Whether the ball joint needs to come with it depends on one thing first: whether your control arm's ball joint is a separate, serviceable part or a permanently integrated one. On a lot of modern vehicles it's the latter — the ball joint is pressed or cast into the arm at the factory with no separate replacement option, which means "do I need to replace the ball joint too" isn't really a choice, it's a fact about your car's design. As for doing just one side: yes, that's allowed, but whether it's a good idea depends on why the first side failed.
Does the Ball Joint Need to Come With It?
Start here, not with "is the ball joint worn" — the structural design of your control arm decides the question before condition does.
If the ball joint is integrated (pressed, cast, or riveted into the arm): There's no separate part to inspect or reuse. A new control arm assembly comes with a new ball joint whether you wanted one or not, because they're sold as a single unit. This is genuinely common on modern vehicles — not an edge case.
If the ball joint is separately serviceable (bolted or independently press-fit): You have an actual choice. A ball joint in good condition — no play, no torn boot, clean grease — can be left alone. But most shops recommend replacing it anyway once the suspension is already disassembled, for the same reason covered in our bushing-vs-whole-arm guide: the labor to get back to that joint is most of the labor of replacing it, and paying for that disassembly twice (once now, again later when the joint finally does fail) is the more expensive outcome, not the cautious one.
To figure out which situation applies to your vehicle, see our guide on identifying press-fit vs. bolt-on ball joints — it covers how to tell the two apart by inspection, plus the third case (integrated, non-serviceable) that this article assumes you'll need to rule out first.
Other Parts Worth Checking While You're In There
Since the suspension is already apart, it's worth a quick inspection pass beyond the ball joint:
- Tie rods
- Sway bar links
- Struts/shocks
- The opposite-side control arm
None of these have to be replaced just because the control arm is — this is an inspection list, not a mandatory parts list.
Can You Replace Just One Side?
Yes — there's no mechanical requirement to replace both control arms together. But the right call depends on why the first one failed.
Single-side impact damage (hit a curb, dropped into a deep pothole, bent from a collision) doesn't automatically put the other side at risk. If the opposite arm is in good condition, there's usually no reason to replace it just because its partner got damaged.
Normal wear from age and mileage is a different situation. Both sides have seen the same miles, the same road salt, the same potholes — if one side's bushings or ball joint have worn out from that exposure, the other side has been through identical conditions and is likely not far behind. Replacing only the worn side is still allowed, but it often just delays a second, nearly identical job by a few months.
There's a practical cost to that delay beyond the parts themselves: a control arm replacement requires a wheel alignment afterward regardless of how many sides you did. Doing both sides in one job means paying for one alignment instead of two.
The Short Version
- First, find out if your ball joint is integrated or separate — that answers whether "replace the ball joint too" is even a decision you get to make.
- If it's separate and in good shape, you can leave it — but replacing it while the suspension is apart is usually the more cost-effective call, not just the cautious one.
- One side alone is fine for impact damage. For wear-related failure, check the other side before deciding — it's probably close behind.
- Either way, budget for a wheel alignment — see our guide on why that's required after any control arm replacement.
Related reading: Should You Replace Just the Control Arm Bushing, or the Whole Arm? · Do You Need a Wheel Alignment After Replacing a Control Arm? · Press-Fit vs. Bolt-On Ball Joints · A Torn Ball Joint Boot: What It Means
