Saturday, June 19, 2010

Reflex Racing Special Project: the little Mini that could...


PN says: Do you plan to go to KO race in March?

Joe says: Yup

PN says: Maybe I will build a 90mm AWD for the Mini Sport Class

Joe says: AWD 90mm?

PN says: KO race will have a Mini Sport Class for 90mm cars only

Joe says: Ah awesome! I should do that too

PN says: 2WD or AWD? They are running them together

Joe says: I have a Mini Cooper MR-02 right now

Joe says: Turns so quick, but traction rolls

Joe says: I need to try and fit a sway bar on it

PN says: Yes maybe you need a harder front tire

Joe says: I think I’ve got 25’s on it!

PN says: You should try 30. Or stock tire

Joe says: Yah I guess so


And that's how it started.

We all knew that Philip would never leave his beloved MR-02 chassis for the AWD...

Missing my old 1:1, I had built up a Mini Cooper MR-02 using PN narrow front end just to goof around with.


PN says: 90mm motor mount sample is here

PN says: I just assembled it. Sooooooooooo sweet

PN says: I can’t wait to try

Joe says: *&$% it! Send me a pic

Joe says: Maybe I’ll try to sneak out of work to pick it up.

And just like that, the PN 90mm MM MR-02 motor mount was born. I couldn't sneak out of the office in time to pick up the test sample, so I had Philip send it to me. I rebuilt my 2WD Stock MR-02 with all the new Mini chassis components just in time to MISS the last day that Kenon would ever be open. For some reason, I didn't understand what Philip meant by "I'm closing the track today." I just thought, "Yeah I know. I'll try to stop back by tomorrow for some testing..."


PN says: I tested the motor mount today. The setup is GOOD!

PN says: I beat Chad in stock class at last Friday

Joe says: hahahaha

Joe says: awesome

Joe says: what spring

Joe says: are you running wide tires?

PN says: on my track, front yellow

PN says: F40 body

PN says: yes

PN says: 1 front, 0 rear

Joe says: yah i'm going to run mini cooper

PN says: another choice is AE86

PN says: also very good and stable

Joe says: yah

PN says: when i put on the F40, sooooooooooooo good

PN says: huge difference

PN says: wide rear tire

PN says: i also used an F1 shock on top, much better

Joe says: interesting

Joe says: i never liked the f1 shock

Joe says: prefer the oil shock

Joe says: but may be too high for this setup

PN Philip says: oil shock is too big, try the f1

PN Philip says: i can set you up

Joe says: i don't care i'm still running mini cooper

Joe says: will be fun

Sure I had committed to running the Mini Cooper body, but I still had a few tricks up my sleeve. I decided to abandon the front swaybar attempt since there was just no room in the chassis for any of the conventional setups. First thing I did was lighten up the body. The "sunroof" mod is popular with racers, and remains legal in most classes. It usually results in a few 0.1g from the top of the car. The funny thing about the mini cooper body is that the roof is only glued to the windows and has no other attachment points to the body. This makes it very easy to remove and thin out with a dremel and wire brush attachment. I would be running an MR-02 chassis with the PN MR-0175 tower bars to reduce the roll with this already tippy setup.

The other big upgrade would be the rear wheels and tires. I've experimented with semi-wide (9.5mm) rear tires in stock class before with some success. I find that in certain traction/temperature situations, they work as well as full wide rear tires. I had some sample semi-wide SSG's laying around, and I knew that these would be just the ticket. The standard 8.5mm narrow wheel/tire setup leaves room in the Mini Cooper wheelwell, so I knew we had some space to play with. Simple math said that 9.5mm semi-wide tires on a -1mm offset semi-wide wheels would give me the same rear track width as the standard 8.5mm narrow setup.

