Subaru suspension: what wears out, what it sounds like, and what it costs

Most suspension work starts with a noise. A knock over a speed hump that was not there last month. A creak pulling into a car park. Or it starts with a tyre fitter pointing at the inside edge of a rear tyre that is bald while the rest of it looks fine.

Here is what each of those actually means on a Subaru, and why the answer is a bit different on these cars than on most.

The short answer

Struts and shocks are the headline item, but they are rarely the first thing to go. Bushes, strut top mounts and sway bar links usually get there first, and they are the ones making the noise.

The Subaru specific part is the rear end. These cars have independent rear suspension where rear toe is adjustable and rear camber is not. That means worn rear link bushes cannot be dialled out with an alignment. They have to be replaced.

And because Subaru publishes one of the tightest tyre matching tolerances in the industry, suspension wear on an all wheel drive Subaru is not only a comfort and tyre question. It is the thing that quietly walks the car outside its own tyre spec.

What actually wears

Struts and shock absorbers

No manufacturer publishes a kilometre life, and anyone who gives you one is making it up. The useful reference points: Monroe Australia recommends inspection every 20,000 km and offers a three year or 60,000 km warranty on many units as a benchmark, and KYB notes that by around 80,000 km suspension components have gradually worn down.

The reason to care is not ride comfort. Monroe publishes two figures worth knowing: at 50 km/h, one worn shock absorber can increase stopping distance by up to two metres, and worn shocks can add as much as 20 per cent to stopping distance. Those are Monroe's numbers rather than an independent study, but the mechanism is not controversial. A damper that cannot control the spring lets the tyre leave the road.

Strut top mounts and bearings

This is the one most people have never heard of and the one that most often makes the noise. The mount carries the top of the strut and, on the front, includes a bearing the whole strut turns on when you steer.

KYB is unambiguous: if a strut has failed it is highly likely the strut mount, dust boot and bump stop are worn out as well, and mounts and bearings should be replaced with every strut change. Their strut kit comes with all of it in one box for exactly that reason. Subaru itself, in a bulletin about a knocking noise over bumps at low speed, instructs technicians to investigate the strut mounts next if the noise persists. Replacing struts and reusing tired mounts, bearings, bump stops and boots is a false economy, and you pay the labour twice.

Control arm and rear link bushes

This is where the Subaru detail matters. Alignment trade guidance on the Forester and Legacy is clear on three points: rear camber is not adjustable, the lower longitudinal link is not adjustable, and rear toe is adjustable with an inboard cam bolt.

The consequence is the useful bit. Worn link bushings cause negative camber and toe, which leads to inner edge tyre wear, and because rear camber has no adjustment, that wear cannot be corrected on the alignment rack. It is a parts job. An alignment afterwards stops it getting worse. It does not undo it.

Worth knowing too that a cracked bush does not always affect how the car drives, so a visual crack is not automatically a verdict. A deflection check under load is the better test.

Sway bar links and bushes

The end links and bushes wear far more often than the bar itself. Symptoms are clunking from around the wheels, loose steering, and noise or reduced control when cornering. These are cheap parts, and leaving them produces uneven tyre wear that costs more to fix than the links did.

Wheel bearings

A normal wear item with an Australian accelerant: water and dirt get in, the lubricant breaks down, and gravel road driving wears them faster. If you do the Dandenongs and the gravel beyond them, assume a shorter life than the brochure case.

Springs and ride height

Springs sag. On older Foresters and Outbacks a car that sits lower than it used to is usually springs, though a collapsed upper strut mount or a bent strut shaft can do the same thing, so it gets checked rather than assumed.

One trap worth flagging if you are buying springs for a wagon: some Outback and Forester models have self levelling rear suspension, and a spring maker's own catalogue warns that if it is fitted, a shock absorber for non self levelling suspension must be fitted along with the spring. Fitting the spring alone gets you a car that rides badly and an owner who cannot work out why.

In Victoria, restoring sagged springs to the original ride height is maintenance, not a modification. That is worth knowing before anyone tells you it needs engineering.

