Why does the Suspension Squeak?

In this brief article, we will discuss suspension squeaking, the causes for suspension squeaking and steps to prevent it.

Why does the Suspension Squeak?

Suspension Squeak is caused by multiple factors depending on the particular type of suspension setup that your car has. The most probable sources of squeaking based on suspension type are:

Leaf Spring Suspension

  • If there are multiple leafs like in the semi-elliptical type, then inter-leaf rubbing can cause squeaks
  • Spring hanger Pins, in many vehicles, are of the serviceable type. Lack of proper greasing can cause squeaks and rattles.
  • Spring hanger pins that have a rubber bushing can start to squeak when the rubber has disintegrated

Double Wishbone

  • A Double wishbone suspension setup usually has rubber bushings to connect the wishbones to the chassis. When this wears out, it could create squeaking noises when there is metal-to-metal contact.
  • The wishbone-to-knuckle connection is almost always using a ball-joint. The ball-joint fails whenever there is a lack of lubrication and eventually leads to noise issues.
  • Many cars in the mid-segment have front and rear subframes under the monocoque frame. The suspension control arms get mounted onto the subframe at very tight clearances with rubber bushings as a connection. Whenever the suspension bushing connections to the subframe are worn out, it could lead to the wishbone or control arm hitting and rubbing against the subframe, leading to metallic squeaks.

Anti Roll Bar Connections

  • Most independent suspensions come with an anti roll bar. The anti-roll bar is mounted to the chassis or subframe through rubber bushings. 
  • When there is a lack of lubrication at these locations, it could lead to squeaks.
  • Rear suspension control arms are sometimes attached to the chassis or subframe through conical rubber bushings that are compressed while torquing the joint. 
  • Due to weathering, sometimes, the rubber could grip the metal portions and cause squeaking noises.

MacPherson Strut Suspension

  • The Lower Control arm is usually mounted to the subframe through a bush connection leaving only just enough clearance for the arm to articulate. 
  • Once the bush deteriorates, there is more freedom for the control arm to move about and rub against the nearest portion of the subframe structure, leading to squeaking noises.

Shock Absorber Failure

  • Shock Absorbers work based on their internal sealing action between the Rod, the Piston and the cylinder. The sealing effect is achieved by means of flexible sealing interface rings that are susceptible to wear in the long-term.
  • A Failed shock absorber would have the internal piston rubbing against the cylinder when the seal has worn out completely. The  resulting metal-to metal rubbing leads to squeaking noises.

Rusted Parts

  • In cases of extreme corrosion and rust, where the suspension arm or subframe has lost material to flaking, there is a high probability of squeaking.
  • In the cases of extreme rust, it is mostly observed that the vehicle could be operating in the ‘Salt Belt’

How to prevent Suspension Squeaking Noises?

  • It would be advisable to inspect all the rubber bushings in the suspension at the OEM recommended intervals and see if the rubber portion has any cracks or disintegration. Timely replacement of these parts could help prevent the occurance of squeaks
  • One way to prevent squeaks is to ensure lubrication of all the serviceable ball-joints at regular intervals.
  • In the case of sealed ball-joints, make sure to replace the joint whenever there is either a crack or tear observed anywhere on the protective rubber boot surrounding the ball-joint.
  • In joints where the rubber bushing is compressed and tightened against the mating surfaces, make sure to use Anti-seize which is meant for rubber joints. Anti-roll bar mountings are also usually of this type and therefore require lubrication.
  • In the case of semi-elliptic leaf spring suspensions where there is more than one leaf, the interleaf contact surfaces are either lubricated with silicone-based product or spaced with thin low-friction layer wear pads or both.

Can I drive with a squeaky suspension?

Yes, it is possible to drive with a ‘Squeaks’ in the suspension, in most situations. 

As a word of caution, it is always best to inspect the suspension before commencing driving. 

If the squeaking is due to some rubber bushings deteriorating, it is probably OK to drive till they can get sorted.

The only situation where it would be not advisable to drive, is where the squeaking is due to rusting of the suspension structure. When the squeaking is due to rust, it means that the structure has disintegrated and that it is only a matter of time before the suspension collapses completely.

Conclusion

In this brief article, we have discussed suspension squeaking, the causes for suspension squeaking and steps to prevent it.

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