So where do you get -1mm semi-wide wheels? You make them! Starting with Atomic -1mm wide wheels, I carefully sanded them down to the correct width and glued up the semi-wide SSGs. Why all this trouble for wider wheels and tires? Well first of all, we would be running PN 70T stock motors which have more than enough grunt with race batteries to overpower narrow rear tires. The smaller contact patch of narrow rear tires not only affects the power application, but the consistency of the handling via squirm. I thought that a narrow aspect ratio (unless trued WAY down) might squirm badly under the combination of acceleration and cornering loads on exit. At this point, I hadn't figured out whether the chatter/traction rolling in my previous setup was generated from the front or the rear of the chassis. I suspected a little bit of both - sometimes the nose would tuck in corner entry, sometimes the rear would hop around on exit. I hoped that the semi-wide rear tires would give me a more consistent and stable rear contact patch to apply power during corner exit and solve 1/2 of the problem.

Just for good measure I also sanded some Atomic +1 narrow wheels down to 8mm width for use in the front. With camber, they had no issues rubbing, and I thought they might help in the front end stability department...

Took the new setup + a few options out to OC/RC to shake her down. Better than before (due to the damper plate system), but I was STILL traction rolling when the tires got up to temperature and if I started pushing it. I tried going stiffer on the suspension, damping, etc. to control the oscillation, but no help. The car did feel very consistent when I backed the pace off to 80%, and the thing could turn on a DIME. It was very interesting being able to run so deep into a corner, stay wide, turn in late and not wash out and blow the apex. On top of that, the car could actually tighten the line on exit under power. This would come in handy a little later...

Race Day!

After a long drive up to NorCal, we got set up in the mall area. This was my first mall race and Binh and the Inside Line crew really put together an awesome venue! There was an escalator leading to the second floor where spectators could gather for a bird’s eye view of the racing action below. Practice was VERY crowded with a line 20-30 racers long waiting to get their shot on track in timed intervals. I knew my F1 car was fine, and I really wasn’t that concerned about Stock 2WD, so I focused on the Mini. As usual the track started off very green and slippery which brought the push out of most cars.

Some of you may wonder what those stupid pink flowers are all about. I always like to grab a random memento at each big race. In our rush, I hadn’t packed a pit towel or napkins or anything to wipe down the tires after gluing. We happened to be pitted next to this plastic flower bush, and the mall kindly “donated” some flowers so I could wipe the excess CA off the sidewalls (critical on the Mini fronts). I found the flowers in my pitbox a week later and there you have it.

I started out with semi-wide SSG’s on the rear with -1 offset Atomic wheels that I had shaved down. They provided plenty of forward traction, but I was struggling with finding the correct front tire for balance. I tried a variety of different tires from sticky to hard, and fiddled with the dual rate to dial in the steering. As the grip came up, traction rolling started rearing its ugly head. I ended up having to lift before the sweeper and bend it in to prevent the little Mini from flipping off the track. I miscalculated this more than a few times resulting in some pretty spectacular crashes much to the delight of the crowd that had gathered above. Lots of oohs and aahs and groans from the onlookers didn’t do a lot for my confidence. It felt like everyone in the mall was watching my little red cannonball careen off the track…

Come the qualifiers I really focused on blocking out the crowd and getting some solid conservative runs in. I managed to save a few of the traction rolls with some rather entertaining bicycles in the sweeper and the infield. This brought a smile to my face, and I really started having fun. I ended up qualifying at the rear of the grid in 9th, but I was confident that if I could keep it on all 4, I could fight my way into the top 5 for the main. I was the ONLY Mini Cooper in the field surrounded by F40’s, RX-7s, and other low slung coupes. While the top-heavy Mini had its issues, I was able to turn under just about anyone on exit, as long as the car didn’t end up on its lid.

For the main, I rolled the dice and tried a trued PN 20 degree front tire – stickier than I had been running in qualifying. I dropped my dual rate down and tested the front into the sweeper on the warm up laps. My hunch had paid off! Reducing the steering angle had all but eliminated the traction rolling! It wouldn’t hold up to a Scandinavian flick, but I could finally bend the little Mini into the sweeper at speed. I still had plenty of steering in the infield, and the reduced steering scrub had totally freed up the car for some pretty amazing corner speed.

