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In total the car ran 9 sessions that day, and it was a bit hectic with a LOT of traffic putting in wildly differing lap times in even the yellow and red groups. At least they were gridding us by lap times, so I was usually P1 or P2 in our group. Amy and I agreed that I would skip a session, give Amy the car two sessions in a row, and then I'd go out after she skipped her last session.

This way the brakes might be cool enough for me to make ONE hot lap. I knew the two previous 2:02.7 best laps were slower than the car had in it, but the track surface was getting warmer so I doubted I would find much time. But with a cooled off car, a slow out lap (you can see I'm just talking to the camera and keeping the C6 ahead in sight in my video below), and a focus on getting my FIRST hot lap in clean... I managed this.

In-car video of my final session, first hot lap was a 2:00.619
That was a pretty decent lap, if I say so myself. I've driven a LOT of cars out here in the past 10 years but never have I run a 2:00 flat lap in anything with street tires. It took every amount of restraint I had to not "over brake" any one turn on that one hot lap - and the brakes were getting worse in every major braking zone - but it was just enough.


Eight of the top 10 cars were Z06, Grand Sports, or other Corvettes with lots of mods. KenO's E46 M3 TT3 race car with aero on Hoosier A7s took FTD and our piggy Mustang with no brakes managed 6th overall and "won our class". Don't ask about classing here, its something based on autocross classes and PAX factors that will make your head spin. We were 4 seconds ahead of the next Mustang, another S550 on RE71Rs. I was happy with that, considering how marginal the brakes were. I look forward to coming back here with better brakes to see if we can dip under a 2:00 lap on street tires.
FIRST S197/S550 TECH TIP BRAKE VIDEO
This first video explains our experiences with the S197 4 piston Brembos and then our frustrating experiences with the 14" S550 base GT brakes.

The video above is the first in a series of videos about these brakes we made and we feel it is worth watching.
SCCA AUTOCROSS EVENT # 2, LONE STAR PARK, MARCH 25, 2018
So while I missed the March 4th autocross with our local SCCA region due to a drivers license debacle, I was excited to finally autocross the car - and this time on real suspension, wheels and tires. Jon had made us some magnetic door cards for STP/W and CAM-C classes. We had another race car in our trailer but this is a street car, right? So we decided to drive the car to the event, across town. These are street tires after all!
Well there was a lot of construction going on in our area and we think the car got a flat leaving our neighborhood. Amy was driving and said "Hey, its really pulling pretty hard to the right." Hmm... turn around and go back to the house to air up/check the tire, or drive down the road to the gas station to check it there? We needed fuel, so I said to heck with it, let's go another 2 miles down the road. Mistake.

She's on the highway, within a half mile of the gas station, and the tire lets go. Pop! This car just does NOT want me to autocross it!



Jon was just ahead of us on his way to the event (he would be co-driving) and when we called, he ran back to his house, grabbed a floor jack and the right socket, and we put on the spare. He brought a plug kit in case it was just a flat, but when we removed the tire and saw the inner sidewall gone, we knew it was way beyond saving this day.
LESSONS LEARNED
Every time I make a mistake in my life I try to learn from it. I haven't had a tire blow out in a sports car in... well, ever. And getting caught with the wrong lug wrench and no jack was a dumb mistake, so I bought a cheap 1/2" torque wrench, thin wall lug nut long socket kit (17, 19, and 21mm), and a short 1/2" extension. Probably spent $50 but I won't be stuck again. I actually doubled up on all of this so my 1/2 ton truck would have the same setup on board.


I also bought the Ford Racing TMPS kit shown above, along with the programmer. Having on-board tire pressure readouts is super handy and would have prevented this blowout completely - the instant the pressure dropped below 30 psi we would have seen an alarm. The next time I have these tires off these wheels we will install these sensors, program them to the car, and never be without tire pressure data any longer. #500psi #streettires


