I had a rather bad experience with my Cayman at VIR today and thought I would share my experience for the benefit of my fellow track rats. I haven't been posting very much on RL since my GT3 came to an untimely end at Road Atlanta last year (downsizing to a condo has also consumed a good bit of my time as well.) My GT3 .2 is slated to arrive in January and after I've been driving my Cayman S on the track in the interim. I'm posting in the GT4 forum since I've modded it to be more like a GT4 than a Cayman S. The Smokies gang knows it as the franken-GT4. The car has been mostly incident free until today (track day 61) and with the mods I've made I've been running good times at Barber, Road Atlanta and VIR. I ran a 2:04 this morning at VIR and had a few predictive 2:03s until I hit traffic.

About 25 minutes into the first session today I had a catastrophic brake failure coming into turn 4. Had it happened on the back straight, I'd probably be in the hospital or morgue right now. The front driver's side caliper bolt dislodged from the upright which caused my caliper to come undone, which in turn tore up my wheel and tire. The caliper bolt still has all its threads, so the issue wasn't with the bolt or caliper. As many have noted, changing brakes frequently can be an issue when you have to take your calipers off and they are secured to an aluminum upright. In the incident today, it all happened relatively quickly, and it left a gaping hole in my tire and meant I was reduced to driving on 3 tires. BTW - the car pushes a bit in this situation - not recommended. A perfect weather weekend at VIR is shot; next weekend at Road Atlanta is shot; but hey, at least I'm alive.

My Cayman S has the GT4 bodywork, DSC controller, tractive coilovers, tarret suspension bits (drop links, toe links, solid bushings), R7 tires (235/295), race headers, plenum, TB, Cobb tune (engine and PDK). Compared to my GT3, I'm faster through most corners and only lose time on the straights. BTW - the recent Cobb PDK tune is awesome; my upshifts and downships are dramatically crisper than the stock setting and much more like my GT3.

Which brings me to the main lesson learned I want to share. If you are tracking your car a lot (in my case, today was track day 61 with the Cayman), I'd suggest you do two things: 1) put in caliper studs so you avoid the specific issue I had, and 2) look at the Clubsport maintenance schedule and decide what items are considered "consumables" if you are driving the car really hard. This may seem obvious to many of you, but it wasn't for me. The car had run great and never had an issue so I got complacent. The light bulbs should have gone off when I snapped an axle in my GT3 and some folks on RL said this just doesn't happen. Well, it does, and axles are considered consumables on cup cars. The uprights, where the caliper bolts attach, are also considered a consumable in cup cars, but not in street cars. I'm now refactoring all my expense costs based on my incident today, and have come to the realization that I should have just bought a real race car if I planned to drive at this frequency and at this level. The costs would have been a bit higher, but I'd least I'd be a lot safer with a full cage.

I spec'd my .2 GT3 as more of a street car, with lots of leather and PCCBs since I was already considering a move to a dedicated track car. Today probably sealed the deal - I'm headed in the direction of a real race car and a real race car maintenance schedule. I got really lucky today and I hope this post causes a few others to rethink their trajectory and move to a safer game plan.

 

Well, maintenance is one thing, but the standard brakes are very different from GT4 brakes (tell me, I used to track a Cayman R before I moved up to the GT4). Glad nothing happened to your health!

 

I think the issue is clearly applicable to a GT4. The Clubsport comes with caliper studs, as do the cup cars. The GT4 has a regular caliper bolt that attaches to the aluminum upright, just like my configuration. BTW - I upgraded my front brakes to 991S calipers and I run RT RE10 pads. The brake performance has been excellent, with no fade at all and great modulation. I just forgot one critical step in the upgrade.

 

Crazy, thanks for sharing the lessons learned. So the upright threads were completely stripped out? Do you think this happened during a brake change where it was cross-threaded or over-torqued?

 

^ This... You had a bolt backout? Who was last on this bolt? Was a torque wrench used?

 

Glad you are OK Rich. Good lesson for the rest of us.


Tal

 

Great post, people only think of tires and brakes as consumables, but everything has a life cycle.

How many track days or miles per year are you experiencing?

 

yes, the upright threads were completely stripped out but the bolt had all the threads intact. The caliper bolts were torqued properly at the last change and no issues were noted. You can always second guess a maintenance event, but my main point is that had this been a Clubsport, the uprights would have had caliper studs and they still would have been swapped out well before this many track miles.

 

I've had a similar experience when tracking my 997.2 wearing out components that nobody had trouble with that tracked recreationally. Not an upright thank goodness, but still just the same conclusion. If you track hard, buy a race car and keep it maintained per race car maintenance recommendations.

For this reason I don't track my street cars any longer, and happier (as well as safer) for it!

 

I'm doing around 20-30 track days per year.

 

Glad you are OK!
The caliper bolts are supposed to be a one-time use item. They are a torque-to-yield part.
Studs are far better of course.

 

Yes, I replaced caliper bolts on a regular basis. They still had their threads. What stripped was the aluminum threads in the uprights - the female part of the equation.

 

Rich,
Glad you are alright. Installing studs is good advice. I put them in the GT3 and 4.

 

Yikes. Glad you are ok as well. I still can't figure out why Porsche stopped the easy in/out brake pads that stopped with the 997/987

 

Agreed!!