One the front suspension of a vehicle when you steer, the front knuckles pivot between two points at each front wheel. For an independent front suspension vehicle those two pivot points are the upper and lower ball joints. Solid axle four wheel drive vehicles also use upper and lower ball joints on each front corner as pivot points for steering. On a Macpherson strut suspension, the two points are an upper strut bearing and a lower ball joint. On some newer design multi-link independent suspensions there are two upper and two lower ball joints per corner, though this style is generally only replaceable with the whole control arms.
A ball joint is just what it sounds like – a stud with a ball-end that’s trapped in a socket, so it can rotate and pivot and move relatively freely. On the stud side there’s a tapered pin with a threaded end, so it locks into a machined tapered hole in the knuckle or in a control arm (depending on how it’s oriented) and is then locked down with a nut. The ball end sits in a carrier that is either pressed into or bolted onto a control arm or knuckle. Many ball joints are non-serviceable, having no grease fittings. Others have fittings that are traditionally greased during an oil change service. Most of the time nowadays it’s necessary to ask to have the chassis lube-points greased during an oil change, if that’s applicable.
Replacing ball joints isn’t usually too difficult, given a few special tools. To break the taper loose there’s a tool called a “pickle fork”. Then if the ball joint is a press-fit a special ball joint press is used, with various adapters to fit various models. After ball joint replacement the alignment does need to be re-done.
Costs of Ball Joint Replacement
On average, it costs about $300 to replace a ball joint on a passenger vehicle. It costs about $500 on average to replace a pair of upper and lower ball joints (one side) on a four wheel drive vehicle.
For some more specific estimates of the cost to replace ball joints on common vehicles, using $100 an hour as a labor rate, and adding in an average amount for a wheel alignment:
For a 2007 Subaru Forester, the labor to replace the front lower ball joint is .8 of an hour. Like most Subarus it’s pinned at the control arm and held at the knuckle with a pinch bolt, so it separates out pretty easily. A factory part costs about $43, or a Moog part costs about $28. This makes the job about $223 using factory parts, or about $208 using aftermarket parts.
For A 2003 Honda Civic, the labor time to replace the front lower ball joint is 2 hours. It’s pressed into the knuckle, which is usually removed for the service. A factory part costs about $65, or a Mevotech part costs about $35. This makes the job about $365 using factory parts, or about $335 using aftermarket parts.
For a 2000 Jeep Grand Cherokee four wheel drive, which uses a solid front axle, the labor time to replace the upper and lower ball joints on one front corner is 1.9 hours. A factory pair costs about $150, and a pair of Delphi ball joints costs about $63. This makes the job about $440 using OE parts, or about $353 using aftermarket parts.
For a 1997 Chevrolet K1500 four wheel drive with torsion bar suspension, the labor time to replace the front ball joints on one corner is 4 hours. This has an independent suspension, but has the disadvantage of the original ball joints being held in by heavy rivets, which must be cut and driven out. A factory upper and lower ball joint set costs about $165, or a Mevotech heavy duty set costs about $72. This makes the job about $665 using OE parts, or about $572 using aftermarket parts. There are also a variety of different suspensions and sub-model options for that truck, so often visual inspection and measurement are needed to get the correct parts and labor times.
Inspecting Ball Joints, and What Can Go Wrong
Ball joints are typically inspected for play. In most cases there should be no side play and no up and down play; technically that’s radial and axial play, respectively. In principle the ball joints should be inspected and the amount of play measured, and then that compared to the amount of allowable play. Ball joints are considered safety items, so all that is published and commonly available information. But in practice, in most cases, a good ball joint is “tight”, and a ball joint with any amount of play is recommended for replacement. This can lead to some mistakes in diagnosis. It is always fair to ask the questions “how much play is allowed?” and “how much play does it have?” A mechanic who did an inspection correctly generally appreciates being able to inform a customer.
In some cases ball joints are sold for “leaking”, which is not an actual cause for replacement. Whether they are sealed or have grease fittings they will use a flexible boot to hold grease in the socket. Frequently these will leak, but that isn’t necessarily a problem. Older ball joint designs were engineered to leak, and the general rule was you knew there was grease inside if you could see the grease outside. A newer non-greasable ball joint will likely have a shorter lifespan if the boot protecting the socket is torn, but there’s still no great reason to replace a ball joint that hasn’t failed yet. Unless, perhaps, it has to be removed for other service.
When using the cheapest parts available, which at the moment are certain Chinese manufactured ball joints sold under various names, one problem that comes up sometimes is that the tapers aren’t ground correctly. When the bolt or castle nut is tightened down to lock the taper, the stud can be pulled too far up through the machined opening to install a cotter pin effectively. It can also draw up to the point that the ball binds in the socket. In either case the best solution is to utilize the parts warranty and try another ball joint; a safety item that doesn’t fit right shouldn’t be installed.
Generally not. The ball joints are an important part of the vehicle’s steering and suspension, and if a ball joint is worn past allowed limits, that means it is unsafe. Ball joint failure can mean the suspension coming apart and loss of vehicle control.
Fairly often there are no indications, but noise going over bumps can be one. There are many other more common causes though.
If a vehicle is in for a wheel alignment the ball joints are usually inspected. Also, if a safety inspection is requested the ball joints should be checked. In most cases they are pretty durable and reliable; not a common problem at lower mileages.