For those of you who haven't installed a aftermarket upgraded sway bar, do yourself a favor and install one. Transformed my car's handling in corners. OMG!! This is how the car should have come from the factory.

I installed a ALTA 22mm bar.

 

 

Great to hear - planning on installing an NM rear sway in the next couple months once I find a free weekend.

 

Now get a front one, it will transform the car even further.

 

+1 Front sway bar

 

 

A rear bar doesn't dial out understeer, it accentuates over steer, the front still plows.
A larger matched front bar will reduce also understeer.
I pulled the trigger on my F56, and will never go back to saying a just a rear bar is good enough.

 

 

 

 

I dont know what kind of thinking this is but its false. Vehicle manufacturers design with safety 100 percent of the time. Cars are designed to loose control front bumper first. Front impact accidents are always the safest in any car. Front tires loose grip first by design, period! If vehicle manufacturers had cars going off the road sideways everywhere there would be huge amounts of deaths and lawsuits. By enlarging the rear sway bar we reengineer the handling of the car to allow it to go into a corner flat. If we loose control and hit a pole and kill a passenger as a result of the swaybar change the manufacturer is absolved from wrongdoing and we get sued. Think of Porsche and a certain movie star. Those things are death traps because they corner flat. When they loose grip they dont hit head on. Back to a mini, if you increase both rear and front sway bars equally you will still end up with a nose heavy car, just with less body roll.

 

I'm not done
weight transfer, by enlarging the rear bar you transfer front weight to the rear wheels. Thus the front is lighter and rear is heavier. The goal if to transfer as much weight equally as possible. You want all four tires to get equal weight and not overcome the elasticity of any single tire.
Regular old passenger car tires are the safest tire that can be put on a car. High performance tires are considered unsafe on unaltered cars. When a passenger tire and performance tire loose their modulus of elasticity they do so in two different fashions. A passenger car tire loses grip sooner but holds the road much longer. A performance tire holds harder but loses that hold very quick once the modulus of elasticity (MOE) is passed.
how does this relate to sway bars?
think of an unaltered car with aftermarket performance tires. The front end is designed to be heavy to go off the road first. Once the performance tire has lost its MOE the car is very hard to recover and in a nose first crash. Now same car with passenger tires. The car may be in a nose slide going off road but because it still retains some grip you may be able to steer it to safety.
by and large the best change to a vehicles cornering performance is with a larger sway bar.
one last comparative study, if anyone has pulled a heavy trailer they have probably used a load distribution hitch. Like a sway bar they distribute the weight away from the actual ball, moving the center of gravity towards the front of the tow vehicle. This is very similar to a sway bar, it moves the weight around the vehicle for best performance.

 

Yes by far the rear sway bar is the best bang for the buck. For the 2nd gen cars we always use our WMW 25mm hollow rear bar same as the Hsport. It on the middle setting is ideal and has bushings with a proper grease channel that will hold the grease and keep it quiet longterm. Also being a hollow bar it only weights 5.5lbs vs 12-14lbs of a solid 22mm bar, both are the same stiffness.
https://www.waymotorworks.com/wmw-rear-sway-bar.html

 

^ that is all unmitigated BS.

Most front engine cars have > 50% of their weight on the front wheels. Front wheel drive cars like the MINI are 60/40 or even 65/35, there's never going to be equal weight on all 4 tires. Sway bars don't change the weight distribution front/rear at all, they change stiffness side to side at the front or rear. And it isn't modulus of elasticity - it's coefficient of friction. Pictures of front wheel drive cars autocrossing or on track often show the inside rear wheel in the air in hard cornering, so the coefficient of friction for that tire is zero, but the car is still going around the corner even with the "front end heavy".

You're making a dangerous, stupid, and factually incorrect generalization when you say "high performance tires are considered unsafe on unaltered cars." What about a stock BMW, Porsche, or Corvette? The handling of my Mini (and my lap times) improved dramatically when I got rid of the "regular old passenger car tires" (the stock runflats) and put on Michelin Pilot Super Sports. Better tires means better roadholding which means better cornering, better handling, better ability to maneuver to avoid an accident, less likelyhood of understeer OR oversteer. Period. But Michelin PSS tires, as good as they are in dry or wet conditions, would be impossible on snow or ice, just as all season or snow tires are the wrong thing for the track or autocrossing. The safest tire for a car is the one that provides the best traction for the conditions at the moment. Now if you put high performance tires on the front and a set of crappy worn out tires on the back, you'd have a problem but that would be moronic.

