Everyone exhaults the MINI's performance in the corners. However, I find the car to be extremely pushy when going thru 90 corners (lots of them here in PHX). DSC kicks in and slows the car. I turn it off, and the car pushes like a pig! I can go thru similar corners at the same speed with other vehicles will narrower tires without pushing. Is something messed up with my suspension? Or is it just the 17" run-flats?

 

>>Everyone exhaults the MINI's performance in the corners. However, I find the car to be extremely pushy when going thru 90 corners (lots of them here in PHX). DSC kicks in and slows the car. I turn it off, and the car pushes like a pig! I can go thru similar corners at the same speed with other vehicles will narrower tires without pushing. Is something messed up with my suspension? Or is it just the 17" run-flats?



You need the sway bar! Talk to RandyBMC!

He'll set you up right!

-Jim

 

1- The stock runflats are notoriously for their lack of at-limit grip. Switch to a softer, non runflat tire.

2-A thicker rear sway bar will correct 90%+ of this issue.

Between my KW springs, Madness rear sway on the tight setting and Yoko AVS ES100 R16s on my vspokes, well...little Zeek is neutral as all get out now. Goodbye to understeer...unless I'm doing 50mph+ and try to "turn on a dime". Ya, well you'll still get a bit there, but duh, no kidding.

Honestly, get the Madness rear sway. Sub $200 and EASILY installed by yourself in under a couple hours, beer in hand.

R

 

>>You need the sway bar! Talk to RandyBMC!

From my days of racing R/C cars (1:12, 1:10, 1:8), a stiffer rear sway bar only decreases the amount of traction at the rear of the car. It does nothing to increase traction on the front of the car. The model car becomes more neutral feeling, but the front still doesn't have more grip. Does a stiffer rear sway bar in full-size cars (1:1) really give the front more grip?

 

Not knowing the drive configuration for the R/C cars.....

Typically speaking, a thicker/firmer rear sway should be place on Front Wheel drive cars to increase overall traction. A thicker/firmer front sway should be placed on Rear Wheel drive cars.

R

 

>>
>>>>You need the sway bar! Talk to RandyBMC!
>>
>>From my days of racing R/C cars (1:12, 1:10, 1:8), a stiffer rear sway bar only decreases the amount of traction at the rear of the car. It does nothing to increase traction on the front of the car. The model car becomes more neutral feeling, but the front still doesn't have more grip. Does a stiffer rear sway bar in full-size cars (1:1) really give the front more grip?

I have the rear-sway upgrade and I can absolutely tell you it's a different car. :smile:

Anyone else willing to testify?

One caution, the rear of the car will break free a LOT easier so you better know what you're doing. It holds better but is less forgiving.

-Jim

 

Sorry to disagree with you Davbret, but sway bar balance has nothing to do with which end the car is driven from. Sway bar sizing is about roll-stiffness and front to rear balance.

In the case of a car that understeers, as with virtually all modern factory delivered cars, either more rear bar or less front bar will bring the handling into balance between understeer and oversteer. More bar will give more roll-stiffness and better cornering grip, less bar will give a more comfortable, compliant ride. But either can help balance the front to rear characteristics.

Here's a way to visualize why: If you put a smaller diameter wheel on the left rear of the car and then drove through a right-hander, the weight of the car would shift to the left wheels. Since the left rear wheel is smaller, the car would pivot on the front left and right rear wheels, lifting weight off the front right wheel. With less weight on the front right wheel, overall grip at the front of the car is reduced, producing understeer. Soft rear suspension and roll stiffness will have the same effect as that undersized wheel since as the wheel gets weighted in the corner, the soft suspension will allow it to give away (compressing the suspension).

A sway bar ties the left and right suspensions together, resulting in a stiffer suspension in roll conditions (cornering). The suspension is not stiffer when both sides compress at the same time (like going straight over a speed bump). Stiffer springs can achieve the same cornering improvement, but at the cost of straightline comfort. That's why good suspensions use a combination of spring stiffness and swaybar or roll-stiffness.

These fundamentals apply to front, rear, and all wheel drive vehicles. The only difference will be the sizes of the bars, depending on the weight and weight distribution.

For more on this topic, including definition of some of the terms, see this previous thread:
Rear Sway Bar Thread

Cheers,

James

 

Plowing through the corners is a sign of lots of understeer. You can cure it several ways already mentioned in this thread:

Add a stiffer rear sway bar.

Grippier tires

A couple other options:

If you have stock sway bars then try inflating the rear tires up about 5-8 psi higher than the fronts. This somewhat helps get the rear end around.

If you are running coilovers w/adjustable rebound settings, experiment with backing the fronts off to a middle or moderate setting, while locking the rears to full hard.

