Vorshlag 2011 Mustang 5.0 GT - track/autocross/street Project

[Vorshlag-Fair]

When I went to slow down into 10A after the looooong back straight during an extra long stint - the pedal went to the floor. And didn't come back. While doing about 155 mph.

It was a hard hit, and I think most of my damage (compression fracture to vertebrae T-11 and broken rip at T-12) happened where the picture shows, coming OUT of the gravel trap. It was about a foot high ridge of dirt where they cut into the earth to dig out the hole for the gravel pit.

I didn't black out so I remember most of the hit, but I couldn't breathe for about 90 seconds (knocked the wind out of me) and I knew I had broken something in my back. I managed to avoid the two cars ahead of me, all of the walls and the bridge itself, steered it into Pit In, and coasted right in front of the medical building. I then popped the straps and rolled out of the car, where the medics were on me in seconds.

I stupidly refused a hospital visit at the scene and waited until this past Monday to get X-rays, and saw the broken bones. I just got back from another doc visit (pain meds FTW!) and go in for an MRI next week. Oh well, live and learn.

27 years of doing this stuff, dozens of offs at all sorts of speeds, but this is the first time I got hurt. Car doesn't even look that bad.

---

Yes, we are reevaluating all of my and the car's safety gear, and I will be adding a HANs device before I take another lap in anger. Which would help for a different kind of wreck than this, though.

This impact at Road Atlanta was almost entirely VERTICAL in nature. This shunt didn't trigger any of the airbags (which are functional) and would have popped with any forward-type impact, so a HANs device would have had no affect on my outcome. Neither would a full roll cage, in this instance. This car does not race wheel-to-wheel and is still a STREET DRIVEN and STREET LEGAL car, so this one won't ever get a "full cage" while we race it for the rest of 2014. I'm not keen on driving around on the street with steel tubing next to my head, even with SFI padding that is a recipe for disaster. It is a rare car/driver combo that can have a fully functional cage and still be 100% safe for street driving with a non-helmeted driver.

Look guys, I appreciate the advice, and I've heard it all this week from every expert on the internet, via Facebook. Again: a full roll cage and a HANs would have had ZERO effect in this somewhat unusual impact vector (Z-axis) shunt. We have only a handful of events left in this car this year and then it will likely be de-modded back into a 100% street car/daily driver while we prep and develop the 2015 Mustang to race for the 2015 season in TT2 or TT3.

But... yes, we are going kind of fast at some tracks for an un-caged car, I know (although it does have a robust 4-point roll bar with diagnoal, an FIA halo racing seat, Schroth 6-point harnesses, etc). And the 2015 Mustang might be faster than this car (we should know weights and power numbers next week, by 5/20), and if so I've already negotiated with Amy to potentially make the S550 Mustang to have a more gutted/caged/race car type of safety gear prep. But to do that I have to make this red 2011 GT into a real street car again, and revert it back into her "pretty pony" by removing the splitter, wing, super-loud exhaust, RR2 dampers and some of the more racey bits.

Will the 2015 "S550" Mustang GT be significantly more powerful and/or lighter than the S197??

We shall soon see. It all kind of depends on how well Ford designed the 2015 GT, and/or if the "GT350/Voodoo" car comes out in a short time frame. If the 500+ hp Voodoo Mustang engine is real, significantly faster, not boosted, and comes in a car available for under $75K within the calendar year (aka: a Z/28 fighter!)... the 2015 GT we already have on order will be used as a temporary development mule and will get "bolt-on only" mods. Then we will switch to the Voodoo car and go hod wild... caged, flared, carbon ceramic brakes, and faster.

More soon,

 

[ddd4114]

I stupidly refused a hospital visit at the scene and waited until this past Monday to get X-rays, and saw the broken bones.

As I'm sure you've learned, this was your real mistake.

I know you've heard too much of this recently, but I'd certainly recommend some kind of head/neck support. However, the best safety equipment in the world will not prevent your brain from smashing into your skull in a serious impact. You'd still need to get checked out ASAP to see if you're ok.

One of my friends ran his car into a wall a couple weeks ago and didn't see a doctor until a few days later. The crash didn't look that bad on video, and he said it didn't hurt that much. However, over the next few days he noticed a lot of disorientation, and when he finally went to the doctor, he was diagnosed with a pretty serious concussion. He still hasn't recovered.

