I first want to say thanks to the people at Sunriders AutoX for their efforts to provide a great day of autoxing and making it conviently close to my home (5 miles away)

Second, I'd like to punch the local weather man in the face who said it was going to get into the mid 60's here in florida. I don't think it got over 52 deg and there was 10-15mph winds.... Me and my sweatshirt now have a cold....

My MCS is stock with respect to suspension and I have the 17" Pirelli runflats... The car was actually not as good at Autox as I had expected it to be. I'm sure my car handles better than most other cars from the factory but it sure needs some improvement for Autox. The course was all corners as most Autox tracks are and I was able to spin the tires anywhere I wanted... disturbing that I couldn't get the power to the ground.... This is my first Autox ever but not only that this is the first FWD performance car I have ever driven, that's going to take some getting used to. And I HATE UNDERSTEER. I would much rather have oversteer than understeer and I was envious of the RWD cars spinning the tires while sidway's in the corners. I was only able to get the backend to come around a few times braking hard, late and turning into the corner. The rest of the time I was braking hard, late and heading for the cones..

I left the Autox somewhat disapointed with my MCS wondering If I should have kept my 1990 miata.... but the drive home cured me of that. Will I go again next month? probably but after installing the Pulley, Intake and exhaust on my MCS it left me wishing I had spend the money on springs, sway bar, wheels and tires.
Well, my birthday's in March so I think a sway bar will be at the top of my list.

Also, the left decreasing radius 720 with 3 kinks in it left me wishing I had a harness and a race seat... I know what the view from the passangers seat would look like around this corner.

 

Don't give up on the MINI just yet. Go to a stock Cooper bar to reduce understeed. I came from a 92 Miata and found the MINI to be a great car to drive. No more threshold braking, just remember the MINI is even more of a momentum maintenance car than a Miata. My MINI rotates with the smaller front bar, 52 f/r tire pressures and Konis on full firm rear, 3/4 firm front. I've heard of drivers going with large amounts of toe out on the rear to get rotation. Tire pressure is the easiest way to get rotation. With Hoosiers if the rears are lower than the front by about 10 psi, the car goes to neutral handiling 9with smaller front bar).
Cars don't understeer, drivers do. Oh and I know what you mean about temps, last weekend we only reached the mid-50s in SoCal.
Chris

 

Wheels made my biggest difference between the first one I did there and the one I did in Ocala. (you simply MUST go next time, ask Ferman, they are planning another.)

Address your concearns with Pat Wallis or Orbhot, who posted 1st and second in their class. They will have good advise for you.

I do not know if you are on Sunshine Minis, but if not, please follow the link in my sig and sign up.

There is another autox this coming weekend in Gainesville. I may just be going to spectate, but it is sure to be fun.

Those conditions SUCKED, as our tires never got warmed up enough to grip.

Take a look at this video if you want.

http://wbar17.tmp1-4-8-126-206.tmp1....nrdrsautox.mov

Be sure to watch the end.....

 

correct sig here:

 

>>http://wbar17.tmp1-4-8-126-206.tmp1....nrdrsautox.mov
>>
>>Be sure to watch the end.....

hhmm... the link didn't work for me?

 

I host that stuff and the server was down for a few today, it ought to work fine now.

 

Hmmm. That's odd that you say to REDUCE rear psi to 10 lbs. less than the fronts. I've had decent luck (on a road course--not AutoX) by INCREASING the pressure on the rears by about 5 psi over the fronts. Of course, I've also heard that you get nearly identical results by reducing/increasing rear pressure relative to fronts, but this doesn't make sense to me. Reducing pressure should do nothing but increase grip (up to a point), right? So how would increasing rear grip help the car rotate, i.e. slip in the rear (which it doesn't naturally want to do)? Also, a stock Cooper rear bar to reduce understeer? Is it firmer than the stock S bar?

 

>>Also, a stock Cooper rear bar to reduce understeer? Is it firmer than the stock S bar?

He was refering to the standard Cooper FRONT bar. More difficult to put in but legal for stock class. Not that super_MINI's car is stock legal.

 

Oh cool. Thanks Motoring. So, you'd be softening up the front end, but with the same net effect--AND you could remain in stock class? Really? Interesting.

