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Jesse headed back to Thunderhill Raceway Park with his C5 Corvette

US-based track day enthusiast, Jesse, has been striving to optimise his 1999 C5 Chevrolet Corvette for some time now, applying an extensive list of modifications to the car in the aim of improving lap times.

He recently headed back to one of the venues he frequents regularly – Thunderhill Raceway Park in California – with EBC Brakes Racing’s SR-11™ sintered brake pads installed in his sports car.

You can read how these uprated brake pads performed in his own words below. This is an extract from a more detailed blog post which can be viewed here.

“Going into this track day, I was mostly looking to confirm that my DIY chassis-mounted wing yields an improvement in handling that will hopefully equate to better lap times than the last time I was at the track. The track weekend though was also a present to myself, as it took place the day after my 40th birthday! That said… a few small tasks turned into a bunch of stuff… so much for keeping it simple and just sending it! Overall though, it was a success and I had really positive results from my modifications.”

Modifications, Maintenance & Thoughts Before the Track Day

“Everything seemed to hold up pretty good from the last track day, so there weren’t any critically outstanding issues. There’s a few standard items and then one stretch goal I may or may not get around to.”

Swapped Out Spring Rates

“So, as part of upgrading aero on my car and discussing the handling with a variety of other folks out there, it became apparent I was running too low of a spring rate. I spoke with the folks over at Eaton Motorsports again and they were able to order up some Eibach springs for me in the right size and in spring rates of 700 front, 750 rear. This should upgrade handling overall and help me keep a car with balanced handling to a potential hair of oversteer. We’ll see how I like the car driving with these new spring rates and I’ll report back on it all.”

Testing Out EBC SR-11 Brake pads

“While the Carbotech XP-10 brake pads treated me quite good at the track, lasting nine track days and providing excellent braking characteristics, the new EBC SR-11™ brake pads are currently all the rage for performance AND durability. So, I grabbed a pair to test out. Per EBC recommendations, I scuffed up the current rotors significantly to help remove material from the old pads and to help the new pads bed in quicker. We’ll see how these hold up!”

Added DIY Splitter Ramps to the 9LR Splitter & Confirmed Hardware

“So, you can read all about the DIY splitter ramps over in my 9LR Splitter article, but the short version is after researching various splitter ramp options ranging from $150-200… I decided to just make my own. We’ll see if they hold up at the track. The good news is they’re fairly reasonable to remove, but I’m fairly confident they should be able to do the trick. This should yield a modest bump in downforce on the front of the car, which may help with that bit of understeer I’ve been dealing with. It’s also worth mentioning I took the entire thing off to begin with as it felt a bit loose, but sure enough, it’s all as secure as can be!”

MPI Wheel Bearing Concerns

“I had play going into the previous track day, but decided to risk it. The play didn’t change at all it would seem, but it is enough when moving the wheel there’s a bit of a ‘clunk’. I measured the distance out to be .026″ with a feeler gauge, so that may not be enough to worry about. I let the folks at MPI know I was having this issue and we’re still in communication about it. They understandably can’t see it themselves, so I took the measurement above and sent them a video of the clunking. They got back to me and are sending me two new front wheel bearings and will be taking these two back to take a look at. Hopefully the issue was just a fluke, and if not even more hopeful that they will continue to refine the product to be more robust.”

Improved Airflow Throughout the Car

“So, what started as plan for a few small airflow improvements turned into a whole bunch of small modifications that were quickly adding up to a tonne of notes. I decided to write about all of my C5 Corvette DIY airflow projects in its own article. The short version though is I focused on improving airflow to and through the radiator, along with diverting a little bit extra fresh air up to the cold air intake air filters.”

Tires Swapped Out

“So, back on track Day 20 I picked up a nail through one of my tires that couldn’t really be properly fixed. I got a whole new set of four tires, chucked the one bad tire, and kept the other three around just in case. Well, turns out I needed them as my rear tires were positively roasted after my last track day. They perhaps had one, maybe two track days left in them… but given I had a set of tires around with 2-3 days left in them I figured I’d swap those two in and keep the other two around as spares just in case.”

How The Track Day Actually Went

“With all of the last few details buttoned up and a track full of tonnes of gear, we made the eight-hour drive down to Thunderhill. We stayed in the nearby town of Willows, CA, which has a nice little Airbnb/hotel that is decent enough to stay at.

“Saturday was about the usual scene for a winter track day. Colder temperatures were present along with a constant breeze. Still though, not too bad overall. This particular group was a Shelby club, so it was loaded with a wide variety of mustangs. It was interesting to see how my 25-year-old Corvette stacked up against far newer cars. I’m glad to report back that it held up well, catching all the other Mustangs even with lots of aero in all of the turns. Unfortunately, the straights were the issue. More on that to be written on the post-event write-up.

“One bummer for me going into the track day is that we were running the ‘Cyclone’, which was a bummer simply because I wanted to compare my times this weekend to the previous time here without the wing on the car.

