Post #128
adam b wrote:
Will have a chat with you in the near future about the tender progressive springs as that might be the answer to my Volvo ride quality problems. Its having different springs today (longer 400s) so hope that will sort it out. I've been thinking for some time that smaller progressives with a stronger main spring might be the way forward, but bit looked into it.
When you run two springs, one on top of the other, this is the same as having two resistors in parallel. So that overall spring rate is lower than smallest.
So with my 250-550lb tender progressive and 650lb main springs the overall rate starts with 180lb when the front wheels start to touch the ground. Goes to about 270lb with the car on the ground, then it is 300lb when the tender progressive closes and the spring rate goes to 650lb.
What it means in practice is that you get very low spring rate when driving in a straight line. Once you turn in to a corner and weight transfer happens – the outside of the car rides on very stiff spring which resists the roll. As a bonus, as the other side gets unloaded – there spring gets softer and it pushes up less = still less body roll!
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