Symptoms, and what they usually mean

About the bounce test

You will be told to push down on a corner and count the rebounds. It is not useless, but it is much weaker than its reputation. It can show a grossly dead damper. It cannot detect one that has lost half its control, and it tells you nothing at all about mounts, bushes or springs, which is where most Subaru suspension noise actually comes from.

Monroe's own advice is a workshop inspection and a road test by a technician, which is a fair thing for a damper manufacturer to say and also happens to be right. We would rather drive it than bounce it.

Why this matters more on a Subaru

On a front wheel drive car, worn suspension costs you tyres and ride quality. On a symmetrical all wheel drive car there is a second consequence, and it is worth understanding properly rather than being scared with.

Subaru publishes an unusually tight tyre matching requirement. Alignment guidance for these cars sets it as a precondition before the car even goes on the rack: all four tyres matching brand and model, wear even, circumference varying by no more than about a quarter of an inch, and tread depth within about 2/32 of an inch. That is among the tightest tolerances any manufacturer specifies, and the reason it exists is the driveline. A permanent front to rear speed difference has to be absorbed somewhere, and on most modern Subarus that somewhere is a clutch pack.

Now put the two things together. Worn rear link bushes produce rear camber and toe you cannot correct. That wears the rear tyres at a different rate from the fronts. Do that for long enough and the car is outside its own tyre matching spec without anyone having fitted a mismatched tyre.

Being accurate about this

Each link in that chain is well supported on its own. Worn bushes cause misalignment. Misalignment wears tyres unevenly. Subaru sets a tight circumference tolerance because of the driveline.

What we have not seen, and will not claim, is a published study joining them end to end into a documented failure pathway. Treat it as the reason the tolerance exists and a good reason not to ignore a worn bush, rather than as a prediction about your transmission.

What a proper Subaru alignment involves

There is a real difference between a Subaru alignment and a cheap front toe adjustment, and it is not sales talk.

1. Tyres first. Matching brand and model, even wear, circumference within about a quarter inch, tread within about 2/32. If the car fails that, the alignment is being set around a problem rather than fixing one.
2. Ride height measured before anything else. Alignment angles change with ride height. A sagged spring makes every reading meaningless.
3. Then camber, then toe, in that order. Subaru advises a sequential process to avoid the angles interfering with each other, and toe is set last because it is the most critical and the most easily disturbed.
4. All four corners, not two. Rear toe is adjustable on these cars and thrust angle is set by it. A front only alignment cannot touch either. On an all wheel drive Subaru the correct adjustment is both rear toe bolts turned equally in the same direction.
5. Steering angle sensor calibrated afterwards. Change toe or thrust angle and the sensor needs recalibrating with a scan tool.
6. EyeSight considered. Alignment and the replacement or repair of suspension components are both listed among the situations requiring EyeSight calibration. That is not only a lift kit issue. It applies to ordinary strut work.

Subaru Australia does not put alignment in the scheduled maintenance at all. It appears in the owner responsibilities as an item for which a charge may be made, with the note that the frequency of these services depends on driving conditions. So nobody is going to tell you when it is due. Published advice ranges from every 10,000 km for maximum tyre life to around 30,000 km or 30 months, with shorter intervals on rough roads.

The non negotiable triggers are simpler: after you hit something, after any abnormal wear pattern appears, and after replacing any major suspension or steering component including wheel bearings, racks and most bushes.

What it costs

Published Australian figures, with one warning attached. A lot of the suspension pricing on comparison sites is template content: the same front shock range appears on every Subaru model page and on cars from other brands entirely. We have left those out. These are the ones that vary properly by job and look real.

What we charge at Baywrex

Shocks and struts: from $300. · Four wheel alignment: $89 to $150.

Those sit inside the published national ranges above, and that is deliberate rather than accidental. We are not cheaper than the market on routine suspension work. What we are is specific about what the job includes, which on these cars is where the money is actually won or lost.

