Test and Tune - Autocross

[Mike's Competition]

I thought here was a thread about this... Guess not.

You guys missed some good practice. And there were novices at the event.
There was not a lot of testing going on. I expected to see people turning wrenches and getting some of the experts to drive or ride to diagnose things to change. It looked like most people were using it for driving practice and a few new people who who got an intense immersion into racing.

The course was two slaloms, a couple offsets, and ridiculously long, arcing sweeping turns. Big engine RWD cars would have loved it.

I threw on the free tires that came with a set of wheels I bought, and knew they were pretty low for grip from last year's fill in while waiting for tires that were back ordered. Turns out they are actually greasy at room temperature and useful only to simulate gravel and rain driving on dry blacktop.
I messed with damper settings a little. About all I figured out was that I need the race tires to learn anything and tuning with skates was going to teach me nothing.
So I started left-foot-braking. The morning was 11 runs, 6 were LFB, and I ran about the same speed either way (just as slow). The difference seemed to be that with regular driving, the front end would plow in some spots from carrying too much speed, while the LFB would have the car sucked down to the pavement and turning. The reason the LFB runs weren't quicker was messing up by either riding the brake all the time, locking the fronts and sliding directly through the cone wall, or locking everything and spinning before the end of a slalom.
The afternoon was 12 runs. They reversed the course, which caused some anxiety. I tried a couple runs with the front dampers turned way up too high, just to see what bad would feel like. Then set it back where it was for the morning, and ran as many runs as possible to practice LFB. The anxiety was that the finish was at the end of the long, sweeping turn. A 1/16 mile, increasing radius turn, then a sharp right angle turn in front of the fence, into the finish lights. And I started noticing high brake temperatures. 500 degrees on the rotors and 275 degrees on the brake caliper. The rotors were a nice shade of blue. I was terrified that if I carried too much speed while riding the brakes around that long turn, I would mash the brake down to make the sharp kink at the end, and discover that the pads had turned to liquid while I spun through the fence and into the pitted cars from the other run group. So I chickened out and backed off at the finish on each run.

I did a little looking on the internet, and it looks like 1000 degrees for the rotor is common for highway speed panic stops, and the chart for the pad shows it going all the way up to 1300 on the Wilwood website. Scary numbers. I guess the only concern is that the conventional fluid I am using boils at 480 degrees.

 

[mmarshall]

Bill it sounds like you got to try some new techniques. I woke up to rain in the AM and decided I did not feel like chancing being rained out. Plus you would have constantly flashed your wipers at me!

Keith's car is down for a while with tranny problems which is why he did not make it.

I think I am using the left foot brake a little differently. Outside of normal braking zones, I use LFB to quickly check speed or settle the car. I never try to ride the brake as it will overheat the brakes. I do come in with the brakes before fully lifting off the gas and often start to add throttle before I am completely off the brakes. I do often run so deep into the braking zone that I don't think it will ever slow enough. At those times I can only imagine what my passengers are thinking.

Sounds like everyone had fun and maybe learned something. See you at the next event.

 

[Mike's Competition]

It drizzled during setup, but no rain. That was pretty funny with the wipers at Event 8.

The left foot braking thing seems to have a couple different uses.
Mahen, who runs the A-Mod wing car with the big Hurst written across the wing, talks about always applying a little bit of brake almost as if it were adding down force. It makes sense, if acceleration loads the weight on the rear tires, and deceleration loads the weight on the front, then doing both at the same time should load both ends at once.
O'Neil, the guy running the New England rally school, talks about reducing understeer and inducing oversteer. This sort of sounds like the idea of throttle steer and brake steer at the same time, and applying both at the same time, adding more or less of each to balance the cornering trajectory. This is the thing that really appeals to me.
And a lot of people talk about eliminating the dead time between braking and accelerating, when the right foot is between pedals. So this would allow braking later and getting on the throttle immediately.

For the offsets and the box which was really the same as another offset, I could hold the acceleration longer and stab the brake hard to slow just before turning.
The slaloms had sharp turns at the ends. Seems like they always do. More of the same, holding the speed and the gas pedal, then stabbing and turning, but also the ability to kick the tail out by overlapping the brake and gas, get the car turned, and hold the line tighter on the exit by adding more brake mid turn and on exit.
And with the big sweepers, the McKamey/Evo Phase 1 has the roundabout to teach you to slow down and hold a tighter line, which is quicker than jamming the gas pedal down and sliding all over the place in a wider arcing turn. But, being able to apply the brakes and gas at the same time, I could use the brakes to pull the car in tighter on the apex cones, while holding the gas pedal down to actually accelerate through the sweeper.
It's supposed to be good for slaloms to, but I think all I managed was a couple spins, but they were truly impressive spins... If done correctly, I imagine it would be something like flinging the back end of the car to the outside of the cone while holding the front so that the inside tire barely clears the cone.

 

[Mike's Competition]

I only had enough material to do complete sets of titanium shims for my front calipers. The smaller rear shim I have only two of (need four). The other two have to wait for the next batch, if there is space. Tomorrow I'll do the fronts and bleed them to see if the fluid did actually boil.
Hope I remember what I learned a month ago for Sunday.