► Official APEX VW SM-10 Flow Formed Wheel Thread

[GTIfan99]

Except paper clips are steel, which does not suffer from cyclic fatigue like aluminum, but does fail when pushed past it's limits, like bending it 180 degrees multiple times. There's a reason I replace my aluminum seatposts and handlebars on my bikes fairly frequently but don't worry about the titanium seatpost nearly as much. Nothing worse than a snapped seatpost saying hello to your posterior.

I guess bad example. But yeah, aluminum fails spectacularly when it does. Surprise bunch biopsy of the prostate is no fun.

 

[bentin]

My dad had a '93 FD RX7, they had comically light wheels, but they cut a few corners and they liked to fail in dramatic fashion. I always give FD RX7s a little extra space on track. There are more graphic pics of the whole hub face ripped out, but I can't find them at the moment.

 

[TheProfessional]

Except paper clips are steel, which does not suffer from cyclic fatigue like aluminum.

Steel DOES suffer from cyclic fatigue, but the fatigue levels off after 1,000,000 cycles.

Also on the paper clip, when you are bending it, you are inducing strain hardening in the material, which in turn makes it brittle, which is why it breaks.

Sorry guys, I'm just being the dork professional engineer.

 

[bentin]

Sorry guys, I'm just being the dork professional engineer.

Thanks, I was in ME for a couple of years before realizing I didn't want to work with those people and changed to the business school. So I'm dangerous with only surface level engineering smarts.

 

[theDoktor]

Good info on deflection failure everyone- thanks!

 

[bfury5]

It's easy for people to understand that bending a paper clip back and forth will cause it to break, but can't see the same principle applies to track wheels.

This is why track wheels should be considered a consumable, just like wheel bolts and other safety critical items

 

[jmblur]

Steel DOES suffer from cyclic fatigue, but the fatigue levels off after 1,000,000 cycles.

Also on the paper clip, when you are bending it, you are inducing strain hardening in the material, which in turn makes it brittle, which is why it breaks.

Sorry guys, I'm just being the dork professional engineer.

If you dig deeper, the data that leads to fatigue limits is based off a poor interpretation of stochastic data. There's some pretty hefty disagreement on whether or not fatigue/endurance limits are actually a thing.

/Also an enginerd

 

[Will_]

All I’m hearing is an excuse to buy new track wheels every year

 

[bentin]

All I’m hearing is an excuse to buy new track wheels every year

Don’t forget the ti lugs too.

 

[Will_]

Don’t forget the ti lugs too.

I’d be doing a disservice to my future wife and children if I didn’t go for forged wheels too. For the safety, of course.

 

[bentin]

I’d be doing a disservice to my future wife and children if I didn’t go for forged wheels too. For the safety, of course.

Do it for your children!

 

[jimlloyd40]

Do it for your children!

X's 2. Have a spare set ready.

 

[GTIfan99]

I've seen enough wheels fail on track that I will rotate my track wheels to street duty after 3 years if I'm tracking regularly. YMMV. The last few years my track time has dwindled, so I sound be fine.

I'd imagine forged wheels and wheels designed specifically for track should last longer.

 

[ExtraChrispy]

So my tire pressure warning came up today. Looks like America's Tires filled the front to 35 psi and the rear to about 31psi....I know I read about different tire pressures for different load ratings but this is just off. Going from the stock bridgestones to Michelin AS4. Should I be setting them to the door jam 39 psi or slightly lower due to the new load rating?

 

[GTIfan99]

So my tire pressure warning came up today. Looks like America's Tires filled the front to 35 psi and the rear to about 31psi....I know I read about different tire pressures for different load ratings but this is just off. Going from the stock bridgestones to Michelin AS4. Should I be setting them to the door jam 39 psi or slightly lower due to the new load rating?

I like 35 psi on the street.