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Andy Hollis on Data and Suspension Tuning

Long-time readers of this blog will know that we’re huge fans of using data (especially video) to improve driving performance. A recent talk given by Andy Hollis at the SCCA Motorsports Expo reminded us that data comes in many shapes and sizes; and that it often involves zip-ties.

Andy started his presentation with the rhetorical question, “What is Data?” He asserted that data is the digital representation of a car’s performance across a set of constraints, either recorded or perceived. Your “butt-dyno” just isn’t calibrated fast enough for the rate of inputs per second of a car at speed. The advantage of data over “feel” is objectivity.

For example, do you sense that your suspension is bottoming out in a given corner? Put a zip-tie around the strut shaft where it meets the tube and see how far it moves. If it moves as far as the photo below, then it is bottoming out.


Want to know how much body-roll you have?  Someone is always taking pictures at autocross or track events, so find a good high-resolution image of your car head-on and measure the angle? A good amount is probably in the two to four degree range.  More and you get too much weight transfer to be efficient, too little and you’re losing grip.  If the angle looks good, what is the loaded tire doing? Do you have enough negative camber?  How about air pressure?  This photos shows body-roll of about three degrees, but the loaded front tire is deforming suggesting more negative camber is needed.

Roll Angle

Data will show some surprising results, such as all other things being equal, a narrower car will be faster through a slalom (think old vs. new Miata). In Andy’s experience, tire compound is more important than width.  And testing requires a different mindset than competition.  You need to be consistent and remember your objectives when testing so you can isolate and focus on the aspect that you are testing.

For suspension tuning, he starts on the skid pad.  Time is the most important factor, not feel.  Use zip ties to see if bottoming out.  Look at tire temperatures front/rear and side to side. To get good data run in 3rd gear.  He uses a 100 foot radius skidpad.  For alignment changes, work on the end of the car that lets go first. For a front heavy car, a thicker front bar can help it push less (again counter intuitive.) Rake is important, but consider dynamic toe effect when changing rake after changing ride height. Once you have steady state on round skid pad, then go to oval skid pad and introduce the pitch variable.  If too extreme, go back to round skidpad and adjust. Next add braking/acceleration on the oval skid pad.  If the rear steps out, it could be a brake bias issue.  If you can’t adjust bias, then go back to suspension. Next he moves on to the slalom and takes acceleration of out if to just work on the transitions.  This requires a constant speed through the slalom. For autocross, a little toe out in the front can help (not recommended for the track.) For an underpowered car with over-steer a little toe out in the rear can actually help, but can also make for an interesting ride in a straight line over bumps. The B Spec cars in PWC are running as much as a half an inch toe out [which is nuts.] In the end you may have to compromise, but consider where you spend most of your time on course.  If you’re running autocross in a small parking lot with many tight turns, you may make changes that are different if most of your time is spent in long sweepers.  The same goes for the track.

Elliott Forbes Robinson on Racing

Elliott Forbes RobinsonElliott Forbes Robinson gave an interesting keynote at the SCCA Motorsport Expo last Saturday talking about what he’s learned during his 37 year career in racing. Following along with Randy Pobst’s theme of fear, he noted that if you’re feeling the adrenaline rush while driving, then you’re probably doing it wrong. It should feel awesome, yes; but not exciting. Exciting is often bad and can lead to surprises. And surprises are often bad as well: wheels falling off, fluid on the apex, no brakes, throttle stuck. It’s not that good driver’s don’t make mistakes, it’s more about how they recover. Like good actors who miss a line in a play, the observer may not notice. For a good driver that mistake could be too fast corner entry, or going off course — just without drama. But it is more a matter of style. He always tries to turn in early (something I hear attributed to Mike Skeen once too.) By turning in early, he’s able to make constant adjustments, but more importantly, he can get on the throttle at the right place, every time. He hardly ever trail-brakes and thinks of braking as the least important aspect of the corner. He tries to get all of his braking done in a straight line. As a result he consistently gets better gas mileage while maintaining competitive lap times.

Fear: Fight, Flight, or Freeze

Randy Pobst at MSX ExpoRandy Pobst was the keynote speaker at the first day of the annual SCCA Motorsports Expo in Charlotte, North Carolina last week. His speaking topic was fear, but his message was really about vision. We know instinctively that fear causes the fight, flight, or freeze response. Randy noted that rational fear helps control risk.  It can help us perceive scary cars or situations on the track and it nags us to check fluid levels, lug nuts, and safety equipment.  But he also observed that fear hurts driving performance as well.  When we get the white-knuckle grip on the wheel, our pumped-up forearms are incapable of subtle movements. Instinctively we realize the car isn’t handling right, but the tight grip doesn’t give any feel for what the car is really doing. Fear also adds to the physical and mental workload associated with driving, and can cause a loss of focus, causing the driver to miss flags, gauge warnings, or objects in mirrors.  He cautioned that mirror fear also causes mistakes and sets one up for easy intimidation by the competition. That in turn causes timidity, getting run-over, stagnation, missed opportunities, and no improvement.

