rear end noise. knocking, thumping

[yukonaetahoe]

i noticed it when i hit a speed bump kind of fast. The rear when the shocks were supposed to absorb the impact, it thumped. by thumped i mean like slamming a hammer on a nail.
when i drive i notice this thumping noise whenever there are bumps or holes or anything that gives instant impact.
the shocks were good, but still got them changed and has done nothing to help. it isnt the shocks because when i go slow on a speed bump everything works. Its just those instant quick impacts that hit real hard. this isnt normal because its never happened before till now.
i hear also some knocking noise when the ass moves left to right. might be totally different but just a coincidence.
Looked underneath and nothing seems loose. the exhaust pipe seems like it could be of some problem, but the clearances are huge, and like i said the noise is from where there is instant impact ONLY, not long deep shock travel.
hope someone can push me in the right direction..... if not thanks for hearing me out.

 

[blueflamed03]

crawl under, have a HEAVY friend jump up and down on your rear bumper while your underneath...gotta be suspension somewhere hitting.

 

[SunlitComet]

and check your axle u-bolts too.

 

[yukonaetahoe]

i will have to try that blue flame. Im a heavy guy and i jumped on the bumper over and over and no knocking whatso ever nor thumping. Its always only when im driving and there is a instant impact like a crack on the road or a pothole. weird.

sunlitecomet, i will check them as soon as i figure out what they are lol im googling it right now. ima get under there and start moving everything hopefully i can find whatever is loose.

tomorrow will be the day hopefully

 

[SunlitComet]

They are essentially the long hanger bolts in u-shaped form that hold the axles to the spring packs.

Get yourself a hard mallet and start hitting things and watch for movement. Works very well.