The Complete Guide to 1977 Datsun 620 King Cab Suspension Parts

If you own a 1977 Datsun 620 King Cab, you know it's a classic compact pickup with a loyal following. Keeping its suspension in good shape is key to maintaining ride quality, handling, and safety. Whether you're restoring the truck to original condition or upgrading for better performance, understanding the available suspension parts is essential. This guide covers the most common components, replacement options, and practical advice for choosing the right parts for your 1977 Datsun 620 King Cab.

Common Suspension Components for the 620 King Cab

The 1977 Datsun 620 King Cab uses a front independent suspension with torsion bars and a rear solid axle with leaf springs. The main parts you may need are coil springs (front), leaf springs (rear), shock absorbers, sway bars, and various bushings and hardware.

Coil Springs

On the front suspension, the Datsun 620 uses torsion bars instead of coil springs. However, many aftermarket setups convert the front to coilovers, but for stock restoration, you'll be dealing with torsion bars. Torsion bars are adjustable for ride height, and replacement bars are available if the originals are sagging or damaged.

Leaf Springs

Rear leaf springs are a common wear item. Over time, they can sag, crack, or lose their arch. Replacement leaf springs for the 1977 Datsun 620 King Cab are available in standard height or lowered versions. You can buy complete leaf spring assemblies or individual leaves. Look for springs that match the factory load rating if you carry heavy loads.

Shock Absorbers

Shocks are critical for ride control. The 620 uses twin-tube hydraulic shocks from the factory. Replace them with gas-charged shocks for better damping and longer life. Options include standard replacements, heavy-duty shocks for towing, and adjustable shocks for performance driving. Make sure to get shocks specifically for the King Cab, as it has a different weight distribution than the standard cab.

Sway Bars

Front and rear sway bars help reduce body roll. Some 620s came with a front sway bar, but many did not. Adding an aftermarket sway bar can significantly improve cornering. Rear sway bars are less common but available for a flatter cornering stance.

Bushings and Hardware

All suspension components have bushings that wear out. Common bushings include control arm bushings, leaf spring bushings, sway bar bushings, and shock bushings. Polyurethane bushings are a popular upgrade because they are more durable and improve handling, though they can transmit more road noise. Rubber bushings are better for a stock ride comfort.

Stock Replacement vs Performance Upgrade

Decide whether you want to keep the truck original or improve its handling. Your choice affects which parts you buy.

OEM Replacement Options

For a true restoration, use OEM-style parts. Many manufacturers produce exact replacements for the 1977 Datsun 620. These include torsion bars, leaf springs, shocks, and bushings that match factory specifications. The ride will be soft and compliant, like when the truck was new. Prices are moderate, and installation is straightforward.

Aftermarket Performance Upgrades

If you want better handling or a lowered stance, aftermarket parts are the way to go. Common upgrades include:

• Lowering leaf springs or blocks for the rear
• Adjustable coilover conversion kits for the front
• Performance shocks (e.g., KYB, Bilstein, Monroe)
• Polyurethane bushing kits
• Heavier sway bars These parts can transform the driving experience, but they may require some custom fabrication or modification. Performance parts often cost more, but they last longer and give you the ability to tune the suspension.

How to Choose the Right Parts

Selecting the right parts depends on your goals, budget, and mechanical skill.

Spring Rates and Ride Height

For stock replacements, spring rates are fixed. For aftermarket leaf springs, you can choose between standard, heavy-duty, or lowering springs. Lowering springs reduce ride height by 2-3 inches and have higher spring rates to prevent bottoming out. Check your local laws on ride height.

Shock Valving and Damping

Shocks come in different valving. Stock shocks are linear, meaning they provide consistent damping. Performance shocks often have valving that varies with speed. For a daily driver, twin-tube gas shocks are fine. For aggressive driving, monotube shocks like Bilstein offer better heat dissipation.

Bushings Material Selection

Rubber bushings are cheap and quiet but wear faster. Polyurethane bushings are more expensive and require periodic lubrication, but they last much longer and reduce suspension flex. For a street truck that sees occasional hard cornering, polyurethane is a good middle ground. For a restoration that will see gentle use, rubber is acceptable.

Tips for Installation and Maintenance

Replacing suspension parts on a 1977 Datsun 620 requires basic mechanical skills. Always work safely with jack stands. When replacing leaf springs, support the axle and chassis separately. Tighten all bolts with the suspension loaded (on the ground) to avoid preloading bushings. After installation, get a front-end alignment. Torsion bars are adjustable for height; turn the adjuster bolts to raise or lower the front. For leaf springs, you can add shims to correct pinion angle if you lower the truck. Periodically inspect bushings for cracks and shocks for leaks. Lubricate polyurethane bushings with silicone grease to prevent squeaking.

Final Recommendation

For most 1977 Datsun 620 King Cab owners, a balanced approach works best. Start with replacing worn shocks and bushings with quality parts (KYB gas shocks and polyurethane bushings are a smart upgrade). If the ride height is saggy, replace the leaf springs and torsion bars with stock spec parts. For those seeking better handling, add a front sway bar and upgrade to performance shocks. Avoid extreme lowering unless you are prepared for reduced ride comfort and clearance. Stick to reputable brands that specialize in classic Japanese trucks. Check your local auto parts store or online specialty retailers—just avoid generic listings that don't list the correct application. By focusing on the main components and doing the work yourself or with a trusted mechanic, you can restore or upgrade your Datsun 620's suspension without breaking the bank.