Understanding Delrin Bushings

Delrin, an acetal homopolymer, is a high-strength, low-friction engineering plastic commonly used in performance suspension applications. Unlike rubber or polyurethane, Delrin offers minimal deflection under load, providing precise geometry control and immediate steering response. This material is especially popular in racing, track-day cars, and high-mileage vehicles where consistent alignment and reduced bushing compliance are critical.

Delrin bushings resist oil, grease, and many solvents, and they maintain dimensional stability across a wide temperature range. However, they transmit more road noise and vibration than rubber, making them less suitable for daily-driven comfort-oriented vehicles. When installed correctly in control arms, Delrin bushings eliminate the slop associated with worn rubber, tighten suspension feel, and extend the life of ball joints and tie rods by reducing unwanted movement.

Tools and Materials Needed

Having the right equipment ensures a smooth installation and prevents damage to the control arm or new bushings. Below is a detailed list of required items.

  • Jack and jack stands – A floor jack rated for your vehicle weight and a set of four jack stands. Never rely on the jack alone.
  • Socket set and wrenches – Metric or SAE sizes that match your vehicle’s control arm bolts. A breaker bar and torque wrench are mandatory for final tightening.
  • Ball joint separator – A pickle fork or a screw-type separator to disconnect the control arm from the steering knuckle without damaging the ball joint boot.
  • Hydraulic press or bushing installation tool – A shop press (10-ton or greater) is ideal. For on-car bushing replacements, a specialized bushing tool with threaded rods and cups can work, but a press yields better control.
  • Lubricant (silicone-based, high-temp) – Prevents galling during insertion and aids future removal. Avoid petroleum-based lubes that can degrade Delrin.
  • New Delrin bushings – Obtain a set matched to your specific control arm make and model. Some Delrin kits include outer sleeves; confirm compatibility.
  • Safety gloves and eye protection – Press work creates pinch points and metal shavings. Wear cut-resistant gloves and impact-rated safety glasses.
  • Wire brush, penetrating oil, and rust remover – For cleaning the control arm bores and freeing rusted bolts.
  • Rubber mallet and brass drift – Useful for aligning parts during reassembly without marring surfaces.

Preparation and Safety

Proper preparation reduces risk and installation time. Begin by parking the vehicle on a level surface, engaging the parking brake, and chocking the rear wheels. Use the jack to lift the vehicle at the designated lift points, then place jack stands under the frame rails or subframe close to the control arm pivot points. Lower the vehicle onto the stands and verify stability before proceeding.

Loosen the wheel lug nuts before lifting the vehicle. Once raised, remove the wheel and set it aside. If your vehicle has a strut assembly or sway bar links that obstruct access, disconnect them according to the factory service manual. Photograph or label connections to simplify reassembly.

Workspace Setup

Work in a well-lit, ventilated area. Lay out tools on a clean surface. Place the hydraulic press on a stable floor or bench. If using a press, ensure it is bolted down or adequately weighted to prevent tipping. Keep a fire extinguisher nearby when using penetrating oil or solvents.

General Precautions

  • Never work under a vehicle supported only by a hydraulic jack. Always use jack stands rated for the vehicle weight.
  • Wear safety glasses when hammering, pressing, or cleaning with wire brushes.
  • Disconnect the battery if working near electrical components or if the control arm is attached to a steering rack sensor.

Removing Old Bushings

Removing factory rubber or polyurethane bushings requires controlled force. Start by unbolting the control arm from the vehicle. Typically, there is a pivot bolt at the frame side and a ball joint or lower strut connection at the knuckle side. Use the ball joint separator to break the taper without damaging the stud threads. Remove the control arm completely; this allows you to work on a bench or press.

Cleaning the Control Arm

Inspect the control arm for cracks, bending, or corrosion. Use a wire brush to clean the bushing bores inside the arm. Apply penetrating oil to any stuck hardware and wait several minutes before unscrewing. If the old bushing has a metal outer sleeve, it may be rusted in place; apply heat cautiously with a propane torch (avoid heating near fuel lines) to expand the steel sleeve before pressing.

Pressing Out Old Bushings

Position the control arm in the press with the bushing centered over a cup or receiver that supports the arm’s outer diameter. Use a drift or a press adapter slightly smaller than the bushing OD to push the bushing out. Apply steady, even pressure. If using a bushing tool with threaded rods, tighten slowly and check alignment frequently. Disassemble any bonded rubber bushings by first cutting the rubber with a saw or torch to relieve tension, then pressing out the shell.

