1940 Chevy Car Bolt On Parallel Rear Leaf Spring Kit - Chassis Engineering

The 1940 Chevy Car Bolt-On Parallel Rear Leaf Spring Kit (AS-1020CG) by Chassis Engineering provides a complete rear suspension conversion for 1940 Chevrolet passenger cars. Designed as a direct bolt-on replacement for original torque-tube setups and obsolete factory springs, this kit accommodates modern open-driveline rear axle housings up to 3" in tube diameter and is engineered around a recommended 58" to 60" rear track width.

By pairing 2-1/2" wide slider leaf springs with matched gas shock absorbers, this package modernizes rear-end handling, absorbs road noise, and improves overall ride stability.

Key Features & Design Highlights

• Factory Hole Alignment: Front and rear spring mounts bolt into existing factory bracket holes once rivets are removed, streamlining frame installation.

• 2-1/2" Parallel Slider Leaf Springs: Uses wide leaf springs equipped with rubber bushings to absorb road harmonics and permit natural suspension flexing without harsh vibration.

• Cross-Frame Upper Shock Crossbar: Transverse mounting tube fits securely between the frame rails above the axle centerline.

• Reversible Lower Shock Retainers: Lower shock plates can be mounted angled up for standard ride height or down for lowered/lowrider applications.

• Complete Hardware & Shock Package: Includes gas shocks, shackles, spring pads, U-bolts, mounting brackets, and grade-8 hardware shipped in 3 boxes.

Technical Specification Matrix

Step-by-Step Installation Summary

1. Teardown & Factory Bracket Removal: Remove original rear axle, leaf springs, and shocks. Carefully remove factory rivets at front and rear mounts to preserve original frame mounting holes.

2. Front Mount Setup: Clamp front mounts to the frame with tabs facing toward the rear and inside. Temporarily attach leaf springs, axle housing, and wheels/tires to visually check for wheel centering within the fender opening before final 3/8" drilling and bolting.

3. Rear Mount Setup: Bolt new rear mounts using original frame holes (drilled out to 3/8"). Verify clearance around the gas tank flange to avoid rattles. Shackle mounts face toward the rear and inside.

4. Upper Shock Mount Crossbar: Clamp upper shock bar between frame rails using the 28" reference dimension as a starting point. Verify body/floor pan clearance before drilling 3/8" frame holes and bolting in place.

5. Spring & Axle Assembly: Bolt leaf springs into place using rubber bushings up front and shackles at the rear. Position axle over spring pins (removing the Nova-style center pin spacer if unneeded for your axle housing).

6. Lower Plates & Shocks: Install U-bolts, lower shock retainers (with shock studs pointed forward to the center and facing the rear), and gas shocks. Torque all fasteners.

🛠️ Important Tech & Break-In Notes:

• Spring Settling: New leaf springs naturally drop up to 1" within the first 500 miles of operation. Arching flat, slightly upright, or slightly reversed under vehicle load is normal behavior.

• Frame Snubbers Required: Ensure suspension travel bottoms out on rubber frame snubbers (such as Chassis Engineering AU-0082, sold separately) rather than fully compressing the shock absorbers to prevent shock body damage or shaft breakage.

• Bushing Material: Rubber bushings are required to absorb road noise and provide proper lateral flex; solid or hard polyurethane bushings are not recommended for this suspension geometry.