The rear single leaf springs on my car are from a Reliant kitten, but with the Rover v8 power, heavy steel a35 body and MGB GT rear axle, they are just too soft and wallowy, even with adjustable dampers. So after a bit of research I found that instead of single leaf springs, the Reliant Fox van had some stiffer multi-leaf two stage type springs on the rear to carry a heavier load.
I have bought a pair in the hope these will stop the rubbing of arches on corners and leaning when the driver sits in!! Now I haven't fitted them yet, but they feel about the same as the Kitten ones I have just taken off (simply judged by standing on them both and comparing the two that is). Since they are progressive, so are stiffer the more load they are under, should these still be stiffer once I have the fitted and under load? I don't want to fit them if they are not going to be any help whatsoever.
Top are new fox springs, bottom old single leaf kitten ones