Installing a new suspension system on your Nissan 240SX is one of the most rewarding upgrades for improving handling, ride quality, and overall driving dynamics. Whether you are installing coilovers, lowering springs, or a complete strut-and-spring assembly, a methodical approach and the right preparation are essential. This guide provides a comprehensive walkthrough covering tools, step-by-step procedures for front and rear suspension removal and installation, ride height adjustment, common mistakes, and post-installation checks. By following these instructions and respecting torque specifications, you will achieve a safe and reliable setup that transforms your 240SX.

Essential Tools and Safety Equipment

Using the correct tools not only speeds the job but prevents damage to components and ensures safety. Below is a detailed list grouped by function.

Lifting and Support

  • Hydraulic floor jack – capable of lifting the front and rear crossmember.
  • Jack stands – two pairs (four stands) rated for at least 3 tons each. Never work under a vehicle supported only by a jack.
  • Wheel chocks – place behind the rear wheels when lifting the front, and vice versa.

Hand Tools

  • Socket set – 1/2” drive with metric sockets from 10 mm to 22 mm. A 14 mm, 17 mm, and 19 mm are most common on 240SX suspension bolts.
  • Combination wrenches – same sizes as sockets for tight access.
  • Torque wrench – a 1/2” drive beam or click-type (30–150 ft-lb range). Calibrate before use.
  • Breaker bar – 18” minimum for stubborn fasteners.
  • Pry bar – 24” for separating control arms and ball joints.
  • Rubber mallet – for freeing stuck components without damaging threads or aluminum parts.
  • Allen/hex keys – 5 mm, 6 mm for some coilover lock rings and sway bar end links.

Specialty Items

  • Spring compressor – required if reusing factory springs on new struts or installing aftermarket springs on OEM struts. A manual bolt-type compressor is affordable and safe when used correctly.
  • Ball joint separator – fork-type or pickle fork. Avoid hammering on ball joint threads.
  • Penetrating oil – WD-40 Specialist or Liquid Wrench. Apply a day before to seized bolts.
  • Thread-locking compound – medium-strength (blue Loctite) for nuts that see vibration, such as sway bar links.

Safety Gear

  • Safety glasses – protect from debris and spring tension accidents.
  • Mechanics gloves – cut-resistant and oil-proof.
  • Work light or headlamp – undercar visibility is often poor.

Preparation: Workspace and Vehicle

Proper preparation prevents delays and hazards. Follow these steps before removing any bolts.

  • Park the 240SX on a level concrete surface. Gravel or sloping asphalt is dangerous for jack stands.
  • Engage the parking brake and place chocks behind the wheels that remain on the ground.
  • Loosen the lug nuts on all four wheels while the car is on the ground. Then lift and support the vehicle on jack stands positioned under the front subframe and rear axle assembly (refer to the factory service manual for lift points). Remove the wheels.
  • Clean suspension components with a degreaser and wire brush. Dirt and rust will make bolt removal difficult and can hide cracks or damage.
  • Inspect the existing suspension for leaks, bent parts, or excessive bushing wear. Replace any damaged components now to avoid repeating the job.
  • Photograph or label the orientation of strut top hats, sway bar end links, and control arm hardware. This is invaluable for reassembly.

Removing the Old Suspension

Removal procedures differ between front and rear. Work one corner at a time to keep the other three corners as reference points.

Front Suspension Removal

  • Remove the brake caliper and secure it out of the way with a zip tie (do not let it hang by the hose).
  • Disconnect the sway bar end link from the strut body.
  • Remove the ABS wheel speed sensor bracket from the knuckle if equipped.
  • Remove the two lower bolts securing the strut to the steering knuckle. A 17 mm socket is typical. You may need a breaker bar.
  • Remove the three nuts on the top strut mount inside the engine bay. Hold the strut from below with one hand while removing the nuts.
  • Carefully lower the strut assembly out of the wheel well. On coilovers with adjustable lower mounts, note the preload setting for reference.
  • For separate spring/strut setups, compress the spring using a spring compressor before separating the top hat. Never remove the strut piston nut without properly compressing the spring.

Rear Suspension Removal

The rear multilink setup has more components. Access is tighter.

  • Remove the rear brake caliper and disc, and detach the parking brake cable.
  • Disconnect the sway bar end link from the lower control arm.
  • Remove the lower strut bolt (14 mm) and the upper strut mount bolts inside the trunk.
  • Remove the trailing arm bolt at the knuckle, then the upper control arm bolts. Label each bushing for reinstallation.
  • If removing the entire knuckle, detach the halfshaft nut (requires a 32 mm socket and a helper to hold the brake). Most DIY suspension swaps leave the knuckle in place and only replace the strut and springs.

Installing the New Suspension

Installation is essentially the reverse of removal, but attention to torque and orientation is critical.

Front Installation

  • Pre-assemble the new strut, spring, bump stop, dust boot, and top hat according to manufacturer instructions. For coilovers, set the spring preload to the initial recommended value.
  • Insert the assembly into the wheel well and loosely install the top mount nuts (20–25 ft-lb if using new hardware).
  • Align the lower strut bracket with the steering knuckle. Install the two bolts and tighten to 80–90 ft-lb for a 14 mm bolt (check your vehicle torque specification).
  • Reattach the sway bar end link. Use new nuts if supplied. Tighten to 30–40 ft-lb while the car is on the ground to avoid preloading the bushing.
  • Reinstall ABS sensor and brake caliper.

