I'm a recent addition to the autocross community in my area. I spent my money on adding HP initially, and upon entering the world of autox now see that my money might have been better spent elsewhere. My suspension is stock and I'm looking to do a piece at a time as the money becomes available, so the question is this: I'm running Falken Azenis 215/40/17 and I'm getting quite a bit of plowing/understeer at the limits. What would be best to get the front end planted and back end rotating a bit (I want predictable oversteer)? I thought about camber plates to get more bite in the front and playing with tire pressure - also considering rear sway bar, but I want to make sure that I'm not setting myself up for disaster on high speed twisties with scary oversteer problems. What's the best first step?

On a seperate note (if anyone has any advice), I have 190 hp and no limited slip which seemed to be a serious handicap on this months course as I couldn't get the power to the ground. Anyone know a cheap way to get a limited slip, ha ha? Anyone racing street mod like me with no lsd, and if so how are you doing? My thinking is that I need to be carrying as much corner speed as possible since my exits aren't going to be stellar minus the lsd, which is why I was thinking that getting the back end to come around would help - it also may help me to straighten the wheel sooner making for better power to the ground. Thanks for the advice!

Oh, by the way - 2007 S Cabrio, CAI, 15%, One Ball, 380cc injectors, Jan tune if any of the helps!

 

Adj. rear swaybar, Adj. camber plates/Koni Sport Shocks (yellows) or Cross coilovers, Hoosiers A6 or Kuhmo 710 tires.

I have the H-Sport Comp. bar on full stiff, IE fixed plates & the yellows. No problem with oversteer on the street. I have a hole drilled in the frame rail to adjust the rear shocks for street use, full stiff pogos too much for me and removal to adjust them became a PITA.

 

The cabrio probably wasn't your best choice for autox-ing, especially if you don't have a triangulated rollcage. You need to stiffen up your chassis. In addition to the recommedations of chuckt, you need to install front and rear shock tower braces.

 

You can do the following to improve the ability to get that power to the ground...try disconnecting the front swaybar (FSB) (one side is all thats needed), this will allow the front end to roll independently and keep the inside front tire planted better. This costs nothing to do and is effective. Adding front camber plates is alittle costly but is money very well spent. Combining the camber plates and disconnecting the FSB will give you the best result in inside tire grip. Adding an adj. RASB will dramaticly change the dynamics of the suspension durring cornering and will completely remove all understeer. The RASB is the best thing (and is very affordable...I'm using the Alta 22mm with excelent results about $200) you can do to improve day to day and track driving handling. These mods are all allowed since the 15% pully puts you straight into SM class. I have my RASB adjusted for slight oversteer and I use tire pressure to regulate how much oversteer I want (tight course more oversteer loose course less oversteer). I do alot of throtle steering on course and find a twitchy back end is better than none. You could adj the RASB for slight understeer (so you can be safe on the high speed sweepers) and fiddle with rear tire pressure to remove the understeer for autocross...it comes down to what you personaly are comfortable with. I hope this info helps you ...any other ?s just post them here and someone will answer them.

Happy motoring

 

Thanks for the responses so far and i think that the sway bar is the best first step - camber plates and possibly shocks later to come, along with chassis braces or strut braces.

I will say though that I hear that about the cabrio a lot though, and while I'm sure that some chassis regididy is missing MINI spent some time addressing this from the factory - there is a large v shaped chassis brace underneath the car as well as front strut tower braces. I'm autoxing for fun mostly anyway, but in my area the fastest times of the day are always the same guys in miatas and S2000's, both the convertible variety. And looking at the gross weight of both the difference isn't substantial enough to make my car uncompetitive in my opinion.

I'll welcome any input on the subject though and I do appreciate the advice so far. Would disconnecting the front sway bar introduce a lot of body roll into the equation? It would seem that without stiffer springs this might not be the hot ticket, but I'd love to hear about any experience with this.

 

Try the rear swaybar before disconnecting the front.

 

that's where I'm going first. I see that everyone likes the H and R 19mm adjustable but I can't find anywhere to buy it - got any suggestions?

 

Here's 1 source:North American Motorsports

 

You can certainly stiffen up the chassis with the M7 chassis products.

http://www.m7tuning.com/parts/index.php?cPath=7_2

 

Though stiffing the chassis is a good idea overall, it will probably tend to increase understeer if anything, handling wise. I think the M7 stuff mostly effects the front end of the car, and that money should go to more effective mods IMHO.

I might try the FASB disconnect trick though. Several GStockers have gone to the Cooper bar up front with success also.

 

unhooking the front bar takes away everything that is good about the handling of the MINI.

To decrease understeer you have three options, increase front grip (add camber), decrease rear grip (stiffer rear sway bar), and fix the loose nut behind the wheel.

