Sound from behind

After raised the height of the rear, every time i go over road bump, there is a "dok" sound coming from rear left area. After Mech Keong inspect, it should be coming from absorber.....

Well.....Aron "sien" already, everything just not in his plan..........

Temporary Solution:

Set both of the rear absorber to the hardest - 16. No problem so far.....and the braking power is improved.