Knocking Noise from the Front End
An intermittent knocking noise from the front end of an automobile can drive even the most stable person crazy. Here we’ll discuss a few problem areas that often create clunking, popping, thumping and knocking type sounds from the front end. Technical service bulletins applying to specific models are also reviewed.
Background on the Knocking Noise
It’s not surprising that the front end of an automobile is capable of generating these kinds of sounds. The independent front suspension turns left and right while at the same time going up and down. However, these are not the only times you’ll hear thumping or clunking noises. When the vehicle stops and then begins moving again can often generate the clicks and pops that aggravate drivers.
Knowing how to reproduce the noise is important to getting it repaired efficiently. If you can generate the noise on command this means you can take a mechanic for a ride and pinpoint what creates the noise and allow the technician to hear it for himself. The analytical mind of a mechanic will associate the movements that create the problem with the root cause and the ultimate solution.
Noise from Sway Bar Links
The front sway bar is responsible for tightening up the independent front suspension as a vehicle negotiates a turn. They stabilize the ends of the sway bar through sway bar links. On older automobiles manufacturers used a threaded rod through rubber bushings. On modern cars they’ve changed this to a rod with ball and socket joints on either end. Play can develop on both types of sway bar links and cause a popping or clunking noise that’s transmitted through the frame and into the interior compartment.
This creates an amplification effect making a small noise very annoying. Certain vehicles are known for having problems with the sway bar links. As an example the 1999 through 2006 Honda Odyssey can exhibit this issue over bumps, when stopping or when turning left or right. Often the noise comes from the same side as the turn. Another vehicle associated with sway bar link problems is the Ford Taurus from the late 90s through the early 2000’s. The pops, clicks and clunks are generated in the same manner as on the Honda Odyssey. Do not confuse this with the common ball joint creaking noise found in the Ford front suspension.
Noisy Steering Parts
Inner and outer tie rod ends use the same ball and socket joint type design that the troublesome sway bar links utilize. When play develops the ball slams around in the socket creating clicking and popping noises. Generally speaking, the more worn out the joint is, the louder they get. Although similar in design there are a few differences in the behavior of a bad tie rod end when compared to a sway bar link.
When sway bar links act up the noise can be intermittent and take a long time for it to get worse. In the case of a tie rod end the noise is usually more consistent and progressively gets worse as time goes on. Diagnosing tie rod ends is performed by rocking the steering wheel back and forth and observing the play in the joint before front end part start moving. Mechanics perform this diagnosis with the suspension loaded. This means the vehicle is on the ground and the wheels straight ahead.
Additional Problem Areas to Inspect
Individual front end parts work together to get the job done. This means these parts attach to each other. It’s where they join together that problems can develop. Bolts can loosen up, reducing the clamping force, allowing parts to shift and become noisy. Areas that utilize rubber bushings should also be carefully inspected.
As an example the control arm mounts to the frame. The mounting bolts are surrounded by a rubber bushing. If the bushing deteriorates or dislodges the bolt will contact the frame and make a clunking or knocking sound. In the same respect they mount the steering rack to the frame or the firewall and isolate it with rubber bushings.
Researching Model Specific Problems
Since the front suspension of an automobile is complex in nature and different across makes and models, problems need to be approached on an individual basis. A good place to start is to make an honest attempt at locating and reviewing manufacturer specific automotive service bulletins.
Chances are if you’re hearing a noise from a particular year, make and model car or truck you’re not the only one. In fact, the manufacturer is probably way ahead of you and has issued an alert to the dealership service department. It’s possible they have even developed improved parts to eradicate the problem.