OKsweetrides

I don't often see it talked about, and I was startled by an event that occurred about a week an half ago while running with several friends at MSR.

Wheels can and do fail.

I feel for my corvette buddy, Bob, who lost his front left wheel(coming out of right turn) after the spokes sheared off appx 1/3 of the spoke length from the central hub radius.

Thankfully, he only suffered only minor cosmetic damage and his brake caliper merely got a lil shaving.

Granted, his car is thoroughly sorted and he is no stranger to putting his car through the paces, this only goes to serve as a reminder that wheels are not infinitely durable; no matter the manufacturing process used.

That's all I wanted to say, just to get the wheels a turnin' in the brain about the conditions of your wheels.

trackboss

If they are cast wheels that have been powdercoated they were set to fail from the beginning.

CDN_Wolf_eh

My OEM Polished Aluminum wheel (Driver's Side - Rear) failed. Wonder if it is a product defect.

UstaB-GS549

What kind of wheels were they? Chromed?

ZR1 MK

I had wheel failure on the front left too. I do a good tech on my car as the wheels get cleaned and checked. No sign of stress before hand.

The manufacturer upgraded the center section in strength, but I will replace the center sections of the three pc design after a certain number of track days.

I was doing a tad less than 90 mph in a right hand turn. I came very close to the tire wall but didnt hit. Very little damage as the wheel floated around till I stopped.

CHJ In Virginia

My stock Z06 Speedlines are cleaned and thoroughly inspected after every event. I have seen several aftermarket wheel failures in the past two years when the cars are tracked. You can't be too careful when playing at triple digit speeds.

sothpaw2

I would only run the aftermarket ones on the rear in the rain. In rain/wet conditions, the speeds are and g loads are considerably reduced.

Have not heard of failures of the C5Z OEM speedlines yet.

OKsweetrides

They were custom forged aluminum units(not naming manufacturer as I don't want to blamed for stuff). He had the wheels for 3 years.

Unfortunately, it doesn't matter what manufacturing process the wheels were produced with (high pressure casting, forging, low pressure, etc) they will all fail eventually.

The manufacturer took them back and is currently running tests to determine the failure point on the remaining wheels. He is getting them replaced free IIRC.

Granted, his car probably see's 1.3g's routinely at 3400lbs many times a day, two days a week, 40 weeks a year. At the extreme end of the scale, yes, but still none-the-less intriguing to track hounds.

edit:
I've seen an OEM wheel on a friend's car fail at triple digit @ TWS, just minor damage. I chalked that up to physical damage maybe, but didn't know better at the time (about 6 years ago). But pretty much any sort of routine high physical loading in combination with a very wide thermal cycle will lead to negative outcomes via fatigue.

MJM Racing LLC

I agree 100%. Unless a wheel is made of steel or titanium, it will eventually fatigue and fail. Only steel and titanium have a non zero fatigue limit that, when not exceeded, will prevent fatigue failure. Aluminum, magnesium etc, all fatigue regardless of the severity of the physical and thermal dimensional cycling. Obviously, the severity of the cycling will determine the number of cycles before failure.

sothpaw2

This is not really the case. Yes it's true that aluminum and other Face-centered-cubic metals (such as magnesium) do not have a finite (mathematical) endurace limit (ie the fatigue curve keeps going down). But there's a practical endurance limit for aluminum and FCC metal based alloys in that often the stress at 10^9 cycles is still is still 10-12 ksi, not zero. 10^9 is such a huge number that you won't encounter it.

Anything if stressed high enough can fatigue. I suspect that this failed with few enough cycles that it was not near the 10^9 cycle limit that is often used with aluminum as a practical limit. If I guesstimate 10 cycles/lap and 30 lap/session and 3 session/day I get roughly 1000 cycles and in the 3 year usage mentioned that is only 240,000 cycles,
2.4x10^5. The endurance limits for steels are high cycle, I think a lot higher than 10^5.

