Looks like this section gets crickets - perhaps it's because it lives at the very bottom of the forum.

Anyways, for 2012 SCCA has made a few rule changes that may interest stock-class Mini people.

1. Road tire classes - Three new classes - RTF, RTR, RTA (Road Tire Front, Rear, AWD) are indexed classes for all regular stock class rules, but on street tires (treadwear 140+.) In RTF, all FWD cars get lumped together, but get scored on the PAX index.

2. Swaybar rule change - before, you could only change the front swaybar. Now, you can change the front OR the rear, but not both. It's mentioned in a few other threads here, but looks like nobody has really done much testing yet.

I'll be driving my 04 MCS in RTF this year, running the 17" Dunlop.

Here's my questions / comments / theory about the rear bar:

I went with the Hotchkis "race." It's a Big Bertha at +314% / +394% / +501% from the stock bar. Heavy as all getup. I've only had it on for a few street miles so far, but the difference is noticeable. You can feel the rear load up much sooner. So far so good.

I'm assuming that the stiff rear roll rate will help wedge the inside front tire down, letting me put power down earlier. I'm also pretty confident I'll be on 3 wheels often. The question is, once you hit 3 wheels, there no more available "wedging" regardless of bar stiffness, correct?

I HAD my rear Konis at full stiff before to try to aid rotation. Since a swaybar basically acts as a stiffer spring when roll is present, I probably can't turn them down too much, right? I guessed and set them at 1/2 of the way through the range when I installed the bar. How do you approach shock tuning with such a large bar? What should I be "looking" for in transition to know if I'm too stiff or too soft?

Last year I pulled every trick to help the car turn - zero toe, stiff damper, rear pressure to the moon. What order should I run things less aggressively in the case that the car is an oversteering monster?

 

I have been autoxing a few years now in various cars. But I ran my first ever autoX in my 07 MCS this past Sunday with Philly region SCCA. It was a little damp and about 50 degrees out. I was stunned at how tail happy the MCS was on 215/40/17 RS3s! I have previously autocrossed an ’00 S2000 for many years, and the Mini was putting the S2000’s oversteering reputation to shame – lift throttle over steer in every corner! I have a feeling it was primarily because I could get the front tires up to temp very fast by spinning them at the start line. And the RS3s on the front were very grippy laterally, not so much in acceleration. But the rear tires remained ice cold, even after completing a 75-77 second run.

I am running RTF as well this year. My car is not prepped at all. Other than the wheels and tires, and a cat-back, it is completely stock. I’ve already ordered one of the Tarret Engineering NASCAR style rear sway bars, but based on my initial experience with this car, it may be completely unnecessary unless the rear starts to stick better once it gets warmer out. I have a set of Truchoice-revalved Konis for the car, and I intend to do the JCW suspension and tuning kit conversions on the car as well.

 

Woah. My car with zeroed out rear toe, rear Konis at near full stiff, and 50psi in the rear tires (Star Specs) wouldn't rotate the way I like. Does the R53 have a reputation of not turning as well as your R56?

 

Well, under cool and damp conditions the back end doesn't stick much on the first run. The RS3 likes a little heat, and I can see quite a bit of wag 'till the tires get at least somewhat warm.

I used to spin on the AS06 about every third event - on the first run. (Slow learner).

But once warmed up, and without camber, I'd expect all of your tricks to be needed to get anywhere near neutral handling. Even with coil-overs and 2.5 negative out front I still run 48 lbs out back with the Z1 as a starting point on a dry course.

Fun though isn't it?

Cheers,

Charlie

 

I ran the car again this weekend. It was much more composed. The only change was I swapped the already-scrubbed-in front tires with the backs beforehand. Also it was much warmer at this event - 75 degrees out this time. There was no lift throttle oversteer at all this time. It rotated OK with lift, but I will definitely be using the Tarret rear bar when I finally get around to installing the Konis.

 

I'll be giving the new swaybar it's first workout this weekend. I'm excited.

That Tarret piece is super trick.

 

yup.. 'dem RS3 likes dat heat huh...

 

Oh my goodness, the Hotchkis Race rear bar totally transformed my car. It feels like I have an unfair advantage out there, the car rotates at will. We did have a long (6 cone) slalom today, and the car got a little buttox happy around the last two cones with my old driving style, but I was able to adjust.

Transitions weren't much quicker, not surprising since so much of the weight is on the front.

Sweepers are mega improved. Once the car sets, you can use the throttle to make your line as tight or wide as you want. Much more grip out of the front, puts power down a lot better too. Even under full throttle, I had noticeably more turning ability in a particularly long sweeper that would have been an exercise in patience with last year's setup.

Lift throttle tightens up lines very well. The rear would come loose into a gentle drift with a heavy throttle drop, but it was very predictable / controllable.

Overall, I was concerned that I went too big, but not a worry. We had cold (45°F) temps and even with cold rear tires on the first run the car wasn't so loose that I felt I had to work hard to keep it in check.

Good times. Tthank you SCCA for passing the rear swaybar rule.