Okay, I've been reading and reading and reading throught these suspension forums and still haven't found exactly what I'm looking for. I understand the concepts of increasing front camber and it's effects on understeer and tire wear, as well as the effects of a stiffer sway bar in the back. (At least on a basic level) Here is what I don't understand. Does adding a stiffer sway bar (and effectively decreasing rear traction, right?) improve your overall traction by reducing understeer? If not, why does the sway bar seem to be everyone's first suspension mod?
It seems to me (in all my vast experience...oh wait, I have none ) that it would make more sense to decrease understeer by creating more negative camber with the plates up front. Somebody, anybody set me straight . I don't necessarily expect a consensus, but maybe I'm missing something that would help me make my own informed decision.
Thanks

 

Actually adding a stiffer rear sway bar doesn't decrease rear traction on the MINI, it aids front traction by shifting the weight of the outside front tire to the inside rear tire which is not loaded as heavily. The downside would be slightly rougher ride in the rear on uneven roads, since the L & R sides are more closely tied together with a thicker bar. My rear sway bar is still in the box, so I don't know if the ride difference would even be noticeable.

Increasing negative camber on the front will increase traction on the front tires up to limit and possibly decrease traction when going in a straight line, but would not affect the rear much. However, you will wear the inside front tires quickly unless you use all that additional negative camber all the time.

The bottom line for me is that I'm on the fence about installing camber plates that I already have (they came w/ a set of springs and shocks I just bought) on my MINI since it is primarily a street car and it's difficult to take advantage of all the negative camber on the street. However, my Boxster has -2.4 front camber and -2.7 on the rear, but I still wear the outside of the tire faster because it is primarily a track car.

I would start with an adjustable sway bar first and adjust the sway bar (for bigger adjustments to balance) and tire pressures (smaller adjustments) to balance out the car. After that, if you find that you wear the outside of your front tires faster than the inside, get camber plates and find a track

 

I know a lot of folks that put the rear swaybar on first. I added camber plates and springs first then added the rear bar. If I wasn't so lazy I'd take the rear bar back out for street driving, I liked the balance of the car better without it. I'd rather have a car with slight understeer at lower speeds and neutral at the 80+ mark, rather than easy rotation at lower speeds and real twitchy at the higher speeds.

 

Yah, changing springs adds another factor to the equation and a softer rear bar may be better in some cases

 

Some folks go with too much rear bar... especially if you're doing other mods like camber plates and springs. Personally, my 19mm adjustable bar gives me plenty of range when combined with front camber around -1.8...

 

The -1.5 to -2.0 camber that most run on their cars should not adversly affect tire wear. When you get above the -2.0 threshold you will probably see a lot more uneven tire wear if mainly just street driven.

Most add the rear sway bar first because it is easier to install. But by going with the camber plates first, you will be able to "balance" out the handling better than by going with a large rear bar. In fact you may find that you don't need a new rear bar at all depending on your driving style. Most find that a 19mm (compared to the stock 17mm) rear bar is more than adequate when combined with the camber plates. Especially when going with a new suspension.

 

I have done it both ways and I suggest adj front camber plates over larger rear sway bar.

On my 2003 MCS with H&R springs and stock stocks, I added a 25mm hollow rear bar (a little stiffer than a 22 solid bar). It was nice for the street and track but the front did not stick like I thought it could. Once I added adj front camber plates it stuck better but the large rear bar was too much as people have stated. I crashed the car before I tried a smaller rear bar.

On my 2006 MSC GP with JCW springs and shocks I went the other route. I added adj front camber plates set at -2. It handles better (front end sticks) than my 2003 did with the rear bar. I always thought that I would also need to add a 19 or 20mm rear bar with the camber plates but I have not done so yet because it is already very good. The JCW springs are pretty stiff so that might have something to do with it but I had H&R springs on my 2003 Mini and they were almost as stiff as the JCW. I do have Limited Slip Diff on the 2006 which I did not have on the 2003 so that also makes it hard to compare.

