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Approximately 13,049 US C8s from 2020-2021 have potentially improperly cast wheels according to GM Service Bulletin N202315730. Here is the notice, and pics.:

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My buddy is taking delivery today so I will check his wheels out when I meet up with him and if I end up meeting him up at the dealership I will bring this up.

Agree. Certainly worth checking your wheels if you own a C8 either yourself or at the dealership.
 

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Thanks Kyle. Certainly puts an exclamation on it.
 

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It makes me wonder if it looks like that throughout the volume (I bet it does) and if those voids, if also present within the volume, cause the wheels to break more easily (logic coupled with physics says it would).
 

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Oh boy, here we go again. At least GM is admitting it this time. There is no excuse for such wheels to leave the manufacturing facility, and be shipped to the Assembly Plant, overlooked by QC, then installed as if everything is ok. Now, the worst part of this is we have only seen the surface of the wheel. What do you think is lurking beneath? Yup, loads of defects which should have been caught by fluoroscopy on the process line. Welcome to a new round of cracked/bent wheel issues.
 

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I would like to see GM stop dealing with the vendors who are supplying the inferior and defective wheels.
I have an order on a 2022 C8 and I am hoping and praying that GM would have fixed all the issues on the C8 by then and I want to receive a beautiful trouble free built.
How could GM accept such inferior junk wheels?
Shame on GM and all their horrible vendors who are supplying junk parts.
Bottom line is that GM is throwing all these difficult issues on the poor owner.....not fair at all.
 

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Indeed JohnUSA, you raise come good points. It is a conundrum.
 

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Oh boy, here we go again. At least GM is admitting it this time. There is no excuse for such wheels to leave the manufacturing facility, and be shipped to the Assembly Plant, overlooked by QC, then installed as if everything is ok. Now, the worst part of this is we have only seen the surface of the wheel. What do you think is lurking beneath? Yup, loads of defects which should have been caught by fluoroscopy on the process line. Welcome to a new round of cracked/bent wheel issues.
Consider this: GM expected that 90% of vehicles inspected will not have a single wheel replaced (see note below ***). I think that customers which have all four wheels with visible defects on the surface are the lucky ones, and that the unlucky ones are those with one or more wheels which have internal defects which are not visible on the surface...

*** One of the images which Jeff posted to start this thread says that GM "estimated that only 10% of vehicles involved will require parts replaced." That implies that each wheel will be inspected individually, and, on a wheel-by-wheel basis, will get replaced if there are surface defects which can be seen. I wonder if they will take the tires off and look for defects on the inner surfaces of the wheels...
 

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like I said, there are supposed to be built in quality checks. This is not a hidden defect! It's as if people knew about it and simply ignored it every step of the way. First, at the casting line. Next, at the shipping location. Next, at 'receiving' at Bowling Green. Next, on the assembly line where workers clearly would have noticed the obvious defects. Next, at final vehicle inspection.

Every OEM wheel casting facility I toured back when I worked in engineering was required to install porosity testing equipment on the line. Wheels that did not meet specification were spit out and re-melted. It's nearly impossible to eliminate all porosity, however, there are high standards that can be met with proper control of the casting process. Porosity to the extent shown in these wheels clearly indicates careless control of temperature during cooling, something that is well known and easily minimalized in the industry.

I do not know if GM is using the same wheel supplier as the C7, but it appears they may have changed sources for the C8. If so, it baffles me that their wheel Lead Engineer approved the vendor based on what I see in the pictures. I suspect the Purchasing Department over-ruled 'quality' in favor of lower cost...throwing the engineering team under the bus. So common in the automotive industry.
 
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