I missed this post (sorry). The front anti-roll bar is held on to the chassis by some D shaped bits of rubber held on by metal clamps. These are unlikely to rust away as they are normally covered in engine oil.
The bar is attached to the suspension by a rusty bolt (that gets seized in) going through a nylon spacer into an oval rubber bush (like an exhaust hanger) with two holes in it - one for the bolt and the other for the end of the anti-roll bar. The bush is held together by a metal strap that goes all the way around. All of these parts rust, crack, and generally disintegrate so I'd guess this is your problem.
Try Renault for replacement parts. Failing that try Liam (you'll find him in the memberlist) for good secondhand parts. Failing that try a small exhaust hanger with a couple of sturdy jubilee clips around it to replace the mounting, or a big nut to replace the nulon bit. Failing that, has anyone tried a R4 without an anti-roll bar. Do they just roll?
:clementi: