Ben's DIY Corner: Ball Joint Replacement, Or, My Week In Hell

A few weeks ago, I started noticing a slight creaking sound coming from under my car (2010 Subaru Impreza) whenever I would start from a stop or come to a stop, or sometimes when turning or even going straight at very low speed. It gradually became more pronounced, became kind of a grinding, then popping at times. Researching symptoms, I finally got under the car and examined all the various rubber parts looking for a broken cv joint boot or loose bushing or something. As it turns out, the front passenger side lower ball joint boot had broken, letting grease out, and gradually allowing the metal ball and socket to start grinding together.

I ordered a pair of Moog-branded ball joints from RockAuto.com, figuring I'd do the driver's side too if the passenger side wasn't too bad.

Sweet, fresh, plump, juicy ball joint ready for installation:

I consulted the factory service manual and every youtube video I could get my hands on, and felt pretty confident that even though there were a few painful areas to watch out for, all in all it should be pretty straightforward. A lot of videos I watched emphasized that for drivers in the rust / salt belt, the bolts securing the ball joint would be almost impossible to remove without breaking off. Fortunately, although my car obviously saw some winter action in the two years of its life before I bought it, all the nuts and bolts were easy to remove with a little PB Blaster and some elbow grease. I was also really glad I watched a video specifically on working on a 2010 Impreza, because the service manual I have is for a 2009, and there were some extra stabilizer link bracket bolts I had to remove that I wouldn't have been expecting if I hadn't had the benefit of other users' experience.

After getting everything else ready, I was ready to extract the ball joint istelf from the steering knuckle / wheel hub holder. The service manual instructions for this step are, "Extract the ball joint from housing." Fortunately, plenty of blogs and forum posts and videos seemed to agree that the easiest way to get it out was to prop a length of wood against the lower control arm and whack the shit out of it with a hammer. After a couple of hours, the first bitter tears of the project, and several shattered lengths of pine, I had made pretty much no progress getting the thing out.

To be fair, I was just using a standard household general-purpose claw hammer, so I opted for a slightly more nuclear option and bought a 3-pound hammer and a 3-foot length of 3/4-inch black iron pipe and an end cap from Lowe's. I padded the iron pipe cap and the control arm with several layers of duct tape to mitigate the damage of such direct force.

Three or four whacks and it was out.

Elation. Piece of cake. I always try to keep Hofstadter's Law in mind when working on a car project: "It always takes longer than you expect, even when you take into account Hofstadter's Law." Sure enough, it continues to hold true every time in my experience. At any rate, all I had to do now was to pop the new ball joint into the ball joint holder and reconnect the lower control arm. Got the ball joint in place and secured with a new bolt:

Weird, though, I can't get the wheel hub to move back inward toward the center of the car so I can fit the ball joint back into the lower control arm. Right around this time, Molly tells me dinner's about ready, so I figure, OK, the hard part's done, I'll just grab a quick dinner and then finish everytjing up. Maybe even take it out for a spin later and see how everything feels.

Quick aside / flashback: one video I watched recommended jacking the brake disc up slightly so that the force of hammering down on the lower control arm would be completely transferred directly into the control arm rather than also pulling the whole hub assembly down. I took that advice, and it worked like a charm, but one side-effect I couldn't have predicted was that, as soon as the ball joint was out of the steering knuckle, something about the geometry of the whole situation meant that the force of the jack upward on the hub also meant force pulling the entire axle outward away from the differential.

So, then, the reason that the wheel hub wouldn't move back toward the lower control arm was that I had inadvertently dislocated the inner cv joint. Fuck. Now it's Sunday evening. I text my boss to let him know I'd be stranded Monday and working from home.

Come Monday morning, I called my trusted auto shop to see whether they had any advice about getting the thing towed. Their basic response was that the car was untowable with the suspension in such a disconnected state, but that if I could extract the entire front right-hand axle I could bring it in and they could reassemble it for me. Fuck. OK. So I know that is beyond my ability and toolset. I look up a few mobile mechanics, call them, submit online request forms, and hear nothing. Meanwhile, I'm going back to the car and trying to cram the cv joint back together with all my might and making no progress whatsoever. I finally call a towing company and tell them the situation. They say, "Yeah, we can do that." I call the auto shop to coordinate a drop-off, and they say first-thing Wednesday morning. OK. It sucks that a DIY project finally got away from me, but at least this is a solution.

...

Wednesday morning, 8:45, towing guy takes one look at the car and says, "I'm not going to be able to move that". FUCK. God damn it. I'm really starting to feel like I'm in a nightmare. How can it be this easy to accidentally strand my car in my own garage in America in 2019? At this point, I come to accept that I am truly on my own. My options as I see them are to either to fix the entire thing myself, or at least to get the cv joint out of the axle so I can put the suspension back together enough to have it towed. Molly comes home and swings me by Home Depot so I can grab a socket big enough for the axle nut. Then we go home and she stomps on the brakes to keep them from spinning while I jump up and down on a breaker bar until the nut breaks loose. Thanks, Molly!

From there, it actually is a pretty straightforward matter to detach the hub housing from the strut, and bang the axle back out of the hub.

I then loosen the inner cv boot's larger (inner) boot band and pull the outer part of the axle (everything on the outboard side of the inner cv joint) out. As it turns out, one of the three spinny wheel things in the inner joint had come completely off its axis and was floating around inside the boot. That joint was never going back together without being disassembled first.

I had to hammer the spinny wheel back into place, no big deal. Then I had to extract the inner part of the cv axle from the front differential. Once again, the service manual is extremely helpful on this point: "Using a bar, remove the front drive shaft from transmission." Thanks. All the videos I watched showed this to be a very simple and easy process, but I think all these guys had their car on big lifts. With just jack stands and a 3-foot breaker bar, I had a hell of a time getting purchase on the side of the transmission case to wedge the thing loose. After a long time, and on the verge of despair, I popped the thing out and whanged the shit out of my knuckles on the underside of the car. Once the entire axle was out, it was simple but kind of scary to hammer the two halves together until all three of the rollers slid past the retainers into the joint. That jack must have been applying a huge amount of force in order to pull those rollers out of the joint.

A boring and frustrating 24 hours later, I finally had the axle fully reassembled and the inner boot secured with fresh bands. Now it was time to reinsert the axle back into the front differential. The sticking point, it turns out, was the lock ring that keeps the entire axle from sliding in and out as the suspension moves up and down while driving (and forces those rollers inside the inner cv joint to do the sliding in and out instead). After a couple of hours of trying to force it in by hand, and taking the advice of an obviously equally-frustrated youtuber, I asked molly to lightly tap the far end of the axle with my new, trusty 3-pound hammer while I forced the axle inward against the differential. She was...unenthusiastic about the prospect, but it turns out that two fairly light taps were all it took to push it back into place. Fuck yes. After that, it was truly rudimentary to fit the outer end of the axle back into the wheel hub and reattach the strut.

I then slid the lower end of the ball joint into the lower control arm, and only then realized that in all the commotion I'd managed to tear the boot of the new ball joint. By this point, I was so numb to the whole thing that I just grabbed the second ball joint I'd bought, popped the broken one out, and replaced it in what felt like about five minutes.

Took it for a spin, no weird sounds or vibrations, all good. Got home, and something smelled distinctly of burning plastic. I popped the hood and saw a fair bit of grease and/or oil smoking on the exhaust manifold. I grabbed the fire extinguisher, but after a minute the smoke stopped. I wiped everything down very thoroughy and will have to remember to keep an eye on things for the next couple of outings.