This isn't so much directed at you as it is other people reading this thread: if you're in a crash and feel strange at all - GO SEE A DOCTOR. It's not worth risking your health to chance.

 

[Vorshlag-Fair]

As I'm sure you've learned, this was your real mistake.

...

This isn't so much directed at you as it is other people reading this thread: if you're in a crash and feel strange at all - GO SEE A DOCTOR. It's not worth risking your health to chance.

No worries, I agree. Not that a hospital visit that day would have done much me much more good than my doctor did on Monday: X-rays + advice. I have seen two doctors since the crash and go in for MRIs early next week and potentially surgery. Wearing a back brace helps a lot, but I still cannot sleep more more than a couple of hours a night. Oh well, it will heal...

 

[ddd4114]

Ouch! That doesn't sound very pleasant. Hope you can recover quickly!

 

[DILYSI Dave]

Jesus - Those are some real injuries man. Even considering the airborn part I didn't figure it was that big a hit, but the launch that you describe makes sense that compression would be an ass kicker. Sorry to hear that it was worse than originally thought. Hope the docs treat you right and you heal quickly.

 

[NDSP]

Terry,

That sure did seem like it was very early in the session for a brake fail like that. Have ya'll been able to pinpoint why the brakes failed like that?

Sorry to hear about your accident and injuries, here is hoping for a quick and complete recovery.

-James

 

[5.0_SD]

Just rest Terry, you have a whole crew of people that can take up the slack. You are no good to them or us being broken and in pain...so rest my brother and get well soon!

 

[Vorshlag-Fair]

Project Update for May 21st, 2014: So where were we? Ah, yes... April events and development work on the 2011 Mustang. First we ran an SCCA autocross in April on street tires - and all of our runs were during a downpour, so that was fun. There was an informal kart shoot-out we hosted the next week, then we created a new mount for a massive new (AJ Hartman) rear wing. Let's play catch up!

Texas Region SCCA Solo at TMS Bus Lot, April 13th, 2014

So there was a Texas Region SCCA event in April that we wanted to use for dry weather BFG Rival autocross testing with the new MCS coilovers. Amy and I co-drove in the 2011 Mustang on this rainy Sunday in April. We both ran in the first heat, in a steady rain that left little grip on for the BFG Rival 200 treadwear street tires. We both raced in the local "MAM" class (Modern American Muscle - a supplemental class to the new "CAM" Classic American Muscle class).



The club had 122 registered entrants, which was pretty dang good for a day everyone knew would have rain. We got there and it was still dry, unloaded the car and applied the hastily made "MAM" class letters that I hand cut the night before. I had Olof mount the same set of 315/335mm BFG Rivals that we used at the USCA/Optima event weeks before. The tires still looked good but the rears were flipped and run inside mount, since I kind of mauled the outer tread blocks on the right rear in my 90+ laps on track at the USCA event.

• Results: http://texasscca.org/2014_solo_results/tr14_2_final.htm#MAM
• PAX: http://texasscca.org/2014_solo_results/tr14_2_pax.htm
• Photo and video gallery: http://vorshlag.smugmug.com/Racing-Events/SCCA-TMS-041314/

We had 5 runs each and Amy took 4 of hers first, then I took a couple of runs, then she took her last, and then I took my final 3. The rain was pretty hard at the beginning of the 1st of 4 heats and we still had to run the wipers on our last runs in the heat. It rained even into heat 2, stopped raining finally sometime in heat 3 and by heat 4 it dried up completely and times dropped by 10 or more seconds.



I worked in the trailer in heat 2, announcing, and took lunch with 2nd place MAM finisher Jay Payson from HP Tuners. He was in town for business and rented a Penske Mustang GT, which he enjoyed running in MAM. Since we left the rain gear box at the shop I still goat soaking wet, while taking pictures of Amy while she drove in heat 1.


Just a sample of the results showing how slow MAM was running in the wet compared to CAM that ran in the dry

I ended up getting fast time in the 4 car MAM class with the rental Penske 5.0 Mustang in 2nd place and Amy in 3rd. The Penske car had fresh Goodyear 220 treadwear tires and Jay said it was remarkably easy to drive. He normally races an M5 in FStreet class but he said liked the Mustang a lot and we discussed the merits of an E92 M3 and an S550 2015 Mustang for F Street at lunch.



