So I finally got around to installing my new Alta 22mm rear sway bar yesterday. I have the Sport package/suspension, and I set the bar on the middle setting as a starting place. I must say that the car definitely rotates MUCH better now. If anything, I could goto the full stiff settings to get the amount of rotation that I like. It kinda seems like I lost quite a bit of overall grip from this bar though. With the stock rear sway, the car felt like it was on rails, with a strong tendency to push. With the Alta bar, it doesn't feel like my cornering is nearly as quick as before. I can't say for sure that it is slower, but it just feels slower to me because of the rear being much looser now. Anyone else feel the same?

 

nope...my car feels much better and definitely handles better

 

well the rear sway bar basically takes away traction from your rear tires, which is why it helps balance out the understeer and induces oversteer to balance it out.

 

yes and no....when I raced shifter karts, the goal was to get the inside rear tire off the ground so you could rotate thru the middle, thus having a faster lap time, even tho you're overall tire contact patch is now 25% smaller...I'd say it's pretty similar to adding the big rear bar to our cars.

 

I'm happy with mine, but i get thumping sounds on speed bumps (on the way down and off a speed bump).. anyone else facing this? I may need to remove the wheels and take another look at it..

 

Understeer and oversteer are caused by unequal loading on the tires. If more load is on the front tires than available traction the car will understeer. To reduce understeer the load must be more equally balanced between the front and rear tires. A anti-roll bar is used to transfer load to the rear tires, not take it away. Equal loading between the front and rear eliminates understeer because the front outside tire is not overloaded beyond its traction capabilities. A stiffer bar will transfer more load. The opposite applies for oversteer.

A good reference book on suspensions is "Chassis Engineering", by Herb Adams.

 

You may want to try the bar on it's softest setting. The middle setting is better for lowered, stiffer set ups. Neutral handling is your goal.

 

+1

 

I totally agree that neutral handling is the goal. My impressions is that the car rotates almost exactly how I want it to, and that I could go even stiffer to get the right rotation that I like. From the seat of my pants, it feels to me like I am sacrificing overall traction for better rotation. I'll try bumping it to full soft to see how I like it on that setting.

 

If what you want is easier rotation and the ability to corner faster, you would be far better off with the rear bar set on soft (or even OEM) and a set of front camber plates.

This would greatly increase the grip in front while cornering, and reduce understeer. It would eliminate the need to reduce traction on the inside rear wheel, and make the car feel like it WANTS to turn - it will dive into the corner and feel like it wants to pull in tighter when you press the gas pedal.

On my first-gen, I've got IE fixed plates up front with a Mini-Madness 22mm rear bar set on softest, and I've seriously considered going back to the stock rear bar. After recently after installing the camber plates I may get used to the way it feels by next summer, or I might replace the OEM bar if I don't get used to it. Either way, the car has a lot more grip while cornering than it did with just the rear bar installed.

 

That's exactly what I was planning to do for my next mod. Funds are low now, though, as I have to fund a race car as well

 

Your primary goal should be to understand how the physics of handling and your suspension interact. Start by reading everything you can from authors who have credibility via their training and experience with engineering suspension systems. Take everything you read in forums (including from myself), from buddies, vendors, or guys you meet at the autocross with a healthy dose of salt. There is a lot of misinformation, posters with agendas, and downright irrational stupidity floating around in cyberspace just waiting for someone to step in it.

Inform yourself, use your deductive reasoning and logic to test everything you read and are told, and you'll steer clear (perfect pun if I do say so myself) of much silliness.

 

I'm pretty familiar with vehicle dynamics/physics, and chassis/suspension design. I'm a Mech Engineer, and have been driving race cars for some time now. I was mainly trying to figure out what people's opinions of this bar were and to see if it was just me that was feeling what I was feeling. Thanks for the heads up though! It's nice to see that people on this forum are always so helpful and kind!

 

Personally, I've come around to the point of view that the first MINI suspension mod should be camber plates, rather than a rear sway bar.

 

^ I think if I could find one, I would find a smaller front sway bar to help dial out some of the understeer as my first mod.

 

I concluded the same, and added K-Mac camber plates to the Sport suspension. Running 2.5deg -ve camber and 4 deg castor. The biggest difference is that I can accelerate hard much earlier in corners because the car doesn't push wide. (With a Just-a-Cooper, that really helps maintain momentum.) It's still on the understeer side of neutral. Turn-in hasn't sharpened much - except if I brake hard right up until fractionally before I turn, when it just takes off brilliantly in the new direction like a tennis ball off a racket. ie the turn-in has sharpened if the weight is forward. Fun to get right, but a bit spooky because there's less margin for error or surface changes.

 

Just for the sake of discussion:

Installing a smaller front sway bar would have a similar effect on understeer as installing a stiffer rear bar, but at the expense of roll stiffness. So, yes the vehicle is more evenly balanced front to rear, but now it takes less force to cause the vehicle to roll in a turn, which is undesireable. Of course, one can go too stiff, which would be detrimental to handling as would a too soft bar. Determining the optimum ratio begins with load calculations and continues based on driving style and track/road conditions as well as vehicle configuration. As a mechanical engineer, I'm sure you're aware of all that.

As for the camber plates, they will not change the load distribution or balance of the vehicle, they only maintain the contact patch of the tire during corning forces. By adding extra negative camber with the vehicle in a normal state, the deflection caused by high cornering forces brings the wheel/tire to zero degrees camber instead of it deflecting into a positive camper condition. This allows the tire to perform to the limit of its traction capabilities by maintaining it perpendicular to the road surface. Of course if you are one of those that believe there is no deflection because the car is already so stiff, you only have to account for roll, which would be greater with a softer bar.

