Noise from rear n/s suspension?

[Bantam]

Hi, Guys/Gals
Can anyone please give me ideas for locating a loud heavy knock coming from my rear n/s wheel/suspension/axle that only sounds when I go over a particular holes/bumps in the road. On good flat roads I don't get any noise. I have checked the wheel and looked underneath but am not able to find anything feeling loose or rattling.
Many thanks
Bantam

[Bazzalucas]

I guess the likely suspects should be checked first: bushings at the ends of the leaf springs, insure that all the bolts are tight for items like the dampers, etc. Make sure your dampers are filled and with straight SAE 30w or 40w oil. If all else is in order, then
one piece I found gave noise only on small "sharp" bumps was the link from damper to underbody. The rubber was perished, allowing the pivot bit to rattle.

[kennatt]

have a look at the chassis rail just behind the rear spring mount,if you see a mark on the chassis rail, its where the rear shackle has been hitting the chassis, classic sign of soft springs,they get longer as they sag and let the shackle hit the rail giving a lound clonk,proper cure is a PAIR of new rear springs but a temp cure is to make up and fit longer arms to the rear shackles,but eventually new springs will be required.

[bmcecosse]

Are the bump stops present and correct on the axle ? But as above - it's likely to be the link arm from damper to chassis.