Forgestar F14 track day failure....

Forgestar F14 wheel failure and stress cracks after 14 track days.

http://blackflag.jalopnik.com/track-day-bro-has-the-best-reaction-ever-to-a-wheel-fai-1770532706

[ame=http://www.youtube.com/watch?v=vtYjujhW27Q]Forgestar F14 Failure at Buttonwillow - YouTube[/ame]

I think I am gonna find some nice steel wheels for track days!

Thanks for the link. Scary as $hit.

Tells a lot about the manufacturer/manufacturing.

Great reaction. The remains of that wheel were motoring!

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Nice to see the company is standing behind their products and making things right for him. That's a lot of fatigue cracks!

UPDATE: Forgestar is trying to make this right on their end as well. A

by Wiita on the video mentions that the company has offered not only a refund on the wheels, but the cost of a replacement ball joint for his car as well. They’re also going to have a look at the remaining wheels to see if there’s a way to prevent like failures in the future. [H/T WarShrike!]

Another case of you get what you pay for... a whole set of F14s costs about what a single "real" forged wheel like a Volk or BBS would run.

Dude would've probably been fine running a set of cast/flow-formed Enkeis, that were at least well made.

Reading their website, their wheels aren't forged? Says they start with a cast face (where the above wheel cracked) and spin them on a die to produce the barrel. So the name itself is not accurate lol.

As above, you get what you pay for. I haven't seen a (real) set of Enkei wheels break like that. Quick search has quite a few results of "beware of Forgestar" and "cracks in Forgestar" type threads. Running cheap wheels (not that I would), I'd be check them after every session.

for a while there was talk about rota wheels and breakage at the track.

Bent or out of round is perfectly acceptable during punishment. cracking may be due to the chemical makeup of the material being used.

you can take aluminum and bend it 90 degrees no problem.

I saw an enkei rpf1 that had run over a "brick" at laguna seca. it was bent to hell but not broken.

for a while there was talk about rota wheels and breakage at the track.

 

Bent or out of round is perfectly acceptable during punishment. cracking may be due to the chemical makeup of the material being used.

 

you can take aluminum and bend it 90 degrees no problem.

 

I saw an enkei rpf1 that had run over a "brick" at laguna seca. it was bent to hell but not broken.

This.

Here's what you want your damaged (but not failed) wheel to look like:

http://i5.tinypic.com/14c5ydu.jpg

Must've felt that one

And here is how XXR/Rota/etc, and apparently Forgestars tend to go:

http://i110.photobucket.com/albums/n108/wppjr30/Miscellaneous/broken-wheel-02.jpg

http://i110.photobucket.com/albums/n108/wppjr30/Miscellaneous/421141_281872091878655_500904509_n.jpg

Cheap wheels can suddenly become very costly.

Notice how the spokes are fine on the Volk but the rest just shear off.

There's a reason proper forged wheel cost as much as a set or more of the cheap cast wannabes. You can roll/press/whatever forge the barrel, but if the spokes aren't strong, then what's the point?

This.

 

Here's what you want your damaged (but not failed) wheel to look like:

 

http://i5.tinypic.com/14c5ydu.jpg

 

Must've felt that one

I think that'll buff out.

Reading their website, their wheels aren't forged? Says they start with a cast face (where the above wheel cracked) and spin them on a die to produce the barrel. So the name itself is not accurate lol.

They make no false claims on their website - they pretty clearly state that they are bridging the gap between forged and cast wheels. The front is essentially cast, then the barrel is rotary forged (which is a real industrial process, as is flow forming - another forging process) which enables them to shave weight in the barrel (they claim 15%) while maintaining strength and dent resistance. (and the barrel of the rim did just fine - you can watch it happily bouncing away in the video )

The failure in the spokes was due to fatigue cracking - and cold work (i.e., forging) definitely improves resistance to fatigue cracks. Can't really say what the origin was in these without some more detailed fractography - common places are machining marks/surface imperfections (unlikely it was an impurity per se, though could be a second phase particle)

Not arguing that you don't get what you pay for - these rims are cheaper than a full forged wheel for a reason - they cost less to make - and a forged wheel is better in a racing application - the issue here was clearly not appropriately inspecting things before hitting the track. Fatigue cracks take time, and would have been readily visible long before they became so large that you had failure of the remaining ligament in the spoke.

Any wheel can crack across the face, some are just less likely to do it.

http://i284.photobucket.com/albums/ll37/jjbhoops30/Broken_Lotus_Wheel.jpg

http://i134.photobucket.com/albums/q94/igo4bmx/Broken%20wheel/IMG_3514.jpg

The lesson the driver learned is that he needs to inspect his wheels before and after events. When doing that many track days, wheels and wheel studs become consumables, especially when you have off track excursions or hit track curbs.

The lesson the driver learned is that he needs to inspect his wheels before and after events.

A million times this, no wheel is impervious to fatigue.

The Volk lost a soldier, but that Lotus wheel lost the battle (forged wheel, or cast?)

Is that a Volk CE28 or ROTA Fighter?

Real (and bent) CE28n with the same center cap for comparison:

http://www.japanesesportcars.com/photos/d/600194-2/honda-s2000-volk-racing-ce28n-011.jpg

And here's the rota copy

http://www.rotawheels.com.au/media/made/media/images/wheels/rota-fighter-gunmetallic-18-45_1000_1000_staticimagessitewatermarksrota-large.png_180_38_100_r_b_-20_-20_c1.jpg

Dented rim is almost normal on shitty roads, but we're talking about the spokes here. I haven't seen a proper forged centre shear off like what's been posted above, hence why I asked if that's a genuine CE28. For the generic 73mm hub you can basically put whatever aftermarket centrecap you want.

That Lotus wheel looks like it took a big hit (which any wheel will break). But it looks like a couple of spokes are still intact.

One way to compare would be to buy copy + real wheels (e.g. CE28 and the ROTA Fighter). One side forged one side whatever, identical tyres. Then drive around and swap the wheels from left to right (e.g. after every track session). After X amount, inspect the wheels.

Real (and bent) CE28n with the same center cap for comparison:

 

http://www.japanesesportcars.com/photos/d/600194-2/honda-s2000-volk-racing-ce28n-011.jpg

On a side note to the pic above, It should be common sense not to daily drive on an aspect ratio like this. To those of you who end up with wheels like this: Serves you right! Raise your car back up a little bit and run a larger aspect ratio, and maybe there wont be any tears over your next set of wheels. I see it all too often. End Rant.

http://rennlist.com/forums/attachments/racing-and-drivers-education-forum/533105d1304353243-bbs-mag-wheel-failure-wheel-broke.jpg

http://rennlist.com/forums/attachments/racing-and-drivers-education-forum/533141d1304366565-bbs-mag-wheel-failure-bbs_center_fail_small.jpg

http://www.nbtglobal.com/info/CantFix.jpg

The way a wheel breaks can be determined by many things. Slide into the grass sideways at a decent speed and all bets are off. If that wheel digs down into the dirt or catches something well planted, you're not gonna have a good time.

As I said before, if you do as many track days as the driver with the failure, wheels and wheel studs become consumables. They HAVE to be replaced at some point.

The moral of the story is, any wheel can break.