Rear end banging over bumps
 

My gfs car has this jarring kinda bang/thud sound when going over bumps.. Like riding on real low profile rubber with too much air..

I changed out the rear coil overs with some spares I had here, both set are stock. But still same issue.

What suspension components do I need to check? Rubber bushes etc? And how do I do this?

I don't wanna spend a k on aftermarket coil overs if they're not the problem.

It could be that the second pair of coil overs were stuffed too, I'm not sure. They came from a one year older car.

Thanks in advance.

If u cld attach relevant pics too please as I am a little clueless with suspension components, like sway bars and anti roll etc.

My first thought is blown shock / bump stops gone. Take apart the shock assembly and see what condition the bump stops are in. Ours have a tendency to disintegrate. With a blown shock, the car will also be sitting low in the rear. For reference, mine had about an inch gap from stock tire to fender with blown shocks, but that isn't the most precise method. With it apart, I could move the shock with just body weight, which didn't happen with fresh ones.

Edit: If it does turn out to be shocks, the for sale section has reasonable mileage stock shocks/springs going for pretty cheap.

Id check to make sure the grommets on top if the rear shocks are in there correct/ not damaged.

What about other components, like bushes, rubbers etc that aren't part of the coil over item.?
Remember I swapped hers out with the spares n had the same problem, tho they too could've been stuffed.

Same problem... subed.

Same problem on my BC BR 8K passenger rear coil-over, driver rear is fine only this side makes the noise and only when hit at certain angles. No idea what it is, car sits perfectly level on all 4 corners.

Suspension shop said they are pretty sure it's the shocks, so looks like a change is coming. Of course I'll do the job myself but I needed an expert opinion first.

Think we'll go the the bc br coilovers as we're on a budget n it's the gfs car so it don't get driven hard very often.
Anyone suggest an alternative to BC but in that budget? We want fully adjustable..

My car has been doing the same thing and I talked with my father-in-law about it who was an engineer for Monroe back in the day.

My car has all stock suspension with wider aftermarket wheels (see sig). There is no evidence of oil leaking and the car rebounds as it should when you give it the bounce test, so he brushed off the possibility of blown shocks. I also measured the ride height from center of the hub to the fender and it is well within spec from the service manual, so the springs seem to be fine.

My father-in-law guessed that it sounds like a torsional load problem.

So, I started taking camber measurements, and lo-and-behold, it is way out of spec for the ride height. In fact, one side was almost a degree difference from the other. I finally got the camber adjustment bolts cracked and am working on the adjustment cam on the passenger side. I'll report back after I get the camber back to spec to see if this had any effect on the hard bumps.

Check the crossmembers under the ppf. You should have an inch of clearance. A speed bump or toot will bend the brace (black metal) up, a bump will shift the rear, the ppf will tap the brace and there is no way to tell where the noise is coming from.

So after correcting the rear camber on my car, this problem seems to have gone away.