2011 NCAC

Gwen Habenicht · **Posted:** Wed Oct 05, 2011 10:43 am

JamesShort wrote:

DickRasmussen wrote:

When I started autocrossing in the San Francisco area in the 70's this style of course was the California "norm". Small sites would do multiple laps. Corvette clubs had a big influence on the minimum course widths, etc. so the courses were always open. SF Region of SCCA had a LOT of influence on the National rules to help make sure that Nationals courses stayed relatively open also. We called this style of course design "miniature road race". Lines were used even on small sites so that course following was not difficult. For some clubs the lines were the official course boundaries and cones were to help us find the lines, apexes, etc. Cones were 1 second for the non SCCA clubs and 2 seconds per National rules for SCCA.

The "problem" with this type of course is that nothing else is ever as much fun for many of us. :lol:

Honestly, I prefer a course with a little more transition compared to the pure sweeping action of these mini road courses.

I've been reticent to speak up since, in the big scheme of things, I'm fairly new to the "Nationals scene" with only 2 years of events under my belt. That being said, as much fun as the NCAC courses at Zmax were, they weren't really what I've found to be the norm of "Nat style" courses. Most National event courses are more technical with more transitions and, from my point of view, don't look like little road courses. What makes Zmax a hoot are the elevation and camber changes. Also, the fact that our club's sites don't afford the opportunity to learn how to negotiate large sweepers (Which you WILL see at National events) makes going to sites like Zmax important for driver improvement.

Gwennie (who drove pretty well on Saturday and sucked on Sunday) Baake

DickRasmussen · **Posted:** Wed Oct 05, 2011 11:33 am

Having not been to the zmax event I didn't realize it didn't have transitions. Most SF and "Nationals" style courses I've run do have transitions . . . frequently many. In fact that is why CM cars have moved to stiffer springs than in the past. No time to "wait" for the springs to compress/extend.

BriceJohnson · **Joined:** Thu Apr 13, 2006 7:33 am **Posts:** 2230

The more I see the course and videos, the more pissed I am that I couldn't make it. As far as H-stock cars go, the big advantage Mini's have over my car is transitional ability. I on the other hand get more tire (if I had the $ to spring for the 245's up front), and better power to weight. :banghead:

Kevin Allen · **Joined:** Thu Aug 28, 2003 6:42 pm **Posts:** 3479

JamesShort wrote:

Honestly, I prefer a course with a little more transition compared to the pure sweeping action of these mini road courses.

I don't like sweepers very much, either. If I had a hydraulic handbrake and 500hp, I probably would. Long sweepers are like straights for me - just something you have to endure so that you can get to the next fun part.

So does anybody have a definite answer for why that surface is so understeery and what to do about it? It's exactly the same as the Greenville auto auction site for me. I can't fly into the turns, lift or pull the handbrake and get it to turn, then fly out with the tires spinning/countersteering. I also can't get it to predicably oversteer with throttle if I slow down to the max grip level of the front tires, turn in and gas it - sometimes understeer, sometimes rotation (rarely that). What makes it so different from Danville/Sanford/NCCAR/etc. and how do you fix that? I actually felt like I had more front grip in the rain at NCCAR than at zmax.

Keith Vail · **Posted:** Wed Oct 05, 2011 12:47 pm

I can mirror Gwen's statement as well. Most National events I have been to have many transitional elements. The only thing I could call a transition this weekend was the offset slalom on Saturday. On Sunday they broke it into 2 small in and outs with a big offset in the middle. Other than that it was all sweeping corners.

At Nationals itself you normally end up with one course that is transition intensive and one that is more sweeper intensive. I think this year really magnified that with one course that I referred to as the slalom fetish.

Jason Mauldin · **Posted:** Wed Oct 05, 2011 1:00 pm

Kevin Allen wrote:

So does anybody have a definite answer for why that surface is so understeery and what to do about it? It's exactly the same as the Greenville auto auction site for me. I can't fly into the turns, lift or pull the handbrake and get it to turn, then fly out with the tires spinning/countersteering. I also can't get it to predicably oversteer with throttle if I slow down to the max grip level of the front tires, turn in and gas it - sometimes understeer, sometimes rotation (rarely that). What makes it so different from Danville/Sanford/NCCAR/etc. and how do you fix that? I actually felt like I had more front grip in the rain at NCCAR than at zmax.

It's been a long time since I went to Greenville, but that site was a perfect example of slow down to go faster. Something about the surface seemed to make the car skip right past the limits into understeer very easily, but if you approached the limits slowly, there was a significant amount of grip.

I don't know what makes it different, but being particularly smooth with the inputs seems to be the answer.

DickRasmussen · **Posted:** Wed Oct 05, 2011 3:29 pm

Kevin Allen wrote:

I don't like sweepers very much, either. If I had a hydraulic handbrake and 500hp, I probably would. Long sweepers are like straights for me - just something you have to endure so that you can get to the next fun part.

