This Subaru Forester came in with a knock from the front over bumps. Here is how we found the real cause and fixed it properly.
Job completed: July 2026
| Car | Subaru Forester (boxer petrol) |
|---|---|
| Symptom | A knock and clunk from the front suspension over bumps and uneven roads |
| Fault found | Both front lower arms worn, with play in the ball joints, which also threw the wheel alignment out |
| Repair done | Replaced both front lower arms complete with ball joints as a pair, then did a four-wheel alignment and road tested the car |
| Parts | Original lower arms with ball joints |
| Time taken | Timeline confirmed when you book |
| Cost | About $485 per lower arm with ball joint before GST, plus labour and alignment |
| Warranty | Road tested before handover |
The owner brought in a Subaru Forester with a knock from the front. It came over bumps, humps and uneven roads, the kind of clunk you feel through the steering and the floor. A knock like that is easy to ignore at first, but it does not go away on its own.
The ask was simple. Find out what was knocking and fix it so the car feels solid again. The owner wanted a clear answer and a firm price before any work started, not a guess.
The car is a Subaru Forester with the boxer petrol engine. The front lower arms hold the wheels to the car and let the suspension move up and down. At the outer end of each arm sits a ball joint, which lets the wheel turn while it takes the weight of the car.
Over years of Singapore roads, the rubber bushings in the arms harden and the ball joints wear. When a ball joint develops play, it knocks over every bump and the wheel no longer sits where it should. Putting the car on the hoist and checking each joint by hand is the only sure way to find which part is worn, which is why we inspect before we quote.
We put the car on the hoist and checked the front suspension by hand rather than guessing from the sound alone. A knock over bumps can come from a few places, so we worked through them.
Once the wheels were off the ground, the picture was clear. Both front lower arms were worn, and the ball joints had play in them. That play was the source of the knock, and it had also pushed the wheel alignment out, which was starting to wear the tyres unevenly.
We showed the owner the worn arms and quoted firmly before any work began, so there were no surprises later.
The front lower arm carries a ball joint at its outer end and rubber bushings where it bolts to the car. Both wear with age and mileage. On our roads, with the humps, kerbs and potholes, that wear comes sooner.
When the ball joint develops play, the wheel gets a small amount of free movement it should not have. Every bump lets it knock. Left alone, the play grows, the tyre wears unevenly, and the steering feels loose. This is normal ageing, not something the owner did wrong. Greasing or tightening does not bring back a worn ball joint, so the proper fix is to replace the lower arm complete and realign the wheels.
We did the job properly rather than patch it and hope.
We kept the owner updated through the job. Replacing the arms as a pair and realigning took the time it needed. We did not rush it, because a suspension that has to come apart again helps no one. The car feels solid over bumps again, the steering tracks straight, and it was road tested before handover.
On this Forester the original lower arms complete with ball joints were about $485 each before GST, with labour and the four-wheel alignment on top. The work covered a pair of arms and the alignment after.
What moves the price is which parts are worn and whether one side or both need replacing. We replaced both arms here because both ball joints had play, and matched parts wear evenly. This is why we put the car on the hoist and check first, then quote for exactly what is worn rather than guessing high.
The earliest signs are small. A faint knock over speed humps, a clunk when you turn into a rough carpark, or steering that feels a touch loose. Uneven tyre wear on the front is another clue that the alignment has drifted.
Catching it early matters. A worn ball joint only gets worse, and the longer it knocks the more it wears the tyres and the rest of the front end. Getting any new knock checked early lets us catch a worn arm before it damages more parts, and keeps the car safe and quiet.
This Subaru Forester (Front lower arm and ball joint replacement with wheel alignment) was handled at 1 Car Service, an independent workshop in Sin Ming AutoCity, Singapore. We hold a 4.9★ rating from 1,775+ Google reviews.
WhatsApp us your car model, year and what the knock sounds like. We'll put it on the hoist, find the real cause and tell you what it costs before any work begins. Every suspension job is road tested before we hand the car back.
On this Forester the original lower arms with ball joints were about $485 each before GST, with labour and the four-wheel alignment on top. On this Forester we fitted a pair of original lower arms complete with ball joints, then aligned the wheels. We put the car on the hoist and check first, then quote before any work begins.
On this Forester both front lower arms were worn and the ball joints had play in them. That play let the wheels knock over every bump, and it had also thrown the alignment out. A knock over bumps usually points to a worn suspension joint, which is why it needs a proper check on the hoist.
It depends on what we find on the hoist. On this car both ball joints had play, so we replaced both arms as a pair. Matched parts on both sides wear evenly and keep the steering balanced. If only one side is worn we will tell you and quote for just that side.
Worn ball joints let the wheels sit out of position, which is why the alignment was out and the tyres were wearing unevenly. Fitting new lower arms resets the geometry, so a four-wheel alignment afterwards brings the steering and tyre wear back to spec.
It is not something to leave. A worn ball joint only gets worse, the knock grows, the tyres wear faster, and the steering feels loose. In the worst case a badly worn joint can fail. Getting a new knock checked early is the safe move, and it usually costs less to fix before it damages more parts.
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