“The refined aero and stiffer springs felt great and were far more confidence inspiring entering high speed turns. In mid-speed turns, the wing still helped a bunch, which combined with my willingness to rotate a car at 80mph being greater than 112mph balanced itself out nicely.

“One big standout was the EBC SR-11 brake pads. They had way better initial bite and feel than the Carbotech XP-10s and held up to heat way better throughout the course of a day. It’s not entirely fair to compare these brake pads as the XP-10s are streetable, and in my opinion the SR-11s are not. Still though, what an improvement in being able to brake far better than ever! With that initial strong bite, I could also heel-toe/side-foot far easier. Overall, a big improvement to the car! I’ll be curious to see how they hold up!

“Engine temperatures were excellent as the DIY cooling mods clearly worked! I never exceeded 243 degrees Fahrenheit all day when previously even with colder weather I’d push well into the high 250s. I also only pushed above 240 after many back-to-back all out laps, where as normal lapping, especially in traffic, stayed at 237. So, I’m pretty confident the engine cooling modifications must all be working, though since I did them all at once I can’t really point to any specific one as being superior to the other.

“On Saturday I put down a best time of 2:06.310. I felt pretty good about that, but knew I was leaving time on the table in a few places. It’s one of those things were small hesitations here or there can cost a good chunk of time. Brake just a few MPH more than necessary from 120 down, give up a tenth of a second. Don’t launch it into turn 3? There goes some time. Overly square up the Cyclone hill? Throw away another tenth.

“Sunday afternoon I really picked up some time on my laps though. I was chasing a far higher horsepower Mustang than mine and gaining on them every lap despite their near 33% higher power. Then, in a subsequent session I put down two back-to-back 2:05 laps, with my best being 2:05.036 per timing the lap from video. 10hz GPS Bluetooth Track Addicts has it at 2:05.307, so right around that time. I’m stoked though as I was able to drop a full second from Saturday. What was interesting was comparing daytime temperatures, wind, and when in my sessions my time dropped. Since Sunday was just a bit hotter and less windy in the AM, track temperatures were up a bit as were car temperatures. I saw a peak oil temperature of 243 degrees, which was a sure-fire indicator I was pushing faster lap times… but I also was starting to slide the car more as the tires got hot. Now normally, I’m told sliding is slow… but for me being able to rotate the car into a lot of the turns definitely helped me pick up time. While in some places it surely lost time as I’d understeer and push a bit wider than intended and have to saw the steering wheel to regain traction, but in other places I could pitch the car sideways a bit early while braking so when I entered the turn I’d already have the car rotated a bit. Not only was that fun, but apparently it was fast!

“Other minor observation from out there at the track day was that leaving turn 11 I was always faster if I stayed in 3rd versus 2nd. While I had way more acceleration out of the turn in 2nd, it was really easy to accidentally step the rear out more than intended, and the time lost making the shift was notable. Every single time I stayed in 3rd and pulled through that section I’d be shifting to 4th right at the exit cone for turn 13. If I grabbed second, I’d always be shifting to 4th afterwards.

“Another place I’d carry a lot more speed was going into turn 1 and just staying in 4th. If I downshifted to 3rd I’d have more drive into turn 2, but I had plenty of drive in 4th and the addition of a shift into that braking zone unsettled the car just that little bit extra and resulted in me shedding extra speed.

“To get a lot of faster I think I need to get better at looking at session data and being able to compare lap times when trying different lines or gear selections. For example I tried two variations of the Cyclone, and in those variations were also gear variation. I settled on a line a friend showed me and staying in 3rd gear as I’d hit turn 6 just as quick… but perhaps that was just a matter of perception, as a tenth of a second isn’t much of a difference at all!”


“In a strange turn of events, my back straight speed was up 4mph on average. I feel confident saying it wasn’t because of my superior line choice either as I’d often be a bit off-line as I’d overcook that last turn. Perhaps it’s the extra aero hold through turns 10-13 meaning I hit the straight with a higher top speed? OR… perhaps it’s because I stopped grabbing 2nd and just went with third. Yeah… it’s probably that.

I can’t really ascertain massive gains here, and this is just looking at a single metric which is peak speed, not peak speed over time which equates to lap times. Some gains can also clearly be related to a change in technique (pulling 3rd vs going to 2nd when going through turn 12). Overall. I can’t say for certain the wing put me way ahead of the previous times, but overall it seems based on a few sample areas I was in general traveling faster with the new aero and brakes… so there’s a probable correlation.”

SR-11™ Race and Endurance Pads

The latest sintered race material from EBC will launch in spring 2022 and promises to eclipse most of today’s organic, semi-metallic, and carbon-based racing brake pads.

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SR-21™ Race and Endurance Pads

A variation of SR-11™ that offers ultra-high friction and is targeted for the front and rear of race cars with bias controls only. SR™ bites harder and lasts longer.

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