My 10 year old Corsa (bless her) is doing well for her age although she has a bit of a knocking problem in the offside rear.
Sometimes happens with two people but gets embarrassingly loud with 3 or more people. It knocks when going over tiny bumps in the road or when going uphill.
Thinking it was the suspension I've had it up on a ramp in Kwik Fit (I was desperate) and I've had my regular mechanic under it. Both say they can't see anything wrong with suspension. Somebody mentioned it was the exhaust knocking on the cross member.
I asked how I could rectify it and the mechanic said get your passengers to lose weight. Not a terribly helpful comment.
Seriously, I've no idea how I can rectify this if it's not the suspension! Anyone any ideas?
Could be someting simple as weak springs and the suspension bottoming out when going over a bump.
Get it checked out by a competent mechanic - be safe.
It's the probably the exhaust hitting the floor at the rear - my daughter had the exact same problem with a Corsa. Slacken the join at the rear box and move it slightly to see if that helps. Other than this you may need to renew the rear springs.