Regular inspection of axle and suspension parts is crucial for vehicle safety and performance. Worn or damaged components can lead to poor handling, uneven tire wear, and even accidents. This guide walks you through a thorough visual and physical inspection process, covering everything from ball joints to axle shafts. Whether you’re a DIY enthusiast or just want to understand what your mechanic checks, these steps will help you identify common issues early.
Before You Start: Safety First
Park your vehicle on a level surface, engage the parking brake, and chock the wheels. For most inspections, you’ll need to lift the vehicle safely using a jack and jack stands. Never rely solely on a floor jack. Wear safety glasses and gloves. If you’re unsure about any step, consult a professional.
Tools You’ll Need
- Floor jack and jack stands
- Flashlight
- Pry bar or large screwdriver
- Tape measure or ruler
- Wrench set
- Gloves
- Safety glasses
Visual Inspection Overview
Start with a walk-around. Look for obvious signs of trouble: leaking fluid, broken parts, or sagging suspension. Check the tires for uneven wear patterns—inside edge, outside edge, or cupping—which often point to suspension issues.
Step 1: Inspect the Axle Shafts and CV Joints
What to Look For
- CV joint boots: Cracked, torn, or leaking grease. A split boot allows dirt in and grease out, leading to joint failure.
- Axle shaft: Bent, rusted, or damaged. Check for play by grabbing the shaft near the wheel and trying to move it up and down.
- Clicking or popping sounds: While turning, if you hear clicking, the CV joint may be worn.
How to Inspect
With the vehicle lifted, turn the wheels fully left and right. Inspect the rubber boots on the inner and outer CV joints. Use a flashlight to see cracks. If grease is slung around the area, the boot is compromised. Rotate the tire and listen for clicking from the joint. Any play in the shaft indicates wear.
Step 2: Check Ball Joints
What to Look For
- Loose ball joint: Excessive vertical or horizontal movement. This can cause clunking noises and loose steering.
- Worn rubber boot: Torn boot leads to contamination.
- Moose test: A classic method—grab the top and bottom of the tire and try to rock it in and out. Any movement beyond slight indicates wear.
How to Inspect
For upper ball joints, place a pry bar between the control arm and the steering knuckle. Pry gently and watch for movement at the joint. For lower ball joints, jack the vehicle under the lower control arm to compress the spring, then use the pry bar. If you see more than 1/8 inch of movement, replacement is needed.
Step 3: Examine Tie Rod Ends
What to Look For
- Loose tie rod: Steering wander, uneven tire wear, clunking.
- Damaged boot: Torn or missing boot exposes the joint to dirt.
- Excessive play: Grasp the tie rod near the inner end and try to move it up and down.
How to Inspect
With both wheels off the ground, have a helper wiggle the steering wheel while you watch the tie rod ends. Any clunk or visible movement indicates wear. Alternatively, grab the tie rod shaft and try to push it up and down; if it moves more than a tiny amount, replace it.
Step 4: Inspect Control Arm Bushings
What to Look For
- Cracked, torn, or deteriorated rubber: Bushings allow controlled movement; when they fail, the control arm shifts causing alignment issues.
- Metal-on-metal contact: Severely worn bushings can cause knocking sounds.
- Visual cracking or bulging: Inspect around the bushing edges.
How to Inspect
Use a flashlight to look at the bushings where the control arm attaches to the frame. With the suspension loaded (car on the ground), look for gaps or tears. With the vehicle lifted, use a pry bar to check for excessive movement in the bushing. If the rubber is dry rotted or separated from the metal, replacement is necessary.
Step 5: Check Sway Bar Links and Bushings
What to Look For
- Worn sway bar links: Clunking noise when going over bumps or turning.
- Damaged bushings: Cracked, flattened, or missing rubber.
- Broken link: The sway bar can detach causing serious handling issues.
How to Inspect
With the vehicle on the ground, try to shake the sway bar links by hand. They should be tight. Then lift the vehicle and inspect the links and bushings where the sway bar attaches to the frame. Use a pry bar to check for play. If the link moves easily or the bushing is shot, replace it.
Step 6: Examine Shocks and Struts
What to Look For
- Leaking fluid: Oil on the shock body indicates seal failure.
- Damaged mount: Cracked or broken strut mount can cause noise and poor handling.
- Bouncy ride: Push down on a corner of the vehicle; if it bounces more than once, the shock is weak.
How to Inspect
Look for wetness around the shock rod or body. Check the rubber bushings at the top and bottom for cracks. For struts, inspect the coil spring for breaks or sagging. A sagging spring reduces ride height and affects alignment.
Step 7: Inspect Wheel Bearings
What to Look For
- Growling or humming noise: Especially when turning, indicates bearing wear.
- Play in the wheel: Grab the tire at 12 and 6 o’clock and rock it. Excessive movement means bearing issues.
- Roughness when spinning: Slowly rotate the tire; listen for grinding.
How to Inspect
Lift the wheel off the ground. Place one hand on top of the tire, the other on the bottom, and try to rock it. If you feel clunking or movement, the bearing may be loose. Spin the wheel; if it doesn’t spin freely or makes noise, further diagnosis is needed. Note: some bearings are sealed and not serviceable; replacement is the only option.
Safety Checks After Inspection
- Verify torque: If you removed any bolts, tighten them to manufacturer specifications.
- Test drive: After reassembly, take a slow test drive and listen for new noises. If something feels off, recheck.
When to Replace vs. Repair
- CV joint: If the boot is torn but no grease leakage, you may replace just the boot. If clicking is present, replace the entire axle.
- Ball joints: Replace in pairs (upper or lower) when worn. Some are pressed in, others bolt-on.
- Tie rods: Replace inner and outer together if one is bad. Get an alignment after replacement.
- Bushings: Polyurethane bushings offer longer life but can transfer more NVH. Rubber is OEM-like.
- Shocks/Struts: Replace in pairs (both front or both rear) for balanced handling.
- Wheel bearings: If you suspect bearing wear, have a professional confirm before replacement.
Final Recommendation
Inspect your axle and suspension components at least once a year or every 12,000 miles—more often if you drive on rough roads. If you spot any damage, replace parts with quality OEM or equivalent components. Always get a wheel alignment after replacing any suspension or steering part. When in doubt, consult a certified mechanic. A thorough inspection can save you from costly repairs and keep your vehicle safe on the road.