How do you know if your strut mounts are bad?
Author: SuperPro
The classic bad strut mount symptoms are a clunk over bumps that comes from high up near the guard, a creak or grind when you turn the wheel while parked, steering that feels notchy or will not return to centre, uneven inner or outer tyre wear, and visible cracks or a gap at the strut tower.
Most lists of bad strut mount symptoms are written by someone who has never had a hand on a strut tower. Five bullet points and no method leaves you guessing between a mount, a sway bar link and a worn shock. Strut mount, strut top mount, top hat and strut tower mount all mean the same part, and it is one of the easier suspension faults to confirm in your own driveway with no tools at all.
We design and test polyurethane suspension components in Brisbane, so we spend a lot of time diagnosing parts before replacing them. Below is the order we work through, from what you hear while driving to what you feel with the bonnet up. If you already know the answer, our range of strut mounts is where to go next.
The symptoms, in the order you notice them
A clunk or knock over bumps, coming from up high
Usually the first thing anyone notices. The detail the generic lists leave out is where the noise originates. A worn strut mount knocks up near the top of the guard, roughly at bonnet height, because that is where the strut rod is banging against a mount that no longer holds it. A ball joint, control arm bush or sway bar link knocks down at wheel height. Place the noise vertically before you place it horizontally.
A creak, groan or grind when you turn the wheel slowly
Park up, wind the window down and turn the wheel lock to lock while stationary or rolling at walking pace. A dry or contaminated thrust bearing makes a sound owners describe as a rusty gate hinge, a groan, or a gritty grinding. It repeats at the same point in the steering travel and is loudest when the suspension is most loaded.
Steering that feels notchy or will not self centre
A healthy front strut rotates freely under spring load. When the bearing seizes or goes rough, the steering catches at certain angles and the wheel does not return to centre by itself as you unwind out of a corner. Many owners blame the power steering or the alignment, and both get checked first.
Uneven wear on the inner or outer shoulder of a front tyre
Run your hand across each front tyre. Wear on one shoulder means camber has been wrong, and a mount that lets the strut top move means camber is wrong only sometimes, which is why the car can drive straight and still eat a tyre edge. If the wear has come back since your last alignment, the mount is the prime suspect.
Visible damage at the strut tower
Open the bonnet and look straight down at the top of each strut. You want cracked or crumbling rubber around the centre of the mount, a gap between the rubber and its steel, rust staining washed out from inside, or a strut rod sitting off centre in its hole.
ReadyStrut Top Cap to suit Toyota Land Cruiser 300 Series 2021-on
The driveway check, step by step
Fifteen minutes, no tools, and more reliable than any symptom list.
1. Park on level ground with the engine off and the handbrake on, then do the visual on both sides, comparing the two mounts to each other.
2. Bounce each corner. Push down hard on the guard above each front wheel a few times and let go. A knock or creak on the rebound is the mount or the strut, not the tyre.
3. The hand on the tower test. This is the one that settles it. Rest your palm firmly on top of the strut mount with your fingers spanning the mount and the surrounding tower sheet metal, then have someone start the car and turn the steering slowly from lock to lock. A healthy mount transmits smooth, even rotation. A failing one sends clicks, grinding or jolts into your palm, and a separated one lets you feel the strut top shift against the tower.
4. Repeat around centre. Small movements back and forth, hand still on the mount. Any knock you feel as the steering changes direction points at play in the mount.
5. Check both sides. Mounts age together, so the good side is your reference and your second replacement.
If you feel movement at step three, get the car looked at properly rather than driving it to see whether it worsens.
What else makes the same noises
Half the value of a diagnosis is ruling things out, so this is what we check first.
|
What you notice |
Could be the mount |
What else to check |
|
Clunk over bumps, high up |
Very likely |
Loose strut rod nut, coil spring seat |
|
Clunk over bumps, at wheel height |
Unlikely |
Sway bar links, ball joints, control arm bushes |
|
Creak or grind turning at low speed |
Very likely |
Power steering fluid level, CV joint if it clicks on lock |
|
Steering will not return to centre |
Likely |
Caster out of spec, seized lower ball joint, steering rack |
|
Inner or outer shoulder tyre wear |
Likely |
Alignment out, worn control arm bushes, bent component |
|
Nose dive and floating over undulations |
No |
The struts or shock absorbers themselves |
The most common misdiagnosis we see is a sway bar link blamed for a mount, or the reverse. Links are cheap, so they get replaced first and the noise is still there a week later. The height of the noise separates them.
What to do once you have confirmed it
Because almost all of the labour is spent removing the strut and compressing the spring, the part you put back matters more than usual. Our polyurethane resists oil, heat, ozone and UV better than rubber, and it will not delaminate the way a bonded rubber mount does, so the failure that brought you here does not restart on a new clock. It also holds the top of the strut in position under load, which keeps the camber and caster your aligner sets. Where a vehicle is lowered or outside alignment tolerance, our offset mounts add negative camber or extra caster, backed by our lifetime warranty.
Frequently Asked Questions
Looking for more information? Below we answer the most commonly asked questions
How do I know if my strut mounts are bad?
What does a strut mount do?
Can I drive with a bad strut mount?
Can you check strut mounts without removing the wheel?
How long do strut mounts last?
Do I need an alignment after replacing strut mounts?
Once the hand on the tower test confirms it, the only decision left is what to fit. Our range of strut mounts covers direct polyurethane replacements and offset designs that correct camber and caster, engineered and tested here in Australia.
