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Since the weak spot is the inner edge of wheels that are farthest from the spokes, I think flow-forged wheels would be just as good, including ZR1 OEM wheels. Add mentioned before, the barrel section of flow forged wheels is forged.
The cracked wheel thing is, unfortunately, an old story. Check the ZO6 forum for multiple threads on the same issue. The wheels are made either in China (early models) or Mexico (current). They are cast and prone to crack on the inner barrels with somewhat ordinary road issues such as a 1" ridge hit a speed combined with the run-flats which have no give on the side walls and transmits the entire energy of the impact to the wheel. Your fix is to go to quality forged wheels - not flow-forged which is just a cast wheel with a forged rim edge.
See the details about wheels below:
1. Cast aluminum wheels 2. Flow-Formed wheels
3. 1-piece "Monoblock" forged wheels
4. 2-piece welded construction wheels
5. 2-piece bolted construction wheels
6. 3-piece bolted construction wheels
Cast Aluminum Wheels
These are the lowest priced wheels, and are typically what are found on production vehicles. Cast aluminum wheels are created by pouring molten aluminum into a mold that is shaped like a wheel. This produces a wheel casting. Some final machining work is then done to clean up the rough surface, and paint/finishing is applied.
Pros: Lowest price, easiest to mass-produce.
Cons: More brittle than forged wheels. Spoke details and edges aren't as sharp as a machined forged wheel. Heaviest weight of all wheel construction types. Lowest quality. Limited offsets, width increments, diameter selection available. Nearly impossible to repair when cracked or severely bent - safely, that is. A damaged cast wheel usually needs to be replaced.
Flow-Formed Wheels
Flow-Formed wheels start out identical to cast poured wheels, but with different hoop thickness. The casting process above is used to create the spoke pattern only. Then the wheel castings are put into a flow-forming machine to form the outer hoops. This is done using high heat and high pressure rollers, which "flow-form" the outer hoop. This results in a stronger outer hoop, with aligned aluminum grain structure. The resulting wheel is a cast faced wheel with a hoop that has properties similar to a forged wheel. They are stronger and lighter than cast wheels.
Pros: Low Price, Lightweight, Higher strength than cast wheels.
Cons: Cast face still lacks the sharp edges and details of a machined forged wheel. Limited width increments and diameters available. Hard to repair when severely bent or cracked.
1-Piece Monoblock Forged Wheels
The term "Monoblock" is used throughout the industry to describe the 1-piece forged wheels. "Mono" meaning one, and "Block" meaning it was created from one block of aluminum. The block in this case is actually a round bar stock of high quality, aerospace-quality 6061-T6 Aluminum Alloy. The round bar is pressed in a huge forging machine, to stamp out a wheel shaped blank. Forging is a hot working process, and helps to align the grain structure of the alloy. This results in a very strong, very lightweight wheel construction material. The wheel blank is then flow-formed to create the outer barrel shape. Following that process, the wheel blank is loaded into a CNC milling machine and there the spoke pattern is milled out.
Pros: Lightest of the forged wheel construction methods.
Cons: Priced about the same as expensive 3-piece construction. Difficult to repair when bent or severely damaged.
2-Piece Welded Construction Forged Wheels
These are considered the entry level forged wheels, as they are priced slightly lower than 3-piece forged wheels. The centers start out as a blank of forged 6061-T6 Aluminum alloy, and the spoke patterns are CNC machined with a milling machine. The wheel hoop is also a forged aluminum material. On a 2-piece wheel, the center is simply welded to the hoop on the backside of the wheel. Some manufacturers also offer cast aluminum centers, to reduce cost. Quality and weight of the cast centers is not as good as forged/machined, however.
Pros: Lowest Price of the Forged wheels. Same weight, appearance, quality as 3-piece wheels.
Cons: Limited widths increments available. Cannot easily chrome plate or paint the lip, since it has to be welded on. More difficult to repair a bent lip compared to a 3-piece wheel, as the center has to be cut out and a new hoop welded on.
2-Piece Bolted Construction Forged Wheels
These are built very similar to the 2-piece welded construction wheels above, but use a hoop that has a bolting ring already in place. Instead of welding the center to the hoop, it is simply bolted on. This is the least common method of forged wheel construction, as the hoops tend to cost more than simple welded hoops. Some manufacturers also offer cast aluminum centers, to reduce cost. Quality and weight of the cast centers is not as good as forged/machined, however.