And any thoughts on the tire thing?

 

ahh the tire thing.... tires have an optimum pressure that they work at.... any pressure over or under the optimum will decrease grip... if you plotted pressure vs grip on a graph it would look like a mountain with a rounded top... so in the case of a MINI get the front to the optimum pressure... then play with the rear to get what you like.... some people use high pressure in the rear to get rotation... some use low pressure... what works best depends on driving style... and the type of car ... set up ect ect.... last year on Kuhmo tires I was using 50 to 55 front pressure and arround 40 to 45 rear with a little toe out in the back...(this setup worked well but was not suited to all conditions.... esp long sweapers) I did not have the car the full season so that is the setup I ran at Nationals... For the 04 season I will have new tires and plenty of time to properly dial in the setup... (well ok the Feb. Pro will be on last years Kuhmos... if they can last 12 more runs)

 

>>ahh the tire thing.... tires have an optimum pressure that they work at.... any pressure over or under the optimum will decrease grip... if you plotted pressure vs grip on a graph it would look like a mountain with a rounded top... so in the case of a MINI get the front to the optimum pressure... then play with the rear to get what you like.... some people use high pressure in the rear to get rotation... some use low pressure... what works best depends on driving style... and the type of car ... set up ect ect.... last year on Kuhmo tires I was using 50 to 55 front pressure and arround 40 to 45 rear with a little toe out in the back...(this setup worked well but was not suited to all conditions.... esp long sweapers) I did not have the car the full season so that is the setup I ran at Nationals... For the 04 season I will have new tires and plenty of time to properly dial in the setup... (well ok the Feb. Pro will be on last years Kuhmos... if they can last 12 more runs)

So how do you know what "Optimal" pressure is for the fronts? Is it trial and error or is their some calculation that can be used?

 

I tend to run higher pressure in the rear to get rotation. This tends to use the center of the tire rather than the edges. We use the edges too much in the front as it is. I haven't played too much with low pressure in the rear.

 

I have been using 50 psi for the fronts more out of necessity to prevent cording the outsied edge of the tires. (You know you are a grassroots racer when...you know what color of spraypaint to use to hide cords on Hoosiers). My co-driver last year for Petersburg, DC and Topeka is a very fast (national) driver with much experience drivng RWDs. He prefered the "assy" feel of the Miata and we tried to replicate it on the MINI. We came close, but I prefer the neutral feel of a car (or did at the time), now I prefer a little oversteer. On day two at Topeka, we tried to change the pressures to get the car to rotate more. He went from the normal 50 down to 32, in hopes of making the tires sloppy loose, it had the opposite effect and made the car tighter. The advice we were given was from a MINI driver who had a lot of toe out and low pressures. My car had toe-in and low tires. I am thinking of running 0 Toe in the rear to get the baseline, then once the new A3SO4s come out I am going to try to find the optimum pressures without regard to wear.
Chirs

 

Sounds like you had a fun time. Might I suggest a performance improvement like this?

https://www.northamericanmotoring.co...amp;topic=8527

 

>>Sounds like you had a fun time. Might I suggest a performance improvement like this?
>>
>>https://www.northamericanmotoring.co...amp;topic=8527

Without a doubt the best performance improvement for the $$$. I need that bad, Still would like to improve the car so that I know it's all up to me. Kinda like making sure you buy the right tool to do the job, then learn how to use it. I would also like to do a few more Autox before getting instruction so I feel more comfortable with the car and can focus on making the necessary driving improvements that the instructors suggest.

 

That sounds like a good plan (similar to what I did). I was reminded of my experience when you wrote about how much your MINI understeered. Along with the other participants who felt their cars understeered WAY too much at the start of the course, by the end of the course, there was unanimous agreement that our cars were just fine.

 

Yes, I think you maybe right about the Understeer. I'm just so used to RWD cars and learned to like and control Oversteer. FWD car is a new experience for me and I'm just feeling like I'm missing that extra control with respect to whipping the back end around.