Normally I -love- racing in the rain but as usual, the conditions varried too much to compare with other classes/run groups. And at this particular event we were definitely at a disadvantage here, with too much power and tires with too much width. See, in the rain it actually helps to have more pressure on the tires, just like in the snow, so you want a narrower tire with deep tread voids - which we definitely did not have on the well worn 315/335 Rivals. The new, deep tread, 255mm tires on the rental car were what you wanted in this instance, as strange as that sounds.



And Jay almost whipped me in a car he had never driven, so I felt lucky to come out ahead. Everyone else in the class ran their fastest run on their 5th and final attempt, except me. I was 3 tenths quicker on run 5 but stepped on a cone, so I had to settle with my 4th run. I had to drive on my best behavior in these conditions, which was driving me nuts, but I managed to "throttle" my normal tendency to over-drive and just did the rain dance. Tip-toeing on the gas and smoothing out my inputs as much as possible. We also ran a tick more tire pressure than normal, and dumped the compression damping on all 4 shocks to zero.


This was the slow in-car video from my 5th run. Its not very impressive, trust me.

The rain lessened all day and by the 4th heat we heard it was completely dry and times dropped dramatically, so the PAX results aren't very representative for everyone. Heck, the only group I'd want to compare any times with was the first heat, of which I think there was one car quicker than us in the 59.8 second range (STS winner JJ). It got progressively drier in heat 2 and 3 but by heat 4 it turned into a beautiful day and was fully a dry weather autocross. That would have been fun to make a few blasts around the course, but you run in the heat you are assigned. Oh well.


Left: We got to slog it out in deep puddles while... Right: The 4th run group had completely dry runs by day's end

Overall this event was a bust for testing with the Rivals. Why? Well we're only testing these with tires to use at the Optima Ultimate Street Car shootout in November, which is held in Vegas. The chances of rain for the ENTIRE day of that event in Las Vegas are virtually ZERO, so wet weather testing does us no good for that series. I will say the Rivals have surprisingly good grip for as wide and as bald as they were on this day.

Oh well, we got to see a lot of old friends and drive around really slowly. At least we didn't have any tire wear, ha!

Vorshlag Kart Fight 3

We are lucky to have a world class outdoor karting facility on the East side of Dallas called Dallas Karting Complex (DKC). Virtually all of the track, autocross, time trial and karting racers in DFW know about this place and have driven their rental karts before. We had a couple of Vorshlag sponsored Kart Challenges in 2011 and I was on a team of 4 in the first DKC 4 hour enduro in December of that same year. We got really busy in 2012 and 2013 and didn't have another Vorshlag-sanctioned karting competition for those two years, but I drove rental karts there many many times.



Instead of the structured, all day Saturday, 3-round shootouts we held in 2011, this time Vorshlag just held an informal night competition event at DKC on April 17th, 2014. This was a Thursday night and we posted up a Facebook event on our main Vorshlag page a few days beforehand just telling people, "hey, come join us from 6-9 pm, run a few races, turn in your time sheets, and the fastest time of the night gets a trophy".



We called it the Vorshlag Kart Fight 3, as this was out 3rd karting competition event since 2011. For something kind of thrown together at the last minute we had a surprising number of racers show up. By the end of the night we had nearly 40 people who came out to fight for the VKF trophy.



Kyle and Olof built this awesome trophy out of some broken Subaru drivetrain parts, TIG welded together and bolted to a base. The competition format was simple: show up, pay $15 a race (each race is about 10-12 minutes in length), and your best times run that night from 6-9 pm in the regular We had some swag and gift certificates for 1st through 3rd places. We also used NASA TT rules for offs and spins: if you put 4 wheels off or spun 180 degrees or more on track ALL times from that session were voided for that driver. We all spotted for each other.

continued below

 

[Vorshlag-Fair]

continued from above


Left: I went over the driving line, as I run it, with anyone who'd listen. Right: Fastest time of the night went to Alpha LS1 Miata tester Jason Toth!

I kept getting the same slug of a kart all night (excuses - I has em!) and while I had an early lead, I never improved on my first session times and could only manage 2nd quickest time of the night, a couple of tenths back from 1st. NASA TT racer Jason Toth was the winner, and (taking myself out of the running) 2nd place went to Billy Jack Smith and 3rd place swag went to NASA TT racer Jefri Tan (who runs in TT3 with me in a red EVO). We had one guy flip his kart (no injuries) and another NASA racer who put his kart so far off track he ended up in the sippy hole, and went home sopping wet. But no injuries and everyone had smiles on their faces.