Most modern cars have the suspension tuned for understeer, that's because 99% of drivers can't deal with oversteer. They go into a corner too fast, the car starts to understeer, the instinctive reaction is to lift off the gas and perhaps brake, which (generally) brings the car back into line and the driver stays in control. (The exception is pre-1990s 911s where initial understeer followed by a lift is a good way to experience oversteer.) Not because a head-on crash into a tree is safer than a tail-first crash into a tree, it's because it's the best way to keep 99% of drivers in control if they get a little bit past the limits.

One of the inherent limitations in cars with MacPherson strut front suspensions (such as the MINI) is camber loss during hard cornering due to body roll - the top of the tire is leaning toward the outside of the turn, which reduces the contact patch and therefore the coefficient of friction. Two ways to help solve that, one is stiffer springs, the other is increased negative camber. MINIs really benefit from increasing the negative camber in front, anyone who autocrosses or tracks their car will tell you that. When I added camber plates and had the car aligned for -2 degrees of camber all around, it totally transformed the car.

I highly recommend this video titled "The Physics of Racing" , it explains all of this stuff. Very educational.

 

Do your home work, center of gravity is changed by sway bars. I've been building cars for 40 years, I've got a pretty good understanding of how they work.

 

 

 

I posted somewhere about the F/R Eibachs feeling like the factory setup (favoring understeer to neutral) just more aggressive/responsive feel. I would not go back to the factory bars.
Note: I've seen people do the same job (engineers/tradesmen/mechanics etc) for many years and do it wrong.

 

Sometimes it's done so wrong you will see a car going around a bend on three wheels. The center of gravity is so far removed that the wheel in the air weighs exactly nothing. If a triangulation of the center of gravity is done you would see that it is way outside of the car itself.
I also teach about "center of gravity" for a living. It's in an industrial environment but I have studied this crap for a while. I lowered my first car in the mid eighties and, heaven forbid, I put four tires and rims that were all the same on it. Most people were still putting big honking tires on the back and jacking it up to the stratosphere.
still the cheapest way to improve road performance is to add a rear sway bar and lower it. Center of gravity moves back towards the middle of the car and is lowered closer to the road surface.

 

 

 

"a triangulation of the center of gravity" can't ever show that it is outside of the car itself. The center of gravity, or more accurately the center of mass of an object, is always inside the body of the object. For it to be outside of the object, here would have to be some mass that magically appeared outside the object but was somehow connected, or some part of the object would have to have negative mass, which doesn't exist (unless you count anti-matter.) The center of mass is always going to stay in the same place inside the car. (Technically it will move slightly due to movement of the wheels and suspension components, but that effect will be very small because of the magnitude of the masses moving - wheels, tires, etc. - are small compared to the mass of the rest of the car.) The reason a car might be on 3 wheels during hard braking is because the springs are soft enough that the car can pitch and roll far enough to one corner that it exceeds the downward suspension travel on the opposite corner. The wheel and tire still have the same mass and are creating a downward force (weight) on the car, but are not supporting the car or providing any lateral acceleration.

When people talk about "weight transfer" under braking or cornering, etc. what is really going on is the change in the moment around the car's axis of roll or pitch causes an increase in force on one axle or side and a decrease on the other. It is easier for people to think of it as "weight transfer", but the center of mass of the car is still in the same place, just the forces that support the car have moved due to the moments changing, which changes the forces on the tires and therefore the relative grip of each tire. Lowering the car is beneficial because it reduces the moments since the center of mass is lower relative to the roll and pitch axes of the car. Stiffening the rear sway bar won't move the center of mass, the only way to move the center of mass toward the rear of the car is to either remove weight from the front, or put a sandbag in the trunk.

Check out the Physics of Racing video, the guy is a physics professor who autocrosses and does time attack, he took the time to derive the equations and do the research and then explains it in a way that anyone can understand.

 

I was thinking about my assertion that the center of mass is always inside the body of the object, and realized that there are some cases where this is not true, for example a toroid (donut), or a U shape like a horseshoe. In those cases the center of mass is outside the body, but still within the 3 dimensional envelope of the object, which is the point I was making about the car.

I agree that a stiffer rear sway bar is the best bang for buck modification for handling. Next is better tires, then lowering. Lowering is a tradeoff though, stiffer springs and reduced suspension travel mean a harsher ride.

 

 

Center of gravity is the correct term for this discussion. COG can move outside of a vehicle. This is how a car would roll over taking a corner to quick for its abilities. This is the same with heavy equipment to which I train people for a living. Its is a difficult concept to accept that somethings weight can be outside of its physical properties but it is how it works. There are more things going on with a vehicles suspension than can be discussed here. For anti sway bars it's the same. They help prevent body roll and transfer weight side to side and front to back by balancing the center of gravity.
agian manufactures create nose heavy cars for safety purposes. To balance this out we add a stiffer rear bar to move the COG more central to the car. It may be called an antisway bar but it is moving weight around.