Originally Posted by ustcc evo

The reason this topic is so confusing is that we are neglecting the effect of roll center on a macpherson strut suspension.

Some people say a bigger rear bar/spring takes dynamic load off the front and puts it on the rear, reducing understeer. This is correct.

Some people say a bigger front bar/spring reduces understeer as well. This is correct as well, but ONLY IF YOUR CAR IS LOWERED TOO MUCH. Lowering a strut too much makes the lower control arm get into a bad angle, usually near horizontal and above, which lowers the front roll center relative to the center of gravity, making the front tires doing more work and making the rear lift like a beer drinking dog.

Stiffening up the front masks the problem by reducing roll and limiting how bad the angle gets on the front lower control arm.

So, if you put a stiff bar on the front and it understeers less, it means you have unfavorable geometry in the front and need to buy a roll center correction kit or make them custom like I do.

Originally Posted by ItalyIX

Is the Roll correction kit something that can be done DIY?