Car Suspension Problems: Symptoms, Causes and Repairs

Suspension wear is gradual, which is exactly why it catches people out. The ride gets slightly firmer, the steering gets slightly vaguer, and because it happens over years the driver adjusts without noticing. Then a new set of tyres wears out in half the expected mileage, or the MOT flags a leaking damper.

British roads make this worse than most. Potholes, sunken drain covers and high kerbs put shock loads through components that were designed for smoother surfaces than we actually have.

What does a car's suspension actually do?

It keeps the tyres in contact with the road and controls how the body moves. Comfort is a by product, not the main purpose.

The system has a few distinct jobs happening at once:

• Springs carry the weight of the car and absorb the initial impact of a bump
• Shock absorbers, properly called dampers, control what the spring does next. Without them the car would keep oscillating after every bump
• Control arms, ball joints and bushes locate the wheel so it stays at the correct angle through its travel
• Anti roll bars and drop links limit body roll in corners
• Wheel bearings and hubs let the wheel rotate without play

When any of those wear, the tyre stops sitting flat on the road at the right moment. That costs grip, braking distance and tyre life long before it costs comfort.

What are the symptoms of worn suspension?

Ten symptoms cover almost everything a driver will notice. This table maps each to its usual cause.

The rest of this article works through each of these in more detail.

Worn shock absorbers: how to tell

A worn shock absorber lets the car keep moving after the road has stopped pushing on it. The classic signs are a floaty ride, excessive nose dive under braking and a car that feels unsettled over a series of bumps rather than a single one.

Symptoms.

• Continued bouncing after a bump rather than settling in one movement
• Longer stopping distances, because the tyre is lifting off the surface momentarily
• Reduced grip and control, particularly on undulating roads and in the wet
• Scalloped or cupped patches around the tyre tread
• An oily film running down the outside of the damper body
• Front end dipping heavily under braking and squatting under acceleration

The bounce test. Push down hard on one corner of the car and release. A healthy damper returns the car to level and settles in a single movement. If it rises and falls two or three times, that damper is worn. Bear in mind that modern dampers can lose a significant amount of performance while still passing this test, so it identifies bad units rather than proving good ones.

Solution. Replace them in pairs across the axle. Fitting one new damper alongside an old one leaves the car braking and cornering unevenly, which is worse than two matched worn ones. Top mounts and bump stops are usually replaced at the same time, since the labour is already done.

Uneven tyre wear and wheel alignment

Uneven tyre wear is a symptom of the wheel not sitting square to the road, and the pattern tells you which angle has moved.

• Both outer edges worn. Underinflation, not alignment
• Centre strip worn. Overinflation
• One inner or outer edge worn. Camber or toe out on that corner
• Feathered, saw toothed edges you can feel by hand. Toe angle out, commonly after a pothole
• Cupping or scalloping. Worn dampers or a bent component

Causes. Potholes and kerb strikes are the main ones in the UK. Worn bushes and ball joints also let the geometry drift gradually, which is why an alignment on a tired car can be wasted money until the worn parts are replaced.

Solution. Have a four wheel alignment measured before you spend money on tyres, not after. A printout showing the before and after figures is worth asking for. If a reading is out and cannot be adjusted back into tolerance, something is bent or worn and needs replacing first.

Clunks, knocks and squeaks over bumps

Noises from the suspension are almost always something with free play in it, and the character of the noise narrows down which.

• A single sharp clunk over small bumps is typically an anti roll bar drop link. These are among the cheapest suspension parts on a car and one of the most common MOT advisories
• A heavier knock over larger bumps points at worn control arm bushes or a failing ball joint
• A creak or groan on full lock, or when the car rocks at a standstill, usually means dry or perished bushes or worn top mounts
• A rhythmic clonk when turning at low speed can be a worn constant velocity joint rather than suspension proper
• A rattle that changes with speed but not with bumps may be a loose heat shield rather than suspension at all

Solution. Diagnosis needs the car on a ramp with the weight off the wheels, where a technician can lever each joint and feel for play. Bushes and drop links are cheap. Ball joints and control arms cost more but are still routine. What matters is not letting a worn joint run long enough to damage the arm it sits in.

Why is my car pulling to one side?

Check tyre pressures first, because an uneven pressure across an axle produces exactly this symptom and costs nothing to fix.

If pressures are equal, the likely causes are:

• Wheel alignment knocked out by a pothole or kerb
• A brake caliper binding on one side, which also produces a hot wheel and a smell after a drive
• Uneven tyre wear or mismatched tyres across an axle
• A worn or collapsed bush on one side letting that corner steer itself slightly
• Road camber, which is normal. Test on a flat, empty surface before assuming a fault

Solution. Pressures, then a road test on level ground, then alignment. A car that pulls under braking specifically is a braking fault rather than a suspension one and should be treated as urgent.

