Need help/advice on rear suspension knocking Mazdaspeed with Cobb Sport springs

[highonpsi]

I have an '07 Mazdaspeed 3 with Cobb sport springs. I bought the car recently and only when people sit in the back, when going over bumps, there is a knocking noise. Does anybody have any feedback on what might be causing this? From my understanding, Cobb Sport springs only lower the car 1 inch. Is that enough to throw the stock shocks off to the point that they might be bottoming out, or could this be something else causing the noises. It was certified, so nothing was found to be bad when (obviously) nobody is sitting in the back and it is on the hoist.

Any advice would be greatly appreciated.

[S.F.W.]

I am not an expert but seems like the rear shocks are worn.

[Impressive]

I am not an expert but seems like the rear shocks are worn.

Agreed.

[The Wolf]

I've noticed the same thing on mine in the last couple days actually. Oh well, guess it's time for coils ;)

[Mr Wilson]

I have an '07 Mazdaspeed 3 with Cobb sport springs. I bought the car recently and only when people sit in the back, when going over bumps, there is a knocking noise. Does anybody have any feedback on what might be causing this? From my understanding, Cobb Sport springs only lower the car 1 inch. Is that enough to throw the stock shocks off to the point that they might be bottoming out, or could this be something else causing the noises. It was certified, so nothing was found to be bad when (obviously) nobody is sitting in the back and it is on the hoist.

Any advice would be greatly appreciated.

A slight breeze will throw off the stock MS3 shocks/struts.

Agreed with everyone else. If you're in T.O. take it to Jimmy up at Street Performance and he can diagnose with more certainty than us.

[McGuyver_3]

If shocks were to be gone my opinion is that you would hear the noise more often and or consistantly. When my l/f shock made noise it was constant mainly when going over bumps. In order to diagnose it though you would have to take it to a shop and have them look at it.

[CelestSpeed3]

Are you sure you aren't rubbing the tires on the fender?

Without seeing the car its hard to speculate, I agree with Mcguyver have someone take a look at it.