I have checked out how to get equal spring rates.
Start with one spring – we need equal spacing between coils, equal material rigidity and equal wire diameter. Cut it to two equal lenghts – but first read below.
Rule: The spring rate is constant over the central 60 percent of the deflection range. Good to know as we want a constant spring rate.
On a Tomy Bit the gap is about 5mm – so we need a spring 6-7mm in length. This will place the spring inside the central 60% of deflection through the whole range of travel for the front wheels.
To get a stronger spring you need:
Bigger wind diameter
Bigger wire diameter
More active coils (If stretched out less spring rate)
More rigid material
In conclusion, try springs form different sources until you find one that suits your driving style. But remember they must follow the rules above to give a constant spring rate.
