Something that I am not clear on, that I wish to clarify. I thought sway bars can't change teh amount of weight transfer-just changes how fast it occurs and amount of body roll. And yet you see guys with larger sway bars getting wheel lift. So theoretically running larger sway bars gives you less traction to power out from.

if one end of the car is a lot stiffer (more sway bar) than the other, the stiff end can lift as the soft end articulates

Something that I am not clear on, that I wish to clarify. I thought sway bars can't change teh amount of weight transfer-just changes how fast it occurs and amount of body roll. And yet you see guys with larger sway bars getting wheel lift. So theoretically running larger sway bars gives you less traction to power out from.

The way I understand it, the sway bar transfers lateral load to the outside wheel. So this can cause the front inside wheel to lift on a lot of M3s.

The shocks/struts control the speed of the weight transfer, the springs (or swaybar) control the total amount of travel at steady state.

The shocks/struts control the speed of the weight transfer, the springs (or swaybar) control the total amount of travel at steady state.

Right but if the total distance to travel to get to SS decreases, then the time to get there decreases as well. Hence, sway bars speed up weight trasnfer.

Every car generates a certain amount of body roll. The swaybars work together to absorb this force. You will hear this commonly refered to as roll couple.

This is my very simplistic explanation on how to understand it:

Essentially the force of the car driving through a corner generates a torque on your chassis on the roll center from the center of gravity. If one bar is significantly stiffer than the other it will lift a tire. In this situation you have two options. Soften that bar or stiffen the other so propotionally it does more work. Based on the suspension geometry, ride height, roll axis, etc etc etc, roll couple percentage can vary greatly and honestly doesn't matter because theres not much you can do to change it. Just get good adjustable bars.

In practice you want a 'stiff' front bar on your BMW. How stiff? Until you can barely lift the front tire under max loading. Then adjust the rear bar so the car turns properly. Overall a car with stock geometry will like alot of roll stiffness.

Speed of transfer will vary greatly with changing the ride height. There is a roll moment as well which varies greatly with mass and height.

Car (Solo II) in sig has stock bars, but 700/750 springs. I should stiffen the front (bar) to lessen the lift?

Or is the lift something to be overly concerned about?

Nope.

Basically, one end of the car can only absorb a certain amount of roll before you lift a tire. Once you lift a tire stiffening the bar will only lift the tire further and have really no effect on the handling. You would soften the front bar a tad to get that tire back down on the ground. Or if the car pushes now, add a tad of rear bar for a simple adjustment. If the car is allready loose maybe a bit of rear spring and lose some rear bar and an alignment adjustment would work too. There are lots of ways in reality to get that tire back on the ground. It just depends on what the car is doing and how you drive it.

There is also a jacking effect to be concerned about.

Most important thing is to make sure your droop travel is sufficient.

Big front bar and no rear bar is a pretty good setup, just dial in the spring rates for your tires/application.

There is also a Big rear and big front setup that works with high front spring rates (15% or so).

Swaybar are excellent tuning devices, but they also have thier downsides.

BMWs tend to plow pretty bad. Even the M3s. It doesn't make sense to put a really stiff bar on the front and have a very weak one the rear, even if it means sacraficing the contact patch on the front. In general I know a lot of drivers install stiffer bars in the rear to help these cars get around the corner. So I am just a little curious how this would work.

BMWs tend to plow pretty bad. Even the M3s. It doesn't make sense to put a really stiff bar on the front and have a very weak one the rear, even if it means sacraficing the contact patch on the front. In general I know a lot of drivers install stiffer bars in the rear to help these cars get around the corner. So I am just a little curious how this would work.

Incorrect information, please do a search, this topic has been discussed in depth before.

The front roll center height is the topic you need to research.

The classic saying "stiff front bar will induce understeer" does not apply to this application.

Run a big bar and no rear bar in an e36 with decent spring rates for the track you are at and you'll be Pleasantly surprised.

I don't know of any pro e36/e46 that ran small front bar and a big rear bar, just does not work with this suspension.

Hrmm. well after reviewing some autox pics w/ the new suspension i'm lifting my front inside wheel a coulpe inches in places...

The car felt wonderful. should i try to fix this or leave it alone?

Right now i'm running GC coilovers w/ 450/550 springs and TMS bars, 4/5ths stiff front and full soft rear.

I'm debating between softening the front or stiffening the rear.. I really like the response and roll control w/ the stiff front.. but i also like have a planted rear end.. especially on track (like VIR's uphill esses)..

Any advice? I think i'll try stiffening the rear since i've never tried it. maybe it wont be so bad.

It is impossible to "fix" wheel lift in an autox BMW. You can't get rid of it without making the car slower and harder to drive.

There is also a jacking effect to be concerned about.

Most important thing is to make sure your droop travel is sufficient.

Big front bar and no rear bar is a pretty good setup, just dial in the spring rates for your tires/application.

There is also a Big rear and big front setup that works with high front spring rates (15% or so).

Swaybar are excellent tuning devices, but they also have thier downsides.

This is imperative, in my opinion. Although lifting drive wheels is less of a problem on a rear wheel drive platform, autox is all about putting (driven) rubber to the pavement, and I can't imagine that a massive rear bar would be helping this. Coming from a car (4wd) with a need for lots of droop travel, my bias will always be towards a big front/small(no) rear bar setup.