Project Corvette dominates SCCA Time Trials National Tour at Sebring | Project C5 Corvette Z06

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Update by J.G. Pasterjak to the Chevrolet Corvette Z06 project car
Apr 6, 2022 | Chevrolet, Corvette

Even though our Corvette C5 project is nearing the end of its tenure with us, we’re still throwing it around the track in the name of editorial and science (and, full disclosure, it’s also fun).

As such, we jumped at the chance to compete in the SCCA Time Trials National Tour series when it made a stop at the historic Sebring International Raceway this past weekend. While we’d competed in TT events on the short course in our Corvette before, this would be our first, and likely last chance to compete on the full 3.7-mile course which still had rubber and marbles down from the IMSA 12-hour contest just a couple weekends ago.

We started the weekend by properly heat cycling a set of Goodyear Eagle RS tires, hoping our sticky R-compund rubber would be of some use on a weekend that was expecting at least an 80% chance of rain for both days of competition.

We’ll discuss proper heat cycling at length, and why it’s so important, in a future update, but suffice to say the Goodyears really woke up on the first morning of competition as we laid down the fastest time in the first competition session by more than 6 full seconds.

Unfortunately, while our tires were waking up, our ABS was going to sleep.

During the closing laps of our session, the ABS light came on, the system shut off, and braking effectiveness severely diminished. This condition has happened before, mostly at very bumpy tracks, but a simple power cycle has always cured it.

Not this time.

The fault persisted after a power cycle, so we started digging deeper into the issue. With limited resources at the track, we checked the fault codes through the Corvette’s Driver Information Center and saw codes being thrown for both front wheel speed sensors. Our car had just gotten brand-new SKF XTracker hubs with integrated speed sensors, and while out-of-the-box failures on hubs are not unheard of, we found the diagnosis suspect. Still, we checked all the connections at the hubs, and reset the codes.

The condition persisted, but we took to the track for our next session anyway, mostly as an “if we have to run the rest of the weekend with no ABS, let’s at least see if it’s possible” experiment.

The answer was that we could do it and run at the front of the pack if we had to, but it was a bit sketchy. C5 Corvettes heavily rely on the ABS system for brake biasing, and the “raw” bias is fairly wonky. It’s drivable, but you need a very light foot on that middle pedal.

Once the competition day ended, we took some advice tossed our way by Marc LaCorte on the Corvette Track Enthusiasts Facebook group and cleaned and reseated all of the underhood chassis grounds. To our delight, the light went out and the ABS returned, and stayed functional through three track sprint sessions Sunday morning plus our final track sessions Sunday afternoon.

Now that we’re back in the shop, we’ll go through all the proper testing to see if we can replicate the condition and put a proper fix in place. Without proper elimination of possibilities, we can’t be sure whether tightening the grounds was causal or coincidental to the ABS returning, but we have our fingers crossed that it was simple electrical foolery.

Aside from that, the weekend was stellar. The Goodyear Eagle RS tires would simply come alive and turn into Velcro on about lap 2 and then hang around as long as we needed them, meaning we could throw down a flyer, do a cool-off lap, then throw down another one with ideal tire conditions. The second or fourth lap of every session was always our fastest.

By the end of the weekend, we managed to lower our Day 1 lap time, win all three phases of the competition, and take the overall top time of the event by more than 15 seconds. That’s not a bad way to continue our Corvette’s farewell tour, and a great way to continue the GRM lockout of the SCCA time Trials National Tour series that started the week prior with contributor and tire tester extraordinaire Andy Hollis’s overall win at the Carolina Motorsports Park event.

Here’s our fastest lap of Sebring International raceway, and some play-by-play commentary by the project manager and driver JG Pasterjak:

Sunday’s track was a bit different than Saturday’s, as heavy rains Saturday night washed some of the sticky rubber off of a few corners, but also washed some of the blown sand and grit off others. So it felt like the track might be faster in some sections, but slower in others, making a true strategy tough to calculate on the fly.

Going into this lap, I knew it would likely be my final flyer for the session as I probably didn’t have fuel for another hard one.

I also knew the Camaro was in front of me and I would catch it at some point, so I tried to time my attack so I would go by it either on the front straight if he was taking a cooldown lap or between T1 and T3 if he was on it.

Coming out of 17, I could see that he was into the gas, so I just hoped he saw me and knew I was on it, too.

When I threw it into T1, I could see him moving outside a bit, so I tightened up through the exit of Turn 1 and drove around him and actually went a bit green on my predictive, even though this wasn’t a truly optimal line. Remember what I said about some areas being stickier after the rain?

I stayed fairly good on the predictive until a lousy exit at T5 sent me into deep red territory. So my strategy at that point was to see if I could get a good exit from the T7 hairpin and get green again (or at least close), or I’d abandon the lap and try again in the afternoon session. I was also being a bit tentative on the braking zones, as I never knew when or if the ABS issue would crop up again.

I got my solid exit from T7, so the lap was back on. Watch that delta time dropping starting around the 47-second mark and you’ll see why I still had hope for the lap.

I gave some of it back with more tentative braking into T10 at around 1:02, but a good exit brought it back, and great mid-corner in T13 (1:18) put me green again. Unfortunately, that good entry into Turn 18 made me pinch the exit a bit and I couldn’t reap the true benefits of that entry and mid-corner gain. But at least I had minimized my losses at that point and was at least even.

Still, I was running out of opportunities to improve, so I figured the only shot I had left was to go all-in through Turns 15 through 17 and hope it was one of the spots that the rain cleansing had improved. I stayed flat to the floor through Bishop’s Bend (1:27-1:32), which put me a little offline for braking into T15, but I threw in in there nonetheless (hey, there’s just endless expanses of concrete runway to slide across if I guess wrong) and–all praise to St. Goodyear–the darn thing just stuck. The predictive went hard green around the 1:34 mark, and it was game on.

Hoping T16 was as sticky as the T15 complex, I went in a little hard there as well and managed to keep it on the pavement and enjoy a nice green (but diminishing) predictive down the back straight.

Only needing to successfully negotiate Sebring’s Turn 17 (no problem, right), I summoned the ghost of Terry Earwood, even though he isn’t dead yet, and recalled the sage advice he once gave me about Turn 17: “My daddy built this track, and even I’ve never been through Turn 17 worth a damn.” Cool. Thanks, Terry.

Anyway, somehow I managed to get a decent entry and a strong exit from T17–watch that predictive start to plummet as I go under the bridge at 2:05, and fall even faster as I nearly rub the driver’s side mirror off on the wall at the exit–and finished up with my best time for the weekend.

After that session, the car went on the trailer. The Garmin catalyst was telling me there was another half-second of time out there, and my own knowledge of the mistakes I had made on that lap backed that up, but at that point there were no stakes left except obsessively chasing a few more tenths in the final session of the weekend, and that’s when things can get bad in a hurry. Sometimes you have to be able to enjoy your victories before you ruin them.

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View comments on the GRM forums
GCrites80s Dork
4/5/22 12:16 p.m.

Bumpy 'ol Sebring loosening the grounds

Erikl New Reader
4/5/22 12:45 p.m.

Hmmm love this car.  How much will you be asking for it?

David S. Wallens
David S. Wallens Editorial Director
4/5/22 12:52 p.m.

Sadly my laps around Sebring don't resemble JG's....

CAinCA GRM+ Memberand HalfDork
4/5/22 3:17 p.m.

Nice driving JG! You were hauling ass.

Lof8 - Andy
Lof8 - Andy GRM+ Memberand SuperDork
4/5/22 3:37 p.m.

Very nice!  Congrats!

That car and driver can haul a** around Sebring.

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