When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Some quick thoughts as a mechanically minded person—but no engineer!
This is where some thoughts from someone like PeteVB or Linton would be interesting to get. There are other very bright minds here with experience in this area, too. Keys would be to come up with the thinnest/strongest solution possible—which would to me suggest carbon-fiber. If we are talking about something washer-thin, I wouldn't hesitate to install it and I wouldn't worry about shortening dampers, etc. That's well within the tolerance of ride height...or if I had to raise the rear by a washer to match the front end that's a washer higher, I'd happily do it.
I had the same thoughts about the thickness. Taking away 1-2mm for a cup insert would hardly change anything to the suspension travel.
Originally Posted by O5C4R
I've done 6 Tarmac Rallies (and a lot of track days) and both the front and rear shocks have bottomed out, coil bound, massively 100's of times on very bumpy closed roads, I simply cannot believe my car's in one piece after reading this thread ( I hope I haven't jinxed myself). On these rallies there a 2 people in the car, I have a full cage, fire extinguishers etc and with a full tank the car weighs in total 1600kgs. that's on the heavy side and the strut towers have held up. As its a cast mount there must be variations in the quality of the casting for a pot hole to do this to some cars.
Last year due to the front shock hitting the bump stops so much with so much force I installed longer travel Tractive Shocks, this may have been saving my car for the last 4 tarmac rallies.
anyone have any feedback on the SP motorsport solution? it looks like the strut tower would just peel away regardless doesn't it?
That is reassuring and might suggest that the problem could be a bad batch of material, or a production problem. Maybe stress cracks in the stamping on some cars? Just some wild guesses. I also realized and it should be emphasized, that internet forums blow this stuff way out of proportions. Yes, it is worrisome, but only to a certain extend. Chances are slim that it will happen to any of us.
Originally Posted by Switchfoot614
With anything cast, chemistry of the metal and heat treatment determine the final strength. The least destructive way to determine what each chassis has in place would be to verify the hardness. Equotip though not widely accepted as being repeatable is the least intrusive followed by rockwell. To really understand, a destructive sample would have to be extracted and charpy impacts performed. If anyone who has experienced a failure can obtain a sample of the broken strut tower, I'll take it from there. If we have low impact resistant strut towers in our cars, a reinforcement really won't do much to prevent the failure unless it essentially replaces the entire strut tower and ties back to sound material.
I'm pretty sure the strut tower is a stamping not a casting, but regardless, I agree with the idea that it could be a material inconsistency that makes some of them weaker. I own a machine shop and every once in a blue moon we get a bad batch of material. In the 30 years that I have been in the industry, I have only seen it a handful of times, but it does happen. This is where traceability to material certs comes in handy, and every car manufacturer needs adhere to those standards, so if Porsche is made aware of the few cases, and traces them back to one batch of shock tower mounts ,then they should be able to determine, or rule out, if it is in fact so.
Do we know how many failed so far and what production date they were?
I'm pretty sure the strut tower is a stamping not a casting, but regardless, I agree with the idea that it could be a material inconsistency that makes some of them weaker.
The front and rear strut towers on 981 and 991 cars are definitely cast aluminum. They are not stampings.
The front and rear strut towers on 981 and 991 cars are definitely cast aluminum. They are not stampings.
Thanks for clarifying. That surprises me. Never thought a part like that would be made from a casting. That definitely raises the likelihood of a production failure a lot. Much more plausible of something going wrong with a casting, compared to a stamped part.
^ Something else to consider here is mating surface of the strut top with the strut tower. Agree that "forum example" math is obscenely disproportionate, but the examples are also real and cannot be ignored (esp give cost of repair), but it seems most of the failures seen have been a very small number of GT3s (1-2) and a small number of GT4s (how many now?), which are "extreme use" vehicles and which also use a strut top that is different to the one in non-GT cars. Perhaps the mating surface is worth considering, as the only non-GT car I can think of that had this happen...if I recall correctly, was lowered on aftermarket suspension and (I think?) went over a curb at a high rate of speed with other damage resulting.
In any event, there are some good thoughts here and I think what people are after is some peace of mind.
With anything cast, chemistry of the metal and heat treatment determine the final strength. The least destructive way to determine what each chassis has in place would be to verify the hardness. Equotip though not widely accepted as being repeatable is the least intrusive followed by rockwell. To really understand, a destructive sample would have to be extracted and charpy impacts performed. If anyone who has experienced a failure can obtain a sample of the broken strut tower, I'll take it from there. If we have low impact resistant strut towers in our cars, a reinforcement really won't do much to prevent the failure unless it essentially replaces the entire strut tower and ties back to sound material.
I just asked my service advisor to ask the tech to keep the strut tower. I'll take you up on this offer.
This is what caused my failure. It would have likely caused damage to most sports cars. It's still a shame that the point of failure is the strut tower on ours. This was on I35 southbound in Dallas.
This is what caused my failure. It would have likely caused damage to most sports cars. It's still a shame that the point of failure is the strut tower on ours. This was on I35 southbound in Dallas.
While that is a bad road for sure, I would never have expected it to cause that kind of damage. Is your car on stock suspension? What is the build date?
While that is a bad road for sure, I would never have expected it to cause that kind of damage. Is your car on stock suspension? What is the build date?
This is what caused my failure. It would have likely caused damage to most sports cars. It's still a shame that the point of failure is the strut tower on ours. This was on I35 southbound in Dallas.
An ugly pothole but should not have caused a strut tower failure. Did you try an insurance claim? Porsche warranty? What were their responses?
Man, that's a bad hit—and a bad place for a rock to be in general, let alone for a competitive event. There's a part of me that loves that there's still an event like this out there—and a part of me that says that rock should have been blasted out of there eons ago.
But that guy Tony Quinn might just win for more agreeable, coolest competitor ever. Talk about shrugging it off. Inspiring...
02-22-2019, 11:27 AM
