Since I feel the original Cale thread is a Tribute thread and should not include what may become some heated discussions, please post your educated thoughts here. There may never be an indisputable cause found. As a fellow S2K track driver I truly hope someone can figure it out.

I am still doing research and listening closely to Rob's actual findings, I have no educated opinion.

Lou

 

I Thought it was from Brake Failure.

 

[QUOTE=erker72,Nov 19 2008, 12:21 PM]i'm trying to put myself behind the wheel of cale's car.

 

Updated Info - After disassembling Cale's car I beleve I have found the root cause of the accident. See Page 2 of this thread for my final analysis.

I copied my accident analysis from the "Cale" thread. I was an aircraft accident investigator for the US Air Force and I have some knowledge of automobile accident analysis. I was on track about 3/4 of a mile behind Cale when the accident occurred. Cale's insurance company may conduct an investigation but no state or federal investigation is being conducted. The following is my analysis and theory regarding the accident.

Here's a picture of Summit Point's Turn 1 taken about 10 minutes before the accident:


Accident Summary

Entering Summit Point Main's Turn 1 Cale's car began the turn in to the right from the normal braking zone on the far left edge of the track. The car then sharply reversed course to the left and began to slide while still on the track. The car then went three wheels off through the grass and gravel trap with the left front wheel on the access road. The car continued to slide across the access road and through dirt and grass until the right side of the car struck a bare concrete wall. The car hit with the right side flush against the wall. The car came to a stop a few feet from the wall.

Assumptions

The car was traveling approximately 128 MPH at the beginning of the braking zone for Turn 1. My data logger shows my S2000 at 125 at the braking zone and Cale's best lap time was about three mph average faster than mine.

Cale was applying the brakes. The SCCA corner worker that worked Turn 1 said she saw the car did not decelerate and she noticed the brake lights were lit as he went by. This rules out driver incapacitation as the cause.

A stuck throttle was not the cause. The post crash car examination showed the throttle butterfly was closed with the throttle cable working normally. Also, simply pushing the clutch in would allow the brakes to stop the car.

A suspension failure did not cause the accident. All four skid marks on the pavement were uniform. A broken suspension would normally put more weight on the opposite diagonal tires and the skid marks would show heavier, darker marks.

Analysis

My car was behind Cale at the start-finish line when the accident occurred. My in-car video shows Cale's car in the distance entering Turn 1 from the normal position at the left edge of the track. His car then begins to move right into Turn 1 and gets about 1/3 of the way across the track but then rapidly reverses course to the left. Dust from the gravel trap is then seen as the car moves left and goes out of sight behind the trees.

A small "flash" from the right side of Cale's car can be seen as he begins to turn right into Turn 1. I originally thought it was tire smoke, but when I examined the car all four of Cale's tires were still inflated--I actually checked the air pressure. After studying the video very closely I see that the flash occurs when the car begins to turn right into Turn 1. With the late afternoon sun angle the "flash" from the right side of the car could have been the sun glinting off the right side window as he began the turn-in to the right. Also the Turn 1 corner worker did not notice any "smoke" from his car as he went by. I no longer believe the "flash" on the video is smoke from the tires or brake dust and debris, but simply sun glare.

I got a chance to examine the car at the BSR maintenance facility and I went out to Turn 1 to look at the accident site two days after the accident.

The skid marks at the track were easy to follow from the impact site at the wall back to about 50 feet up the track. I could not follow the skid marks any farther up the track due to a newly laid patch of black asphalt near the beginning of the turn-in point. As the skid marks come out of the asphalt patch the car was already in a four wheel slide with about 20 degrees of left yaw. All four tire marks are very similar and there's no evidence of any ABS--the skid marks are uniform and appear to be from the slide, not brake lock or ABS cycling.

The car's brake fluid level was normal and all of the brake pads had plenty of material left. The car's right side brake rotors were both cracked which most likely was caused by the impact. The rear rotor was completely broken from the hub, but too much of the rotor was found near the impact site to support a rotor "disintegration". We did a sweep along the braking zone and didn't find any brake parts but BSR has been running training on the circuit since the accident. The loss of a rotor can allow the brake caliper piston to fully extend which would allow the brake pedal to soften or even go to the floor, but I found out that there is actually a piece of rotor still sandwiched between the brake pads in the right rear caliper. This would have prevented the caliper piston from hyper extending so the braking at the three other wheels would have been unaffected if the rotor had indeed disintegrated.

Scot Burner, an S2000 H1 racer, crashed at VIR in July due to a probable rear rotor failure.

Last year on the Summit Point Shenandoah Circuit I had a brake failure in my S2000 which was caused by running the left front brake pads down to the backing plate, which caused them to overheat and melt. These were not Carbotech brake pads that failed. I have run a set of Carbotech pads to the backing plate and they did not "melt" like these pads did.

The melted brake pad allowed the caliper piston to push into the brake pad backing material which together with the excess heat caused the left front brake piston seal to fail (the brake fluid leaking out of the piston actually caught on fire). Brake pressure for the left front and right rear dropped to zero.

