Wreckers are brilliant for saving money on parts. But some components degrade in ways you can't see, test, or predict. These five parts sit between you and serious injury. Saving $50 on any of them is a terrible bet.
1. Tyres
Used tyres look like a bargain. You see 6mm of tread, the rubber looks fine, and they're $40 each instead of $150. The problem is rubber degrades with age regardless of how much tread is left. A tyre that's been sitting in a shed for six years has hardened compounds that reduce grip dramatically, especially in the wet.
Every tyre has a DOT date code stamped on the sidewall. It's a four-digit number -- the first two digits are the week of manufacture, the last two are the year. A code reading 2319 means the tyre was made in week 23 of 2019. Any tyre older than five years is past its use-by date, even if it's never been on a car.
Hardened rubber loses wet grip before you can feel the difference on dry roads. You won't know your tyres are cooked until you're standing on the brakes in the rain and the car doesn't stop.
Used tyres can also have internal damage from running underinflated or hitting kerbs. Belt separation, sidewall cords weakened by impact -- none of this shows on the surface. A blowout at highway speed is catastrophic.
Buy new. Budget brands like Hilo, Westlake, or Maxxis run $80 to $120 per tyre for common sizes. That's a small price for knowing your rubber will grip when it counts.
2. Brake Pads and Rotors
Brake pad wear is hard to judge by looking at them. A pad that appears to have 4mm of material left might have glazed friction material that reduces stopping power by 30% or more. Glazing happens when pads overheat -- common in stop-start city driving and towing.
Rotors are worse. A rotor can look perfectly smooth but have heat cracks below the surface. These cracks spread under repeated braking and can cause the rotor to shatter. Used rotors may also be warped, causing pedal vibration and uneven pad contact.
A set of aftermarket brake pads costs $30 to $60. Aftermarket rotors run $50 to $100 each. For a front axle, you're looking at $130 to $220 for pads and rotors. Compare that to the cost of not stopping in time.
Buy new. Aftermarket brands like Protex, DBA, and Bendix make quality pads and rotors at a fraction of dealer prices. Your mechanic can fit them in under an hour.
3. Airbags
A deployed airbag is obvious -- the bag is hanging out and the module is destroyed. That's not the risk. The risk is buying an airbag that hasn't deployed but has been stored badly.
Airbag inflators contain a chemical propellant that degrades when exposed to moisture and temperature cycling. This is exactly what killed people in the Takata airbag recall -- moisture entered the inflator housing and caused the propellant to break down. When the airbag fired, the inflator ruptured and sent metal shrapnel into the cabin.
A wrecker airbag has unknown storage history. You don't know if the car sat in a flood, parked in direct sun for years, or had a leaking windscreen dripping water onto the steering column. The inflator canister gives you zero visual clues about its internal state.
In Australia, fitting non-genuine airbag components can void your insurance and create personal liability if the airbag fails in a crash. Some states require an ADR compliance plate for replacement airbag installations.
Buy genuine from the dealer. Yes, airbags are expensive ($400 to $1,200 depending on the module). There's no alternative that's worth the risk.
4. Seatbelts and Pretensioners
Modern seatbelts are more than a strap with a buckle. They contain pretensioners -- explosive charges that fire in a crash, yanking the belt tight against your body in milliseconds. Once a pretensioner fires, it's spent. It can't fire again. Fitting a used seatbelt from a crash-damaged vehicle means you might have a pretensioner that's already done its job.
The seatbelt webbing itself also degrades. UV exposure weakens the nylon fibres. A seatbelt that's been baking in the sun for a decade can tear under crash forces. You won't feel the weakness when you pull the belt across your chest normally.
Retractor mechanisms wear out too. A retractor that's slow to lock up gives you extra slack in a crash. That extra slack means your body travels further before the belt catches you, increasing the force of impact on your chest and neck.
Pull the belt all the way out and inspect the webbing for fraying, discolouration, or cuts. Give the belt a sharp tug -- the retractor should lock immediately. But even if it passes both tests, you can't check the pretensioner without specialist equipment.
Buy new. Aftermarket seatbelt assemblies with pretensioners run $150 to $350. Dealer units cost more but come with a warranty and guaranteed ADR compliance.
5. Fuel Lines and Rubber Hoses
Rubber fuel lines, brake hoses, coolant hoses, and power steering hoses all degrade from the inside out. The inner lining cracks, swells, and eventually leaks. Fuel lines are the most dangerous because petrol leaking onto a hot exhaust manifold starts fires.
A used fuel line might look fine on the outside. The rubber is still flexible, the clamps are tight, and there's no visible weeping. Inside, the lining could be cracked and flaking, narrowing the fuel flow and dropping material into your fuel system. One good vibration from a rough road and the weakened section splits.
Brake hoses are the second-highest risk. Rubber brake hoses swell internally when they degrade, creating a one-way valve effect. Brake fluid pushes through under pressure when you press the pedal, but can't return properly when you release it. This causes brakes to drag, overheat, and fade when you need them most.
Cracking or crazing on the outer surface. Swelling or soft spots when you squeeze the hose. Oily residue around connections. Any of these mean the hose needs replacing -- not with another used one.
Buy new. Fuel hose by the metre costs $8 to $15. Pre-formed fuel lines cost $30 to $80. Brake hoses run $15 to $40 each. These are cheap parts that prevent expensive disasters.
Parts That Are Fine to Buy Used
Not everything at the wreckers will kill you. Plenty of parts are perfectly safe second-hand and will save you serious money. Here's what to grab without guilt.
Alternators and starters -- electrical components that either work or don't. Test them on the spot if the wrecker has a bench tester. Most wreckers offer 7 to 14 day warranties on electrical parts.
Side mirrors -- check the electric motor works and the glass isn't cracked. Easy to inspect, easy to fit, and wreckers have thousands of them.
Door handles -- internal and external. These are simple mechanical parts. If they're not broken, they work.
Interior trim -- door cards, console panels, dashboard pieces, sun visors, glovebox lids. Colour-match to your car and you're done.
Wheels -- inspect for cracks around the spoke bases and bead area. Run your finger around the inside lip checking for dents. If it's straight and crack-free, it's good.
ECUs and body control modules -- these either work or they don't. Some need coding to your vehicle, which a dealer or auto electrician can do. Match the exact part number using your VIN.
Transmissions -- buy from a wrecker who offers a warranty (30 to 90 days is common for gearboxes). Ask for the km reading from the donor vehicle. A transmission with 120,000 km still has plenty of life.
Radiators and condensers -- pressure test before fitting. If they hold pressure and the fins aren't too damaged, they'll cool your engine just fine.
The Bottom Line
Wreckers save you money. That's the whole point. But the savings only make sense on parts where failure means inconvenience, not injury. A door mirror failing leaves you without a mirror. A seatbelt failing leaves you without a life.
Stick to the rule: if the part sits between you and a crash, buy it new. Everything else is fair game at the wreckers.