Sadly the Right Front tire (which took the most wear at the MSR-C event) that popped had 6/32" of tread left, as measured above left. They only come with 7/32", so it was wearing nicely! Instead of buying just ONE replacement Bridgestone tire I bought TWO - so we would always have a spare with us in the trailer, for any unforeseen mishaps in the future away from home or the shop. And by damn this would be the LAST time we did NOT tow this car to an event. Three people missed out on autocrossing this day due to our lack of a proper spare RE-71R tire, TPMS sensors, etc. This sure isn't going to happen again over a $330 tire or the ease of loading/unloading a car in our trailer.
BRAKE MODS, ROUND #3 (PP 15" ROTORS & 6 PISTON CALIPERS)
When I saw an opening at the normally sold out Optima series event at NOLA coming up in a week, without much thought I signed up. I knew this track well, plus we found a Track Night in America test the Thursday afternoon before the Saturday-Sunday Optima series event. Time for an Intermediate Brake Upgrade and subsequent test...


Since we might use them only for one event I got the cheapest Centric rotors and rebuilt calipers
I knew this track would need better brakes than our 14" stuff, and our prototype S550 380x34mm Powerbrake kit wasn't going to make it in time. With little to no research I ordered some Centric 15" rotors and rebuilt Brembo 6-piston calipers off of the 2015-18 Performance Pack Mustang GT. There was some small hardware to round up, new front pads to order (G-LOC R16 once again) for the new calipers, but the brake hoses would fit. There would be zero time to do a local track test before going to the Optima event so this was a total roll of the dice! But again, I had used the stock brakes at ECR in 2014 with good luck... they should work fine.

It was a pretty tight schedule and everything we needed only showed up with hours to spare before we loaded up for the 9 hour tow to NOLA. The "Tech Tip" video in the section above shows many of these caliper/rotor weights, as I shot that as soon as the calipers and rotors arrived. The above gaggle parts were also ordered and arrived, including: ARP long wheel studs for the rear, Ford Racing hubs with ARP long wheel studs for the front, and Ford Racing trailer tie-down hooks.


First Ryan put the hubs, rotors, and calipers on then fabbed up prototype 4" cool brake backing plates for these 15" OEM brakes.


These prototype brake backing plates (we will have these in production later this summer for the S550 15" PP brakes) serve two purposes. First, they cool the front hubs - which get hot and become a wear item over time (just like we saw on the S197). Second, they pump air inside the "hat" of the rotor, seal the air into this area, which then forces it into the vented portion of the rotor - which acts as a centrifugal pump and pushes this cooling air through the center of the rotor casting, to cool both the inner and outer rotor faces.

We have seen a few people propose that you can "make brake cooling for the 14" inverted hat rotor", but we feel that is pretty much pointless. While this might help cool the hubs, it would do little to cool the rotor itself, especially the outside face - since there is no way to pump air through the vented portion of the 14" rotor. This is a lot of work for very little benefit. Now if there is a non-inverted hat 14" rotor on the market that fits the 14" 4 piston calipers, yes, that might be worth trying. But we've moved beyond the 14" bits on our car.
HOW THE MOVE TO 19" WHEELS MAKE 15" BRAKES POSSIBLE
We stuck with the 14" brakes on our 2011 Mustang for 5 years mostly because of one thing - we ran 18" wheels that didn't clear the 15" brakes. At the time we were using Forgestar F14 wheels in 18x10, 18x11 and 18x12" widths. And back from 2012-2015 the Forgestar F14 wheel in 18" could barely clear a 14.5" rotor/caliper setup.


Forgestar knew that the 15" / 6 piston Brembo kit was coming down the pipe from Ford (S197 GT500) so when they introduced a newer wheel design - the CF5 5-spoke above, they changed the barrel to clear this 15" / 6 piston profile. The shape of the inner barrel on the older F14 is very different than the newer design CF5, which I am holding below.

Starting in late 2016 Forgestar began phasing out the old tapered barrel design of the F14 to the "stepped" barrel (above) of the CF5. So if you have 18" wheels of the F14 style from this company bought in the last 2 years they likely look like the black wheel above and can clear the 15" brakes. Barely.

Of course many S197 and S550 drivers have moved up to 19x11" wheels due to the abundance of 305/30R19 street tire options available. But when it comes time to slap some Hoosiers on this car well... we will likely go with 18x11" wheels, so we will have to watch out for that rotor/caliper to inner wheel barrel clearance.
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