switchface

Hmmm, interesting thought process, I guess that makes sense. Still, if these are indeed a weak point, even if they tend to be more prolific on the curb-side, potholes happen everywhere, so you'd think we'd have heard of one on the driver's side by now.

Sorry to all of those that are having to deal with this. Please keep us posted if Porsche or your insurance covers the repair and what it ends up costing. Best of luck.

sonorous

I tend to agree with this theory. I believe that these failures are fatigue. I am a mechanical engineer but not a fatigue expert. In any case, fatigue fractures can occur in metals when the structure is exposed to cyclic stresses. These stresses can be much lower than the rated tensile or yield strength of the material. The cracks start at a microscopic level and then propagate slowly. Eventually they hit a critical point and fail catastrophically. The Wikipedia page on fatigue actually has a pretty good summary. https://en.wikipedia.org/wiki/Fatigue_(material) The geometry of the structure plays a huge role in fatigue sensitivity but also the material used and variations in that material such as porosity. Since this is a cast component, porosity is certainly a variable to consider.

Cyclic stresses would likely be more frequent and of higher amplitude on the right side of the road at least in the US.

Also this quote is kind of interesting in relation to how the failures have manifested in the real world:

venom51

It is quite frankly the same as flexing the bottom of a beer can. Eventually it will tear.

Arcanum

The strut tower failures in the UK are on the right-hand side as well. As the UK drives on the other side of the road from the US it would seem more likely that the right-hand side of the car is structurally weaker than the left.

sonorous

That is actually not completely the same if I understand the example correctly. FWIW what you describe is similar to bending a paper clip back and forth until it breaks. In that case the material is being physically deformed creating stress greater than yield strength. This stress work hardens the material making it more brittle with each bend. This type of failure is actually very predictable and repeatable. In the case of fatigue, yield stress is not exceeded. The crack manifests and grows very slowly over time after a very high number of smaller amplitude cycles. It is very difficult to predict and can be random in occurrence.

venom51

Makes you wonder why they thought this was only necessary in the rear of the car.

ajw45

Yes! That's it, the piece that's riveted into the rear strut mounts. Any idea what the part number is? Would love to order both sides and see if that could be modified to fit.....

Former BMW

I need to verify the aftermarket suspension parts but I think it was limited to linkage allowing for more camber adjustment using shims.on the lower control arms. Springs and shocks are all stock. Wheels are 20" stock (because of PCCB). Tires are Michelin Pilot Sport Cup 2's.

Former BMW

Update on latest GT4 strut tower failure:

I heard back from the track insurance broker today. He said coverage wasn't likely because there was no accident. Mechanical failures are not covered especially if it is a known problem. I guess I would have been better off if the failure had caused me to slam the car into a barrier. Not looking too good for an inexpensive fix right now. Probably time to call the dealer to start the repair process and see what Porsche position will be.

d00d

recall number two

sonorous

This failure puts you in a very unfortunate insurance grey area. This is kind of a worst case scenario with this failure mode. Track insurance not covering it because it was not an collision, road insurance not covering it because it was on track, and Porsche not covering it because they have not covered any other yet and that would be an admission of design flaw.

Have you tried your road insurance? I seem like if road insurance have covered other failures reported here that either your road or track insurance should cover it. You might have to lawyer up at some point. With the repair costs noted on RL, it is enough to warrant legal action IMHO...

okie981

Back to my post #839 above. This issue really needs a sticky and a managed database (spreadsheet) with details of failures like the 3rd gear failure thread. The 3rd gear issue is now an official Porsche recall. If the strut tower fractures were collected in an organized manner, it would benefit the Porsche owner community. As some posted earlier in this thread, they were concerned this was a fluke issue and if it were a sticky it would stain the reputation of the 981/991 GT cars. IMO, enough of these have occurred there should be some organized data with visibility, in a sticky thread. I would rather head toward understanding the cause so a solution or workaround can be developed.

domkrz

Another one bites the dust...

venom51

I haven't been able to locate a part number. I am sure there is one but since this is likely only ever to be replaced by a body shop it may come bonded to that rear structure and may not be available separately.

ajw45

+1. This or a new tracking thread as a sticky.