Mussl Kar

I drive my GT3 RS at autocross only and after 2 runs in the afternoon yesterday I was watering my tires to cool them down. I noticed a line on one of the spokes so I put some water on it and thought it would rub off. Nope. Very definite broken spoke. Easy decision not to continue. Anybody ever have that happen? I am thinking metal fatigue as those wheels were new in 2008. Going to junk the other rear just because it is not worth it.

edfishjr

Been puttin' cold water on a hot wheel, I betcha…serves ye right! (J/K!)

If you have the other wheel magna-fluxed or dye-penetrant inspected and it shows no cracks you are good. Racing teams inspect this way regularly and don't throw anything away unless they see a crack. The crack may have started in an unusually large flaw that doesn't exist in the other wheel, so it might last many, many more years. But as you have decided, junking the other one and buying new is relative cheap insurance.

Mussl Kar

You peeked! The last few events I started watering the barrel to get heat out. Water the tires too but with so much heat inside the tire it takes a lot of water. Never ever sprayed it on the spokes or brakes though.
New wheels arrived a few hours ago and already have tires mounted. Gotta love having a Hunter tire changer in my garage.

paver

I had a rear wheel crack like that. The retailer, GMG, said it was due to them being recoated. They said the process of heating for curing the powder coat or paint(I don't know which was done as the prev owner had it done) weakens the aluminum.
Any idea how much use yours had on them?

Mussl Kar

Apx 2000 autocross runs of a bit over 65 seconds per run. They do get very hot in the summer. So much that your hand is not comfortable on the tire and the air I bleed out is uncomfortably hot.

edfishjr

Holy Smokes! And I thought I did a lot of events…

As for the wheel, you may be the first person I've ever heard of that ruined a wheel with thermal shock/temperature-delta-induced internal stress.

I understand the motivation. At Nats we were draping towels soaked in ice-water over our wheels on the hot day.

sjfehr

I spray icewater on my tires every event. At nats, I even sprayed down my exhaust, which seemed to help keep control heat soak into the rear-tires. My friends in STX were spraying down their wheels as well as tires.

I see people so squeamish about spraying, but if you think about it logically, these cars are designed to handle it. Come down a mountain, and your brakes will be glowing red no matter what time of year it is; if it can't take running through a big puddle of icy water, that's a huge design flaw. I can't recall anyone who's ever reported an issue from running through a puddle (water intrusion into electronics aside...).

Mechanical flaws happen. I suspect that's what happened here.

Mussl Kar

I suppose I could cut the spoke out and examine the broken ends for signs of metal fatigue. I know they flex a fair amount under load.
Current plan is to check each wheel in the morning when adjusting pressures, and keep an eye on them at each pressure check. It would have been very $$$ if it broke during a run, not to mention the huge time delay.
Not cutting the spoke out though. The 18s are just about the right diameter for the base of a bar stool. Weld 5 castor sockets on and just need a post and seat.

philstireservice

Never put cold water on a very hot wheel........ever!

sjfehr

Hot wheels can't be driven through cold puddles?

philstireservice

If we are talking under normal driving conditions, chances are the so called cold puddle isn't that cold because of ambient temps......

We're talking about ice cold water on a 300 degree wheel here....that's a no no

Earlydays

2000 runs is a lot of wheel flex.....could be a reason for the failure??

Mussl Kar

I said uncomfortably hot. 300 degrees would leave the skin of my hand there. And the paint burning. Saw that once. But not on my car.

Mussl Kar

For sure it is flex. The barrels of my front wheels are scraped from flex. I was supposed to have 3mm spacers with my setup (per Rad). Bill only had 3mm spacers and that left me with .020 clearance from barrel to caliper. Even though the front is light it still made a lot of noise on sweepers. Even with the 5mm spacers a small stone sometimes gets caught and make a very un natural noise.

mopar bob

Ya I have heard my spoiler scrap with my C2, but my springs are a lot softer. Boy that GT3 has to be a E ticket ride.