The bottom line is that if the stressing is a lot lower (like with street tires), the aluminum may well last forever as a practical matter if manufactured and designed properly. With slicks (ie a higher g loading)
they can also be desigend and manufactured to last practically forever. The trick is to design for a low enough stressing. Wheel companies are probably not doing much stress analysis.

ZR1 MK

My wheel supplier stated my wheel failure didnt make sense based on their stress test results.
Does wheel offset make a difference? I have quite a bit in the front and Im thinking that could be a contributing factor.

MJM Racing LLC

Offset (spacers) will effect the bearings in the hubs, but should not have much of an effect on the wheels. Extra offset also adds load via lever arm on the hub mounts and the upright.

Sothaw2, I think we are saying the same thing in two different ways. When you say "The trick is to design for a low enough stressing" and I say "the severity of the cycling will determine the number of cycles before failure", it's basically the same thing from two diffent approaches.

I'm refereing to test samples of a given material and you are refering to designing to a particular load for a particular part, as in how much material is required.

When refering to wheels, one would hope that the manufacturer had a significant safety factor in their design, but lightweight racing wheels may very well cut deeply into the safety factors to shave the weight.

rfn026

There's a reason I run CCWs on my car. I pull 1.2 g and have never had a problem. Most of the aftermarket stuff is coming from China. Besides CCW I would trust BBS. Beyond those two I'm not sure who's doing a good wheel today. Oh - the GM wheels seem to work nicely too.

If you want bling then expect problems.

Richard Newton
Tire and Wheel Handbook

sothpaw2

MJM,

I was just reacting towards the statement that Ti or steel is better than Alum. It is not better. Both can be made to work and at low weight. Steel is not very efficient and likely to be heavier if sufficiently strong. Buying a
Ti or Steel wheel does not necessarily mean you are safer.

There are a lot of factors that could have caused the failure. A sulfuric hard anodize causes a lot of problems. Any sharp geometric feature could also be an issue. A smooth surface finish is paramount. Also, it would be very detrimental to store your wheels outside at the Beach near the salt water.

I'd say a 25% decrease in stress will increase life by 10-fold. So if you have a failure, unless there was some abuse (chipped or exposed to salty air) something in either the design or manufacture was way off from the intended useage.

MJM Racing LLC

Very true. Steel or titanium wheels do not make you any safer. Poorly designed wheels in any material are dangerous. Well designed and well made aluminum wheels will last longer than most cars will. I was just using those materials as examples. The intent of my original post was more along the lines of ... know the history of any used wheel you intend to track and buy quality new wheels. Most aftermarket wheels are designed for street use only. I don't know what wheels the OP is refering to.

I would never buy used aluminum race wheels unless I knew how old they really were and approximately how much track time was on them. Like I said, good wheels will likely outlast a car, but maybe not two or more.

AU N EGL

I clean my CCW classics are inspect them very closely after each event.

fatbillybob

Please post the name of this company. Racers all know wheels can fail. A company who stands behind their product I want to do business with.

a friend of mind broke a kinesis wheel (after the sale to the new guys) and kinesis told him to pound sand. My friend could have died and they did not even offer to make him a deal on getting a new center!


CCW which most of us T1 guys are using is a very good company too. John readily will sell us parts to rebuild our wheels as needed. He knows exactly what we need to do the job and get it done fast.

fatbillybob

A friend of mine used to work for toyota as a failure engineer on wheels. Later she went to work for aftermarket wheel makers again in failure analysis. Her general feel is that OEMS make stronger wheels with more headroom for dumb drivers doing bad things like curb banging and hitting stuff. Her opinion is that the OEMS have deep pockets and overengineering wheels is better than paying money out in lawsuits. There are some aftermarket guys who are very very good and many that in her opinion are pretty marginal.

sothpaw2

Not surprising. This is my opinion on most of the aftermarket. With large volume production comes larger profit so there is more money for QC and also a lot more risk to the company if something goes to hell.