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Suspension Clunks: What Wears Out First and What to Upgrade First (Redlined 101, Ep 05)

3 min read

A front suspension corner drawn in cutaway: strut, spring, control arm, knuckle and tire, labelled WHAT FAILS FIRST.

That clunk over bumps? Something in your suspension is worn out. Here's what fails first, how to check each part yourself, and what to upgrade first.

Watch Redlined 101, Ep 05 on Instagram →

Bushings

Bushings are the rubber pieces where your control arms meet the car. Over time they crack and go soft. Worn bushings clunk, make the car wander on the highway, and wear your tires unevenly.

The upgrade is polyurethane: it flexes less than rubber, so steering gets sharper and more direct, with a little more vibration coming through.

Suspension cutaway with the control arm bushing circled, labelled clunks and wanders.
Bushings: where the control arms meet the car.

Ball joints

Ball joints hold the knuckle to the control arm. To check them, get the car safely on jack stands, grab the tire at the top and bottom, and rock it top to bottom. Any play? Replace it. This one isn't optional: a ball joint that fails completely can collapse the wheel.

Suspension cutaway with the lower ball joint circled, labelled on jack stands, rock top to bottom, any play means replace.
Ball joints: rock the wheel top to bottom.

Tie rod ends

Tie rod ends steer the wheel. Check them the same way, but grab the tire at 9 and 3 o'clock and rock it side to side. Play here means wandering and bad toe, and bad toe eats tires. Get an alignment after you replace them, because new tie rod ends change toe (here's why toe matters).

Suspension cutaway with the tie rod end circled and a view from above, labelled rock side to side, wandering and bad toe.
Tie rod ends: rock it side to side, then align.

Shocks

Push down hard on one corner of the car and let go. A healthy shock settles it in about one movement. If it bounces more than once, the shock is done. The other signs are oil leaking down the body and the nose diving hard under braking.

Suspension cutaway with the shock highlighted, labelled push down hard, more than one bounce means done, leaks.
Shocks: push down hard; more than one bounce means they're done.

End links and top mounts

  • End links connect the sway bar to the suspension. Worn ones rattle over small bumps, and they're the cheapest fix on this list.
  • Top mounts sit at the top of the strut. A clunk when you turn the wheel while parked usually points here.
Suspension cutaway with the sway bar end link circled, labelled rattle over small bumps, cheapest fix.
End links: the rattle over small bumps, and the cheapest fix.

What to upgrade first

  1. Good tires. Every other part works through them.
  2. Replace anything worn. New performance parts bolted to worn ones still feel sloppy.
  3. Dampers. Quality shocks or coilovers (coilovers vs lowering springs).
  4. Sway bars. Flatter cornering, once everything else is tight.

Lowered? Add adjustable control arms to bring your camber back into spec, so the inside of your tires survives.

Upgrade order list: 1 good tires, 2 replace anything worn, 3 dampers, 4 sway bars.
The order: tires, worn parts, dampers, then sway bars.
Meme: a monkey puppet glancing away nervously, captioned Mechanic: who did this install??
Every DIY install, eventually. From our meme page.

Recap

  • Clunk over bumps: bushings, ball joints, shocks.
  • Rattle over small bumps: end links.
  • Clunk turning while parked: top mounts.
  • Wandering: bushings or tie rod ends, then an alignment.
  • Jersey potholes wear all of this out faster. Check it every spring.

What's clunking on your car? Tell us in the comments on the reel.

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Previous: ← Tires explained · Next: Cast vs flow-formed vs forged wheels →

Frequently asked questions

What usually causes a clunk over bumps?

Most often worn sway bar end links, control arm bushings or ball joints, and sometimes tired shocks or top mounts. The type of clunk is a clue: a rattle over small bumps points at end links, a clunk when you turn the wheel while parked points at the top mounts.

Is a worn ball joint dangerous?

Yes. A ball joint holds the knuckle to the control arm, and one that fails completely can let the wheel collapse. If you find play, replace it before driving it hard.

Should I get polyurethane bushings?

If you want sharper steering and more feedback, yes. Polyurethane flexes less than rubber, so the car feels tighter, at the cost of a little more vibration and noise in the cabin.

Do I need an alignment after replacing suspension parts?

After tie rod ends, control arms or anything that moves the wheel, yes. New tie rod ends in particular change toe, and bad toe wears tires fast.