The biggest impact of fear, Randy noted, was that it makes us look at what we fear — the vision connection.  It makes us look where we fear we’re going, not where we want to be going.  He calls it Mother Nature’s revenge for the industrial revolution: all of our instincts are wrong.  You go where you look and your hands just work it out. (So, by Randy’s own admission, you should still be looking at the apex when you hit the wall.) If you aren’t looking where you want to go, you’ll feed in the power at the wrong time/wrong amount.  It seems intuitive, but if you aren’t going where you want to go, why do you want to go there faster?  Yet you’ll often hear drivers back on the gas in a spin. Look not at what you fear — sound advice.

So how do you alleviate fears?  You can extinct fears by creating new memories. Always be learning, whether that’s attending driver’s schools, seeking coaching or mentorship, or reading.  Randy recommends “Going Faster” by Carl Lopez — the Skippy Bible.  But most importantly is to ask for help “especially if you’re bad…” Randy is a huge fan of the skid pad and getting a stable car set-up.  Remember, under-steer is frustrating; fear is over-steer.  Most importantly, have fun.  Thinking about fun reduces fear.

Talkin’ B-Spec in Charleston

I was in Charleston, South Carolina on business this week (which, I must say is a nice place to be in December when there is a foot of snow on the ground at home.) While there, I stopped by MINI of Charleston which is the home of the Spec B Championship winning MINI of Brad and Robbie Davis. (Brad is the General Manager there and Robbie is his son.) MINI of Charleston will also provide a conversion kit or complete car so you can go Spec B racing. I’ve been having some issues with my rear brakes at the track so I figured who better to ask advice than someone who races MINIs at a top level, so I spoke with Stuart Kestenbaum who was their crew chief this year.

Objects in Mirror Are Losing

Spec B or Touring Class B (TCB) in Pirelli World Challenge speak, is designed as a way for club level racers to get exposure to professional racing, competing in the exact configuration as they do in SCCA Club Racing, but racing on Pirelli 15-inch racing slicks. B Spec cars have preparation limited to shocks, springs and the required safety equipment. The cost of preparing an R56 MINI is under $8,000 and you can order one new built to the spec for about $26K. In racing trim, the car weighs about 2,600 lbs. The B Spec MINI was competitive right out of the box. They run a restrictor plate and only have 90 hp. Their biggest competition is the Honda Fit which has an advantage in lower gearing off of the line. I was interested in seeing the gutted interior and talking about brakes.


TCB MINIs have to run stock brake calipers with Carbotech Competition pads. Spec B rules do not allow brake proportioning valves to be used. I wanted to know if they had any of the problems with excessive heat that I did. During track weekends I might get 2-3 hours of track time on Fridays (compared to less than 2 hours for the rest of the weekend.) During the last few event weekends, I completely burned through a set of pads in the right rear. At first I thought it was only on the unloaded side, but after running in the counter-clockwise direction on the Shenandoah Circuit, I realized it was always the right side. Stuart thinks I might be binding the emergency brake cable somehow and causing light pressure to be applied to the right rear caliper. This would account for the excessive wear and heat I’ve been experiencing lately. They had a similar issue with a previous model car where they also ran a stiffer rear sway-bar. I’ll have to get under the car and check it out. If nothing else, I can put some slack in the cable before my next track session. While talking brakes, I learned some interesting things about their experience in the B Spec MINI. They do not run any brake ducting. They have to use stock calipers and only used one set of rear pads for the entire season. In fact, they only changed the front pads once. I’ll have to try the Carbotech pads next year before I decide to go the route of upgrading to a big brake kit.

I’m not ready to gut the interior of the GeorgeCo MINI just yet, but it was nice to see how they were able to take advantage of the MINI door pockets to push the door bars out and maintain as much space in the cockpit as possible. Their cage was fabricated by Kirk Racing Products. I would like to get more supportive seats into my car, but don’t know how far I want to go down that road. Stock MINI seats have Thorax airbags built in. They don’t offer any additional protection on the track when you run with the windows down, but removing them would have an effect on the overall safety of the car on the street. I guess it brings up the point as to when I’m willing to abandon dual-use and just dedicate it to track use. I can start with a Kirk roll hoop without crossing that line. (The Kirk roll hoop can be made into a full cage later.)

Baltimore Grand Prix

Labor Day weekend brought what is likely to be the last Indycar Baltimore Grand Prix to the streets of Baltimore. For the past 3 years it has been an enjoyable way to spend the last long weekend of the summer season. The city never really embraced the event, however, and didn’t do much to improve the racing surface. Most of the events were marked by brief periods of intense racing followed by tedious caution periods to pick up the pieces. But, it did make for an exciting photo opportunity. Many more photos here.