like i said...it was an initiative some dealerships made...and i think tehy were only in ca...namely inifiniti nissan...but i could be wrong and probably am....

 

Revisiting the thread. Have ANOTHER cracked rim.. I guess it's time for aftermarket

 

if the aftermaarked rim crackes , its time to find a new passion.

 

Someone is trying to kill me in my Z. 5/5 Spokes were cracked when I removed my rim today... Pics up later.

 

Jesus, they HAD to have been weakened by the pcoating

 

Doubt it was hot enough , my wheels were over 350 degrees the past weekend at the track. ( i cooked my brakes)

 

Now this is a cracked rim....

 

Here's the thing, were you VERY careful about how they were powdercoated? Did they sand blast them or bake off the old paint to prep them? they always want to bake off the paint. Not only is that a 450-500F+ process, it also relies on them paying careful attention to your job. Alot of shops will just leave them in until the remember to come back and get them :/ or take them out, only to realize it wasnt complete and put them back in, making another very hot heat cycle. Also, they preheat them.. then PC them.. then bake them again.. sometimes they have other parts in the oven, so if they take those parts out, your parts get heat cycled again. Or for whatever reason, they PC doesnt flow out right, they might bake again. You could have a min of 4 or more heat cycles, sometimes 5 or 6

They also can overtemp them during the PC'ing, if they have huge walk in ovens, the heat may not be consistent. There are lots of reasons your wheels may have seen more heat (350f) than you expected. You could have "aged" your forged rims by years if not more. (that is open to argument tho)

From all the research I did, I dug into some very technical docs regarding aerospace pc'ing. While the aluminum will not technically anneal until nearly 600F, coming close will make your forged parts actually more brittle, not softer. as you found out

I had my cast wheels PC'd and insisted on a low temp job (<275F media and no bakeoff) for this reason. And insisted the keep they heat cycles as few as possible. And it ended up really sh$tty, you really do need 350+ to do it right. Alot of money wasted and now I have to find a way to strip them.

 

Truthfully, if I didn't pass that car and by chance had my music down, I'd probably have the same pic. Although, I doubt I would have been the one to post it

I trust the shop that did it.
People are blaming the PC but what I can't figure out is why my rears haven't been affected. They see much more abuse than my fronts (I would imagine anyway being rwd). No one else seems to be having this problem

I'm going to check the rims tomorrow and try to figure out if they came out of the same mold/cast.

Aside from people assuming on here, I have not been able to find a single person to tell me they've seen something similar. I have heard from people who have had 06 rims crack on them though

 

Well I have 4 stock 07 rims lying around

 

^Not the be a dick, but there is a reason why you can't create your own for sale posts. Get active in your community and try there.

 

I think he was just offering in case you needed new rims. I thought it was a nice gesture. If he really was in a hurry to sell them I'm sure he would put up a f/s ad......sheesh

Oh and by the way it was more than likely the powdercoating process that did this to your rims... You've probably compromised the integrity of all of them...now it's just a matter of time. I would feel unsafe driving around on those rims....

 

The fronts take a lot of deflection and twisting. Unless you have alot of wheel hop, the rears are not under the same loading.

There are several instances were Enkei split spokes have failed (if you believe everything you see on the web ) after PC and Enkei blamed the PC. Most of the examples I have seen on the web are smaller multi/spit spoke, not the larger spokes you have. And in at least one case I know of, R compound tires contributed to the abuse the wheel was taking.

I guess thats where alot of people split hairs on this, whats safe. What is the margin of safety. Clearly the majority of people PC wheels with no problems. Virtually all PC'ing is safe based on the numbers that never fail. But, if you have a marginal wheel to begin with, as the 06's seem to be, you've significantly reduced the margin.. Or do something extreme like R compound track tires.. Non-PC'd wheels crack under those conditions too.. but I think it does increase the likelihood depending on the design and mfg process of the wheel.

in short (too late for that ), I think your 06s would have failed at sometime. the PC'ing probably brought the failure much sooner

 

tware,
Thanks for your information and passing on all the research you have obviously done. You are the type of person that makes this forum so valuable. Pretty objective comments too.

 

lol

why cant you blame it on the powdercoating? Ive heard chrome dipping can weaken a wheel.

 

Oh, it was because I saw he had blatantly thread jacked at least one sellers thread.

 

I had a rear wheel stock of a my '03 Z crack all the way through. I didn't find out until I took it in and had my Hotchkins sway bars put in. I'm 2nd owner of the Z and the Z had over 45,000 miles on it. I was driving on that wheel for awhile.

 

No laughing!
I don't know anymore, I give up. I'm going to go find some 22"s and roll on those bishes.

 

Well, I hate updating this thread AGAIN. 3rd rim cracked today at an autocross...