Forum:
I've just had some stiffer rear springs made for my YRV 4trak, they were made by the same company who made BobF's springs for his sirion 4trak, and his sirion rally4.
I'm concerned that they've made mine to the rally4 spec (which is shorter). My springs have arrived and they are 1 inch shorter than the originals. They are however 40% stiffer, and I'm wondering if that is actually normal, as if they were the original length and stiffer it would raise the ride height?
(I can squash the very soft originals down by hand to the same height as the new ones).
I have fitted them, so I can worse case take my originals to get more made to the correct length. The car does seem to stand correctly, and drives better than before (very neutral, no real understeer to speak of,
There just still doesn't seem to be much space before the bump stops if I sit on the boot edge and bounce up and down.
Spring length
If you want your car body to be the same unloaded height with stiffer springs then they must be shorter to start with.
There isn't much space before the bump stops bottom at the rear. With standard springs and a heavy load in the rear, bottoming is inevitable, as many of us have found out.
My progressive rear springs, the design commissioned by Daihatsu NL to solve the problem, lift the static rear ride height by 15mm. The progressive design of the springs makes the first stage of compression softer to try to retain some element of rear ride comfort. I'm not sure that they succeed with that aim, but certainly they've never bottomed and I'm sure your new ones won't. From the driver's seat, the car rides well and it corners very flat
There's plenty of comment and pictures on this topic on the forum.
YRV Tony