So does anybody have a definite answer for why that surface is so understeery and what to do about it? It's exactly the same as the Greenville auto auction site for me. I can't fly into the turns, lift or pull the handbrake and get it to turn, then fly out with the tires spinning/countersteering. I also can't get it to predicably oversteer with throttle if I slow down to the max grip level of the front tires, turn in and gas it - sometimes understeer, sometimes rotation (rarely that). What makes it so different from Danville/Sanford/NCCAR/etc. and how do you fix that? I actually felt like I had more front grip in the rain at NCCAR than at zmax.

Kevin,

The 500 HP comment is funny. I learned to love sweepers with my first autocross car . . . a 160 HP 1974 Datsun Z with an open diff. A mid second gear course would allow just enough "tail out and inside wheelspin" to have a great time in a lot about the size of Greenville. My CM car has the best power to weight ratio I've ever driven (about 10 lb per hp).

Was it mostly awd and fwd cars that had problems with understeer at Zmax? Is the problem lack of total grip or too much rear grip (maybe due to lack of transitions to help "get the car to rotate with steering/throttle lift")?

I never really had an understeer problem at Greenville with either Miles Beam's C4 Vette on Kumhos, my 01 Mustang on street tires, or my CM car on slicks . . . even in the first gear corners. I suspect your problem may be the inherent understeer of your car.

FYI I HATE understeer so it isn't that I can tolerate it :lol:

Maybe that is just another reason that I've avoided awd or fwd autox cars for so long.

DickRasmussen · **Posted:** Wed Oct 05, 2011 3:34 pm

FYI for you folks who have to deal with understeer in certain types of corners. CM cars have that problem in some situations also. One technique that I learned many years ago from a Corvette guy but I understand that even F1 drivers like Michael S use in 180"s is to "diamond" the corner. In very general terms it means "early apex" the entry, steer "HARD and FAST" at mid corner to rotate the car, and unwind the steering FAST to prevent push and to settle it back on the inside tires. Can work very well at autocross speeds for mortals.

Edit to add:

Relatively early apex in, late apex out.

Avoid looooong "last forever" constant steering angle. My Z would "naturally" use its trailing throttle "positive rear wheel camber" to transition to oversteer as I trail braked into the corner and then get rear grip by applying power to go back to "less positive camber in the rear". Front tires were always positive camber.

Vincent Keene · **Posted:** Wed Oct 05, 2011 4:01 pm

DickRasmussen wrote:

I suspect your problem may be the inherent understeer of your car.

Winner. Imagine an 300HP AWD dump truck and you'll get the image of understeer in an STi. That is unless you can yank the e-brake.

Kevin Allen · **Joined:** Thu Aug 28, 2003 6:42 pm **Posts:** 3479

Quote:

FYI for you folks who have to deal with understeer in certain types of corners. CM cars have that problem in some situations also. One technique that I learned many years ago from a Corvette guy but I understand that even F1 drivers like Michael S use in 180"s is to "diamond" the corner. In very general terms it means "early apex" the entry, steer "HARD and FAST" at mid corner to rotate the car, and unwind the steering FAST to prevent push and to settle it back on the inside tires. Can work very well at autocross speeds for mortals.

I do that a lot of the time when I'm going for fast times, and not just drifting everything. I was trying that at zmax, but it really killed momentum.

And what Vincent said - if it's just a long, steady turn, and I haven't rotated it already and am doing some countersteering, it's understeering. Supposedly you can fix it by spending a lot of money on the suspension.

JamesShort · **Posted:** Wed Oct 05, 2011 4:34 pm

Rear bar time Kevin

.

Keith Vail · **Posted:** Wed Oct 05, 2011 4:43 pm

DickRasmussen wrote:

Was it mostly awd and fwd cars that had problems with understeer at Zmax? Is the problem lack of total grip or too much rear grip (maybe due to lack of transitions to help "get the car to rotate with steering/throttle lift")?

I can't speak for FWD or AWD but we had some issue with the CS RX8. It was pushy at first so we upped the rear tire pressures a couple psi so they were the same front to rear and it felt better but was still a touch pushy for my taste. I just drove around it, but for all I know the car is always like that as I had never driven it before. Plus we were on old tires that gave up the ghost on my final run of the weekend so that might have contributed to the balance as well.

Either way you just have to learn quickly that the site is low grip and you adjust your driving style to match that.

Steven Carter · **Posted:** Wed Oct 05, 2011 4:57 pm

Keith Vail wrote:

Either way you just have to learn quickly that the site is low grip and you adjust your driving style to match that.

A point that was aptly proven by the over-driven Cobalt SS in the first run group. I enjoyed the sweepers as it gave me a fair amount of time to figure out when the right slip angle was exceeded as well as what real understeer feels like..eg, entering the uphill sweeper on Day 2 too fast and sensing that nice juddery feeling in the wheel.

I also find that some alignment tweaks and changes in rear pressure help with understeer. The best tip, however, is to commit to turning before you think you need to, knowing the car will "get it" in time to be tight on the cones.

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