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Yes, there was a poll here some months back on cracked bent wheels by model type, and the GS wheel recorded far more damage reports, followed closely by the Z06 wheel. Z51 wheels had very few reports of damage.
The spokes on the Z51 design are much thicker, and I can't help but think that makes them sturdier.
Yes, there was a poll here some months back on cracked bent wheels by model type, and the GS wheel recorded far more damage reports, followed closely by the Z06 wheel. Z51 wheels had very few reports of damage.
The spokes on the Z51 design are much thicker, and I can't help but think that makes them sturdier.
It’s the wheel width of the gs/Z06 wheels combined with the cheap manufacturing process.
The spokes on the Z51 design are much thicker, and I can't help but think that makes them sturdier.
That's good to know, as I hate dealing with bent wheels (my wife's BMW has two that are badly bent and my C5 and C6 both had slightly bent wheels that could never be properly balanced (obviously) So the strong Z51 wheel design (which was the standard issue wheel on my base model 2018) combined with the softness of the base suspension hopefully means I'll never have to deal with bent wheels on my C7.
As long as you keep your autocross skills sharp. I do a lot of autocrossing around potholes on our worst roads. Even the strongest forged wheel can be taken out by a particularly nasty pothole.
I could care less about Tadge, the wheels cracked and bend easily. It’s well documented. This is specifically on the GS and z06 not z51
Originally Posted by swaite
It’s the wheel width of the gs/Z06 wheels combined with the cheap manufacturing process.
GM has the data. Have seen comments that they don’t know what has been replaced but I would think most folks complain to the dealer so expect they have enough to support their “same percentage” comments. Expect the large increase in wide wheels are a factor with half the sales going to the Grand Sport with few now buying Z51s.
I also don’t agree that rotary forging is a “cheap” manufacturing process! Lots of cold work that strengthens the rim. It is the width that is the issue. Also agree with Foose comment. From my observation the spokes on my optional Machined Faced Aluminum wheels do “look” somewhat stronger than the base GS wheels. Realize that is subjective but an educated opinon.
It appears GM could benefit by increasing the spoke and perhaps barrel thickness. They could also go to a rim construction technique I saw at Honda, albeit for ATV production. Friction Stir Welding a rolled up barrel! Could even use very high strength aircraft 7000 series aluminum as that welding process does not reduce the very high strength HAZ like arc welding!
I have found Tadge is a straight shooter and really appreciate his posts. You may not agree with his analysis but he has the data and may use some marketing hedge words but, in this case it was an excellent post, IMO.
PS: This is some data on 6061-T6 forged wheels material versus some 7000 series aluminum. 45,000 psi tensile strength for the 6061-T6 forged wheel versus 85,000 psi for some 7000 series alloys. Typically the aerospace folks avoid welding and just machine from a sold stock but with Friction Stir Welding it can and is being done! Like solid fuel rocket motor cases!
It is not subjective that the Z51 wheel has the thickest spokes of any design. That is obvious. Moreover, the Z51 design is now standard on base cars, so it doesn't matter fewer Z51 are sold these days. Base car plus Z51 sales exceed combined GS/Z06 sales.
GM has the data and have seen comments that they don’t know what has been replaced but I would think most folks complain the the dealer so expect they have enough to support their “same percentage” comments. Expect the large increase in wide wheels are a factor with half the sales going to the Grand Sport with few now buying Z51s.
I also don’t agree that rotors forging is a “cheap” manufacturing process! Lots of cold work that strengthens the the rim. It is the width that is the issue. Also agree with Foose comment. From my observation the sponges on my Optional Machined Faced Aluminum wheels do “loolk” somewhat stronger than the base GS wheels. Realize that is subjective but an educated opinon.
It appears GM could benefit by increasing the spoke and perhaps barrel thickness. They could also go to a rim construction technique I saw at Honda, albeit for ATV production. Friction stir welding a rolled up barrel! Could even use very high strength aircraft 7000 series aluminum as that process does not reduce the very high strength HAZ like arc welding!
I have found Tadgevis a straight shooter and really appreciate his posts. You may not agree with his analysis but he has the data and may use some marketing hedge words but in; this case it was an excellent post, IMO.
z06 and gs wheels are cast, not forged, cast wheels are cheap. The wheels don’t get covered under warranty by most dealers as they just say you should have bought wheel protection.
z06 and gs wheels are cast, not forged, cast wheels are cheap. The wheels don’t get covered under warranty by most dealers as they just say you should have bought wheel protection.
