Ouch! Team dynamics spoke failure!

[PCA-1]

Once powder coated, no warranty. Standard fare in the wheel industry. Additionally, warranty extends to original owner. Not in the office. Will touch base.

 

[PCA-1]

Just how 'common' is this type of failure on the 1.2s??

It is not.

 

[dyn085]

Yeah, thats my wheel. I didn't hit any pot holes or hard bumps. Noticed it last night when I was pulling up to my house, was making a weird noise. The wheels were purchased brand new in February by my friend (also has a FiST) and powder coated. He hardly put any miles on them and I've only had them for 2 months.

Honestly, it doesn't make any sense that 'new' wheels were purchased and then immediately powdercoated. The fact that they were powdercoated so ridiculously early would have made me very suspect from the beginning. I could understand if it was some wild or drastically different color than what TD offers, but they chose something very similar to the anthracite that's already offered...

Sent from my SM-G930V using Tapatalk

 

[Adamleebmx]

He wanted them blue, and the only ones in stock at the time were a color he didn't want. I've done that with scooters in the past. Buy everything then send it off to powder. It's personal preference.


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[PCA-1]

After having sold a few thousand of these wheels, I can count on one hand the number of cracked spoked wheels. These wheels, on there own, just don't crack like that. The level of force required to crack a wheel like that is pretty high. The lack of a tire bruise is even more of an indication the powder coating is at issue, either that or the damage started with the previous owner, perhaps not picked up visually (micro fracture) which was further weakend by the PC.

You can find quite a wide variety of excellent wheels that have failed after being powder coated. Enkie RPF1's, Volk TE37's, ect., on down the like to the cheapest wheels.

 

[re-rx7]

Lots of gd info in here.

 

[Plainrt]

Yep if never powder coat any wheel. I thought everyone knew this.

 

[re-rx7]

Sticky? Just for future people out of the know.

 

[M-Sport fan]

It is not.

That's what I thought, and I did not catch the powder coat part of the story until everyone mentioned it in latter posts.

What is Rimstock's painting process for the 1.2s?

 

[WhiteFords]

My dad recently cracked a $1k Jongbloed wheel, no pothole or curb damage, just a streetcar that goes to track days now and then. The Jongbloed wheel is a 3 piece type wheel, with a forged and hard anodized center. The wheel is a 14 spoke design that cracked three spokes.

So for everyone who cries about cheap wheels cracking, here is an example of an expensive, very well engineered wheel which suffered the same fate.

It is interesting to hear about powdered coating processes weakening wheels. I thought that powder coating shops had developed processes to coat the wheels without compromising the structural integrity. Or at least that is what I have heard via the almighty interwebs.

 

[PCA-1]

What is Rimstock's painting process for the 1.2s?

"Rimstock's super advanced paint and treatment facility houses fully automated wet and powder lines with robot handling systems, all enclosed in a controlled air movement atmosphere. The use of complete water based environmentally compliant coatings is also a policy of Rimstock. "

 

[StayPuft]

My dad recently cracked a $1k Jongbloed wheel, no pothole or curb damage, just a streetcar that goes to track days now and then. The Jongbloed wheel is a 3 piece type wheel, with a forged and hard anodized center. The wheel is a 14 spoke design that cracked three spokes.

So for everyone who cries about cheap wheels cracking, here is an example of an expensive, very well engineered wheel which suffered the same fate.

It is interesting to hear about powdered coating processes weakening wheels. I thought that powder coating shops had developed processes to coat the wheels without compromising the structural integrity. Or at least that is what I have heard via the almighty interwebs.

Exactly. I think the scientific jury is still out on whether powdercoating wheels = failure. Powdercoated wheels fail and nonpowedercoated wheels fail.

Really theres only 3 steps to PC a wheel--prep, powder, heat-- so where does the weakening occur? Is it in the prep? Does chemically stripped vs media blasted make a difference? Does a soft media like walnut vs. a more fine or hard media make a difference? Is it the 350* for 30 minutes? Ask the racers who have the surface temp guns out after 30min lapping and see if the wheels are hotter than 350, I really don't know. Is it the fact that cured PC is bonded so well to the surface that it changes the metal's ability to expand/contract?

Just because the wheel industry doesn't warranty a product after it's been powdercoated doesn't mean it's evidence of a cause and effect. For example, look at the automakers and powertrain warranties. If a valve drops after a turbo upgrade it doesn't mean the turbo caused it, but good luck having Ford replace your top end when you roll in with your basically stock hybrid. It's low hanging fruit to blame PC for a failure and there are too many questions left unanswered.

 

[RAAMaudio]

I believe the TD wheels are heat treated, at least that is what I recall reading quite some time ago, heating them up in an phase of the PC process could change the strength of the wheel considerably if hot enough.

Normally I would not read a thread like this except a few posts but wanted to see if anything was mentioned about TD heat treating the wheels so please correct me if wrong.

 

[BRGT350]

A few years ago on Corner-Carvers, there were some posts showing Corvette factory wheels cracking across the spokes and some where the spokes and hub separated. In those cases, the wheels were powder coated by the owner and not the factory. The wheels may have been the optional C5 magnesium wheels, but I can't confirm. The general consensus was to not send wheels out for powder coating. Factory finish is ok, paint is ok (white being the best for crack detection), polished is the best (until you scratch the surface and get a stress riser), and chrome and powder coating being less desirable. This was for wheels seeing high amounts of stress and heat. Seeing this type of failure on the street is not something I have seen much of, but believable due to the powder coating.