"Helmet-Cam" Video from Marc Sherrin

NASA TT1 racer Marc Sherrin took the video above with a Go Pro strapped to his helmet, which is a compilation from about 3 sessions. As you can see we started off in daylight but it quickly got dark, and the track cooled off. They have excellent night lighting, so that made for extra fun NIGHT RACING! He even caught a glimpse of the kart that flipped in his video. We had 6 NASA TT racers, a lot of SCCA autocrossers, and various other local gear heads in attendance.

Vorshlag Kart Fight Photo Gallery: http://vorshlag.smugmug.com/Racing-Events/Vorshlag-Kart-Fight-3/

Five people from Vorshlag were there and Brandon managed to snap some pics while we were there. Thanks to everyone that came out to join us - we'll do it again soon!

New Massive Rear Wing on Mustang!

Let me first start off saying: I am not an aerodynamics guru. I have a mechanical engineering background/degree, and I understand some basic concepts of aero, but Jason here at Vorshlag studied hydrodynamics in college and I rely on his expertise. I also know other people are aero gurus that I listen to, and read from. So I will try to cover rear wings in this section without butchering the science of it too badly.



We have had an APR GTC-300 "3D" wing on our 2011 Mustang for the past 2, almost 3 years? This was supposed to be a temporary fix until we found a better 2D wing, from APR or another source. At the time APR was only making 3D wings, but have since come out with their own carbon 2D design. I initially bought this 67" wide GTC-300 carbon fiber wing element to use on another car, and we actually did use it on Brianne's Pikes Peak Subaru in 2012 for the PPIHC event that year. It is a good low speed wing (PPIHC is fairly low speed, as are many of our Texas tracks like ECR, MSR-C, MSR-H, HHR, TMS and others) but is somewhat "draggy" at higher speeds, and never was meant to work at the heights we ran it with on our car.



We designed and water jet cut that original wing mounting set-up very quickly, over the course of a few of days. The goal was to re-use these uprights with a 2D wing to be installed later that year, which never materialized. Because we had planned to use a 2D wing with these, and from my insistence, the APR 3D airfoil was mounted about 6 inches above the roof line - against the wishes of Ryan and Jason. At this height about half of the GTC-300 wing was doing nothing but generating drag.


Testing at both high and low speed tracks showed we were faster at max AoA on the APR wing: 12 degrees at the center

After we kept this GTC-300 wing on the car for a year, and after constant advice from aero folks, Jason and others, we eventually cut down these uprights by about half to lower the 3D wing element below the roofline. It seemed to work a little better at this lower height - which is the opposite of what you normally want to do with an airfoil.


Moving this 3D airfoil lower actually helped, due to the curved center shape of the wing

Why is this rear wring shaped this way? Answer: To meet certain class rules. This "3D" wing profile was made to help improve downforce when used in some racing classes on sedan-shaped cars that limited the mounting height of the wing element at 6" to 8" above the rear trunk lid height. This rule was made to limit rear downforce and slow cars down, so aero engineers came up with a way to trick these low mounted wings into producing more downforce at this low height by tilting part of the airfoil element upwards by 10-15 degrees right behind the greenhouse (aka: the bubble of glass and steel above the shoulder line of a car that houses the passenger compartment).


I always look at the C5R, C6R and C7R Corvette race cars for some of the latest aero tricks - not ashamed to admit that!

So the center section of this type of wing is angled upwards compared to the outer edges, to grab more airflow coming down over the roof and following the rear window. It really only works well when mounted low, and should only be used when class rules mandate a low wing mounting height. But this became so widespread in professional GT racing and looked so "high tech" that they caught on with racers who didn't need to mount them low.


CFD data shown on GT2 classed Corvette C6R race car (at left) and a striated smoke wind tunnel picture on a 911 GT2 at right

I've even heard other racers try to tell me that this type of 3D wing is better than a high mounted 2D wing. Which is wrong. Don't confuse popular solutions for another set of rules to mean that there isn't something better for your class. It is always worth looking at the "why" of a design.


Here is a chart of Drag (HP), downforce (pounds) and AoA for the 14" x 72" AJ Hartman Racing wing run through CFD software

You can see the CFD data on the GTC-300 airfoil at this link. And remember to look at the same units - the APR data is shown with speed in MPH (SAE) but force is shown in Newtons (metric), so you have to divide that Force data by 4 to see it pounds of force. The AJ Hartman wing just has better data, as you can see when comparing the two.