It is hard to compare because of various differences but I think the before and after handling is better with just adj camber plates than with just larger rear sway bar. My GP handles great for street and canyon driving. If you are going to Auto-X you would want more rear bar to go with the camber plates.

Another advantage of camber plates are they eliminate strut tower mushrooming and the top rubber strut bearing that fails (tears about). However, as people have stated adding a rear bar is easier than adding adj camber plates. There is also alignment costs after adding the plates. Also, some camber plate designs add ride height, I went with Hotchkis that do not add ride hieght. The TSW plates might also be a good choice.

 

It's all a question of balance for what you do with the car. My routine includes maybe 25% of miles driving on lovely twisty mountain roads.

Without camber plates, I was wearing the outer 1/3 of the front tire tread a lot faster. I had a 22mm bar set on medium, and it worked well.

I then installed IE fixed camber plates, which gave me -1.75 in front, with the stock -1.5 in the rear, the bar was way too much - I cut it back to the softest setting, and the car was still too prone to oversteer when adding power after the apex of a turn. Tread wear was evened out by the camber plates in my driving.

Yesterday I got a new 20mm bar installed, set on Medium. That's about 85% of the stiffness of the previous bar and setting. The car now shows mild understeer when I feed it gentle power, changing to mild oversteer if I put more foot in it, so the bar and the camber plates do interact fairly strongly.

I'll leave it that way for now, and perhaps even go to the softest setting in summer, which would be roughly equivalent to the medium setting on a 19mm bar.

All of life is a series of engineering tradeoffs. If I were considering a bar to go with camber plates (not much point in adjustables, unless you are going racing) I thnk the 20mm size is just about right for agressive road driving, as all three of its settings are within the reasonable range on a MINI, unlike 19mm or 22mm bars, each of which has one of its three settings that is pretty useless.

Overall, camber plates, with a moderate rear bar, do increase cornering traction more than just a rear bar, as they keep the tires more nearly perpendicular to the road when cornering, which a rear bar does not do.

 

Well i am on the threshold of doing my install tomorrow,my car is going to be a daily driver and therefore am looking at a conservative -1.5 up front on the IE Adjustable camber plates,also i'm installing an H-Sport 19mm rear bar and wondering which setting on the bar to use for starters,should i go middle or start soft and work my way up.

 

Just a matter of how you drive and what you're comfortable with... I started with the middle hole on mine and have never felt a need to change it either way... but my car will differ from others, I have a cabrio (which should be inherently less stiff) but it has the massive cabrio under-chassis brace on the rear, and the front strut tower braces, and I've added the M7 USS and a GTT strut bar... so my chassis is pretty much a brick now...

 

Traction/grip are at times mutually exclusive to control. A driver needs control in order to get the car pointed in the right direction. Cornering power limits how fast it will go in that direction.

From my perspective, a rear sway bar on a front driver is used to improve traction out of corners...and as an aside it helps to point the car where intended...for me this is an important philosophical orientation...usable traction therefore sets the limit of the swaybar.

Camber angle or curve is defined by the instant axis. Where the tire spends most of its time in this camber curve will be affected by adding a larger rear swaybar...the wheel will move thru a smaller portion of this arc in theory. Hence, it will maintain better contact with the road. The stiffer a setup the more likely the last scenario. I beleive that really soft setups require more camber compensation since weight transfer in this example will cause more lean and ask the wheel to work in a larger camber range.

This is an important consideration with Mac Struts since these typically gain some positive camber at full compression.

I am certainly capable of plotting all of the values I need to come up with a package that is perfect for a track. But, like many of us, I do not have the time nor the drive, my rig is just a daily driver. So my advise is to find a quality adjustable bar and experiment. And when you do, you may well find that a really predictable setup is far better than a pure 'g' machine.

