If you don’t have a drive-on lift, you’ll be forced to use the creeper to confirm the diagnosis. Using a mechanic’s stethoscope, have an assistant push and lift on the fender or rock the vehicle side to side as you confirm the source of the noise. If you suspect the tie rod end, a twist of the rod should result in the same noise. With our Sentra, we could duplicate the noise, but couldn’t really pinpoint the source.
After hearing it on the road test, I was surprised we couldn’t duplicate this noise in the shop using the same technique that revealed the squeak. We looked closely for any free movement in the suspension, paying particular attention to the sway bar mounts and the links. We didn’t see any, so our search for the knock continued back on the frame contact lift. Using pry bars, we again tried to move the sway bar and its links, as well as the lower control arm bushings, but still couldn’t find any movement.
We looked at the bolts that mount the sub-frame to the unibody, keeping an eye out for rust around the bolts, since it’s a dead giveaway that movement is taking place. But, we didn’t find anything there either.
At this point, we began to replace the suspected lower ball joint, planning to confirm the problem as the job progressed. With the joint separated from the knuckle, it moved freely and quietly. But, any movement of the control arm confirmed the noise was coming from the bushing.
In this case, the outside of the bushing was loose in the control arm, resulting in metal-to-metal contact and the squeaking noise. Side movement on the now-unloaded arm revealed a small amount of play at the outside of the same bushing, which was causing the knocking noise. As the arm was removed, the problem was obvious. The bushing had separated and was moving in the bracket. While this is not a common Nissan problem, you can be sure we’ll look more closely at the bushings in the future.
The more common cause of knocking noise is the sway bar attachment points and links. As I stated earlier, any movement in these components will result in a substantial noise inside the car. Many times, you’ll pick up these noises as the car is driven in the parking lot at slow speeds; they will usually be easily duplicated in the shop by rocking the car. A good way to isolate the noise is to simply put your hand on the link as the car is moved — the play will be obvious.
If the noise is more of a rattle than a knock, I’d be looking at the brake pads to be sure all the anti-rattle hardware is in place and doing its job. Lightly applying the brakes should confirm that pad movement is causing the noise.
Another common customer-missed cue will have them complaining of a suspension noise when the real issue is a bad CV joint that’s clicking when turned; another case where the customer comments can get you in trouble without an initial road test.
Drifting or Pulling Culprit
Not all your suspension complaints will be noise-related. If you’re faced with a drifting or pulling complaint, look first to the tires for the cause. It doesn’t take much stagger (difference in circumference) to cause a pull. We use a narrow 10-foot tape that conforms nicely around the tire. In minutes, all four properly inflated tires can be measured, letting you make an educated decision on where to mount them on the car. At the same time, take a look at the tire wear for any alignment issues.
The same goes for vibration complaints. The most important thing we need to establish is when the vibration occurs, and if it’s a noise or something the customer is feeling. We’ve had many customers complain of a vibration, when they’re actually talking about an exhaust shield rattle or the growling noise caused by a bad wheel bearing or cupped tire.
We’re all experienced with tracking down steering vibrations and should have no trouble with Nissans. Tire condition has to be considered, especially if rotation service has been ignored; it’s not unusual for cupping to take place on the rear tires. Such uneven wear will often mimic a bad bearing, and will certainly cause a noticeable vibration through the seat.
This cupping is often thought to be the result of weak rear struts, but I would hesitate to recommend strut replacement if cupping is the only symptom experienced. A better solution is regular tire rotation. If the struts are showing signs of leakage, or fail the time-honored push test, they should be replaced. But, still recommend regular rotation service.
While we’re talking about vibrations, we have to consider the front-drive axles, CV joints and brakes. If the shake changes under load, it’s a safe bet there is a worn inner CV joint. The challenge is determining which side is the offender; it could be both. Since we see this only on high-mileage vehicles, we recommend replacing both axles with quality, rebuilt units.
If the customer reports an intermittent vibration that can’t be pinned down, look for evidence of a sticking brake caliper and the overheating it causes. You would think the driver would smell the overheating brakes, but that isn’t always the case. The vibration, however, will get the attention of anyone. We also have to consider the vibration caused by warped rotors.
Brake Problems
That brings us to the brake portion of this article. Brake problems will present themselves in a couple of ways. Like the suspension system, the most common complaints are noise-related. Nissan, like many other manufacturers, makes use of the simple and effective tab-type sensor that will contact the rotor when the pads need to be replaced. The resulting, high-pitched squeaking noise has proven to be very effective in getting the driver’s attention. That’s not to say that people won’t ignore it and drive until the brakes are making that distinctive grinding noise that indicates the friction material is gone and metal-to-metal contact is taking place.
Many of the occasional, annoying noises that disc brakes make are a small trade-off for the braking performance delivered by the system. Often, just explaining that to a customer goes a long way toward settling their concerns that something is wrong with their brakes.