Photo of my brake pads after the brake failure last year:


The S2000 has a dual diagonal brake system, meaning if one circuit fails the opposite diagonal wheels will still have brakes. When my brake failure happened it felt like total brake loss to me with the pedal going to the floor, but I did have enough braking to slow from 80 down to 35 MPH to make the pit entrance. The video of my brake failure can be seen here: Rob's Brake Failure It does not appear Cale had even this much braking available.

The corner worker confirmed that the right rear corner of the car struck the end of the tire barrier with the rest of the car hitting the bare concrete wall. The car's right side hit the wall pretty much flat against the wall while still in the slide. I estimate the impact vector relative to the occupant at about 60-70 degrees right.

All the safety equipment was intact. The Sparco Evo seat, six point harness, custom four point roll bar and cockpit were not compromised and both airbags were deployed. After seeing the impact marks on the wall,and realizing the severe high speed side impact he took, I don't believe a head and neck restraint would have saved Cale's life.

Theory

With the corner worker confirming that the brake pedal was pressed (brake lights on), the lack of deceleration, the speed at impact, and the skid mark evidence, I now believe the brakes failed for a still undetermined reason. Cale began the turn to the right and then turned the car sharply to the left, perhaps to make the access road and its gap in the wall. Because of the excess speed he slid, put three tires in the gravel trap (the left front stayed on the access road) and overshot the access road. The car hit the wall on the far side of the access road. The corner worker said the car came completely off the ground after impact and bounced away from the wall. That is consistent with what I saw when I drove by the accident site--I could see the right side of Cale's car as it was away from the wall.

Recommendations

I plan to be more cautious with my brake rotors and pads. I've always run my rotors until they have small cracks and push my pads until the very end, going metal to metal several times. I had always assumed the rear rotors were bulletproof since they are solid and the rear brakes don't take as much abuse as the fronts, but that doesn't appear to be true. The rear rotors should probably be replaced at least annually.

While on the track if you are unable to make a turn and must go off track, it is usually best to go straight off into and through a gravel trap. Turning while going off track can lead to roll-overs or side impacts. The safety equipment in our cars is optimized for straight on impacts, especially if the airbags are still installed.

Invest in quality safety equipment. Although you can run on the track with just a stock car and a helmet, consider adding a roll bar, racing harnesses, racing seats, and a head and neck restraint. Many of us have already purchased head and neck restraints.

Rob Robinette

 

Thanks Rob, that pic actually helps clarify things. I am usually so focused on the line it has been hard to understand where Cale went.

We should petition BSR to extend the tire wall, if they are not doing so already.

 

I'm not by any means an expert on this matter but one thing that I have not heard or read yet is the possibility of emergency brake engagement. I wonder if during the moment Cale realized that the brakes was not working well that he momentarily engaged the emergency brake which probably jerked the car and caused the car to veer left?

 

Third gear is the normal Turn 1 entry gear, but if the brakes failed it's possible Cale was too busy trying to control the car to think about releasing the clutch.

The skid marks on the pavement were very uniform--all four looked like they were caused by the left slide. If the emergency brake was applied the rear skid marks would have been heavier.

 

Rob - I believe you are correct. In the heat of the moment sometimes you are powerless. it would be nice to be able to relive the moment and do something different!!!!


Budman - i had what may have been brake failure at VIR last summer at the end of the front straight on the last lap of a hot race.... i hit a bmw fairly hard (You can see the link from Eric Wongs camera on one of the threads) which slowed me way down... when I got towed back to pits my left rear rotor was missing but I thought it was due to contact. as this was happening my foot stayed planted on the brakes despite them not doing much.... It happens so fast that I wish I had thought to dump the car in a lower gear but......

I will never know if i had brake failure, as I have overcooked brake zones a few other times but at the time I sure seemed like I had no braking and was lucky the BMW was there (sorry bmw) to keep me from going off at a zilliion miles per hour...

Good out of bad - i think everyone we know is getting a Hans and I know I will either put my center net in properly (it is in there to pass tech right now but would do nothing) or buy a seat with the side wings. and people (me included) are paying more attention to rear rotors.... apparently they get way hotter than the fronts despite not doing nearly the work.

 

It seems that side nets and halo seats are the 2 options that are mentioned related to preventing neck injuries in side impacts. Cale had neither to my knowledge. I would like to know what role side nets play in minimizing side impact injuries. We'll never know if this would have made a difference for him, but it may help one of us in the future.

From my reading online, halo/containment seats seem like the best way to minimize side impact injury. However, a number of posts state that they would get in the way of egress through the window; an obvious problem in a fire. That leaves side nets. From what I see there are a couple issues with them.

1. Opinion seem mixed on whether or not they will actually help prevent neck injury. I believe HANS recommends their use as a way to complement the HANS device, but other say they are just to keep you/parts of you from flying to the left or right.
2. Can you attach a left net with a soft top?

 

Robs analysis sounds very logical. What a tragedy but the only way good can come of it is if the rest of us learn from it.

Any idea what kind of speed the car was traveling at impact? My guess would be whatever the turn in speed of turn 1 normally is, minus about 20-30 mph (from the slide). That's scary.