Measurements or design for front wishbones

[Aussie_Haynes_MX5]

Hi all, i am from Australia and am currently working on getting the plans laid out for my build.

The chassis will be a standard book build, with extra triangular bracing to help with the torsion and twist testing that i will be required to do over here to get it passed for rego. (The Australian version of your SVA) And it's a bugger of a thing to go through

I will be using NC Mazda MX-5 uprights. Wheels i will be using will be 15x7 4x100/4x114.3 15 Offset and will have a 205/50 R15 tyre. The rear track will be made using a Toyota Hilux differential, and will be 1350mm (axle flange to axle flange).

So far i've found out that i should have 5 degree castor, and the king pin inclination from a standard NC MX-5 is 11 degrees.

So, what i need to find out is
- What height does the roll center need to be
- what should the front track be given the rear will be at least 1350mm
- is the KPI of 11 degrees workable, if not what is a better option
- any other things i need to find out to start the drawing and claculations for setting out where i need to mount the front arms.

Reason for mixing and matching the MX 5 bits and the hilux bits is that getting an independant rear end over here is pretty expensive. This will be my first car, and with some experimenting and experience, i should be able to make the IRS work. I was thinking of using a Subaru rear diff assembly as they are more common over there than a Sierra, which are as rare as rocking horse poo.

Thanks in advance

Ben Sherlock