1999 Ford Expedition Rear Suspension Parts: A Complete Guide

The 1999 Ford Expedition is a full-size SUV known for its towing capacity and cabin space. Over time, the rear suspension components wear out, leading to sagging, poor ride quality, and noise. If you're looking to replace or upgrade rear suspension parts for the 1999 Expedition, understanding the options—from OEM replacements to aftermarket upgrades—helps you make a smart choice. This guide covers the key parts, common problems, and what to consider when buying.

Rear Suspension Overview for the 1999 Expedition

The 1999 Ford Expedition came with two rear suspension types: a standard coil-spring setup (on base models) and a load-leveling air suspension system (optional on Eddie Bauer and higher trims). The coil-spring version uses shock absorbers and coil springs, while the air suspension replaces coils with air springs (airbags) and uses an onboard compressor and height sensors. Identifying which system you have is critical before ordering parts.

Common Rear Suspension Problems in the 1999 Expedition

Sagging Rear End

A common issue on high-mileage Expeditions is rear sagging. On coil-spring models, the springs fatigue and settle. On air suspension models, leaking air springs or a failing compressor cause the rear to drop, especially after sitting overnight.

Bouncing or Rough Ride

Worn shock absorbers or struts (on air suspension) allow excessive bouncing. The rear of the vehicle may feel loose or unstable over bumps.

Clunking Noises

Worn sway bar links, bushings, or control arm bushings produce clunks when going over bumps or turning. The 1999 Expedition uses a solid rear axle with trailing arms and a Panhard rod; bushings in these components wear out.

Air Suspension Failure

If equipped with air suspension, common failures include cracked air springs (usually the front bags, but rear bags also leak), a failed compressor, or faulty height sensors. Many owners convert to coil springs when the air system becomes too costly to repair.

Key Rear Suspension Parts and Options

Coil Springs

For coil-spring models, replace sagging springs with heavy-duty or variable-rate springs if you frequently tow. OEM-style springs restore stock ride height. Aftermarket brands like Moog offer durable replacements. Check spring rate: Standard for Expedition is around 200-250 lbs/in; heavy-duty options go higher.

Shock Absorbers

Shocks control rebound. For standard coil suspension, you can use twin-tube or monotube shocks. Monroe and KYB offer quality options; Bilstein 4600 series are firmer for better handling. For air suspension, the shock is integrated into the air spring assembly; replacing the entire unit is common.

Air Springs (Air Bags)

For air suspension models, aftermarket air springs from Arnott or Firestone are popular replacements. They come as complete assemblies (air spring plus shock). Some kits include new solenoids. OEM replacements from Ford are expensive; aftermarket is more economical and often more durable.

Compressor and Height Sensors

If the air compressor fails, the rear will not lift. Replacement compressors are available from Arnott, Ride-Rite, or aftermarket brands. Height sensors can be replaced individually; check wiring for corrosion.

Sway Bar Links and Bushings

Worn sway bar links cause clunks. Replace with polyurethane bushings for longer life. Moog offers greasable links that outlast factory parts.

Control Arm Bushings

Rear upper and lower control arms have bushings that wear. You can press in new bushings or replace the entire arm. Polyurethane bushings reduce flex but transmit more road noise.

Axle Bump Stops

These rubber stops compress on large bumps. If deteriorated, replace with new ones to avoid metal-on-metal contact.

OEM vs. Aftermarket: Which Is Right for You?

OEM (Original Equipment Manufacturer) parts from Ford fit perfectly but cost more. Aftermarket parts vary in quality: budget brands may use softer rubber or thinner steel; mid-range brands like Moog, Monroe, and Raybestos offer good balance; premium brands like Bilstein or Arnott deliver higher performance. For critical components like air springs and shocks, quality aftermarket is fine. For bushings, polyurethane is an upgrade over rubber.

The Coil Spring Conversion Option

Many owners of air suspension Expeditions convert to coil springs to eliminate future compressor and air bag failures. Conversion kits include coil springs, shock absorbers, and adapter brackets. Strutmasters and Arnott sell complete conversion kits. Pros: lower future cost, simpler repair. Cons: loss of self-leveling ability; ride height changes if not adjusted properly. Towing capacity remains similar when using heavy-duty springs.

How to Choose the Right Parts

1. Identify your suspension type. Check the VIN or look for a compressor under the hood, air lines near the rear axle, or a switch for load leveling. If in doubt, look at the rear shock: air suspension shocks have an air line port; coil shocks do not.
2. Assess your driving needs. If you regularly tow or haul heavy loads, choose heavy-duty coil springs or upgraded air springs. For occasional use, OEM-style replacements suffice.
3. Set a budget. A basic shock/spring replacement for coil suspension costs $200-400 in parts. Air suspension repairs (air springs + compressor) run $400-800. Conversion kits are $300-600.
4. Prefer kits vs. individual parts. For air suspension, a complete air spring/shock assembly simplifies installation. For coil suspension, buy shocks and springs as a matched set if possible.

Installation Considerations

Replacing rear suspension parts on a 1999 Expedition is a DIY-friendly job if you have basic mechanic skills and tools (jack, jack stands, spring compressor for coil springs, socket set). Air suspension components require bleeding the system and may need a scan tool to reset heights. If not confident, a professional installation runs $200-400 for labor, depending on the job. Always replace parts in pairs (both rear springs, both shocks) to maintain even ride height and handling.

Final Recommendation

For a 1999 Ford Expedition with coil springs, replace sagging springs with Moog heavy-duty coils (part 81027) and pair them with Bilstein 4600 shocks (24-186321). This combination provides stable ride height and improved damping. If your Expedition has original air suspension and you plan to keep the vehicle long term, consider converting to coil springs using a Strutmasters kit (KF-8945-99) and adding Monroe shocks. This eliminates expensive future repairs and simplifies maintenance. For those who want to retain the self-leveling feature, replace air springs with Arnott A-3760 assemblies and a new compressor if needed. Regardless of your choice, prioritize quality parts from reputable suppliers and always replace worn bushings and links at the same time to avoid chasing problems later.