Tag Archives: RX7

That’s Racing

You can test all you want, but that’s no guarantee that the car won’t break as soon as you start a race weekend.

That was the lesson I took away from last week. We went testing on Monday with CFRA, who had a rare 105 decibel day at Laguna Seca. At the race weekend at Laguna a few weeks prior, we had had a lot of setup and balance problems with the car, with lots of understeer and trouble getting traction off the corners. So we dedicated the CFRA day to putting a lot of laps on the car, and making sure the brakes were working and the balance of the car was feeling right.

photo 1

We got a pit garage and shared it with Shan, who was feeling better driving the Miata after she’d had the wheels balanced. Phil changed anti-roll bar settings, ride height, rear springs, and rear wing angle, and we eventually wound up with a setup that felt like a good compromise between understeer in turns 3 and 4 and oversteer coming out of the corkscrew and turn 11. The car was reliable all day long and we booked a lot of laps.

I should have known the following race weekend was cursed from the very start. I picked up the trailer Friday night and trucked up to Willows. It was when filling up with gas in Williams that I realized that I had left the keys to the trailer on the bumper of the truck, and of course the keys had fallen off many miles ago. I talked to Phil and we resolved to get some bolt cutters from Walmart in the morning.

Saturday morning rolls around, and of course Walmart is out of bolt cutters. And the bolt cutter Phil got from a random hardware store isn’t up to the job of cutting off the locks. Luckily we were able to borrow Tom Wickersham’s angle grinder and Phil cut the locks of literally minutes before first practice started.

photo 5

We just barely got out on track for practice, and we didn’t have enough time to put enough air in the tires. The car was sliding like it was ice on the cold under-inflated tires, but things were about to get a lot worse. Three laps in, the car suddenly veered right while turning into turn 6. I took a long detour through the grass. I thought I had a puncture on the front-right because the car drove very strangely on the way to the pits, having a lot of difficulty in left-hand corners.

When we got it up on jacks, Phil found that the front subframe had actually cracked a weld where it connected to the lower A-arm on the suspension. The car that had been fine for dozens of laps on Monday had a broken subframe on Saturday.

Amazingly, Phil was able to get it back into place and welded up at MCE racing for a mere $40. Even the alignment felt right afterwards. Great work Phil!

We also found that the rear tires were corded, which might have explained some of the lack of grip. So we swapped on a new set of Hoosier R6 tires, which were DOT legal unlike the R100 racing slicks we normally use. There was only three cars in V8 SS that weekend, so we switched classes to the ITE class that had five cars, but that necessitated running DOT tires.

IMG_3346

With the car welded back together and fresh tires on for qualifying, we went out to break in the tires and set a lap time. Immediately the car felt great on the R6 rubber. DOT tires have a much wider temperature range where they have grip, as opposed to the more binary grip of racing slicks. With slicks, you either have no grip or tons of grip, and they are utterly silent and sudden when they lose traction. DOT tires, on the other hand, act a little more like street tires. They have less ultimate grip, but they slide progressively and make noise when they do so. This makes them much easier to drive on the limit than a racing slick.

A few warm-up laps into qualifying, and I had a nasty surprise in the form of a black-and-orange “meatball” flag being waved at me. I came into the hot pits, and they said the car was 3 decibels over the 103 decibel sound limit! This was the same exhaust system we had run at the 105 decibel Laguna day earlier in the week, and it sounded subjectively quieter than the original exhaust system that clocked just 95 decibel! So I drove into the pits, where Phil was ready with an exhaust “elbow” that directs the sound away from the sound meter. Despite the heat of the exhaust system Phil was able to install the elbow in seconds.

I drove back to the track with just a couple minutes left in qualifying to set a lap. This meant that I would have one lap to get the tires warm, and one flying lap to set a time, so the flying lap had to count. These kind of high-pressure situations can be incredibly fun and challenging for a driver, and you feel a bit like a F1 driver when you have just one lap to get the job done.

I set a 1:51.7 time on my one flying lap, good enough for third overall on the grid behind Darrell and Frank Emmett. This was about 2 seconds slower than my best time at Thunderhill, but we were expecting the R6 tires to be 1-2 seconds slower than the R100 slicks.

Screen Shot 2013-05-31 at 11.02.04 PM

The first race was later that afternoon, and I was starting behind Darrell and Frank and ahead of Rob Davis and Michelle Nagai.

