Impreza WRX GD Rear Noise Causes And Countermeasures

About a month has passed since the car was delivered as a used car. From the beginning, I was worried about the abnormal noise from the rear while driving, such as when starting, stopping, or overcoming steps.

Possible causes are …

1. I don’t know about Subaru, but the deterioration of the stabilizer link, which is common in Honda cars, etc
2. Loose bolts including the upper mount
3. The trunk striker is hitting somewhere
4. Loads including genuine jacks

I tried and errored considering the above causes, but no improvement was made.

When the coil spring expands and contracts, a force in the direction of rotation is generated, and I thought that the deviation would generate noise, but it seems to be wrong.

When I unload the luggage in the trunk and put your weight on it like straddling a spare tire and shake the car body up and down, the noise is generated.

It is a photograph of the rear shock absorber. I tried cleaning the damper part, thinking that the damper was not moving well and there was a sound that would get caught in the seal when it was activated.

For cleaning, jack up (you don’t have to remove the tires) and flip the dust boots through the gaps in the coil springs to touch the damper rods. I tried cleaning the left and right rear damper rods with a waste cloth using a silicone spray.

As a result, the sound disappeared surprisingly! In the same way, it does not come out even if you ride on the trunk and shake it, and it does not come out at all even if you run.

There seems to be no doubt that the damper part was the cause.
It is necessary to verify how effective it is, but since it is only jacking up, I will try again when there is a noise.

If the noise starts to come out too soon, I’ve seen something like a dry lube for reducing the resistance of the damper part, so it may be worth trying.

The precautions when working are as follows.
1. Silicone oil is used for the damper
2. Do not use lubricants such as CRC (because it deteriorates the rubber of seals)
3. Do not use high-viscosity grease (causes dirt to adhere)
4. Lightly spray the silicone spray and wipe it off immediately with a waste cloth

I hope it will be useful for those who are suffering from the same symptoms.

Postscript:
I rode it for about two months after cleaning, but there was no noise at all. I was surprised just because I thought that the same noise would start to come out soon.