Rear Installation

  • Install the new strut/coilover into the trunk mount. Tighten upper bolts to 25–30 ft-lb.
  • Connect the lower strut bolt to the knuckle. Tighten to 70–80 ft-lb.
  • Reattach trailing arm and control arms in reverse order. Tighten all bolts to factory specifications (typically 60–100 ft-lb depending on diameter).
  • Reattach sway bar end link, brake caliper, and parking brake cable.

Critical Torque Points

Always consult a factory service manual or a reliable online resource (such as the NicoClub 240SX service manuals) for exact torque values. Common specifications include:

  • Strut-to-knuckle bolt: 80–90 ft-lb
  • Top strut nut: 35–45 ft-lb
  • Lower control arm ball joint nut: 55–65 ft-lb
  • Trailing arm bolts: 100–110 ft-lb
  • Rear lower control arm: 80–90 ft-lb

Setting Ride Height and Corner Balancing

Improper ride height adjustment is a common source of poor handling and premature tire wear.

Coilover Height Adjustment

  • With the car on jack stands, adjust the lower spring perch or the shock body length to the desired height. A rough starting point is 1–2” lower than stock for street use.
  • Lower the car onto a level surface and bounce the suspension several times to settle it.
  • Measure from the center of the wheel hub to the fender lip. Adjust as needed, repeating the settle-and-measure process.
  • Check clearance between the tire and fender at full lock and full compression. If rubbing occurs, increase ride height or roll the fender lips.
  • For corner weighting, take the car to a shop with scales. Aftermarket coilovers allow front/rear and left/right adjustments to balance the chassis. DIY enthusiasts can achieve a reasonable balance by setting all four corners to the same gap measurement.

Spring Preload

  • Most coilovers require the spring to be lightly preloaded (e.g., 5–10 mm) so the spring does not unseat at full droop. Over-preloading reduces droop travel and can cause harshness.
  • Refer to your specific brand’s instructions. A popular guide is the Zilvia.net forum where owners share setup tips for various coilover kits.

Wheel Alignment After Installation

Any suspension change alters toe, camber, and caster. A professional alignment is mandatory after installation. However, you can set rough camber to allow driving to the shop.

  • Toe – on the 240SX rear, toe is adjusted via eccentric bolts on the lower control arm. Front toe is set by tie rod ends. Always set toe after camber.
  • Camber – front camber adjusters (if installed on coilovers) can be set to about −1.5° for a balanced street/track setup. Rear camber is adjusted on the upper control arm using eccentric bolts or adjustable arms.
  • Caster – not adjustable without aftermarket tension rods. For daily driving, keep factory caster around +4° to +6°.

Find a reputable alignment shop that understands the 240SX chassis. Bring your own alignment specs if needed. A good resource is 240SX Motoring’s alignment guide for baseline numbers.

Common Pitfalls to Avoid

These mistakes are frequently reported by 240SX owners and can compromise safety or require redoing the job.

  • Not using a torque wrench – guessing tightness leads to stripped threads or loose fasteners. Always follow torque specs.
  • Neglecting to inspect bushings and ball joints – worn components will introduce clunks and slop even with new struts. Replace them now.
  • Forgetting to align the suspension – driving on a fresh suspension without alignment accelerates tire wear and can cause the car to pull.
  • Rushing the installation – take your time. Plan two full days: one for front, one for rear. Working late with poor lighting increases error risk.
  • Failing to preload suspension before tightening bolts – bushings and end links must be tightened with the vehicle weight on the ground (or on ramps), not in the air. Otherwise, the bushings will twist and fail prematurely.
  • Ignoring the condition of brake lines and ABS wires – stretched or kinked lines can cause brake failure. Secure them correctly with new zip ties.
  • Using old lock nuts or nylock nuts – always install new self-locking nuts on critical chassis bolts, especially top strut mounts and sway bar links.

Final Checks and Test Drive

After completing installation, perform a thorough inspection before hitting the road.

  • Double-check all bolts and nuts against the torque specification list. Mark each with a paint pen as verified.
  • Inspect for fluid leaks (brake line, shock shaft seal, power steering lines near the rack).
  • Turn the steering lock-to-lock to ensure no rubbing of tires or brake lines against the body or suspension arms.
  • Pump the brakes firmly several times to reseat the caliper pistons and restore pedal feel.
  • Lower the car completely and bounce each corner several times to settle the suspension. Check for any unusual noises like clunks or spring binds.
  • Drive slowly at first, then up to highway speed, listening and feeling for vibrations, pulling, or rattles. If any issue arises, return home and re-inspect.

After 100 miles, re-torque all fasteners (especially top strut nuts and sway bar links). A second torque check at 500 miles is recommended for competition use.

Maintenance Tips for Longevity

Your new suspension will perform better and last longer with regular upkeep.

  • Clean coilover threaded bodies and adjusters after winter driving to prevent corrosion. A light coat of anti-seize on the threads helps.
  • Inspect for torn dust boots and bump stops every oil change. Replace damaged ones immediately to protect shock seals.
  • Rebuild or replace coilover cartridges as recommended by the manufacturer (typically every 20,000–30,000 miles for track use).
  • Check alignment every 12 months or after any major impact (pothole, curb strike). The 240SX chassis is sensitive to toe changes.

By following this comprehensive guide, you can complete a DIY suspension installation on your Nissan 240SX with confidence. The key is preparation, patience, and adherence to torque specifications. Your reward will be a car that handles precisely and responds to every input with predictability. Enjoy the improved driving experience.