Wrong! Read my post #13 that quotes the Corvette Chief Engineer's answer to the bending breaking of Grand Sport wheels! They are rotary forged. There was a video of the process by the manufacturer Rondal in the first bash after the C7 came out! Although not that video you can look at the video I posted (#8) which shows that process! The many Ask Tadge post are very interesting and informative!
They don't get covered by GM because their contention is the issue is hitting pot holes etc You may not agree but I have had "0" problems with my Grand Sport wheels.
I’ve seen no less than 30 wheel failures at the track and on the road. I have personally had 2 cracked rear wheels one cracked front and 4 bent wheels. I had zero issues with my 2014 z51. I’m happy your wheels are staying round but I question how you drive the car and how many miles. My cars get driven as they are meant to. No Sunday parade laps for me.
I now have actual forged wheels and guess what, not one issue.
^^^
Hmm, have hit 1.2 "gs" around the fountain at the end of my street I pass every day! Hi "gs" at higher speeds on my favorite 270 degree interstate exit wrap. Often hit redline in 3rd between two 3/4 mile long farm fields! Never any traffic, homes or folks around when doing that.
BUT in Eastern SC we have few pot holes! Granted you can always buy stronger wheels and if folks are hitting road edge bumps at the track can understand some might break. But then like my aftermarket "stuff," I buy what GM has no justification economically installing. Just sayn' with about half the Vettes sold being Grand Sport (with Z06's) a lot more hitting pot holes etc.
With the advent of many folks buying Grand Sports because they liked the look (never understand how anyone can like those spats and NOT why I bought mine) I'm sure some just don't understand that hitting pot holes with wide wheels is not smart! Would never get near one with the 16.5 section width tires and wide rims on my 502 cid ProStreet Rod!
What about the optional Motorsport polished aluminum wheels?
So based on the stamping on the inside of my R86 wheels, they were manufactured on 4/22/2014 in Taiwan. They are "rotary/flow formed" by a company called "SAI, Superalloy". From their description they sure sound like they have achieved another way to produce a strong wheel similar to a truly "forged" wheel. And another consideration is that the extreme high polish that they have achieved could not be obtained in a typical cast wheel with its large crystalline grain structure . Remember the cast 2005 C6 "star" polished aluminum wheels that everyone hated because of the "milky" appearance of the finish that was due to that large crystalline grain structure of that cast wheel that wouldn't take a high polish. Attached pic is what happened when my front wheel of my C6 hit a car running a red light. From their website: http://superalloyengineering.com/services/design/
Forging Forming Technology
Forging and Flow Forming Technology
SAI applies high precision hot die forging technology with 7000T forging machine to manufacture aluminum wheels. Our engineers precisely design, analyze, and control the temperature parameter in order to increase the strength of the wheel structure.Flow Forming Technology
SAI applies cold spinning technology to strengthen the mechanical property of aluminum wheels. The cold spinning process not only increases the strength of forged blank but also achieves higher yield rate (in comparison to the traditional forging process).
Last edited by Walt White Coupe; 09-07-2018 at 09:04 PM.
That's a very graphic example of a broken wheel from Walt's White Coupe accident. But, it's also one that didn't collapse altogether which I would have expected considering all 5 spokes are broken! (I still wouldn't want to drive one block on it!) And while the lack of gloss was apparent from the start, after seeing several/many pics of how those cast wheels held up on impact, rollovers, accidents, etc., my conclusion is it was a pretty strong wheel for what it was, and how it was made.
I can't speak to the new SAI, Z51 or the newer wheel process(es) of other wheels on the C7. The number being bent/broken seems to be relatively high even if, percentage-wise, it's a small number. One thing to note however is that roads are getting worse even with the supposed highway funds being spent, annual repaving, etc.
... The number being bent/broken seems to be relatively high even if, percentage-wise, it's a small number. One thing to note however is that roads are getting worse even with the supposed highway funds being spent, annual repaving, etc.
I'm not defending GM wheels BUT that is what Tadge is saying. When it was only the limited number of Z06 C7s sold they had statistics on wheel failures. Once the Grand Sport was introduced the volumes of wide wheels increased dramatically. Many of us who were buying Z51's as I did in 2013 were now buying the Grand Sport. And lots of folks, "liked the look" as they report so between the two wide wheel C7s the numbers increased dramatically. I accept that Tadge's comment is accurate the percentage of failures remained the same BUT the total numbers at the same percentage would be MUCH higher!
Should GM consider thicker wall barrels and spokes. I think so sacrificing weight. For those avid Trackers who what lighter wheels-go buy them! I don't agree that Rotary Forging is the issue, it's the design!