When to use a 2D vs 3D airfoil: http://www.aprperformance.com/index.php?option=com_content&task=view&id=176

Even APR admits as such in the article above, and now that they make a 2D wing again they are pushing that design. And yes, we could have picked up a carbon APR wing, but when we were looking for one last summer they were having supply and manufacturing problems. Its no secret where their airfoils come from, and I would rather have a U.S. built carbon wing than one from an overseas factory. So we started looking at different wing manufacturers...



After a lot of phone calls, emails, investigations, spreadsheets, data investigations and personal inspection of various brands of U.S. made carbon fiber wings we honed in on two brands. The final decision was a close one but we picked the wing with the biggest span and chord available: AJ Hartman Racing. Their 14" chord length (the front-to-back size of the wing) and the massive 72" max width were simply unmatched by anything in this category for anywhere near this cost.


The Fulcrum wings are super popular here in Texas and I see them used to great effect on ST, AI, and other race cars

This hand laid carbon fiber wing is molded by AJ at his shop in New Jersey. He installs the saddles (bonded and riveted) to the wing at your specified widths, trims the span to your specs and the final wing just looks amazing. They weigh 9 pounds, total, and his wings can support the weight of a full sized adult. You may not know the AJ Hartman Racing name now, but the original airfoil design and molds were purchased from Fulcrum Aeroworks, which was a company formerly based right here in Dallas/Ft. Worth.



The retail price for this AJH wing is only $1300, which is insanely low (this airfoil easily compares to $2500-4000 U.S.-made wings), and now Vorshlag is their first ever dealer. AJ didn't yet have a wing mounting kit for the 2010-2014 Mustang trunk shape so we started designing one as soon as our first 14x72" AJH wing arrived.

In NASA Time Trial we are only limited on wing mounting to a height of up to 8" above the roof, which is WAAAAAY up there, and FEET higher than what the 3D wings were really designed to be used at. A 2D wing is simply more efficient than a 3D wing, when mounted above the roof. This means: they produce more downforce (negative lift) and less drag at a given speed and angle.


I spent most of a day on 4/19/14 making cardboard mock-ups for the 6 mounting pads, then making the trunk profile for the uprights

Since we weren't restricted on mounting the wing anywhere close to the rear trunk lid, we figured we would see more downforce with a 2D wing mounted at or near the upper limits for NASA TT. The higher you can mount the wing, and the farther behind the car, the less turbulent the air will be that is going over and (especially) under the wing. We had originally looked at making a wing that met NASA American Iron and NASA TT/ST rules, but they were conflicting. TT specified a maximum height but AI specified a maximum of 1.5" behind the car.


I transferred the cardboard to thin sheets of wood, cut those out for prototype templates and then bolted up the wing

My first mockups (above) were both AI/TT legal, shown above in wood. After staring at it for a while it just didn't... look right to my engineering eyeball. It was too vertical and not swept back enough.


If we see any trunk deformation at high speeds we will add tubing to brace to these two plates (at right) from the ballast weight bracket

So when I gave the upright layout to Jason I told him to just centrate on the trunk shape and approximate height (we pushed it up to around 6" above the roof, within 2" of the TT max height). He transferred the trunk shape into SolidWorks then moved the actual upper wing mounting portion rearward about 8 inches, which put the wing too far behind the back plane of the car to be AI legal. I kind of knew this first aluminum unit we made would be a prototype that we would later need to tweak, so we will go back and make "production pretty" wing mounting kits for AI and another for TT/ST use on the 2010-14 Mustang trunk.


Check out the video above showing the CNC plasma cutter making a wing upright in about half a minute

After Jason had turned the trunk shape into a CAD drawing I ran to our metal supplier and picked up some aluminum plate in two thicknesses, then rushed over to Friction Circle Fabrications in Lewisville. There Todd Earsley used his brand new CNC plasma machine (see video above) to cut the aluminum I brought into the shapes from the files we sent to him. He cut the six mounting plates and two uprights in less than 35 minutes on his machine, and I was loaded up and racing back across town with the parts still hot.

