After spring/shock install, banging sound from rear

Hi all,

I just finished an H&R race spring and Bilstein strut installation which seemed to go pretty smooth. However, when I take off in 1st gear, I hear a knocking/banging sound from the rear of the car. I have verified that all of the bolts are tightened and torqued down; stocks, lower control arms, and sway bar.
This sound only happens when I take off from 1st, however if I really ease the car from 1st, it won't make the sound.
As a note, I also used my stock spring isolators, however I'm not certain if this would cause a sound such as this.
Any ideas?

Thanks in advance.

As a note, I'm wondering if it is the upper control arm bushing binding, as I did not loosen these when doing the install, only the lowers. Something else I'm going to try.

Bosko5.0 said:

maybe the pinion snubber is hitting....

is it one knock or a bunch of knocks?

Click to expand...

It's just single knock, which does not occur when hitting bumps, just when taking off in 1st.