Verts vs handling.

[CorvallisBMW]

Are you referring to this? Ive had this in my favorites for 2 or 3 years now. As long as ive had the vert

http://www.strong-strut.com/Butt-Strut.htm

So you really like it on your car? I've never seen it before, but I'm thinking about getting one for my vert now. How much of a difference did it make?

[DaveSmed]

Regarding sway bars...... Buy a rear bar. IE's 19mm SpecE30 bar is a nice match for the front stocker. With the huge cabby bar in the front, and the same spaghetti strand the coupes have in the back the thing has an annoying tendency to go in a straight line when you don't want it to. I would consider a rear bar a must, especially for what you prob have in mind.

Also, the front strut brace does in fact help. And when pushed, the damn thing still flexes like crazy. Have a passenger watch the windows (top and windows up obviously) when you are really working the car. They do some strange things from what I have heard from passengers.

Other than that, suspension as normal. take the normal E30 recipe that suits your taste and apply.

[PУCCKAЯ_e30ka]

So, would cabrio front and iX rear be a direct swap in? (different bushings ofcourse)

[Jordan325iC]

Just FYI, the cabrio bar is 1mm thicker than the stardard i6 bar. Might not be worth the trouble to swap into a non-cabrio.

[Wishno87]

Just FYI, the cabrio bar is 1mm thicker than the stardard i6 bar. Might not be worth the trouble to swap into a non-cabrio.

this is true but i read somewhere that with every +1mm it makes the bar 4X stiffer. not sure of the truth value and dont have any links but its something i herd a while ago

[DaveSmed]

So, would cabrio front and iX rear be a direct swap in? (different bushings ofcourse)

Yep, far as I know.

[LivingLegend06]

this is true but i read somewhere that with every +1mm it makes the bar 4X stiffer. not sure of the truth value and dont have any links but its something i herd a while ago

I believe torsional stiffness is proportional to the moment of interia which has units of distance^4. Thus for a solid sway bar the improvent you will see in stiffness (assuming the same material is used) would be (new bar radius ^ 4) / (old bar radius ^ 4). IIRC

[Borat]

^yip, ie a 13.5mm bar is 60% stiffer than a 12mm bar

[funcrew]

this is true but i read somewhere that with every +1mm it makes the bar 4X stiffer. not sure of the truth value and dont have any links but its something i herd a while ago

The correct relationship for torsional rigidity when comparing 2 sway bars is proportional to (new diameter/old diameter)^4. That's why a 25mm bar is much, much stiffer than a 22mm bar, even though the difference doesn't sound like much. Hollow bars don't lose much stiffness, because material close to the center of the bar adds little to the torsional rigidity.

[CorvallisBMW]

The correct relationship for torsional rigidity when comparing 2 sway bars is proportional to (new diameter/old diameter)^4. That's why a 25mm bar is much, much stiffer than a 22mm bar, even though the difference doesn't sound like much. Hollow bars don't lose much stiffness, because material close to the center of the bar adds little to the torsional rigidity.

So if I understand you correctly, the vert front bar (21mm) is 121.5% stiffer than the iS front bar (20mm)?

(21/20)^4=1.21551

[jw 325ic]

ive had two coupes and my vert handles the same...before i did springs. now the vert handles much better than either of the two coupes ive had. the 87iS i had had LSD which was an obvious difference, but the 91 325i coupe i have now has an open diff and handles the same as my vert did when it was stock. now i have springs on the vert so the vert handles much better than the coupe. all in all a vert CAN handle very well. i wish i could deck out my suspension but $$$ is an issue

[funcrew]

So if I understand you correctly, the vert front bar (21mm) is 121.5% stiffer than the iS front bar (20mm)?

(21/20)^4=1.21551

Your calc is correct, but yields 21% stiffer, not 121%. That's by-the-textbook stuff, real world may be different.

[Wishno87]

would M3 front endlinks with welded tabs be a good idea or would that be too much?

[DaveSmed]

would M3 front endlinks with welded tabs be a good idea or would that be too much?

I would upgrade the rear bar and see how you like it. I would make the change if you desire more stiffness up front, like if you got a rear bar thats a little big for your preferences. As it sits stock, going to the M3 style links will increase the effectiveness of an already disproportionally stiff front bar.