This has happened twice now - when i brake hardish and have gone down a pothole or sunken manhole for example there has been an almighty jarring or bang - what could this be. I have a vrs with low profile tyres - could it be the rim banging down onto the road surface for eg??

- could it be the rim banging down onto the road surface for eg??

or the under-tray / sump hitting the road?

or the under-tray / sump hitting the road?

If sump then that might soon become a very expensive pothole to hit.....

It's not simply the fact that the wheel will decelerate extremely rapidly in the moment it's dropping into the pothole due to the fact that it will no longer be in contact with the road, but will still be being braked. Therefore, when the wheel hits the bottom / other side of the pothole, it will be going much slower than the car and so the 'bang' is due to the force on the brakes as it 'accelerates' to road speed again. This might seem daft, but I had many a faceplant in my mountain biking days before I had front suspension, 'cos the front wheel would lock up when it lost contact with the track and then induce a front wheel skid as soon as it was in contact with the ground again...

Most likely just the suspension crashing though as Ap0gee says. Other worthwhile check would be to make very sure you've not broken a spring.

Could just be the ASR cutting in....

What about ARB bushes ??

Re: the potholes - try this out Report a Hazard - FillThatHole.org.uk

There was a nasty raised lump of tarmac in Worcester right on a bend that was there for ages. Every time I drove over it, it shook me apart. I logged it, and it was suddenly marked in yellow spray 2 days later, and fixed within the week

What about ARB bushes ??

Re: the potholes - try this out Report a Hazard - FillThatHole.org.uk

There was a nasty raised lump of tarmac in Worcester right on a bend that was there for ages. Every time I drove over it, it shook me apart. I logged it, and it was suddenly marked in yellow spray 2 days later, and fixed within the week

Rather depends on which authority is responsible then - I've just done a search for reported holes in Hemel and there's 8 logged between between Feb and April this year and not touched. Too busy putting in bloody speed bumps.