Pros: Lips can be easily chrome plated or painted, since no welding required. Easier to replace a hoop when it gets bent.
Cons: Limited width increments available. Few brands offer this type.
3-Piece Forged Wheels
Three piece forged wheels are usually the most expensive wheel construction, mostly due to the assembly labor and components used. The wheels consist of three main pieces; the center, the outer hoop (lip), and the inner hoop. These three parts are held together with a series of perimeter bolts. Silicone RTV is used to seal between the two hoops. Some manufacturers also offer cast aluminum centers, to reduce cost. Quality and weight of the cast centers is not as good as forged/machined, however.
Pros: Most width increments available, truly perfect fitments available. Easiest of all wheels to repair if lip gets bent or damaged, as hoops are easy to replace. Easy to paint or chrome plate lip, since no welding is required. Can have different color rear hoop and outer hoop, since they are two different pieces. Highest resale value for used wheels.
Cons: Most expensive forged wheel construction. RTV silicone seal can be damaged by inexperience tire installers, resulting in leaks.
Thanks for the detailed explanation of the different type of wheel manufacturing. Still shocked that when I asked a forum vendor today whether his ZR1 wheels were cast or forged, he answered “Flow forged”. When I subsequently asked whether that meant cast of forged, he responded “I don’t know.Go to Gm site and maybe they can help you.” Guy was rude and apparently has no idea what he is selling....nor does he care enough to provide reasonable customer service. PM me if you want the vendor’s name.
Last edited by runner61627; 02-28-2019 at 11:52 PM.
I fixed the wheel problem with my ZO6 last year by going to Signature forged wheels from Deity Motorsports mated to Continental Extreme Pro Contact non run-flats. No issues since
Since the weak spot is the inner edge of wheels that are farthest from the spokes, I think flow-forged wheels would be just as good, including ZR1 OEM wheels. Add mentioned before, the barrel section of flow forged wheels is forged.
Unfortunately, not true. Just the edge of the barrel lip is the only thing forged not the whole barrel. Even then the process is by just squeezing the edge to sort of realign the molecules. Think of it as half-baked; better than cast but not as good as monoblocks. There's a reason the forged monoblocks are more expensive: they are stronger. Flow-forged are cheaper and just not as strong. It's a simple matter of metallurgy and a casting is the most brittle type of metal. Think of cast iron vs. steel.
They are cast and prone to crack on the inner barrels with somewhat ordinary road issues such as a 1" ridge hit a speed combined with the run-flats which have no give on the side walls and transmits the entire energy of the impact to the wheel. Your fix is to go to quality forged wheels - not flow-forged which is just a cast wheel with a forged rim edge.
See the details about wheels below: .
Hit a construction ridge last fall. As of January I wasn't loosing air or feeling vibrations but am anxious to see what I see at the spring oil change. In the meantime I've been learning all I can about wheels.
Your post about wheel construction was one of the most useful posts I have ever seen.
Stock front offset is +43 but it seems like many aftermarket wheels are +40.
I went to the dealership today and was told to bring the car back on Monday when the Corvette service manager is in. The service advisor said they have seen this problem before and some are denied as not covered under warranty and others are covered. My leak is slow enough that it will hold air for a day before dropping to 25 psi. So rather than letting the car sit over the weekend, I drove it home where I can top it up to 30 psi each day.
Assuming I need new rims, I'd like recommendations of forged rims that look like the black OEM rims. I'm not one for flashy aftermarket rims and have never had to buy rims before. Please shoot me a PM if you have any recommendations. I don't mind paying for quality, but I also don't want to burn money. I'd hate to send good money after bad and buy new OEM rims that will crack after the next 7000 miles.
Count me in for 4 bent wheels on my 17 GS. Every time I feel my car shudder I cant be sure if its the road or more bent wheels. I have chrome so buying forged is hard as most forged manufactures wont do chrome. They have a mirror finish wheel at forgeline they say resembles chrome but they want 8800 bucks. I just got back from a Tucson to Vegas and back trip and who knows what my wheels condition are.