I'll add, and this is not black and white, that once the inside rear tire leaves the ground, rear swaybar contribution to weight transfer and roll resistance begins to fall off. I've heard some racers say, and I've certainly repeated, that any contribution to roll resistance stops once the rear inside wheel leaves the ground. This is not really true so long as there is still some twist in the torque tube. What is black and white however, is that once the inside rear tire does leave the ground, weight transfer indeed begins to fall off.

These are important observations; the inside rear tire will tell you a lot about your adjustment for any given set of variables. Once it leaves the ground for a given set of variables on a given track or road, you know that you've begun to a plunge into over-doing a good thing...though this may be appropriate for an autoX setup since transitional and rotational kinetic energy is lower.

I would also advise getting to this point in small incriments since an overly enthusiastic setting will cause a snap oversteer condition. And try where possible to experiment on a track...it's safer and you'll really get to push the limits of your setup. That is not possible on the street.

 

+1 - it's all about predictable handling - grip is a nice side-effect. The MINI really isn't very predictable during the stresses of hard cornering, without some aftermarket help.

 

+1 on predictable handling and +1 on starting slow. I still think it's best to start with the rear bar, see how the tires wear and go from there. If the tires are not wearing on the outside, you're not taking advantage of the existing negative camber anyway and more won't help. That said, if you're doing springs/struts or coilovers anyway, you might opt to do the camber plates anyway since adding that to the installation would be trivial.

 

Thanks for the advise guys,the IE adjustable plates and M7 brace are going in because of mushrooming,so i said what the &%#^ why not include FSD's and a 19mm bar and finish the job once and for all.So i;ll take your advise and start soft and work it up to see what it's like.Parts down here are really expensive,a set of OEM shocks are $900,so when i go up to Miami as i just did and get a set of FSD for $630 i'm like a kid with a lollypop sticking out of my mouth.I'll track it as well to get a good idea what these mods feel like,unfortunatley it's being done all at once so will be hard for me to tell what the bar did opposed to the camber.

 

Well i just got my car back in like 4 hrs work camber plates fsd's and a rear bar installed for $175 sounds good to me.Unfortunatley he's found some other problems that need attention,a rear lower control arm is broken half way through and it needs some ball joints up front,i cant give feed back as the car needs replacement parts and an alighnment but i will when these other probs get sorted.

 

Check out the Ireland Engineering rear control arms. Very nice and beefy with a reasonable price.

 

I am leaning towards Texas speedwerks arms as they are claimed to be quiet and oem ball joints,my goal here is a well balanced daily driver,i'm not opposed to going aftermarket,but dont want parts that are going to squeak for the rest of the cars life,please correct me if i'm wrong.The IE adj plates were silent on the drive home which was slow as the car is out of alighnment,the fsd's have raised the front 7 mm and the rear 2mm or could it be the camber plates??

 

It's the camber plates - the FSD's are not gas-pressurized like Bilsteins. That's a great price for the work though.

 

yup Old Rick i was leaning towards the camber plates to be the culprit.This guy is good he's not a mini dude but works on the fastest SUBARU WRX in the Caribbean so installing bolt on's would be a walk in the park for him.He sugested to me to bring it back in Mon and he'll weld the arm while i get the parts,when i look at the car from behind i can see it has more camber on that wheel,i never realised those arms were so flimsy,thats another reason why i'm thinking aftermarket,i'd risk to bet the OEM arm cost more in this place,around here we say BMW stands for (bring money withya)

 

I dont mean to hijack this thread but just a quickie.On research i see BMW has a revised control arm that looks to be much stronger than the piece of junk that's on there,what's your opinion should i get aftermarket or the new OEM,adjustability is not critical as it's FSD on stock springs,further whats the pros and cons of swaybar endlinks.The way i see it after doing shocks camber plates sway bar,i'd like to finish the job properly,but i'm concerned about making the car into a rattle trap,it's a daily driver.??