my bike engined reliant is a bit lighter than the mini and ive got the protech coilovers from mk with 350 front and 180 rear but if i use the same rates as z-cars do in the mini i shouldnt be far out

Unless all your suspension pickups and wishbone lengths etc are the same as the Z Cars Mini, then there's little point in comparing unfortunately, as you can't just consider the weight of the car when speccing spring rates. As an example, a friend of mine has a track car that weighs about the same as my BEC Locost but because of the suspension design it runs ~600lb springs on the front compared to mine which are less than half that.

my front wishbones are within an inch of the length of the mini front lower and upper arms and the coilover sits at the same angle as the coilover conversion i have seen on mini,s and the rear coilovers on mine are nearly vertical as per the design on the trailing arms used on z-cars hence the question.

you need to work out the effective wheel weight the shock is working with/against if you want a direct comparison by calculating the angles and lengths of the wishbone geometry. Otherwise as said the length and angles could make the zcars spring rates pretty useless or unreliable imho.

Ned.

Yep I agree with Ned, unless all the dimensions are pretty much identical it could still be a fair old way out. As another example, on my car I moved the front chassis damper mount from under the chassis rail to the outside face of the chassis rail, and that single change of ~1" meant I needed 25lb difference in spring from what I was running before.

so im still no wiser then i know chris has done a conversion kit for a guy with a kitten saloon using a blackbird engine il find out if they use the same springs on that too, cheers anyway

The mini is mid engined aswell, is your kitten going to be mid engined? If not, then it'll be all wrong.

its a rip off of how z- cars do it , with all the parts in the same place
Rescued attachment smallpixel 003.jpg