I went to the dealership today and was told to bring the car back on Monday when the Corvette service manager is in. The service advisor said they have seen this problem before and some are denied as not covered under warranty and others are covered. My leak is slow enough that it will hold air for a day before dropping to 25 psi. So rather than letting the car sit over the weekend, I drove it home where I can top it up to 30 psi each day.
Assuming I need new rims, I'd like recommendations of forged rims that look like the black OEM rims. I'm not one for flashy aftermarket rims and have never had to buy rims before. Please shoot me a PM if you have any recommendations. I don't mind paying for quality, but I also don't want to burn money. I'd hate to send good money after bad and buy new OEM rims that will crack after the next 7000 miles.
Count me in for 4 bent wheels on my 17 GS. Every time I feel my car shudder I cant be sure if its the road or more bent wheels. I have chrome so buying forged is hard as most forged manufactures wont do chrome. They have a mirror finish wheel at forgeline they say resembles chrome but they want 8800 bucks. I just got back from a Tucson to Vegas and back trip and who knows what my wheels condition are.
What drive mode were you in, or what mode do you typically drive in?
The screen capture below is why i didn't Bent wheels may be able to be repaired. The big issue is cracked wheels.
I like you did not know. Mine have not cracked yet. So I looked at getting tire and wheel protection plan. The GM Plus plan is not much use for a cracked wheel.
That's just the cosmetic coverage portion. If you paid for Tire and Wheel and the optional Cosmetic Coverage, you're covered for a cracked wheel. Your policy should read
T/W plus Cosmetic. I purposely asked MacMulkin about this.
Unfortunately, the bottom line is that the C7 OEM wheels are terrible.
Now, that's a damn shame! You spend 67 grand and up for a car and you get this low quality OEM wheels, a $1995.00 option,Then I have to worry about my automatic transmission ( a $1725.00 option ) giving out on me after a few thousand miles!
No wonder why I can't sleep at night !
Rich K ( Vette Ski )
Now, that's a damn shame! You spend 67 grand and up for a car and you get this low quality OEM wheels, a $1995.00 option,Then I have to worry about my automatic transmission ( a $1725.00 option ) giving out on me after a few thousand miles!
No wonder why I can't sleep at night !
Rich K ( Vette Ski )
Don't forget to worry about a fuel pump leak just like we had to on our C6's too!
Now, that's a damn shame! You spend 67 grand and up for a car and you get this low quality OEM wheels, a $1995.00 option,Then I have to worry about my automatic transmission ( a $1725.00 option ) giving out on me after a few thousand miles!
No wonder why I can't sleep at night !
Rich K ( Vette Ski )
Not to worry. Install a Range module to eliminate the AFM V8/V4 issue. That will save your torque converter. Get some decent forged wheels and problems are solved. Then you can get some sleep and enjoy the car
Now, that's a damn shame! You spend 67 grand and up for a car and you get this low quality OEM wheels, a $1995.00 option,Then I have to worry about my automatic transmission ( a $1725.00 option ) giving out on me after a few thousand miles!
No wonder why I can't sleep at night !
Rich K ( Vette Ski )
Essentially the most important parts of our C7 Corvettes are problematic! It is a crying shame. I have been lucky so far, but I am very sympathetic to the folks that experience these issues.
That's just the cosmetic coverage portion. If you paid for Tire and Wheel and the optional Cosmetic Coverage, you're covered for a cracked wheel. Your policy should read
T/W plus Cosmetic. I purposely asked MacMulkin about this.
The problem is that the policy will just end up getting you new OEM wheels. They will bend and crack too; you end up in ground hog day.
Don't forget to worry about a fuel pump leak just like we had to on our C6's too!
Oh, thanks for the update on the fuel leak. Reminds me why I've bought Toyota's,Honda's and Mazda's since my wife's last 84 T-bird Elan. I guess the theory is correct that the older you become you start losing brain cells.
Rich K ( 'Vette Ski )
Not to worry. Install a Range module to eliminate the AFM V8/V4 issue. That will save your torque converter. Get some decent forged wheels and problems are solved. Then you can get some sleep and enjoy the car
So you have to go spend another $10k on a car that came with defective wheels in order to get a reliable set of wheels.
02-28-2019, 11:08 PM