When the horn sounded, I rolled into the throttle anticipating a pile up in the first corner. Looking for a gap, I ended up getting knocked backwards by a more enthusiastic driver, so I had a lot of work to do. In dead last, I settled down and just tried to nail the same line lap after lap while adjusting to the new steering characteristic. A few laps into the race, the tires came up to full temperature, and I finally got a feel for what I could get away in each corner. By that time I had started reeling in the other drivers. This is where it got exciting. I would pressure for a few corners, wait for a little mistake and duck right underneath. It felt like I was passing someone almost every other lap. When I came up on another driver coming onto the straightaway, I took an outside line in the sweeper just to be safe. Imagine my surprise when the little Mini slingshotted the long way around and completed the pass going into turn 1! The car was so on edge, but if I did my part, I could put it anywhere on the track. Given my tendency as a race announcer, I started providing my own color commentary from the drivers stand infused with plenty of laughter and disbelief as the Mini clawed it’s way through the field.

Being lost so deep in the field, the announcer hadn’t noticed my rise through the running order, but the cheers of the crowd above and my fellow racers in the pits brought to light that I was now sitting in 3rd place! I was stalking 2nd place who was running an excellent tight line. I got the drive coming out of turn 1 and the earlier outside pass in the sweeper made me think I could at least stay on the high line into the tight infield. I was as surprised as anyone when the little Mini carved a beautiful line around the outside and ahead into the chicane. From there, I pulled away in to a solid 2nd position. Up in front Philip’s F40 was gone. His car was turning almost the same laptimes as Stock 2WD. While I couldn’t manage to track down the win, I had just driven one of the best races of my life, grinning and laughing the whole way to 2nd place. From the cheers in the crowd and the celebration in the pits afterward, it felt like a win.

I can’t lie and say that the Mini never traction rolled during the main. I got a little aggressive on the exit of turn 2 and managed to tumble into the chicane, beaching the Mini on the rail. The car was literally high centered in the worst spot on the track for a marshal to get to. My buddy Emu had run into some mechanical trouble with his F40 (which was also ballistically fast), so he was laps down on the field. He had just come around the sweeper when he saw where my car was, rounded turn 2, made a beeline for me in the chicane and plowed full throttle into the rail I was on top of. The result? He could have broken my t-plate. He could have bent my axle. He could have broken his car. He could have flipped me on my lid. None of those things happened. The impact popped the little Mini off the rail onto the other side, landing on its wheels and I was back on course costing only a couple seconds for my mistake! A completely intentional, unselfish gamble by Emu had easily saved me a lap so I could continue mowing down the field. To this day, I still can’t figure out how he managed to spot my car, recognize it, weigh the risks of his track position and mine, formulate his harebrained scheme, and execute it against all instincts (it’s completely unnatural to intentionally drive straight into a rail) – all in about 1 second. It’s things like that that you never forget. Even at a toy car race.

Monday, June 7, 2010

PNWC SoCal Qualifier 6/5/10

I had a rough return to racing this weekend after sitting it out for over a year. I was driving Cristian's old stock MR-03, and it felt pretty darned good. This is a different Kenon track and the grip is really inconsistent with a mix of tiles (age, condition, and height). There are lots of seams that can grab you midcorner, and the surface is really abrasive. I tried a few things here and there, some worked and some didn't. The grip improved over the weekend and the search for front tires was on. I never really hit the tire setup, and just tried to tune it from the rear.

I followed my race plan of running a conservative qualifier and turning it up for round 2 and 3. I got quicker every round, but always felt a couple tenths slower than in Friday practice. In the main, I found out why. My motor let go at around the halfway mark. It had been going south the whole race. I had been running one of Cristian's supertuned motors in practice and it was smooth and punchy at the same time. The handout just felt softer and softer, which affects timing rhythm etc. In the end it just came to a stop, and I pulled off worried I might blow a FET. I've seen this happen to my teammates, but I've always had good luck with handout 70T motors. I guess it was just my turn to get a dud.

In any case, I feel pretty rejuvenated. I wasn't really in the hunt, but just getting warmed up felt good. It was nice to see old and new faces at the track, but I need more practice and experience with tires so I can make good calls come race day instead of just guessing. Will hit it hard over the next few months and see you guys at the Worlds!