Even with the stiffer rear sway bar and performance tires you can still experience plowing if you are way heavy on the throttle coming out of the turn. The open differential (especially noticable in the S) results in excessive wheel spin (inside wheel mostly) for those with heavy right feet. This also feels like plowing. Your only options are to use less throttle (slow down) or invest in a limited slip differential (LSD) -- which is an expense alternative

 

Much of the push concern I have is with corner entry. Yes, I do feel the push coming out of the corners as well, but it is the entry that I really cannot stand.

 

>> With less weight on the front right wheel, overall grip at the front of the car is reduced, producing understeer.

So are you saying front grip will increase with a stiffer rear sway bar on the MCS ?

 

Absolutely. New cars understeer by design due to liability issues (again see the thread I linked above). Many on this site who've put a bigger rear bar on have commented on the complete transformation of the car, especially on turn-in! A bonus is that it won't change overall ride quality to a significant degree.

And contrary to the advice above, increasing FRONT tire pressure will help counter understeer. But I would advise against any radical change to one component (such as a 5-8 psi front/rear tire pressure difference). Performance driving and performance suspensions are all about subtle balance; optimizing grip at all four corners.

I highly recommend calling Randy at MCM (see sponsor directory). He is testing or has tested just about every performance mod for the MINI, on the street, track, and dyno. Others have referred to him as the MINI performance sage.

Best of luck to you,

James

 

>>Excellent!


Cool!


Yep, that's the rumor going around

 

>>And contrary to the advice above, increasing FRONT tire pressure will help counter understeer. But I would advise against any radical change to one component (such as a 5-8 psi front/rear tire pressure difference). Performance driving and performance suspensions are all about subtle balance; optimizing grip at all four corners.

You can go either way on this one. You can increase the rear pressure by 5- 8 psi over the front OR you can lower the rear and boost the front pressures. The result of helping counter the understeer is the same.

All you need to try this is a simple course (an autox course works well) and an air compressor/tank and a good tire pressure guage. This is a simple non-permanent technique and not very radical at all

You can put your tire pressure back to normal in a matter of minutes.

 

The driving technique is different in front and rear wheel drive cars. Get advise about how they differ. I am. When I first autocrossed my 914 I got a lot of understeer until I learned to set the chassis by breaking later and going with a later apex. You might try this in high speed turns and accellerate later. If you accellerate too early you will get understeer. I would also play with the tire pressures. This should make the car understeer a little less. I've got two weeks to try this for real in my mini when it arrives. I wouldn't throw a wad of $$$$$$$$$ at the car until you try some things that are free.
Take the car out to the local autocross and play with the handling and have a great time.
Good luck.
All Red MCS

 

I have the swaybar on my mini (on the softer setting) and yes it does add front grip. Randy explained that the swaybar keeping the rear of the car tight and together only helps to transfer more grip to the front. The car with the sway bar handles very neutral, there is an even amount of understeer, but oversteer is more prevlent but again, this all depends on driving style.

I have found that any sort of hard throttle lifting at or around the apex of a corner will add some oversteer (kick the back end out), at the same time, not lifting the throttle, and going too fast will have understeer, and once the car slows down enough, the front end will catch and whip the backend around, so driving style and skill are critical when driving at the limit with the sway bar, its not for the average joe drive quick, no way.

Bottom line, you want more handeling, get the swaybar, you wont be disappointed.

 

A stiffer rear sway bar will reduce rear traction. here's why: The sway bar is designed to use body lean as a source of torque to correct itself by transferring said torque to the opposite side of the suspension, using it to lift the inside wheel instead of applying torque to the outside wheel, therefore reducing traction.

The R/C car analogy is correct (as I used to race them too), softer sway bar or no sway bar is the most traction. However! full-size cars have much, much more traction due to weight than R/C cars, meaning traction/weight per wheel must be reduced and redistributed for quickest handling.

I would suggest some drivers training courses, my guess is that if you're finding these problems a big a handling limitation as you say, you're driving is a bit off-line. Are you braking Before the corner? Typically, you'll want to maintain a consistent speed around the corner, and do your decel and accel before entry and after exit, repspecively. If you come into the entry too fast, you'll of course have to scrub speed, easiest done by surpassing your traction limit and evoking a high slip-angle.

If you feel the car is the strict source of the handling difficulties, add a few PSI to your front tires, increase your front negative camber, reduce front positive caster a touch, firm up your rear anti-roll bar.

Cheers,
Ryan

 

>> You might try this in high speed turns and accellerate later. If you accellerate too early you will get understeer. I would also play with the tire pressures. This should make the car understeer a little less. I've got two weeks to try this for real in my mini when it arrives.

I think you might be more right then not.. I don't have many problems at all with my MCS, going into turns at high speed... on my way to work, I pick up the thruway right when it starts/ends, and there's a just over 90deg turn, and I can hit it at 50mph easily, w/o swinging the car wide... And this is also in colder weather, when the tires might very well be less sticky.. (stock rims, stock tires (dunlops))

Rocketboy_X