There is no doubt that heat and time change the molecular structure of the material. Cleaning agents along with heat can easily change the surface condition of the material and surface tension is important to reducing stress risers. A great example is glass, scratch it and it will break there because you gave the crack a starting place. I would bet most powder coaters that handle small batches are not going to change their cleaning or baking process for aluminum. Aluminum wheels would be ran with whatever steel parts being ran that day. This could easily cause too high of heat and improper cooling, which will greatly affect fatigue strength.

It is very common for professional race teams to x-ray and use dye penetrate on their wheels after races to look for cracks. Most teams probably have a known number of cycles before they scrap a wheel.

 

[PCA-1]

I believe the TD wheels are heat treated, at least that is what I recall reading quite some time ago, heating them up in an phase of the PC process could change the strength of the wheel considerably if hot enough.

Normally I would not read a thread like this except a few posts but wanted to see if anything was mentioned about TD heat treating the wheels so please correct me if wrong.

Yes, the wheels are heat treated.

 

[Superfly Snook]

Heat treating a wheel in a clean and controlled environment as part of a manufacturing process would be completely different I think from heating a wheel during an uncontrolled powder coating process. That said, I seriously question the hypothesis that a surface treatment like powder-coating could cause an alloy rim to sometime later fail all the way through with the cracking shown in the pictures.

To my untrained eye, the cracking in the picture looks like a failure to me. It doesn't look like the result of an impact. I would think an impact would dent the rim first, for one thing, but again I don't profess to be any kind of expert here.

A few failures out of a thousand wheels seems significant to me - not indicative of a totally poor manufacturing process - but definitely room for improvement. Hopefully TD has a quality system and ideally they'd want to get the wheels that fail back for analysis.

 

[M-Sport fan]

A few years ago on Corner-Carvers, there were some posts showing Corvette factory wheels cracking across the spokes and some where the spokes and hub separated. In those cases, the wheels were powder coated by the owner and not the factory. The wheels may have been the optional C5 magnesium wheels, but I can't confirm. The general consensus was to not send wheels out for powder coating. Factory finish is ok, paint is ok (white being the best for crack detection), polished is the best (until you scratch the surface and get a stress riser), and chrome and powder coating being less desirable. This was for wheels seeing high amounts of stress and heat. Seeing this type of failure on the street is not something I have seen much of, but believable due to the powder coating.

There is no doubt that heat and time change the molecular structure of the material. Cleaning agents along with heat can easily change the surface condition of the material and surface tension is important to reducing stress risers. A great example is glass, scratch it and it will break there because you gave the crack a starting place. I would bet most powder coaters that handle small batches are not going to change their cleaning or baking process for aluminum. Aluminum wheels would be ran with whatever steel parts being ran that day. This could easily cause too high of heat and improper cooling, which will greatly affect fatigue strength.

It is very common for professional race teams to x-ray and use dye penetrate on their wheels after races to look for cracks. Most teams probably have a known number of cycles before they scrap a wheel.

Yes, over on frrax.com, most of the knowledgeable members, and those who race the most, in the fastest and most competitive classes (American Iron/American Iron X,etc.), will tell you; "DO NOT powder coat wheels you will use in competition!"

In fact, most on there will not use anything but actual factory wheels (NO Chinese made 'replicas', which are usually heavier than the factory wheels of the same style/size anyway ), unless they are using actual race spec forged wheels.

 

[RAAMaudio]

Ok, got that straightened out, the TD wheels are factory heat treated and I am sure under very controlled conditions.

If a power coating company heats up the wheels significantly during their process it could nullify the factory heat treatment even to the point of making the worse than if never even heat treated depending on the heat temp, time to soak in, cooling process and time...

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As for using factory only or forged race engineered wheels there is also available for some cars at least flow formed race engineered wheels that cost hugely less than forged wheels and have a superb track record of reliability. I have owned dozens of such wheels and known of hundreds of racers using them just fine

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TD wheels have been used a great deal in racing as well, I do not recall hearing of issues with the factory treated wheels being failure prone on track, I have not used them as did not fit my needs so no personal experience.

 

[M-Sport fan]

As for using factory only or forged race engineered wheels there is also available for some cars at least flow formed race engineered wheels that cost hugely less than forged wheels and have a superb track record of reliability. I have owned dozens of such wheels and known of hundreds of racers using them just fine

Even though I did not state "flow formed" wheels in the post above, I DID mean to imply that they were included under the 'forged' description/mention.

It's just that for the wheel size those people were using (at least 18" diameters, 11"+ wide), and bolt patterns (usually GM's 5x120.65) there are NOT a lot of flow formed options available. (I wanted to use the 1.2s on my Z28, but Rimstock refused to make the offsets/drillings needed. )

 

[BRGT350]

Ok, got that straightened out, the TD wheels are factory heat treated and I am sure under very controlled conditions.

If a power coating company heats up the wheels significantly during their process it could nullify the factory heat treatment even to the point of making the worse than if never even heat treated depending on the heat temp, time to soak in, cooling process and time...

Yep, this is spot on. Depending on the time and temp, the baking process could easily anneal the aluminum or go the opposite direction and make the material harder. Either way, the results are not good.

I am sure a hardness test would quickly confirm if the hardness properties have been changed. Close examination of the failure would also most likely reveal beach marks where the crack had been opening and closing as it propagated through the spokes. There isn't anyway to properly examine a material failure from the pictures posted. I have done very little aluminum failure analysis, but I am confident the baking process altered the heat treatment of the material, the spokes flexed back and forth until a crack began to form, and once formed, the crack propagated through the spokes leading to a fatigue failure. It makes sense that the spokes would flex just past the hub due to the change in cross section. They would just pivot until failure.