These are two completely different concepts, although they may seem to have similar effects. In the final analysis, all suspension components work together and cannot be optimized without considering the other components.

This guy has a wealth of info: Sway bar calculator http://www.fromsteve.net/tech/Sway-Bar-Rate-Calculator

 

The camber plates increase front grip during cornering, so a stiff rear bar, which reduces rear grip by unweighting the inside rear tire, can cause sudden and unexpected oversteer when the rear breaks loose, in the extreme case.

For me, I'll put a few thousand miles on before making another change, but if I do make any more changes, it probably won't be stiffer on the rear bar.

 

You have some very good points, and I can tell you are very knowledgeable about suspensions. Personally, I am from the school of designing the suspension with the best possible spring rates/damping possible, and then adding small sway bars to properly help tune the balance of the car. This is the way my race car is setup. I am unfortunately limited on the modifications on this car. I don't think that the MINI rolls much as is, which is why I mentioned a smaller front sway bar. There is an optimal amount of roll for every vehicle, and from what I am feeling, the bigger rear sway may not be exactly what I am looking for, but perhaps a smaller front bar might. Of course I have no way of testing this as there is no smaller aftermarket front bar.

As for the camber plates, I agree that they do a completely different function. In short, having more negative camber helps increase the contact patch during cornering, and increases traction. I believe this will also help the car rotate a little better, as well as have a better turn-in since it's turn-in camber is also greater (assuming its caster is set properly).

 

I would just like to verify something if you guys don't mind. I have heard different stories, and I would like to get it straight.

Camber plates sound awesome. They do a lot of good, and, for a race car, there is certainly no disadvantage. BUT, what about on a street car? They will increase tire wear correct, or at least, increase it on a certain part of the tire? For example, if most of my driving was on the highway, wouldn't these have a negative effect on my tire life? Now, would this be enough to worry about?

Thanks for sharing your knowledge.

 

D-Unit, you've got it right. Camber plates make the front tires lean inward at the top, so if all you ever did was drive in straight lines, the inside of the front tires would wear somewhat faster. Enough to worry about? Well, it might reduce your tire life by 20-25% at a guess.

However, all of life is a series of engineering tradeoffs: in my case, I do a lot of rapid driving on twisty mountainous roads, and the stock setup was wearing the outside third of my front tires Much faster than the other two-thirds, because the outside tire was rolling under onto the outside of the tread while cornering. I've been getting 9K miles on very sticky summer front tires.

This also, of course, significantly reduced cornering grip. With IE Fixed camber plates, the car corners much better, and actually wants to pull to the inside of a corner when I feed it some gas, to the point that I've ordered a 20mm rear bar to replace the 22mm bar I've been using.

Without the camber plates, I was happy with the 22mm bar set on Medium position. With the plates, I've been running with the 22mm bar set on Soft, and it still seems a little on the oversteer side for my conditions.

By going to a less stiff sway bar, I'll dial a little understeer back in, let the rear wheels operate a bit more independently, and get more cornering grip at the back, because the inside rear tire will have more weight on it, and will have less tendency to bounce over the bumps (these mountain roads are not a glass-smooth race track). There might also be a slight reduction in noise transmitted to the interior.

So I guess the moral is that you've got to evaluate these tweaks based on your conditions and how you drive the car. I've been working on dialing in my car for three years now, and I only now feel like I'm getting it where I want it and understanding why (thanks to to a great deal of information from many NAMers).

 

Well said! Your setup should be completely based on your driving conditions. As mentioned, having camber plates will wear the inside of your tires more IF you only drive in a straight line for most of your trip. If you throw in some hard cornering into the mix, then you will get very even tire wear. If you have zero toe, and some negative camber, then your tires will hardly notice a difference. However, if you have toe in, or toe out, then they will wear on the insides faster than you can imagine. On my Miata, I had -2.5 degrees of camber all around for daily driving. I did not notice any noticeable wear on the inside because I did some hard cornering with it to help wear it more evenly. Now going specifically to your question D-Unit, having camber plates does not mean that you will have an insane amount of camber. You can set it to what you want. Putting a little bit of extra negative camber, say -0.5 degrees, will definitely help your turn-in/cornering, while still being relatively kind to your tires.

 

Camber plate choices are:
- fixed plates from Dinan (adds .75 degree neg. camber)
- fixed plates from IE (adds 1.25)
- adjustable plates from many manufacturers (up to -2.0 or so - all of them add substantial noise to the car)

The first two choices do not add noise to the car. Everyone I've ever talked to with adjustable plates on a MINI have set them and never touched them again.

 

Thank you guys SO much for your knowledge. You guys have been a really big help.

 

Ok folks, I'm just noticing something after having the 19mm alta RSW installed for a week. The ride is much harsher! Is that supposed to happen? I didn't really notice this until I went for a longer commute drive with pretty nasty bumps(I've driven on this road with stock RSW before-pretty much daily actually). The rear end just seems to be like a brick-almost no suspension feel. When the rear end falls off into a crack, it just goes thud.

Initially I thought I might have re-assembled the suspension wrong but yesterday I had the chance to reinspect the rear end while the car is lifted for tire swaps. Nothing is loose, everything seems fine. I have it set to the stiffest setting. Frankly I can live with it because the handling has improved drastically(basically saying I will take the trade off comfort for handling) however I would like to know if this is normal. I'll be switching to coilovers in 6 months or so and hoping that would help.