2013 San Diego National Tour / Test & Tune

An SCCA National Tour is a big event, lots of people from all over come out, usually on fresh tires and stuff, bringing their best to see how they stack up against some of the competition they’re likely to see at the National Championships later that year.

Tours are a 2-day events, 3 runs per day.  Not a place to get some extra runs in for practice.  Generally not the best place to debut a car.

So of course, that’s what I did.  They kindly have a sort of test-and-tune the Friday before, but I didn’t make that either, working on the car up until 4pm or so that Friday.

Thankfully, it held together.

At least, mostly…will get to that later….

First things last – results were terrible.  Myself and the car were extremely slow…much slower than I thought.  Averaged about 5 seconds per day off the pace.

When I first built the 240sx for STS, ran it once stock, with just some used Falkens (then an ok tire) and was about 4 seconds off the pace.  Granted, the 240sx was a rather well-balanced and neutral car from the factory, whereas the Camaro is awful, but in this case, I am an extra second back, and the car already has everything done to it!

There are a few explanations (excuses, perhaps) that might help make the outlook appear less awful than it otherwise might-

• The car really only had about 20 miles on it going into the event.  The engine had been broken in on the dyno but everything else – rear end, transmission, steering, brakes – were all either rebuilt or new.  This had me being a little more conservative than otherwise.
• The car was too loud for SD so sound meter shenanigan-erry impacted the times somewhat.
• I am on a previous-generation tire, the Yokohama AD08, the competition was on Dunlop Z2.  Not sure how much difference that makes, possibly only a tenth or two, possibly more.
• I have not driven competitively on street tires in a long long time.  Last year at the El Toro ProSolo I ran Michael Heinitz’s car on street tires, and ended up running about a second off his times (on a shorter ProSolo course) – which means I was probably giving up 1.5-2 seconds just not driving well (more on that later too).  I take a while to adapt to a car and get fast in it.  Took me 3 years in the Viper!
• The initial setup was way off (let’s get to that now!)

Almost every picture I’ve EVER seen of a first gen Camaro going around a corner, the outside front tire is unhappy at terminal roll.   Remember these?

I wasn’t going to let that be me!

Taking it further, people think “wheel perpendicular to the surface” is an ideal, but in my experience it’s not, especially with street tires, due to carcass (and even wheel) deformation under load.  So I gave the car a lot of negative camber up front – minus six degrees.  Now, the tables were turned, and instead of me thinking everybody has too little negative camber, now everybody approached me to remark on how much negative camber I had.  They couldn’t believe minus 6!

Another thing I’ve heard, is the cars always understeer.  This makes sense too, because of how bad the geometry is, and how people tend to run so little front tire.  Easy to fit a lot of rear tire, and while a leaf sprung live axle isn’t winning any engineering awards these days (or even in the 60’s), at least it doesn’t put the outside tire on its outer sidewall in a corner.  Guys have to sell their souls to make the cars turn.

Not gonna let that be me!

Car got relatively stiff rear springs, and I’d set initial position of the watts link center pivot rather high.   The pivot point determines the rear roll center, and having a high rear roll center means the linkages are taking a lot of the roll moment instead of the springs, which makes it roll less, and shifts the balance towards oversteer.

So, the good news is, I was able to put together a first-gen Camaro that doesn’t understeer!  🙂  The bad news is it was extremely “loose” as we say, wanting to kill me with just about every (admittedly not as smooth as they could be) steering input.

It didn’t really occur to me while running, how loose the car was.  It wasn’t until I saw my in-car video on Saturday that it became clear how bad it was.  Between days I softened the rear shocks considerably (which were set where they were when shipped – full stiff on all 4 settings) – taking them from basically 30/30 to 3/30 on each of the adjustments.  The reduced axle control did produce some axle tramp on Sunday so I’ll have to get some of it put back in, especially for the ProSolo launch.

Below is a link to a Sunday run video – the file is rather large, but I don’t feel like giving Youtube the rights to it, so you’ll have to download from me (~183MB):

Video: Jason Rhoades STX Camaro sdTourDay2Run2

The quality isn’t bad, but not perfect either – the camera is mounted to the passenger seat which shakes a little – ran the video through some stabilization software that makes it less dizzying, but also makes the video appear a bit foggy IMO.  Will work on better securing that seat.

