I've just installed BC racing coilovers and i've been hearing a thumping noise in the rear everytime I hit a bump or dip. It sounds like my springs are jumping up and down. The damping settings for the rear is 20 from hard to soft. I lowered my car by adjusting the ***** on the springs. Am I suppose to adjust the **** on the shocks too?

 

The short of it, yes, you do.

 

Adjusting the **** should not impact the noise you are hearing. There are two possibilities:

1) You didn't set the pre-load in the back correctly. To make sure the shock is properly holding the spring tight enough you are supposed to disconnect the shock from its lower mount and then adjust the shock length (by turning the collars) so it is about 1/4" above the mounting holes in the spring bucket. Then use a jack to lift up the spring bucket that 1/4" so the holes are aligned with the lower shock mount. Insert the bolt and tighten the nut and try again. Before you put your wheel back on, reach in and grab the spring and try to shake it. It should be snug.
2) If you still have noise then welcome to the club. My BC coilovers have made a popping/knocking noise for the past 3,000km. (they started making the noise after around 2,500km.) I have pulled everything apart and I think it is the pillow ball mounts. Another member here tried to grease the mounts but I don't think they had much success.

 

Thanks! I will try that!