Once we got to Vorshlag the crew cleaned up the edges and started mocking up the mounting plates. We were super busy that week on customer cars and it wasn't until Friday afternoon that everything was finished, welded, painted and bolted together. We set-up the upper mounting holes with 3 initial Angle of Attack (AoA) positions: 6, 10 and 12 degrees from level. We left the wing at the lowest angle setting we made, 6 degrees, for our first TWS laps with NASA.


Me (at left), AJ (middle) and Jason (right) posing for a quick pic with the new wing when AJ Hartman stopped by Vorshlag

A couple of weeks after we built this wing, just after our TWS race, AJ Hartman happened to be flying through Dallas after a test with a customer down at CoTA. He stopped by the Vorshlag shop to check out our prototype mounting for our first AJH wing. He pointed out a few things we could tweak to make it better, but overall he liked the set-up. We showed him two more cars in the Vorshlag shop that need to get AJH wings, and he is making those for us now.



That's all we have time for in this installment. Tune in next time when we cover the NASA TT race at TWS with this new wing installed. This Saturday is Five Star Ford at ECR - see ya there!

 

[Sky Render]

Any more info on the MAM class? I like the idea. I ran an SCCA autocross last weekend and got put in CAM. (Because my 2011 Mustang is already a classic?)

Sent from my toilet using Tapatalk

 

[Whiskey11]

Any more info on the MAM class? I like the idea. I ran an SCCA autocross last weekend and got put in CAM. (Because my 2011 Mustang is already a classic?)

Sent from my toilet using Tapatalk

Classic, from my understanding meaning "Of Classic Lineage" of which the Mustang has a shit ton of history behind it.... not "classic" as in the 25 years old nonsense that most DMV's call it.

 

[Bob]

Respectfully requesting an update on the brake failure... since that's pretty relevant to us all.

 

[Sky Render]

Classic, from my understanding meaning "Of Classic Lineage" of which the Mustang has a shit ton of history behind it.... not "classic" as in the 25 years old nonsense that most DMV's call it.

What are you doing bringing logic into this discussion?!

 

[csamsh]

Any more info on the MAM class? I like the idea. I ran an SCCA autocross last weekend and got put in CAM. (Because my 2011 Mustang is already a classic?)

Sent from my toilet using Tapatalk

MAM=CAM. Texas region just splits it into old/new cars.

 

[Vorshlag-Fair]

Respectfully requesting an update on the brake failure... since that's pretty relevant to us all.

We're still not done with repairs but they are wrapping them up today, because we have a track event on Saturday in the car. But here's what we know so far:

1. The front brake pads had virtually ZERO material left, after the crash. Of course these were inspected before we went out on track for both stints at GTA, but they wore down at an unexpectedly rapid rate in that final session. These were Carbotech's hardest compound, the XP20, and we only started the day with 1/2 pad thickness (mistake #1)
2. The fresh Motul RBF600 brake fluid had boiled during my extremely long stints at this seriously brake intensive track. The Motul rep was aghast that we hadn't stepped up to RBF660 already (mistake #2)
3. We knew we were already seeing 490°F temps at the caliper (via the Alcon temp strips) in normal 3 lap TT bursts, but in these 12+ lap/ 30 minute stints we had to have exceeded those temps. We didn't have the Alcon strips on the car at this event, because we had lost the entire packet of them (mistake #3)
4. The 3" front brake ducting hose was recently re-routed to make more room for the 335mm front tires, and in doing so it added more restrictive bends in 2 places. This had to impact airflow greatly to the front brakes (mistake #4)
5. Other racers familiar with Road Atlanta said that they have seen a mysteriously "dead pedal" like this in the same corner, due to pad knock back from a previous turn on the long straight leading up to Turn 10A. One of the tricks I have been told since the crash was when on long straights, like the run from Turn 7 to 10A at Road Atlanta, is to "pump the brake" with my left foot (while still WOT), just to make sure the pads are touching the rotor and to feel if the pedal is mushy. This pad knockback issue can be remedied with this single pedal pump on a long straight, but if it doesn't come back (if there is another braking system problem) at least you know with plenty of time to slow the car down before you would be normally braking.

Lots of little mistakes just added up to this brake system failure at the worst possible corner of a dangerous track. In four years, never had this happen to this car. I own all of those mistakes - it wasn't something stupid, or a single part that failed, and I was obviously over-driving the brakes. Again, this is an unusually heavy car (3800 pounds) and has a good bit of aero.