 

Finding the optimum pressure of a tire is a bit of a black art... lots of trial and error... a few methods include... checking tire roll over... (shoe polish on the tire edges to see how much roll you have) .... Watching pressure gain (a "old timer" gave me the advice to keep raising pressures untill you only gain a few pounds of pressure during a run)... but the best tool is a pyrometer so you can take tire temps ... (shooting for a tire temp that is at the proper working temp for your tires and a relatively even spread of temps across the tire....) your tire rep should know what the ideal working tempreature is.... the only way to get very good temp readings is to use a skid pad... but most of us just take temps RIGHT after a run...

all the above is great but the final factor is how you like the car... I would not just go with whatever everyone else does..... what works for one person may not work for annother.... there is no one perfect setting that works for all of us!!! although for stock MINIS our lack of Camber forces a pretty high front tire pressure... I would keep the fronts in the 40 psi range or higher or you will destroy the front outside edge!!!!

 

Super Mini...
There is some great advice here. I'll throw in my two cents. I have raced a 914 in CS the past four years and finally got to the point of beating the Miatas fairly regularly until the engine went south and got the MCS. Even though the MCS feels slower at times my times on street tires are faster than the Miatas I used to beat with my 914 with my Kumho racing tires. So, your car is probably faster than you think. I know mine is faster than I can drive it at the moment. My advise is to not wait for any lessons. I know I need front wheel help after one season and I was lucky to win our street tire class in the Reno region. As for modifying your car that is up to you but I couldn't put all of the power on the ground with the stock setup with Kumho Mx tires. You are seeing a lot of advise about "rotation". I think this the key to fight the understeer. I have been using trail braking as a crutch to help this and it has been very helpful. The other thing to help understeer is to fight the urge to accerate too early. Try to bum rides from other racers and also follow them as they walk the course and ask questions. Have a great time.

 

>>
>>>>http://wbar17.tmp1-4-8-126-206.tmp1....nrdrsautox.mov
>>>>
>>>>Be sure to watch the end.....
>>
>>hhmm... the link didn't work for me?

sometimes I pulll those files from the servers when I need my bandwidth. they ought to be working again.

I ought to be moving all my local hosted stuff to servers with better connections soon.

 

I drove my car yesterday, the first time I drove it since the Autox. I forgot to reduce the tire pressure in the front tires from what I had put in for the Autox, 42psi. I had mentioned in the post above that I had alot of problems getting power to the ground at the Autox and I noticed I had the same problem on the street with running the higher tire pressures yesterday. I said before, I have the Pirelli Runflats. Does upping the tire pressure to prevent sidewall wear affect the contact patch for straight line grip this much? My tires before the autox were really low in PSI around 24psi at all tires. I could only spin the tires when starting from an standing start or get a chirp between first and second gear with a quick shift. Now with the higher tire pressures I can just about spin the tires anywhere in first gear with the throttle down. I live in Florida, so it's not like there's a layer of snow on the ground causing wheel spin...

FYI, I have the 15% pulley, Borla Race Exhaust and Alta Intake.

 

The higher the tire pressures, past an optimum spot, the more likely you will 'crown' your tire, reducing your contact patch. When you accelerate the contact patch 'moves' to the back part of your tire, exacerbating the problem of over inflation by further reducing that contact patch of an overinflated tire.

In order to get my Mini Cooper to rotate better in H Stock, and this on Hoosier R compounds, I 'over' inflate my rears to get a bit of this crowning effect, while lowering the pressure in my fronts. This helps me rotate the car in my style of driving. Less contact patch in the rear and more up front. I also have Koni Yellows and adjust them as well to help the rotation without sacrificing a lot of the Mini's very cool stock transition characteristics.

Run flats of course have a VERY stiff sidewall and generally are a much harder durometer anyway than non run flats. Hoosiers also have a very stiff sidewall (aids in turning) but are a sticky R compound tire.

So, overinflating a very stiff sidewall and hard tire will IMHO cause you to lose grip more often on your fronts when you aggressively accelerate.

My2cents Augs

 

I think I had the exact opposite setup with respect to tire pressure that I should have had. I think next time I'll try 42psi in the rear and 30-32 in the front. Even at 24psi before the autox I never got wear off the tread even in very hard cornering. This way I'll get back the traction that I lost the first time and also get the car to rotate more with higher pressures in the rear. Thanks for everyones input.