Coming up to the starter stand on the race start, I couldn’t see the starter at all over the looming Mustang of Darrell. So I went when everyone else started to go, and then I ran into the rev limiter at the top of second gear. Rob Davis and Michelle went flying by me into turn 1, and I was in fifth.

After a couple laps, I started catching Rob, whose “Lightning McQueen” Camaro is usually faster than me on the straights. But he was a bit off the pace this weekend, and I passed him on the inside of turn 10.

Screen Shot 2013-05-31 at 11.06.19 PM

After that I started lining up Michelle, who had a great start and was setting some really nice lap times. She was clearly the class of the stock car field, even though she was having her own mechanical issues that day.

We had a good dice, and unlike at Laguna I was able to get around her this time. I passed her on the outside of the same corner that I’d gone by Rob, turn 10.

Screen Shot 2013-05-31 at 11.07.00 PM

I could see Frank Emmett a ways up the road, which was a bit strange as his car is normally 3-4 seconds a lap faster than anything else in our field. Apparently this weekend he was having clutch trouble, slowing him down considerably. I caught him on the front straight, and passed him on the inside of turn 1.

The car was feeling nice and balanced, and so far the race was going pretty well. I was running second overall and I could see Darrell a ways up the road. I had started to gain on him, when coming out of turn 2 I heard a “pop” from the rear, and lost all drive. My race was over.

I pulled off onto the bypass around turn 5, and watched the rest of the race as a spectator. It was a great view from up there, as you could see most of turns 6, 7, 8, 11, 12, and 14/15.

DCIM107GOPRO

When we got the car back to the pits after the race, we found that that right axle had seized up and stripped all the teeth on the axle shaft. The axle was custom, with inner teeth set up for Porsche gears and outer teeth compatible with the Mazda RX7 hubs, so the hopes of getting a replacement on a weekend in Willows CA were basically zilch. Our weekend was over.

photo 2

Just before the race, Shannon and James had taped some dollar bills to “Candy” the RX7, and I guess the car decided that if she was going to be treated like a stripper, she’d live up to the name and strip the teeth on her axle.

photo 4

With WWDC looming I’ll likely miss the next race at Laguna Seca, and we probably won’t get axles in time anyways. So next race will be 4th of July weekend at Sears Point in Sonoma. Should be good ol’ American fun!

Here’s the video of the race:

SCCA races 1 and 2, Thunderhill March 23rd and 24th

First post on the new blog, hopefully this works!

Last weekend was the first race of the SF region SCCA calendar, and my first race in the 1993 RX7 I bought last year and have been prepping for racing. I have entered it into the American V8 Supercar class of SCCA, which is a class of cars with V8 power and 6:1 weight to power ratio. This is what the car currently has:

– Chevy LS2 block and LS3 heads, 460whp / 420wtq

– Tremec T56 Magnum gearbox, Ford Cobra IRS 8.8″ differential w/3.73 gearing

– JRZ 3-way adjustable dampers, 900lb-in springs front, 700lb-in springs rear

– CCW wheels 18″ x 12″ with Hoosier 305/18 R100 endurance racing tires (spec tire for class)

– Brembo GT 4-piston front brakes, Wilwood 4-piston rear brakes, Cobalt XR1 pads

– 2775lbs w/220lbs driver

Image

We went up to test on Thurs March 21st to shake down the car and tweak the setup. This was also a day where no times would be posted publicly, so we wouldn’t show our whole hand in terms of lap times.

Much of the day was spent messing around with the Race Technology Dash2 and DL1 that came with the car. I had to break out an ancient Thinkpad with WinXP to run the Race Technology software, and it was a pain trying to get the dash configured properly. At one point I had the RPM scale set wrong, and revs were reading 2X higher than they should have been. At the same time the car had a flaky ignition switch and made a loud BANG and the engine cut out, and I thought I had overrevved and blew up the engine. But some reconfiguring of the dash and replacing the ignition switch got everything sorted.

The car felt good in testing, and we were running old rubber that the car came with with ~15 heat cycles on it. The fastest time I set in testing that day was 1:50.2, but I could tell the tires were starting to lose their edge. The car had understeer through turn 3, and oversteer trying to get the power down coming out of turn 5.