Here are all fixes that will be in place by this weekend:

1. Brand new full depth set of Carbotech pads
2. A full flush of Motul RBF660 (if this has issues we will move to Castrol SRF). Our maintenance schedule was already enough to warrant going to 660 (which has to be bled more often than 600). SRF has to be completely flushed more often and is usually bled after EVERY track session. Nightmare.
3. All new 4" brake ducting to replace the 3" ducts
4. Replacing much of the corrugated hose with smooth aluminum tubing and just enough 4" flex hose at the wheel to support turning. No tight bends to restrict front brake cooling airflow.

There is a new front bumper cover, new CS Lower Grill insert and new side skirt going on. The splitter was actually pretty easy to repair (strong like bull!) and these new bits are going on the car today.

More on these repairs.... 2 posts from now.

 

[Pentalab]

A local buddy who tracks his car says the last 1/2 of the pads wears at a much faster rate than the 1st 1/2. The heat will transfer at a greater rate through thinner....remaining pads. I think some of the pads come with heat shields... (or a heat shield can be inserted between pad + caliper). New, thicker pads (and perhaps heat shields) should reduce the brake fluid temps a bit.

My orange silicone hoses are smooth bore on the inside....and corrugated on the outside. I thought they all were constructed that way?

I think you said you are using 4 piston brembo's with 14" rotor's ? Dunno if 6 piston caliper's would fare any better. 15" rotor's are used on the newer GT-500's.

What about the rear brakes ? With heavy springs etc, minimizing nose dive vs oem suspension, on paper, more of the load should transfer to the rear brakes. The oem 11.8", 1 piston brakes are probably not up to the task. Some folks have installed 14" rotor's on the rear....and 4 piston variety. Some method of adjusting brake bias inside the car would be the ideal ticket. Some have added brake ducts / hoses to the rear brakes.

 

[kcbrown]

2. A full flush of Motul RBF660 (if this has issues we will move to Castrol SRF). Our maintenance schedule was already enough to warrant going to 660 (which has to be bled more often than 600). SRF has to be completely flushed more often and is usually bled after EVERY track session. Nightmare.

Huh?

I thought the whole point of SRF was that it needed to be flushed/bled less frequently, due to being a lot less hygroscopic.

 

[Boaisy]

I think you said you are using 4 piston brembo's with 14" rotor's ? Dunno if 6 piston caliper's would fare any better. 15" rotor's are used on the newer GT-500's.

The run on 18" wheels which barely give any clearance for 15" BBKs.

 

[NoTicket]

Pad knock back is almost surely to blame. With the level of grip you have up front it is probably impossible to avoid some knock back. Running half thick pads will only make this worse as there is a lot more room for them to be knocked back to.

Even on stock tires you can get some pad knock back on the Brembos. To make the knock back less severe (and keep fluid temps down) I started putting in titanium shims as the pads wear down.

I would not be surprised if this was almost entirely due to knock back and not necessarily boiled fluid.

I'm sure you guys are checking everything... but you might want to check the hubs/bearings to see if they are getting a little worn. With how much grip you have they are under a huge amount of stress over what they were designed for.

 

[modernbeat]

...What about the rear brakes ? With heavy springs etc, minimizing nose dive vs oem suspension, on paper, more of the load should transfer to the rear brakes. The oem 11.8", 1 piston brakes are probably not up to the task. Some folks have installed 14" rotor's on the rear....and 4 piston variety. Some method of adjusting brake bias inside the car would be the ideal ticket. Some have added brake ducts / hoses to the rear brakes.

We actually did the legwork to figure out the 13.8" GT500 rear brake swap and that is what is on the car. We run a very soft rear spring and, obviously, a lot of downforce. We were hoping to not have to duct the rears also, and so far they have not been a problem after upgrading to the larger rotor.

S197 Mustang 13.8" GT500 Rear Brake Upgrade Kit [A9-2035-R1]

Huh?

I thought the whole point of SRF was that it needed to be flushed/bled less frequently, due to being a lot less hygroscopic.

It doesn't absorb water. And that can be a problem. If water gets in the system, which happens when the hot brakes cool off, then the water pools in the low point in the system, the caliper. When it gets hot again, the water turns to steam and abracadabra! you have a soft pedal.

...I would not be surprised if this was almost entirely due to knock back and not necessarily boiled fluid...

While I certainly think pad knockback played a part in this, the fluid absolutely boiled - badly. Days after the incident the pedal was still soft and a flush firmed it up.