The Humble Mechanic: How to Fix a Noisy Suspension

The Humble Mechanic: How to Fix a Noisy Suspension

Charles switches gears to work on a friend’s noisy Toyota. He takes us through replacing a strut assembly.

Today in the shop, we have a 2001 Toyota Highlander with 170,000 miles on it. I know I don’t usually work on Toyotas, but my friend Vince needed my help, so I’m helping him out. For this article, we’ll go through the process of figuring out where Vince’s noise is coming from and, more importantly, how to fix it.

With pretty much any type of noise concern, you want to start in one of two places, either with a test drive or a visual inspection. I usually prefer to do the test drive first so we can attempt to isolate where our noise is coming from. It also really helps if you have a second person who can drive the car so you can listen to the noise. Keep in mind that noises can travel throughout the car. A noise that sounds like it’s coming from the right front may actually be coming from the back.

We want to pay attention to when the noise happens and what the car is doing when it’s making the noise. Are we going over a bump and it’s making a noise going up or is it making the noise going down? A noise on the upside going over a bump is a noise when our suspension is compressing. On the downside of the bump, that’s known as the rebound.

Back at the shop, you can also try and jounce the car up and down and replicate the noise while the car is parked. This is usually my favorite way, especially with someone’s help, because it allows you to move the suspension while doing a visual inspection. Luckily, this one was pretty easy. The strut looks like it’s actually coming apart. As I move the wheel back and forth, I can see where the strut goes into the body; it’s really moving. So, this is definitely the source of at least part of our noise.

For this Toyota, I was able to get a complete strut assembly from Advance Auto Parts. This includes the strut, the spring, the dust boot and the mount already put together. This is very different from the European cars where you have to piece it all together yourself. We’re going to need to get the car up in the air, so make sure if you’re lifting your car, you’re lifting it properly using jack stands, wheel shocks, etc. to be sure you’re being safe.
This was a pretty easy visual inspection diagnosis. Our dust boot is completely destroyed and that allowed dirt and mud to get into our strut, causing our issue. See Figure 1.

Figure 1

We have a few parts that we’re going to need to take off such as the sway bar end link, the lower mounts, an ABS sensor, a brake line that is mounted to the strut body as well as some bolts both under and inside the car, which I pretreated with a rust penetrant.

We’ll start with our sway bar end link. In Figure 2 you’ll notice that this little hole is actually full of dirt. Make sure to get all this crud out of there, or at least as much as you possibly can. That way, when you take your #6 Allen and put it in there, it’s not just mushing in dirt. What we’re doing when we’re using that #6 Allen and the 14mm wrench is we’re counter-holding the sway bar end link and loosening the nut that holds it on.

Figure 2

Next, we’ll take off the 10mm bolt that’s holding our wheel speed sensor bracket on. Then we have a 12mm holding on our brake line. At the bottom of the strut, we have two 19mm bolts holding on our wheel hub assembly. See Figure 3. You want to make sure that you loosen both of the bolts before taking either one out. That way you don’t get in a situation where the whole hub starts moving around on you.

Figure 3

For this next part, where we’re going to loosen the bottom mounts for the strut, I like to grab a floor jack, slide it under and just give a little support to our rear wheel hub. Now for the back, we have to get inside the car, and underneath the little access panel is the top mount for our strut assembly. See Figure 4. This has three 12mm nuts, and I also had to really search hard to find my 12mm socket, because it’s not one I use all that often.

Figure 4

Now that we have everything loose, we’ll take a small pry bar and pry the knuckle away from the strut, and then I’ll carefully drop the whole assembly down, so I don’t scratch up the fender. Make sure to pay attention to where your brake line and ABS wire are. You don’t want to rip any of that apart.

Now, while it’s awesome that our new strut assembly is already put together, I still want to take this old one apart and try to see what’s going on. Check out the video to see what I found. If you ever have the opportunity to take apart something that’s failed, it’s a great learning experience.

Before installing that new strut, make sure you clean any mating surfaces. I’m using a wire brush to clean our wheel hub assembly. You want to make sure to pay attention to the alignment for the top strut plate. This one only goes in one way, but sometimes you can get them out of orientation and that can create suspension noise.

When you’re putting it all back together, you want to make sure you’re supporting that knuckle with your floor jack, and it’s often easier when you have an extra set of hands, one person on the bottom holding the strut and somebody inside the car tightening everything down. See Figure 5.

Figure 5

Going back together on this setup is easy, but there’s still a handful of things you need to pay close attention to. For instance, just like coming out, you want to make sure you pay attention to the brake hose and ABS wiring, and anything else that could get damaged. Also, take a good look at your hardware and make sure none of that needs to be replaced. You also really do want to refer to the repair manual to be sure that none of the fasteners are torque to yield, which means they need to be replaced every time.

It’s also recommended when doing struts or doing shocks on a car to at least do both sides on that given axle. Meaning that if you do the right rear, like we’re doing, you also want to go ahead and do the left rear. It may not be a bad idea to get an alignment done on the car afterward as well.

The only thing left is to take it on a test drive and make sure that our noise is gone.

Watch the video. Check out the show notes for links to everything we used on this one.

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