Studs are very common on race cars. They make quickly changing wheels/tires at the track much easier & simpler.

 

I was curious if it was due to reliability as my J-class 996 lug bolts have 110,000 miles on them. In 18 years of club racing I have yet to see something like Ritter's failure! Yikes!

 

Ritter - when you say you have the car "nut and bolted" after each weekend, are you actually re-torqueing various hardware elements on the car, or just checking the paint marks to see if they are still in position? I'd imagine re-torqueing the hardware numerous times per year will result in hardware/fastener fatigue and not be a favorable practice. Just curious!

 

Both. Visual to check for movement and retorquing depending on the bolts.

 

wow, glad your okay and that explains the 5laps vs the rest of the field

 

I remember a few years back being parked next to a certain dromaeosaurid, who experienced a stud breaking off....and then another....and another, while he was changing tires - scared the bejesus out of me. Always change studs every year now...well until I got this bloody CL system.

 

Yes, that would be Yours Truly. And you get 5 bonus points for correct use of the poindexterish big word

 

I had a similar experience with my former 968 track car. I decided to replace all the studs not knowing how many hours were on them and to avoid a disastrous outcome.

 

Alternate Theory:

Maybe the brake rotor failed first (when you felt the "clag") and then when you hit the brakes the center of the rotor interfered with the main part of the rotor and that tore up the studs.

It seems odd to me that if the 5 studs just broke, why would the center of the rotor gotten destroyed? I assume you hit the brake and that should have stopped the rotor.

Just thinking...

 

That's a blessing to not have anything worse happen, Barber doesn't have lots of runoff room. But thank goodness it wasn't Road Atlanta with much bigger speeds.

Those look like the exact same studs I just got. Certain to be replaced yearly for sure!!!!!!!

 

Seems like a possibility to me. It almost looks like all five studs broke simultaneously which is not how I would expect a stud failure to happen.

 

Very plausible

 

Glad you came out ok.

 

I do mine every two years. Don't over torque them and never torque them hot. I check tire pressures after a session and do bolt torque before a session. If you are worried about forgetting, leave the torque wrench in the driver's seat. I also inspect the wheel for cracks when I torque.

The face of the rotor coming apart is weird, but I'm not all that familiar with Porsches. It's also odd that the fracture points are below the surface of the hub. How did the bolts shear, but manage to keep the face of the rotor attached to the wheel? Is the rotor threaded? How is the brake rotor face staying attached to the wheel?

Perhaps the studs are bent and the resulting friction is what is holding the rotor face to the wheel? If the studs are bent, that seems to indicate the studs failed first, perhaps bound onto the rotor face and tried to pull it off from the wheel loading. Rotor faces are not really strong when being pulled away from the hub. I've pulled rotor faces off while trying to remove stuck rotors and it didn't take a lot of force to do it. The only thing holding the rest of the rotor on the car is the brake caliper.

-Mike

 

Yeah it's weird. Detailed pictures of the fracture surfaces of all studs and the rotor would likely tell which part failed first and by what mechanism.