Sagging or uneven ride height

A corner sitting visibly lower than the others usually means a broken coil spring or a collapsed damper, and it needs dealing with quickly.

Coil springs break more often than most drivers expect, particularly on cars that have covered a few British winters. Corrosion collects at the bottom coil where water and salt sit, the metal thins, and the spring snaps under a normal load. Cold weather and pothole impacts are the common triggers.

Why it matters. A broken spring can drop the arch onto the tyre and cut the sidewall. It changes the ride height and therefore the alignment on that corner. It also fails the MOT. If you have a broken spring, have the car recovered rather than driving it any distance.

Solution. Springs are replaced in pairs across the axle so both sides sit at the same height and rate. If the dampers are also getting on in years, doing both at once saves paying for the same labour twice.

Heavy, vague or notchy steering

Steering problems that come from the suspension are usually about worn joints rather than the steering system itself.

• Heavy at low speed with normal power steering operation points to worn ball joints or seized top mounts
• Vague or wandering at speed suggests worn track rod ends, bushes or alignment out of tolerance
• Notchy or catchy may be a failing steering rack or a worn universal joint in the column
• Whining on lock in a car with hydraulic steering usually means low fluid or a failing pump. Most modern cars use electric power steering and have no fluid to check, but they do have a warning light

Solution. Free play at the straight ahead position is easy to measure on a ramp and hard to guess at from the driving seat. Do not confuse this with the mild self centring resistance that is normal on many electric systems.

Vibration through the steering wheel or seat

Vibration that appears in a particular speed range, typically between 50 and 70mph, is a wheel and tyre problem far more often than a suspension one.

Work through it in this order:

1. Wheel balance. Weights fall off, particularly stick on weights in winter. Rebalancing is quick and cheap
2. Buckled rim. A pothole can put a flat spot in an alloy that is invisible until the wheel spins on a balancer. This also causes the slow puncture that keeps coming back after every repair
3. Tyre condition. A separated belt inside a tyre produces a vibration and often a visible bulge
4. Wheel bearing. Usually a hum that rises with speed and changes when you steer left or right, rather than a vibration
5. Worn suspension components letting a wheel move under load

Kerb and pothole damage rarely stops at the tyre. Buckled and cracked rims can be straightened and refinished rather than replaced in most cases, and diamond cut faces can be recut and relacquered. We cover both through our alloy wheel refurbishment and diamond cut wheel repair services.

Will suspension faults fail the MOT?

Yes, several will, and suspension is one of the most common failure areas on older cars.

Testers check for:

• Excessive play in ball joints, track rod ends and wheel bearings
• Damaged, corroded or broken coil springs
• Shock absorbers with a serious fluid leak, or with obviously inadequate damping
• Split or perished bushes and damaged rubber gaiters
• Corrosion within the prescribed area of any suspension mounting point
• Distorted or damaged control arms and subframes

An advisory on a bush or a drop link is worth acting on rather than filing away for next year. Suspension components wear each other: a worn bush changes the load path into the arm it sits in, and a worn damper accelerates the wear on everything else on that corner, tyres included.

How to make suspension last longer

You cannot control the state of the roads, but you can control most of what shortens component life.

• Slow down for potholes. Braking hard as you hit one is worse than braking before it and releasing, because a compressed suspension has less travel left to absorb the impact
• Take kerbs slowly and squarely. Mounting a kerb at an angle at speed is the fastest way to bend a rim and knock the tracking out
• Keep tyre pressures correct. An underinflated tyre transmits far more shock into the suspension
• Get alignment checked after any significant impact, and whenever you fit new tyres
• Do not ignore small noises. A drop link that clunks for a year takes the anti roll bar bushes with it
• Rinse the underside in winter. Road salt is what corrodes spring coils and mounting points
• Avoid overloading. Springs and dampers are rated for a specified maximum weight, and consistent overloading shortens their life

When to call a professional

Anything involving a coil spring, a subframe or a bearing press is garage work, and coil springs in particular are genuinely dangerous without proper compressors.

Reasonable DIY jobs, given axle stands and basic tools, include drop links, some anti roll bar bushes and replacing worn top mount cover plates. Everything else, including any job that changes the geometry, needs a ramp, an alignment rig and someone who has done it before.

If a pothole or kerb has damaged wheels or bodywork alongside the suspension, that is our side of it. We work from our body shop at Unit C, The Yard, Rear of Constellation Mill in Radcliffe, and mobile across Greater Manchester, Lancashire, Cheshire, Merseyside and West Yorkshire. Full details are on our vehicle body repairs page.