I had someone ask on NAM about the comparison of the rear swaybar vs. the M7 Under Strut System (USS). After some thought, here’s what I posted – I suspect I’ll get asked this again, so here it will be handy to point them to… The context of the question was, “Which makes the most difference? Can you achieve a neutral handling car with just one or the other, or do you really need both?”
In my experience, the USS made the most difference (though I may have thought the same thing about the swaybar had I done the sway first). They really do two different things and make different contributions to neutral handling. The rear sway just lets you “dial out” understeer by making the back end rotate “more” to counteract the feeling that the car is plowing ahead in corners…
The USS actually reduces understeer by stiffening the chassis and allowing the front suspension to follow the road better and translate steering input better into directional change. Or something like that.
I’m not an automotive or mechanical engineer – but this is my theory and is consistent with the changes in “feel” that I’ve experienced, and with all the other folks I’ve talked with about the results of the two different mods.
The USS isn’t adjustable, and in my experience didn’t make the car completely neutral – but went a LONG way toward doing this. I think it actually IMPROVES grip while reducing understeer. But I can’t guarantee that you still won’t have a little understeer with just the USS – though you might THINK it’s neutral at that point.
With a swaybar alone, you can adjust the sway rate to achieve “neutral” handling, but actually may not have as good a grip as with the USS (because the front suspension is still having to fight chassis flex) – So it may “feel” neutral, but I’m very confident that my “neutral” car can do things on the Dragon and in other handling challenges that some “neutral” cars can’t… because of better grip and better front suspension management due to the USS.
Again – all theories. But I DID sleep in a Holiday Inn Express last night. 😉