Whenerver I put in reverse and try to go forward, a few meters away a
> sound like a cog wheel scratching another one starts (it's louder near the
> right front wheel); it stops immediately when I hit the brakes to a full
> stop (and a clock! is heard right before the full stop)
Time to get your (or someone else's) hands dirty. Start by pulling the right front hub apart and looking for damaged parts, broken CV or similar. Check the front prop shaft U-joints (if it has any). If nothing is obvious, move further inwards. Check the front swivel joints are not worn out.
Stewart DIBBS