Atgani

Precisely this ^ Whoever supplied/s the GT4 gearboxes picks up the tab for the warranty costs. If Porsche admit liability in any way shape or form for the strut tower failure, they open the floodgates whereby every GT2/3/4 owner will demand replacement/updated/strengthened parts.
As is usual with Porsche AG, they hope the problem will "go away", threads such as this one and similar threads on PistonHeads in the UK are their worst nightmare. It will only take one serious injury or worse .... and the the floodgates WILL open.
BMW seem far more responsible with their recalls, the E46 rear subframe mount cracking issues were dealt with properly, the current F30 EGR cooler pipework is also being addressed properly, and let us not forget the thousands of V8 and straight 6 Nikasil blocked engines they replaced, all without any drama.

sonorous

This is more speculation but automotive supplier contracts typically have an "epidemic failure" clause. This clause identifies a failure rate when a supplier has to take ownership of some higher level of cost including warranty repairs. It could be something like 3% failure but it varies by contract. So with the transmissions Porsche only needed to wait until the failures hit the threshold and then the supplier is liable for the costs.

If this failure is design related, then it is likely on Porsche. But if somehow this is related to a manufacturing quality defect, and some parts are weaker than others, then perhaps Porsche is just waiting for the failure rate to hit the threshold and then they can bill it to the casting supplier. I doubt Porsche casts this part themselves...

d00d

I would say the choice of specifying a casting is all on Porsche, it could have been a forged part instead, or at least they could have reinforced it with a steel insert like the rear.
A transmission is more of a generic part in which it's mainly up to the supplier to choose materials.

sonorous

The choice of material is a design decision. I agree with you. Forged would be crazy expensive but a steel insert would have added plenty of design margin and prevent these failures.

I am simply saying, that we do not know the true root cause of the failure. Casting as a process does have the potential for variation in grain structure and porosity that can impact strength. So it is a possibility until proven otherwise. If that is the root cause, then Porsche could shift liability to the supplier.

If they had added steel inserts it would have masked any variation in strength by adding significant design margin and we would not be having this issue at all even under severe track conditions.

unclemat

It's only GT4 cars now, and mostly track driven from what I understand. I wondering if over time, maybe a long one, the failures will start appearing in street driven non-GT4 cars due to metal fatigue.

d00d

I agree with your points, and choosing a material that has the potential for variability wasn't the best decision.

suterusu

There have been multiple 991.1 GT3 reports as well.


Side note, have any of these failures been reported to the NTSB? Definitely a safety issue for those instances of it happening on the street.

trkshoe

From what I can tell... the failures appear to be 50/50 (GT3 to GT4).

What I would love to know is if ride height had been tinkered with/lowered on the failure cars, and if there were any aftermarket parts involved (aka shocks/springs).
The opinion of some (more knowledgeable that I) is that spring rates and bottoming out are the primary factor.

I for one will be changing to stiffer linear springs and perhaps large bump stops.

noddy981

Same being said in the UK on Pistonheads forum :

"As these failures are likely to lead to total failure of the steering and brakes, hence leading to total loss of control of the vehicle on the road, these failures ought to be brought to the attention (in the UK) of the Driver and Vehicle Standards Agency (DVSA) for investigation by them. The same ought to be happening in the USA with their appropriate vehicle authority. Details of the postings on this site together with those on Rennlist should suffice to highlight the situation."


jimPH

842 posts

22 months




[report]

911F1

A few people have mentioned that they hope this structural fault has been addressed on the new 718 GT4. My guess is yes, but Porsche isn't going to say
so because that admits guilt for the 981.

noddy981

A glance up into the front wheel arch of the 718 Gt4 will soon see if anything has been changed or added to the strut tower.

On another note, has anyone ever seen a 718 Boxster or Cayman with a broken strut tower, as these were going down the body shop production line at the same time as the original GT4s and therefore must have been utilising the very same batches of strut towers?

ducktails

This is a serious problem that could well cause an accident during spirited driving on-road, but I think claiming total failure of all steering and brakes is going a bit overboard.

d00d

I've had suspension collapse happen on two cars, luckily both at low speeds.
Based on the level of surprise and degree of effort required to recover, if those had happened at higher speed there could have been seriously dangerous outcomes.

noddy981

+1

gbeaty

Some people on this thread are stating the front struts have no bump-stops. If true, this would be 1) really dumb, and 2) present an easy fix for this problem.

Bump-stops in inverted struts are usually internal. Has anyone disassembled a factory strut to see if it has a bump stop?