One of the most common suspension repairs we do at SM Auto is control arm and ball joint replacement. And almost every time, customers ask the same question: "Can't you just replace the ball joint and leave the arm?"
It's a fair question. The ball joint is the part that's worn. The control arm looks fine. Why replace both?
Here's the honest answer — and it's not just about upselling you parts.
The control arm is the main link between your vehicle's frame and the wheel hub. It controls how your wheel moves up and down as you drive over bumps, and keeps the wheel aligned with the rest of the suspension.
On most vehicles, the control arm has two main wear points: the ball joint at the wheel end, and the bushings at the frame end. When one wears out, the rest of the arm has usually been stressed and fatigued alongside it — even if it doesn't look worn yet.
The ball joint is what allows the control arm to pivot while the wheel turns and moves. It takes a massive amount of stress — road impacts, cornering forces, braking — every single day.
In Ontario especially, road salt and potholes destroy ball joints faster than almost anywhere else in North America. The grease dries out, the boot cracks, moisture gets in, and the joint starts to wear. You'll feel it as a clunking sound over bumps, or looseness in the steering.
Warning: A severely worn ball joint can separate completely while driving — causing sudden loss of steering control. This is one of the few suspension failures that can be genuinely dangerous. Don't ignore a clunking front end.
On older vehicles, ball joints were separate press-in components — you could press out the old one and press in a new one while keeping the arm. Some shops still do this.
The problem is that on most modern vehicles, the ball joint is integrated into the control arm as a single unit. They're designed and manufactured together. When you press out the old ball joint and press in an aftermarket replacement, you're forcing a new component into a housing that's already been fatigued, stressed, and possibly corroded over years of use.
Pressing a new ball joint into a worn control arm risks damaging the seating surface. The new joint won't sit as tight, and can fail again much sooner than expected.
Control arm bushings wear at a similar rate to ball joints. If the ball joint is worn, the bushings are likely deteriorating too. Replacing just the ball joint leaves the next failure just around the corner.
Most of the cost of this job is labour — removing the wheel, disassembling the suspension, and doing an alignment after. You pay that labour whether you replace just the joint or the whole arm.
When we install a complete control arm, we can offer our full 1 or 2-year warranty on the entire assembly. A pressed-in ball joint in an old arm limits what we can warranty.
This is the part most customers don't think about. To replace a ball joint — even just the ball joint — we have to:
Remove the wheel. Disconnect the brake caliper. Separate the ball joint from the steering knuckle. Remove the control arm bolts. Press out the old ball joint. Press in the new one. Reassemble everything. Do a wheel alignment.
That's the same labour whether we're pressing in a new ball joint or installing a complete new arm. The difference in parts cost between a pressed-in ball joint and a complete control arm assembly is often $60–$120. But if the pressed ball joint fails in a year because the arm housing was already fatigued, you pay all that labour again.
Replacing the complete arm once costs less in the long run than replacing the ball joint twice.
We always recommend the complete control arm when the ball joint is worn — not to sell you more parts, but because it's the correct repair. One job, done right, with a full warranty. That's how we've built our reputation in Mississauga.
Any time a control arm is replaced, a wheel alignment is required afterward. The alignment settings change when suspension components are removed and reinstalled. Driving on a misaligned car after a control arm job will wear your new tires unevenly within a few thousand kilometres.
We include a wheel alignment check with every control arm job and will advise you if an alignment is needed — which it almost always is.
Clunking or knocking over bumps — especially at low speed going over speed bumps or rough pavement. This is the most common symptom of a worn ball joint or control arm bushing.
Wandering or loose steering — if your vehicle doesn't track straight and you're constantly making small steering corrections, worn control arm components are a common cause.
Uneven tire wear — excessive wear on the inside or outside edge of your front tires, especially if your alignment was recently done.
Vibration in the steering wheel — at highway speeds, a worn ball joint or bushing can cause noticeable vibration that gets worse over time.
If you're experiencing any of these — walk in to SM Auto at 922 Dundas St. E, Mississauga, or call us at (905) 277-1333. We'll inspect the suspension for free and give you an honest assessment.
Free suspension inspection. No appointment needed. 922 Dundas St. E, Unit 6–8, Mississauga.