SIDE BAR
Perhaps because of my background there are other good ways to make quality strong wheels. I recall visiting our Brazilian company in the mid 1990's where we had sold a number of microprocessor based Pulsed MIG welders we developed and produced in the US. They brought me to the applications where they were being used. One was a wheel manufacture who was welding the center section to the barrels. Excellent aluminum welds.
Recalled my '88 Vette that I ordered with the optional larger wheels. There was a GM recall that said bring your car in to have the wheels examined. It was before the days of the Internet so called the Service Manager of the local Chevy dealer where I bought the car to see what the dealer bulletin said. He read it and it said some wheels were found to have pressed in center sections BUT NO Welds! The dealer was to check for welds and weld quality! Heck I could check weld quality better than any dealer service tech, that was my business! I jacked up my car and pulled the wheels off. The aluminum welds from center section to barrel were all there and fine! Not the best shielding as they were black at the edges but no issues about weld shape or strength!
A Forged Center Section with a Rotary Forged Barrel would made a great low cost, light, strong wheel, IMO! Just Sayn!
I'm not defending GM wheels BUT that is what Tadge is saying. When it was only the limited number of Z06 C7s sold they had statistics on wheel failures. Once the Grand Sport was introduced the volumes of wide wheels increased dramatically. Many of us who were buying Z51's as I did in 2013 were now buying the Grand Sport. And lots of folks, "liked the look" as they report so between the two wide wheel C7s the numbers increased dramatically. I accept that Tadge's comment is accurate the percentage of failures remained the same BUT the total numbers at the same percentage would be MUCH higher!
Should GM consider thicker wall barrels and spokes. I think so sacrificing weight. For those avid Trackers who what lighter wheels-go buy them! I don't agree that Rotary Forging is the issue, it's the design!
SIDE BAR
Perhaps because of my background there are other good ways to make quality strong wheels. I recall visiting our Brazilian company in the mid 1990's where we had sold a number of microprocessor based Pulsed MIG welders we developed and produced in the US. They brought me to the applications where they were being used. One was a wheel manufacture who was welding the center section to the barrels. Excellent aluminum welds.
Recalled my '88 Vette that I ordered with the optional larger wheels. There was a GM recall that said bring your car in to have the wheels examined. It was before the days of the Internet so called the Service Manager of the local Chevy dealer where I bought the car to see what the dealer bulletin said. He read it and it said some wheels were found to have pressed in center sections BUT NO Welds! The dealer was to check for welds and weld quality! Heck I could check weld quality better than any dealer service tech, that was my business! I jacked up my car and pulled the wheels off. The aluminum welds from center section to barrel were all there and fine! Not the best shielding as they were black at the edges but no issues about weld shape or strength!
A Forged Center Section with a Rotary Forged Barrel would made a great low cost, light, strong wheel, IMO! Just Sayn!
And if cost was a strong consideration, the above would be my choice as well, but a fully-forged wheel would be my ultimate preference.
^^^
Not sure what happened to my text when I posted this pic of the GM developed aluminum spot welding process developed for the C7 aluminum frame. This is a 12 page PDF I made from pics taken at Larguna Seca of a C7 frame on display. GM hypes the 71 feet of Laser welds and their resistance spot welding process they developed but 80/90% are more convectional Pulsed MIG welds. It's mostly pics of the C7 chassis welds: http://netwelding.com/Aluminum_Chassis.pdf
The Text that was erased said "I'll bet a 7000 series aluminum barrel with a seam made with Friction Stir welding, Laser welded to a forged center section would be stronger and lighter than a "forged" wheel! However I also understand that the perception of "forging" has a long history. Heck the Romans used the process to make swords! lol: However there are more modern better materials and manufacturing processes."
Yep the Marketing Challenge would be to convince folks the product is better. That is what is facing GM as they have to reverse their ad campaign against the use of aluminum in Ford trucks as they're introducing aluminum frame pick-ups! Do soon!
09-07-2018, 03:26 PM
Hi "gs" at higher speeds on my favorite 270 degree interstate exit wrap. Often hit redline in 3rd between two 3/4 mile long farm fields! Never any traffic, homes or folks around when doing that.
I'm not defending GM wheels BUT that is what Tadge is saying. When it was only the limited number of Z06 C7s sold they had statistics on wheel failures. Once the Grand Sport was introduced the volumes of wide wheels increased dramatically. Many of us who were buying Z51's as I did in 2013 were now buying the Grand Sport. And lots of folks, "liked the look" as they report so between the two wide wheel C7s the numbers increased dramatically. I accept that Tadge's comment is accurate the percentage of failures remained the same BUT the total numbers at the same percentage would be MUCH higher!