Dealing with Stubborn Bushings

If a bushing refuses to move, soak the area with penetrating oil and let it sit for 15 minutes. Apply heat to the outer sleeve (not the Delrin if already inserted). Use a larger press ram or a hydraulic porta-power setup. Avoid hammering directly on the control arm; this can distort the bore. If all else fails, consider replacing the control arm assembly — many aftermarket arms come with Delrin already installed.

Installing New Delrin Bushings

Before pressing new bushings, clean the bores thoroughly with brake cleaner. Inspect for burrs or ridges; lightly file them smooth. Verify that the Delrin bushings are the correct size: ID (inner diameter), OD, and length must match the arm. Some Delrin bushings are split or have a lubrication groove; orient them according to the manufacturer’s instructions.

Lubrication and Alignment

Apply a thin, even coat of silicone-based lubricant to the outside of the bushing and the inside of the control arm bore. This reduces friction during pressing and prevents the bushing from seizing. For press-fit Delrin, start the bushing by hand until it is square in the bore. Use a press tool or a drift that contacts only the bushing’s outer rim, not the inner gap. Press in one smooth motion, checking often that the bushing enters straight. Stop when the bushing face is flush with the arm or at the depth specified by the kit.

Setting Bushing Position

Many Delrin control arm bushings require a specific orientation: some have an offset to adjust caster or anti-dive geometry. If the original bushings were offset, align the new ones identically. For centered bushings, ensure the bushing is not twisted. Once pressed, install any retaining clips or snap rings if provided.

Reassembly and Final Checks

Reinstall the control arm in reverse order of removal. Starting the pivot bolt but leaving it lightly snug allows the bushing to settle as suspension geometry is set. Connect the ball joint to the knuckle and tighten its nut to the factory torque specification. Reattach any sway bar links or strut bolts.

Torque Specifications

Use a precision torque wrench for all fasteners. Delrin bushings require the control arm bolts to be torqued with the vehicle’s weight on the suspension (or at least with the suspension compressed to ride height). If you tighten bolts with the arm hanging, the bushings will be preloaded and wear prematurely. A common method: lower the vehicle onto ramps or jack stands under the lower control arm to simulate normal ride height, then torque the pivot bolts. Check the factory service manual for values; typical control arm bolts range from 80–120 ft-lb.

Test Drive and Inspection

After reassembly, check wheel speed sensors and brake lines for clearance. Turn the steering lock to lock and listen for rubbing. Drive the vehicle on a quiet road at low speeds, then accelerate to highway speeds. Delrin bushings may produce initial creaking or squeaking sound; this often subsides after a few hundred miles as the lubricant distributes. If noise persists, recheck torque and bushing alignment. Return to check bolt tightness after 100 miles.

Safety Tips

  • Always wear cut-resistant gloves and impact-rated safety glasses when using a hydraulic press or striking tools.
  • Support the vehicle with jack stands rated for your vehicle’s weight; use a secondary safety stand if working under the arm.
  • Never press a bushing without the correct adapter; using a washer or socket that does not fully support the arm can bend the control arm.
  • Disconnect the battery if the control arm removal might disturb wiring or sensor connectors.
  • Dispose of old rubber and metal bushings according to local recycling regulations; many metal sleeves are recyclable.

Common Installation Mistakes

Misalignment of Bushings

Even a slight angle during pressing can create binding and noise. Always start the bushing straight and stop if it tilts. Use a guide or a bushing press kit with centering shims if necessary.

Over-Pressing or Under-Pressing

Pressing too far can collapse the bushing or damage the control arm. Pressing not far enough leaves the bushing proud, which can interfere with the mounting bracket. Measure the original bushing depth or use a depth stop on the press.

Wrong Lubricant

Using WD-40, grease, or oil can attract dirt and swell Delrin over time. Only use silicone-based lubricants specified by the bushing manufacturer. A thin line of anti-seize on the outer sleeve (if metallic) can help, but keep it off the Delrin contact surfaces.

Ignoring Torque Sequence

Tightening control arm bolts with the suspension unloaded (arm hanging) places the bushing in a twisted state when the car is lowered. Always torque after setting ride height. This is the #1 cause of premature Delrin bushing failure and noise.

Conclusion

Installing Delrin bushings in automotive control arms significantly improves suspension precision and durability when done correctly. The upfront investment in proper tools and adherence to torque procedures pays off with sharper handling and fewer alignment changes over time. By following the detailed steps in this guide — clean removal, careful pressing, final torquing at ride height — you can achieve professional-grade results in a home garage. For further reading, consult the manufacturer’s installation instructions for your specific bushing kit, and refer to reputable resources such as MotorTrend’s suspension bushing guide for additional insights or DuPont Delrin material properties for technical background. Always prioritize safety and accuracy; a well-installed Delrin bushing set can transform a sloppy suspension into a precise, responsive system ready for any road or track.