September 2016 | Things that go bump in the night (daytime, too)

Note: I'm tossing this entry into the blog because it could save Ford Focus owners a bit of frustration and expense. Also, it was personally satisfying to think through the problem and come up with a solution.

I've been driving a Ford Focus SE since May 2012. It has generally been an economical and trouble-free chariot, up to a couple of months ago when a strange clunking noise began emanating from the front suspension. On minor bumps, at speeds up to about 45mph, the front end produced a dull rattle something like a wrench bouncing around in the engine compartment. At higher speeds, the noise diminished, and seemed to be gone around 55mph.

This behavior has been described on various online Focus lovers forums and in Youtube videos, with an occasional suggestion for fixing it. An apparently simple remedy was to smear a gob of Motorcraft XG3A dielectric grease over the shaft on each of the front struts. This involves removing a front wheel, and pulling down the accordion boot and jounce bumper from the top of the strut, after which you slather a couple ounces of grease on the top of the shaft and reassemble. Execution proved not so simple, as the boot and bumper are difficult to break loose and even harder to reseat. I tried this fix, and it accomplished nothing.

In the meantime, the rattle seemed to be getting louder, and it was now clear a parts swap was in order, but what part? Some owners experiencing this problem took the car to dealerships and drove off with stories such as "they couldn't duplicate it" or "they heard the noise but couldn't find anything wrong." Virtually nobody said "they knew exactly what it was and fixed it straight away."

After more research, my attention turned to the sway bar links. A sway bar link is a rod about 11" long with a ball joint on each end (see the picture). A link is positioned vertically at the rear of each strut, connecting the strut to the sway bar, which runs beneath the engine compartment to the other front wheel's suspension. When I greased the strut shafts, I checked the links. Both seemed to be tight. What I didn't realize was jacking up only one wheel at a time flexed the sway bar, keeping tension on the link, so it could seem tighter than it really was. More on this later.

My decision to replace the links was a shot in the dark, but supported by some reasoning. The ball joint socket consists of nylon or some material softer than the steel ball it surrounds, so it was easy to imagine the socket had worn. Further, I could replace the links for a fraction of the cost of having a dealership merely look at the car. If links were not the problem, I would still be ahead in terms of removing a possible cause.

Note: I am not a qualified technician, and have no professional credentials for telling you how or when to change the sway bar links. If you decide to do so, it is at your own risk. There are videos online explain how to do it. That said, I pass on these tips, which should make the job easier:

1. Jack up BOTH front wheels and place a jack stand under each side of the vehicle. Raising both sides removes tension from the sway bar, making it easier to remove a link once you remove the mounting nuts. Otherwise, the link ends will bind in their holes.
2. The portion of the shaft behind the rubber boot should have a pair of flatted surfaces that can be gripped with a 17mm open end wrench. Some aftermarket links have six flats instead of two. Gripping the flats will let you keep the ball end from rotating as you spin off the nut. Usually, the shafts include a recessed Allen socket, but it seems easier to grab the flats with a wrench.
3. The socket for removing the mounting nuts is 15mm hex. You might need a ratchet or short breaker bar to loosen them. A squirt of penetrating oil can make the job easier.
4. When you mount the new link, use a torque wrench for final tightening of the mounting nuts. Online sources list the torque specification for the nuts as 37 lb-ft, and 35-40 lb-ft.

Having done this as somewhat of a gamble, I'm pleased to report the rattle is gone. The shafts on the ends of the old links were easy to move, and much looser than for a new link. The ride seems tighter and quieter at all speeds, suggesting road rumble was getting through, even when the rattle itself was not noticeable.

I spent about one hour gathering tools and replacing the first link, and a half hour on the second. The cost was about $27.00 for a pair of links, but can vary from $20.00 - $60.00, depending on the source and features. Some aftermarket links have grease fittings, chrome finish, etc. The parts are available online, at some auto parts stores, and of course, a Ford dealer.