Ultimately, if you have too much understeer, you entered the corner too fast. With a front drive car you cannot completely eliminate understeer. With proper tuning, you can reduce it, but the worst driver can make any car push...

 

As I like to say, it's not a hardware problem, it's a software issue!

 

M7 has the undercarriage brace which may be just the ticket for a cabrio. That will certainly reduce overall body flex.

 

Excellent points! The MINI is best handled with trail-braking to get the weight smoothly shifted while entering the corner. Getting off the brake before turning in will excerbate and tendency to understeer as the outside front tire will not have enough weight on it to get a good bite.

 

I got rid of my M7 braces long ago and am running a TSW x-brace. The S2000 is incredibly ridgid due to an 'x' style brace and the fitment on the TSW is worlds better than the USS.

 

Thanks for the input. I've been thinking about an undercarriage brace.

 

DON'T disconnect the front sway bar! Big mistake. This will create more roll and put more weight on the outside tire which = less weight on the inside tire. What does that cause? More wheel spin. Motoring is right. Your coming into the corner too hot, this increases the push condition that your experiencing. Remember: Slow in, fast out. Early in, early out. This especially applies to a front driver. Another thing you can do is to put a different tire on the rear. The Hoosier A-spec (for autocross ) for the rear and the Hoosier R-spec (Race) compound up front has worked for many guys. I know a guy who will be running the autox at MOTD who runs that same set-up. The only guys faster than him at his last event were 2 Vettes, and only just barely. You will have to play with the tire pressures until you find what you like, and remember; sun, temp. and humidity all help determine your pressures, the same pressure will not work every time. Start with a baseline and go from there. Keep track of all the factors and pressures, and with time you will find what works best. Those Miata's and S2000's are better handling than your Mini, you have to use your skill and cunning to beat those dastardly dudes!

 

Thanks for all of the advice as it's all good! Here's what I got - the M7 USS and the H-Sport 25mm competition rear sway bar. This is just a start, as camber plates will be next. Your definitely right about front wheel drive having inherent understeer and so I know that driver will ultimately make the difference. I tried easy in and fast out of the turns with horrible results last autox as the inside tire was getting no traction driving like this. My thinking is that if I can get some rotation in the back while I'm entering the turn off throtle under braking (in other words running slightly hot into the turn and scrubbing off speed with the rear) then I'll be able to apply throttle sooner and the wheel will also be straighter hopefully making for better grip from the open diff. This is theory of course as I haven't gotten it installed for testing. This was the advice of Peter at M7, who sounded like he's got plenty of experience on the track so hopefully this is a start to a better setup. He said with chassis flex the bar alone would only make the car unpredictable, which wasn't a good think to me. I think the only advantage the Miata guys have over a correctly setup MINI is rear wheel drive, which in the end may be worth it's weight in gold. I know that I have a lot of room to improve. Last month I finished 4th in street mod and 27th out of 65 overall with my raw time (pax put me at 41 ). First place in street mod is a supercharged miata, and second a 400hp supercharged mustang. I honestly think though that with the correct setup in suspension that a better driver than I could be competing with these guys though. Fastest Pax for the day is a miata in STX (man that guy is good - he almost always wins pax). It's good to have a dialogue going about suspension as there are many opinions and lots seeking advice!

 

we've yet to see proof of this in timeslips, but it sounds nice

TSW doesn't recommend a bar that big in the back...especially for a street car. 22mm is a better/safer way to go. Also keep in mind...there's no free lunch. A stiffer bar always means less independent articulation which also means less traction over less than perfect road surfaces.

 

H Sport doesn't make a 22mm (and that seemed to be the brand most people were recommending). I will definitely use it on the softest setting on the street - I kept reading reviews from the 19mm and everyone was saying they use it on the firmest setting and that it's still not stiff enough for autocross.

 

right....I had the 19mm H-Sport on full stiff. I swapped to a 22mm R-Speed (same as the one Webb sells).

 

How are you liking the 22mm at the track. Are you able to get any rotation at slow speed? Just curious how you like it compared to the H Sport

 

everything is different on my car...hard to compare as the bar went on with everything. old setup was PSS9's, 19mm H-Sport and RE01R's. Current is Cross, 22mm RSpeed and ZIEX912. I'll get the RE01R's back on next month when the new wheels arrive.

 

Okay, here's an update from the Detroit Tuned Site - the H-Sport competition bar is a hollow 25mm bar, which is effectively a 22mm solid bar so in the end the torsional resistance should be the same unless I'm misreading this. So, I should be still on the safe side for the street

 

How do you like the Cross coilovers? Adjustability? spring rate?