest and most cost-effective upgrade is replacing the old sagging leaf springs with a new set from a reputable aftermarket supplier. Look for springs designed specifically for your car's intended use – street performance, drag racing, or handling. Most aftermarket springs offer a higher spring rate and are built with better materials, such as thicker leaves and anti-squeak liners.
Selecting Spring Rates
- Street performance: 130-160 lbs/in front, 160-200 lbs/in rear (approximate). A slight rear bias helps control wheel hop.
- Autocross or road course: 150-180 front, 180-220 rear. Stiffer springs reduce body roll.
- Drag racing: Soft rear springs (110-130 lbs/in) with slapper bars or a traction system.
Many manufacturers offer composite mono-leaf springs as an alternative. These are lighter, reduce unsprung weight, and can provide a more progressive rate. However, they may require a spacer to maintain ride height.
Step 2: Improve the Bushings
Regardless of which springs you choose, replacing the old rubber bushings with polyurethane units is a must. Polyurethane bushings provide a firmer connection between the spring, shackle, and chassis, reducing deflection and improving rear axle location. You'll feel more precise steering and better traction out of corners. For street cars, keep the inner sleeves greased to avoid squeaks. For a race car, consider spherical bearings for zero compliance, but be prepared for more noise.
Step 3: Add a Traction Device
Leaf spring rear ends need help controlling axle wrap during acceleration. Without it, the pinion angle changes, lifting the tires and causing wheel hop. Here are the most popular solutions:
Slapper Bars / Traction Bars
Slapper bars are simple lever arms that connect the axle housing to the chassis. When the axle twists, the bar contacts the spring leaf, preventing additional wrap. They are inexpensive and effective for drag racing and street use. However, they can be harsh over bumps and do nothing for cornering.
CalTracs or Ladder Bars
CalTracs and similar systems use a pivoted bar that actively controls the spring action. They provide better traction without the harshness of slapper bars. Ladder bars replace the leaf springs entirely in some setups, but they are a more involved installation and typically used in dedicated drag cars.
Traction Magnet or Diablo-style Systems
Some manufacturers sell tubular traction bars that replace the front half of the leaf spring. These are unitized with a heim joint at the axle and a bushing at the frame. They allow the spring to work freely while controlling wrap. A good middle ground for street/strip cars.
Step 4: Add Lateral Location – Panhard Bar or Watts Link
The stock leaf springs are poor at controlling side-to-side axle movement. Under cornering, the axle shifts, causing the car to feel loose. A panhard bar is a simple solution: a lateral link from the axle housing to one side of the chassis. It keeps the axle centered relative to the body. Watts links are more complex, using a pivoting center point to keep the axle perfectly centered through the entire travel, reducing bump steer.
Panhard Bar Pros and Cons
- Pros: Simple, inexpensive, effective. Works well for most street and track cars.
- Cons: The axle moves in an arc relative to the body, which can cause slight lateral shift under high G-loads. Also requires a mounting bracket that may interfere with exhaust.
Watts Link Pros and Cons
- Pros: Theoretical perfection – axle remains centered. Reduces bump steer entering corners.
- Cons: More expensive, more parts, harder to package with dual exhaust. Often used in road race cars.
For a balanced street car, a good panhard bar with solid mounts is more than adequate. For a serious corner-carver, a watts link is worth the investment.
Step 5: Upgrade the Shocks
Even with stiff springs and good bushings, a poor shock absorber will ruin the ride and handling. Modern adjustable shocks allow you to fine-tune the compression and rebound damping. For a dual-purpose car, consider a set of double-adjustable shocks from brands like QA1, Viking, or Bilstein. Set the rebound stiffer to control spring oscillation, and keep compression moderate for street comfort. For drag racing, a set of adjustable struts and shocks with a soft rebound setting helps weight transfer.
Step 6: Consider a Coil-Over Conversion
If you want the ultimate in adjustability and weight reduction, a coil-over conversion replaces the leaf springs with coil-over shocks and a four-link or three-link suspension. This is a major modification that requires fabricating mounting points, but it offers infinite spring rate choices, ride height adjustment, and better axle control. Kits are available from several aftermarket suppliers that bolt into the factory leaf spring pockets. You'll also need a panhard bar or watts link and a torque arm if going to a three-link.
Final Recommendation
For most second-gen owners who drive their cars on the street and occasionally autocross or drag race, a simple and effective upgrade path is:
- Replace the worn leaf springs with a set of high-quality aftermarket units (e.g., Hotchkis, Detroit Speed, or similar).
- Install polyurethane bushings at all spring and shackle attachment points.
- Add a simple traction bar system like CalTracs or a set of traction bars from Competition Engineering.
- Fit a panhard bar with heim joints to control lateral movement.
- Upgrade to a set of adjustable shocks, setting them to medium firmness.
This combination will transform the car's behavior: no more wheel hop, more predictable cornering, and a firmer ride that still absorbs bumps. If you plan to hit the track regularly, or you're building a dedicated race car, then a coil-over conversion with a watts link is the gold standard. But for the vast majority of hot rodders, the steps above provide an excellent balance of cost, effort, and performance improvement.
Remember to check all fasteners after a few hundred miles and re-torque as needed. Your second-gen F-body will reward you with confidence-inspiring handling and straight-line traction that you never thought possible from a leaf-spring car.