froggy47

Which of these rims (which years) are the ones that crack & did they (GM) redesign the thin spokes to be stronger at some point?

Many thanks.

VetteDrmr

As I understand it, the early thin-spoke wheels are forged, then around '02(?) GM changed to a spun-cast method. The forged wheels have fairly sharp edges to the spokes compared to the spun-cast wheels, which are also a bit thicker.

Although my thin spokes are for street use only (I've got a set of wagon wheels for track use), the incident rate for the thin spokes isn't very high, regardless of which technique was used to make them.

Also, I've never heard of any OEM Z06 wheels cracking under track use. Not saying it doesn't happen, just that I haven't heard of it.

HTH, and have a good one,
Mike

Aardwolf

http://www.wheelcollision.com/chevy9.htm

That page shows pictures of the sharp spoke version and the rounded. I'm using part # 9593799 (sharp spoke) wheels for track use (street tires) with no trouble.

froggy47

The ones I am looking at are made in Italy.

Would that be like the same mfg (Speedline) of my c5z rims?

Aardwolf

Yes!

I think the C5Z rims were also made in forged and cast?

For the thin spokes the Speedlines are the cast (rounded spoke) and the Alcoa the forged (sharp spoke).

Aardwolf

They are real light, 18 pounds on my crappy bathroom scale. I run four of the rears, 9.5x18". I noticed a difference in accelerating going from the 25 pound stock wheels. I've picked up a pair for as little as $80.

Joe_G

I have factory 02 polished thin spokes and both rears cracked on the spokes where they attach to the rim. The front 17's have not and I've been running my drag radials on them for 4 years now after street driving them for 3 years.

Bill Dearborn

When GM introduced the thin spokes in 2000 they sold two versions. The base rim was painted and the optional rim was the high polished version. The demand exceeded the ability of speedline to build sufficent rims so GM changed the painted rim to the spun cast version with slightly thicker spokes. From that point on the cars with base wheels always received the painted rims with slightly thicker spokes and the forged rims with thin spokes were used for the high polish version. Sometime in 2004 GM dropped the forged rim from its service parts list and if you order a thin spoke high polish wheel from them now you will get a cast wheel with the slightly thicker spokes. The reason I know when the thicker spoke started showing up in high polish version is a friend with a 2002 had the spoke crack on one of his rims. The dealer replaced the rim under warranty but it didn't match the other 3 so they had to replace all 4 rims to get them to match.

Bill

froggy47

I have seen at least 2 cracked myself (street tire autox) so, for myself, I think there may be a somewhat higher incidence of failure on this design.

I "think" they were both rears.

It would be interesting to chart how many broken rims were speedline vs alcoa.

drivinhard

are you talking about the base C5 wheels or Z06 wheels?

froggy47

This whole thread is about C5 THIN SPOKE wheels.

That is a common name for the 5 thin spoke style rim never put on z06 (at least not from the factory)

Also refered to as Y2K rims?

Joe_G

Mine cracked after an HPDE event! 2002 high polished rears. I don't know if they were speedline or alcoa. Fronts are still fine. Though I'm gonna check them closely next time I mount them after this memory has been drug up!

My dealer told me to pound sand though I was still in warranty. They said the tire changer did it (I had my original tires replaced). There was a thread on this in the C5 section years ago, and there were few people posting about it. I don't know if you can get that thread back anymore, the search feature on this site s^cks now.