Hi Gary,
Thanks for the response. I am aware I'm supposed to have a bump stop fitted but have heavily modified the underside of the car during rebuild so there is nowhere for them to go. Also, it never had them fitted before and didn't have the problem. having said that, I think I will try it, I'll strap a couple to the spring and see what happens, if it works I'll make a permanent solution, and of course keep you all informed.
Henry