Very happy with camera position though.  I feel it is extremely important to be able to see the driver’s input in a car video, and this spot picks up not just wheel (most crucial) but also pedals, which is neat.  If the camera had been in one of the traditionally useless places like on the roof or the hood, it would be much less obvious from the video, how loose the car was.

All this said, a good pile of excuses that adds up to three, maybe four seconds.  Finding that fifth second is going to take some kind of real breakthrough, hope I can find it at some point.

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Continuing the story of the weekend, the car made it through Saturday fine.  Jonathan Lugod brought a serious big nylock nut after first or second runs that day, saying someone thinks this fell off your car while on course – it didn’t occur to me at the time but it did later, I had dropped that nut inside the front crossmember while fastening the rear bolts for the front lower control arms.  I fell into an impossible chasm there (at which point I just went and got another one), and the motions of autocross must have worked it loose!

Saturday night I didn’t disconnect the battery, and something in the system drained it down to 11 volts.  This was bad, was barely able to get it started, then kept it running through first two runs Sunday.

Coming in from my second run, discovered the passenger side header bolts had worked their way loose.  Apparently this is a common problem with new header installs.  I have some fancy “Stage 8” fasteners on there with locking tabs that keep the bolts from rotating, but unfortunately hadn’t had a chance to put the tabs in yet, so they were all quite loose.  Shut the car off to tighten them…and then couldn’t get it restarted.  Some of that is heat soak – especially with headers, these cars are notoriously hard to start once the starter solenoid gets hot.  It was really disappointing, as I was starting to get a feel for the car, loose as it was (download the video above if you haven’t already).

This is where I start thanking a long list of folks – several tried to help get it bump-started – Jeff Cawthorne, Steve O’Blenes, Charlie Davis, and probably a few others I didn’t see.  It was fruitless, so Charlie let me run his BMW (huge thanks Charlie!!) as his co-driver Bryan Heitkotter couldn’t make it today.

Hadn’t driven an STX 325 before, and this was a huge opportunity – to experience the car that the leader from day 1 was in, the same car that won Nationals the year before, and was my main competition.  It was also a lot of fun!  The car was very well balanced, power was “okay”, overall it didn’t have any faults.  Made me realize even more, how badly the Camaro had been trying to kill me with ridiculous oversteer…

Dropped almost three seconds with that one run in Charlie’s car.  Still 1.5 seconds back from the day’s (and overall) leader Jeff Stuart’s time…which shows again how much I am leaving on the table as a driver at this point.  Jeff was a ways back from Bryan on day 1 but felt day 2 would have been much closer.

After the run group finished several people helped me work on diagnosing an ignition issue that seemed to develop somewhere that day – this just goes to show you how awesome and helpful the SCCA autocross community is!

• KJ Christopher, who lent me electrical tools and wires, not to mention many electrons charging up the car’s battery, and my now-depleted jump pack
• Eric Clements, who help the voltmeter on some potentially zappy things while I turned the engine over in troubleshooting
• Fred and his wife Alexandra Zust, who helped me push and ratchet the very heavy car up into the trailer on a warm day.  Also to the other fellow helping whose name I didn’t catch.

Thanks to all of you, you guys all rock!!

Have a lot of planned changes in mind to implement for next weekend, the El Toro ProSolo.  The increased grip provided by the surface there should make the car tend towards understeer a touch, but I’ll be lowering the rear roll center and increasing front swaybar stiffness anyway.  Need to put some more rear shock damping in to tame the axle tramp, which you can hear in a couple places in the video.

Last thought here is just on how much fun this thing is to drive.  It is going to teach me throttle (and brake!) control like I haven’t needed since running Gary Thomason’s SM2 Corvette in 2005.  There are some similarities – obviously this is a lot less powerful, but the power:grip ratios feel somewhat similar in that overaggressive application of throttle (the sort of move that would be perfectly fine in any other ST category car) zings the back tires in a way that makes you think you’re either out of gear or have a badly slipping clutch.  If we ever get a good ProSolo launch surface the thing will be an ANIMAL!  🙂