The alignment range moves with the car: a standard Impreza at one end, a lifted Forester or a performance car needing the full four corner geometry and a steering angle sensor recalibration at the other. The shock range moves with the model and with whether the top mounts and bump stops go in at the same time, which on a car past 150,000 km they usually should, because doing them later means the same strut out again.

From $300 is where a straightforward rear shock starts. A front strut is a bigger job on the same car, because the spring, the top mount and the bearing are part of the assembly and the alignment afterwards is part of the job rather than an extra. We quote the whole corner, not the part.

What moves the number, and what we will not quote blind

A starting figure is only useful if you know what pushes it up, so here is the honest version.

• What moves a strut job above that starting figure. A front strut is not one part. It is the damper, the spring, the top mount and the top mount bearing, and on a car with any kilometres on it the mount and bearing should go in at the same time or the strut comes out again inside a year. Add the alignment and the four corner geometry check, and how far above $300 you land depends almost entirely on how much of the assembly is worth reusing.
• Control arm and link bushes. Published Australian bush pricing runs from about $100 to $350 and up per location, and the spread is almost entirely labour. Some bushes press out in minutes. Others are in a subframe that has to come down. Until the car is on the hoist, nobody can tell you which one you have.
• A full front and rear overhaul. We quote this as one job after inspection, and the reason is that almost nobody actually needs every item on the list. Pricing it as a package before looking means either overcharging the car that needed four things or underquoting the car that needed eleven.

What we will not do is give you a number over the phone and then revise it upward once the wheels are off.

Replacement parts, and when an upgrade is worth it

KYB and Monroe both have Australian operations and both are the sensible default for a like for like replacement. King Springs is Australian and catalogues Subaru applications by generation in lowered, standard and raised heights. Whiteline and SuperPro are Australian and make Subaru specific bush kits, including offset and caster correction bushes, which is directly relevant to everything above: those exist specifically to restore geometry that worn rubber has given away.

An upgrade is worth it when the car's job has changed. If you tow, carry weight regularly, or load the car for touring, heavier rate springs and matched dampers are a real improvement. If the car is normally unloaded, heavy duty parts make it ride badly for no benefit, and the honest advice is standard duty. That is also what the manufacturers' own load guidance says, which is a refreshing thing to be able to quote.

What we would not do is sell you coilovers because a bush is knocking.

Lifting a Forester or Outback, briefly

Victoria's guide to modifications allows suspension to be raised by up to 50mm provided sufficient travel is retained, and allows a combination of suspension lift and larger diameter tyres totalling up to 75mm without the certification otherwise required above 50mm. That 75mm path only works with a commercially available kit, specifically designed and tested for your make, model and variant, fitted to the manufacturer's instructions, and you must keep a written statement of the kit's suitability.

The open question, and we are not going to pretend otherwise, is that the tyre provision is written for an off road type 4WD, and whether a Forester or Outback qualifies under that definition is genuinely unresolved. The national code adds a wrinkle by excluding all wheel drive vehicles from the off road tyre category even where they carry the relevant category rating. Talk to a VASS signatory about your specific car and its compliance plate before you buy a kit, and tell your insurer.

Three practical effects worth knowing regardless. Lifting changes CV joint angles, and the issue is sustained angle under load rather than lift height by itself, so a joint can look fine parked and bind at full lock or full droop. EyeSight references a known camera height and static rake, so a lift changes what it is measuring against. And alignment, front and rear, is part of the job, not an afterthought.

What we do

Our suspension check is free, and here is exactly what it is: on the hoist, every bush and joint checked for play under load, mounts and bearings checked, ride height measured at all four corners, tyre wear patterns read, and a road test. Then we tell you what is actually worn and what is fine, and in what order it needs doing.

Not everything that is worn needs doing today. We would rather tell you which two things matter and which three can wait than hand you a list.

Free suspension and alignment check

Baywrex, Tower 2 / 591 Dorset Road, Bayswater North VIC 3153. Call 0410 164 954 or book online.

Subaru specialists. Struts, bushes, mounts, bearings and four wheel alignment for WRX, STI, Forester, Outback, Liberty, Impreza, XV and BRZ.