I have been reading many posts on this sight for some time about good looking chrome replacement wheels and how inexpensive they are. I have gone through some extaordinary steps to get Chrome wheels that are the original o.e.m.s but chrome plated. I would like to explain why so you all can understand what you have and what you will get if you trade to aftermarket wheels. First of all my qualifications. I am an engineer and own a machine shop where we manufacture parts for industry, aerospace, medical and electonics, using state of the art C.N.C. equipment. I have been doing this for just shy of 30 years now.
The process used to make the original speedline Z06 wheels is known as spinning. Spinning is a process that has been around for a long time, but has become much more cost effective with the addition of Computer control in the process. In simple terms, spinning is done by turning a billet of material (in this case aluminum alloy) in a lathe and moving the material around with a tool that has a wheel on the end of it. It is similar to throwing (shaping) clay pots on a potters wheel, where the lathe is the potters wheel and the wheel tool is the hand forming the pot or in this case wheel. The processes used most often to manufacture wheels are casting and machining and machining from billet.
In the casting and machining process, molten aluminum is poured into a mold. When the material has solidified the wheel is put on a C.N.C. lathe and turned (Cut) to the final shape. The casting process yields very inacurate parts due to thermal distorsion and shrinkage during cooling. For this reason the wheel must be machined after casting. The other problem with casting is that in the casting process air bubbles can form,and sand or other impurities can be trapped in the casting. These flaws can not be seen on the surface but can significantly weaken the wheel.
In the machining from billet process, a billet ( chunk) of aluminum alloy is put in a C.N.C. lathe and using tool bits (tools harder than the material they are cutting) cut to the desired shape and size. The wheel will also have to go on a C.N.C. maching center to cut details such as spokes and stud holes. This process yields excelent quality wheels but the wheels are not as strong as the spinning process wheels.
The strength of the spun wheels comes from the microscopic grains that make up all materials and thier structure. In the casting process the grains are very random and loosely packed. A billet also has this structure when first poured from the molten material but is then cold worked by pushing it through rollers to shape it and strengthen it. This cold working forces the grains together and aligns them into extremely strong chains. In the machining process these grains are cut, weakening them slightly but still leaving a strong wheel. In the spinning process, the wheel is cold worked into the final shape. this leaves a grain structure that is far stronger than the machined wheel, just like a forged part (which uses a similar process of moving material around rather than cutting to shape a part)and is much stronger than a cast or machined part. A good analogy is to think of a crank shaft, would you rather have a forged crank or a cast crank. Due to this strength the wheels on the Z06 were able to be made thinner and so lighter. Another advantage is that in the spinning process the wheel produced is better balanced than machined wheels and far better than cast wheels which can be very badly out of balance.
The boys at GM definetly went above and beyond on many parts of The Z06, and the wheels are a shining ( but slightly dull in stock powder coated form) example. Anyone lucky enough to get wheels made with this state of the art process stock on thier car should think carefully before tossing that aside for looks. After all if looks are what your after isn't a convertible or fastback a much better looking choice. I for one chose the Z06 for the amazing performance that comes from the complete package that the enthusiastic GM engineers put together for the performance enthusiast.

 

Nice write-up. Thanks for the info. Two thumbs up for the stock oem Z wheels!

I'll be keeping my stock wheels on then.

 

I assume all Z06 wheels are manufactured this way, even the Z16 wheels. Correct?

Thanks for a very good explanation on this topic.

 

Excellent write-up Jose!!

Thanks for taking the time to explain to folks how these processes work and how it affects the outcome. Structural integrity of the factory wheels is hard to beat. Even if they didn't come with the "bling" look of some of the aftermarket wheels.

I agree with you on the Z06 too. GM engineers went out of their way to make the Z06 be a purely full performance version of the C5. People complain about the looks of the wheels, how much the brakes dust, how the carpet is so thin and there is no insulation, etc... to name a few. Those things are "features", not design flaws. The intent was to make the car faster, lighter, more nimble when driven hard. That means it will feel more raw than a base C5. That IS why I bought the Z06 version over the C5 Coupe!

Now they did forget to put an oil cooler and extend the brake ducts. But I fixed that small oversight

 

More proof that the aftermarket isn't always an "upgrade". I love these type of threads...thanks for sharing your findings with us.

 

I agree.......I'v got 600 dollar boat anchors on the Z right now to prove it.......Oh gee, but they look good.

 

Great write up, could you educate us a little about forged wheels like the 2001 Z06's have?

Thanks,
Jeff

PS agood friend of mine had to have chromes for his 04 Z but I insisted he do the WCC trade for OEM chromes.

 

Thanks for the write up. I agree 100 % with you. If you want the best of both worlds, the stock GM wheels CAN be made "a shining example" with some expert refinishing and machining





MD

 

I was one who made a post about how unhappy i am with my aftermarket wheels.

I don't worry about the strength of them as it seems fine but the excess weight has dogged my car. It feels like the equivelent of about a 30hp loss

I am thinking i am going to have my factory whells refurbished and then polished or chromed. I bought the repros for 620 shipped. I am sure i can get 3-400 back if i sell them on ebay or something

 

I don't understand why you guys didn't just hang on to your stock rims?

My stockers were so chewed up by the previous owner's dates with curbs that it was embarrassing driving around with them. I just knew people would look at them and think "see I told you women can't drive". Soooo

I got a pair of A/M that look great for around town driving and when I am ready to go to the track I have my stock rims to change to.

To me it seems the best way to get the best of both worlds. I know when I am around town driving there are very few opportunities to "test" my car's power anyways and even when the opportunity comes the rims don't make a hill of beans to the cobras and others that line up to me.

But maybe the cam, headers and all that help....