Practice/qualifying day came on Friday, and we kept the old tires on the car because we wanted to see what our competition could do before we went to fresh rubber. There were 7 cars entered in the class last weekend, but our main competition was Darrell Anderson, the founder of the class. Darrell runs a 2004 Mustang with a Chevy LS7 engine putting out between 600 and 800whp (depending on who you ask). But its not the power that we’re lacking compared to Darrell (all competitors are supposed to be 6:1 lbs:hp), but rather the downforce. Our splitter is a little piece of alumilite that doesn’t do much, and as a result we have to run the rear wing virtually flat so as not to upset the aero balance of the car. Darrell, on the other hand, has a huge front splitter with dive planes and as a result can crank in lots of rear wing (as you can see in the below picture).

Image

In qualifying, I got a clear lap and ended up setting a 1:51.5. Darrell set a 1:50.5. Connie Bogan was starting third in her Viper Competition Coupe with a 1:54.

Saturday came and the our race was first at 8:30AM. Apparently Darrell had a problem in qualifying that led to his lap time being invalidated, so he would be starting from the back of the 7-car field. So that put me on the pole. In my year and a half of racing Spec Miata, I had never started a race on the pole so this was a new experience, but leading the field around behind the pace car was simple enough.

I got a good start to the race and put myself out of the reach of Connie, and focused on lap time so as to put as much time between myself and Darrell as possible. The track was really slippery so I struggled to get the tires up to temperature. After a few laps Darrell had dispatched the cars between us, and started pressuring me from behind.

On lap 7 I got held up behind a slower Mustang in Turn 12, and Darrell took the opportunity to pass on the inside coming into Turn 14. It was a clean pass and I set about trying to stick with him.

About a lap later, however, a lapped 350Z almost rolled right in front of me in Turn 5. He got spooked by me in his mirrors and braked too late going into the Crow’s Nest. His car went shooting off the backside of the hill and he tried to still make the turn, nearly resulting in a roll. His car then slid back on the track and nearly took me out.

Image

This lost me some time to Darrell, but a new problem was just rearing its head: brake fade. I started losing more and more braking power, and on the 9th lap the brake pedal went all the way to the floor going into turn 14. I couldn’t get the car slowed down enough, and went into the grass between T14 and T15. I came back on track and proceeded more slowly into Turn 1. After a couple laps I learned that the brakes came back if I pumped them on the straights, but I couldn’t maintain the pace I had before. I finished the race in second, 5 seconds behind Darrell who ended up having a fuel pressure issue towards the end of the race.

Before qualifying later in the day, we fitted fresh Hoosier tires as the previous tires were pretty much done. I didn’t get a single clear lap in qualifying, but I could tell the car was faster through the corners. I qualified second with a 1:51.2, and Darrell had the pole with a smoking 1:49.4. SCCA let him keep his time so I suppose he solved whatever compliance problem the car had in first qualifying.

The race started uneventfully, Darrell got a good start and I slotted in behind him into Turn1. The next few laps we were pretty much glued together, and I was a bit surprised that I could keep up with him. He definitely could get on the gas earlier in high speed corners thanks to the aero, but I found I could catch him on the brakes and in the slower sections of the track that are more about mechanical grip than aero grip. He started making little mistakes here and there, and I decided I was going to press him until he made a bigger mistake and I could get a run on him.

After 6 or 7 laps, my braking issues started to rear their head again, and I was having trouble keeping the pedal firm on an entire lap. I was tapping the brakes with my left foot on all the straights to keep the fluid pressure up, but the brakes were getting worse and worse.

Around lap 10 however, a bigger problem cropped up: I started losing power. The engine started missing, then my gauges started conking out. Turns out the alternator seized up sometime during the race, and the car was running on battery alone. The car died, and I coasted into the pits with no power, my race done.

In the race, Darrell set a fast lap of 1:49.7, and my fastest lap was 1:49.8. I feel like we can catch him if we work on the durability of the brakes. We used thermal paint to get an idea of brake temps, and the rears were too hot while the fronts were too cold. Also, the fluid was coming out of the rears was black, so we were boiling fluid back there. We’re going to adjust the balance on the master cylinders and see if that helps.

Next race is April 12-14th at Laguna Seca. Laguna is hard on a car’s brakes (especially when you’re doing 140MPH into turn 2), so we might add some ducting as well.

Videos of the two races are here: