strut tower failure
12-16-2016, 02:02 PM
#256
Rennlist Member
Bad batch with porosity, ride height, damper design, etc—a lot of maybes.
It will be interesting to see what the real reason is in time, because it will come along sooner or later.
It will be interesting to see what the real reason is in time, because it will come along sooner or later.
12-16-2016, 02:10 PM
#257
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I have purchased a brand new shock tower, driver's side, and will have it next week. My plan is to get a scanned 3D model into a stress analysis software tool and examine effects of different loads, camber plates, etc..
Stay tuned to this bat channel.....
Stay tuned to this bat channel.....
12-16-2016, 02:19 PM
#260
12-16-2016, 02:25 PM
#261
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Unfortunately this Strut Tower is a restricted Porsche part and we will not be able to complete this transaction. We will issue you a full refund and apoligize for the inconveince.
(spelling errors pasted as-is)
Hmmm.... So I'll go to my Porsche dealer next and see what they can do. Will cost me about $20 more, but if they'll sell it, so be it.
12-16-2016, 02:49 PM
#263
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See my post above, order was canceled and refunded by first parts supplier, an interweb parts house that sells OEM Porsche parts.
I called a Porsche dealer, and ordered the part, is supposed to be in my hands middle of next week. If that somehow falls through, I have another option to obtain a new part.
I called a Porsche dealer, and ordered the part, is supposed to be in my hands middle of next week. If that somehow falls through, I have another option to obtain a new part.
12-16-2016, 03:53 PM
#264
https://rennlist.com/forums/gt4/8931...de-height.html
12-16-2016, 05:40 PM
#265
Joe, do you know how much you lowered it? thanks carl
https://rennlist.com/forums/gt4/8931...de-height.html
https://rennlist.com/forums/gt4/8931...de-height.html
12-18-2016, 06:57 PM
#267
Rennlist Member
I have taken few pictures of both my 2016 GT4 & 2016 Spyder, shock tower. Please see following link to access pictures. https://www.icloud.com/sharedalbum/#B0YJ0DiRHJuI3Um
As I mentioned before my wife drove our 981 Boxster S on a curb at at least 40 mph and severely damaged both drive side wheels & tires (front &aback). Actually the front tire had a 3" cut from the impact and front wheel fractured in 2 different locations, and yet nothing happened to shock tower. We drove the car for 2 years after this incident without any issues. Bottom line I can't accept that driving over a pothole can cause this much damage considering my wife drove over a curb at high speed and destroyed the wheels & tires and no such damage ever occurred.
Sure Joe's car could had a bad casting which is still possible, and if Joe is willing to send me the broken shock tower for few days (of course after it is removed during repair), I am willing to run EDS analysis (scan) on the part and see if there is indeed a material's defect and send him the report signed & certified by PE. Or possibly an improper heat treat which results in a brittle part but we should be able to spot that during an EDS scan.
But I keep coming back to OKIE981's observation a while back about The GT4 upper strut design, and in particular the mounting plate. He pointed out the upper plate is smaller than normal cayman and doesn't cover entire mating surfaces on shock tower. This is the reason I have taken few pictures of both my GT4 & Spyder. Here are some of my observations:
1- as OKI981 pointed out the current GT4 upper plate does not cover entire mating seating area, leaving roughly 30% of the seating area not utilized and results in higher stresses. If you look at the pictures I posted of both GT4 & Spyder you can see that very easily.
2- the GT4 shock centerline is offsetted towards the back(firewall) compared to the Spyder where the shock centerline is much more centered. Hence the forces transmitted through the GT4 shock mounting is acting towards the rear of the shock tower and results in an offset loading.
3- upon close examination of the shock tower seating (mating) surfaces, I discovered these surfaces are not machined surfaces on my GT4. The seating area has so many micro casting flashings allover the seating area, which means it was never machined. If you zoom on some my of pictures you should be able to see them. Granted the seating cast surface appears to be flat and mostly clean of flashings. But this combined with smaller seating area and an offset load will further complicate the situation.
I thought to share some of these observations with you. Until we run a full stress analysis on the part we would never know for sure, as OKIE981 pointed out, and as he is planning to do which I am really excited to see. Mark
As I mentioned before my wife drove our 981 Boxster S on a curb at at least 40 mph and severely damaged both drive side wheels & tires (front &aback). Actually the front tire had a 3" cut from the impact and front wheel fractured in 2 different locations, and yet nothing happened to shock tower. We drove the car for 2 years after this incident without any issues. Bottom line I can't accept that driving over a pothole can cause this much damage considering my wife drove over a curb at high speed and destroyed the wheels & tires and no such damage ever occurred.
Sure Joe's car could had a bad casting which is still possible, and if Joe is willing to send me the broken shock tower for few days (of course after it is removed during repair), I am willing to run EDS analysis (scan) on the part and see if there is indeed a material's defect and send him the report signed & certified by PE. Or possibly an improper heat treat which results in a brittle part but we should be able to spot that during an EDS scan.
But I keep coming back to OKIE981's observation a while back about The GT4 upper strut design, and in particular the mounting plate. He pointed out the upper plate is smaller than normal cayman and doesn't cover entire mating surfaces on shock tower. This is the reason I have taken few pictures of both my GT4 & Spyder. Here are some of my observations:
1- as OKI981 pointed out the current GT4 upper plate does not cover entire mating seating area, leaving roughly 30% of the seating area not utilized and results in higher stresses. If you look at the pictures I posted of both GT4 & Spyder you can see that very easily.
2- the GT4 shock centerline is offsetted towards the back(firewall) compared to the Spyder where the shock centerline is much more centered. Hence the forces transmitted through the GT4 shock mounting is acting towards the rear of the shock tower and results in an offset loading.
3- upon close examination of the shock tower seating (mating) surfaces, I discovered these surfaces are not machined surfaces on my GT4. The seating area has so many micro casting flashings allover the seating area, which means it was never machined. If you zoom on some my of pictures you should be able to see them. Granted the seating cast surface appears to be flat and mostly clean of flashings. But this combined with smaller seating area and an offset load will further complicate the situation.
I thought to share some of these observations with you. Until we run a full stress analysis on the part we would never know for sure, as OKIE981 pointed out, and as he is planning to do which I am really excited to see. Mark
12-18-2016, 07:03 PM
#268
I have taken few pictures of both my 2016 GT4 & 2016 Spyder, shock tower. Please see following link to access pictures. https://www.icloud.com/sharedalbum/#B0YJ0DiRHJuI3Um
As I mentioned before my wife drove our 981 Boxster S on a curb at at least 40 mph and severely damaged both drive side wheels & tires (front &aback). Actually the front tire had a 3" cut from the impact and front wheel fractured in 2 different locations, and yet nothing happened to shock tower. We drove the car for 2 years after this incident without any issues. Bottom line I can't accept that driving over a pothole can cause this much damage considering my wife drove over a curb at high speed and destroyed the wheels & tires and no such damage ever occurred.
Sure Joe's car could had a bad casting which is still possible, and if Joe is willing to send me the broken shock tower for few days, I am willing to run EDS analysis (scan) on the part and see if there is indeed a material's defect and send him the report signed & certified by PE. Or possibly an improper heat treat which results in a brittle part but we should be able to spot that during an EDS scan.
But I keep coming back to OKIE981's observation a while back about The GT4 upper strut design, and in particular the mounting plate. He pointed out the upper plate is smaller than normal cayman and doesn't cover entire mating surfaces on shock tower. This is the reason I have taken few pictures of both my GT4 & Spyder. Here are some of my observations:
1- as OKI981 pointed out the current GT4 upper plate does not cover entire mating seating area, leaving roughly 30% of the seating area not utilized and results in higher stresses. If you look at the pictures I posted of both GT4 & Spyder you can see that very easily.
2- the GT4 shock centerline is offsetted towards the back(firewall) compared to the Spyder where the shock centerline is much more centered. Hence the forces transmitted through the GT4 shock mounting is acting towards the rear of the shock tower and results in an offset loading.
3- upon close examination of the shock tower seating (mating) surfaces, I discovered these surfaces are not machined surfaces on my GT4. The seating area has so many micro casting flashings allover the seating area, which means it was never machined. If you zoom on some my of pictures you should be able to see them. Granted the seating cast surface appears to be flat and mostly clean of flashings. But this combined with smaller seating area and an offset load will further complicate the situation.
I thought to share some of these observations with you. Until we run a full stress analysis on the part we would never know for sure, as OKIE981 pointed out, and as he is planning to do which I am really excited to see. Mark
As I mentioned before my wife drove our 981 Boxster S on a curb at at least 40 mph and severely damaged both drive side wheels & tires (front &aback). Actually the front tire had a 3" cut from the impact and front wheel fractured in 2 different locations, and yet nothing happened to shock tower. We drove the car for 2 years after this incident without any issues. Bottom line I can't accept that driving over a pothole can cause this much damage considering my wife drove over a curb at high speed and destroyed the wheels & tires and no such damage ever occurred.
Sure Joe's car could had a bad casting which is still possible, and if Joe is willing to send me the broken shock tower for few days, I am willing to run EDS analysis (scan) on the part and see if there is indeed a material's defect and send him the report signed & certified by PE. Or possibly an improper heat treat which results in a brittle part but we should be able to spot that during an EDS scan.
But I keep coming back to OKIE981's observation a while back about The GT4 upper strut design, and in particular the mounting plate. He pointed out the upper plate is smaller than normal cayman and doesn't cover entire mating surfaces on shock tower. This is the reason I have taken few pictures of both my GT4 & Spyder. Here are some of my observations:
1- as OKI981 pointed out the current GT4 upper plate does not cover entire mating seating area, leaving roughly 30% of the seating area not utilized and results in higher stresses. If you look at the pictures I posted of both GT4 & Spyder you can see that very easily.
2- the GT4 shock centerline is offsetted towards the back(firewall) compared to the Spyder where the shock centerline is much more centered. Hence the forces transmitted through the GT4 shock mounting is acting towards the rear of the shock tower and results in an offset loading.
3- upon close examination of the shock tower seating (mating) surfaces, I discovered these surfaces are not machined surfaces on my GT4. The seating area has so many micro casting flashings allover the seating area, which means it was never machined. If you zoom on some my of pictures you should be able to see them. Granted the seating cast surface appears to be flat and mostly clean of flashings. But this combined with smaller seating area and an offset load will further complicate the situation.
I thought to share some of these observations with you. Until we run a full stress analysis on the part we would never know for sure, as OKIE981 pointed out, and as he is planning to do which I am really excited to see. Mark
Joe
12-18-2016, 07:09 PM
#269
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12-19-2016, 10:15 AM
#270
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Thanks for those photos and comments on your observations Mark. One necessary step in my process of analyzing the part is to have a certified metallurgy lab determine the specific aluminum alloy used and if there is any post processing (heat treat, etc.). This requires a 2 sq. in. piece of the part. I'm not sure if they can use the whole part without damaging it, or if I'll need to sacrifice a small piece of it after I get the 3D scan complete. I'll use the lab results to enter the material properties into the FEA software tool. it will be interesting to see how your material analysis of Joe's broken part compares to the new part I'll have analyzed by a different lab.