Fuchs wheel center failure

[DW SD]

Originally Posted by JeremyD

This was one of the biggest criticism's on the Audi A8 "Spaceframe"

Because of the nature of Aluminum it would have a definite "service life" based on the duty cycles.

At some point - it would need to be scrapped and recycled.

So would jet airplane chassis which have been in daily service for 30 years. It all depends for what amount of cycles they are designed. But those also see very regular inspection intervals, including logging cracks and their propagation.

Sounds like Teo's wheel center might have lived a hard life, even before becoming part of one of his track wheels.

Is anyone aware of any other Lindsey failures (not that one isn't enough)?

Doug

[911teo]

Originally Posted by DW SD

Matteo,
Glad to hear you are OK! Your prudent response shows you are in tune with your car. Is it obvious from where the crack propagated? I have Lindseys too and would intend to inspect regularly, but it would be great to know if there is a generalized weakpoint.

What constitues sticky rubber? What Tire size, brand and compound have you been running?

Doug

It was not obvious where the crack propagated... it is clear that the middle was more stresses than the petals as the crack was already showing a gap, whilst the others weren't.

As per size at the rears I was using the same as you, 315/35 and the tyres are Toyo R888. According to the data logger the cornering Gs generated last time I was at Silverstone are around 1.25-1.3

[911teo]

Originally Posted by DW SD

So would jet airplane chassis which have been in daily service for 30 years. It all depends for what amount of cycles they are designed. But those also see very regular inspection intervals, including logging cracks and their propagation.

Sounds like Teo's wheel center might have lived a hard life, even before becoming part of one of his track wheels.

Is anyone aware of any other Lindsey failures (not that one isn't enough)?

Doug

I don't know about its life before. What I can say is that I was probably a little naive about the wheels.

It is clear the original design has been modified dramatically and possibly it was just a little silly not to think something might like that happen.

So I just wanted to give anybody else that is using their modified wheels on the track the heads up.

[smokintr6]

DW SD,

So would jet airplane chassis which have been in daily service for 30 years. It all depends for what amount of cycles they are designed. But those also see very regular inspection intervals, including logging cracks and their propagation.

True, but this is actually a concern in the aviation world too. I know there are some biz jet size planes that essentially cycle out in critical load areas. Ala, lockheed jetstar. Even some single engine piston airplanes (Bonanza for one) have oulined inspections for structural cracks.

The fact that airplanes are made of aluminum is in itself not a significant arguement that we should no one should worry about having an aluminum frame under their car. What it means is that when deciding to purchase something fabricated from aluminum, one must have faith that the manufacturer properly concidered the design loads. Ultimately, as all cars approach infinity miles, cycles, or what have you...they will be scrapped. It's just a matter of making sure you get enough cycles per dollar invested, to feel satisfied with the product.

[cdrik915]

I knowed that issue could happen with Fuchs Replicas , but not with Lindsey wheels.

Too much work for the wheel on the track !!!!

[JP911]

Originally Posted by cdrik915

I knowed that issue could happen with Fuchs Replicas , but not with Lindsey wheels.

Too much work for the wheel on the track !!!!

This happens to un-modified factory Fuchs as well. Usually when used hard on the track. If you do a search you'll find pics.

[cdrik915]

Thanks for the info , i thought that not happened with real forged Fuchs.

[ski wagen]

Originally Posted by island911

Every cycled aluminum structure will (given enough cycles) fail this way.

A comforting thought for my next airplane flight (think Aloha Air Flight 243) . . .

This type of failure was a big part of my rationale when I ordered the Alton Fuchs over using my old Fuchs centers for 17's.

[Jim2]

Does anyone have an idea if Lindsey heat-treats the wheels after welding?

The problem being with welding which will anneal a broad area surrounding the weld.

FWIW a person does not have to look too far to find a cracked wheel which was on the track. Just within my circle of racing friends we probably stand around a dozen failures, some race-bread, some not.

[island911]

Originally Posted by Jim2

Does anyone have an idea if Lindsey heat-treats the wheels after welding?

The problem being with welding which will anneal a broad area surrounding the weld.....

But, you have to consider the (lower) stress distribution in that area.

FWIW, when I saw what Lindsey was doing / how they manufactured, I briefly had the same concern/thought. Of course now we do have empirical evidence here of the weakest areas. (not the welds)

My only Q at this point is to how much of the failure was driven by (over?) torquing of the lugs. --that is, did the cracks propagate from the center to the lugs, or form the lugs to the center? (there is a good amount of hoop-stress around those steel lugs)

[kepperly]

I have an 87 911 and the reason I went to a different brand of wheel is their age.
I put Fikse fm 10 on mine 10 years ago and no problem since, PERIOD. Three sets of tires since!!

Keith Epperly
87 slant nose turbo look carrera cabriolet

[BigD9146gt]

ski wagon is on it, 100%. No matter how great the welds are, no matter how good the material is, the engineering for this application is not applicable. I don't care what any aftermarket company says, its race only for good reason.

island911: Yes, not the welds... however, i worked for a shop that wouldn't touch aluminum rims for this reason. Heat, regardless of where the failure occurs, will affect the finished product. Aluminums' heat coefficient is unreal. Even if you've got a machine doing your dirty work, your going to have to heat treat the part. Now your going to respond with "what shop?"... and my response: Precision Machine. The inventor of Motion Control equipment (from Star Wars on up), the first successful down hill full suspension bicycles (Rad 1), and countless other inventions that you love and hate in your daily life (I personally helped with printing machines for what we call junk mail...sorry, it was a job.) I'm a metal machinist and welder by trade, study materials on a daily basis, and cracks typically come from brittle parts... Please show me pics of the 15x11 fuchs that do the same as this. Cheers.

[Todd Simpson]

FWIW a person does not have to look too far to find a cracked wheel which was on the track. Just within my circle of racing friends we probably stand around a dozen failures, some race-bred, some not.

Exactly.

That's a *good* wheel failure if you ask me. Plenty of warning before complete disaster.

[island911]

Originally Posted by BigD9146gt

....

island911: Yes, not the welds... however, i worked for a shop that wouldn't touch aluminum rims for this reason. Heat, regardless of where the failure occurs, will affect the finished product. Aluminums' heat coefficient is unreal. Even if you've got a machine doing your dirty work, your going to have to heat treat the part. Now your going to respond with "what shop?"... ....

Well, no. I'm going to respond with; I'm an engineer (mech) and have very methodically mapped the HAZ of welded aluminum. (HAZ -> heat affected zone) It simply isn't anywhere near large enough to cause problems in the areas which cracked.

Edit:
See also: http://www.esabna.com/us/en/education/knowledge/qa/Heat-Affected-Zone-of-Arc-Welded-Aluminum-Alloys.cfm

[island911]

Originally Posted by Jim2

...
FWIW a person does not have to look too far to find a cracked wheel which was on the track. Just within my circle of racing friends we probably stand around a dozen failures, some race-bread, some not.

from another thread

Originally Posted by ttweed

Cracking of forged wheels is not limited to 30 year-old Fuchs. Here is a pic of an 8 year-old Kinesis wheels used solely for occasional autocrosses w/ R-compound tires:


The owner found multiple hairline cracks on all four centers propagating on the back of the spokes, possibly from stress risers just outside the center hub section, .
...snip..
TT

and from Bill V, a cast REPLICA



now THAT is a catastrophic failure mode. (unlike the forged Lindsey)

[burgermeister]

Originally Posted by island911

It simply isn't anywhere near large enough to cause problems in the areas which cracked.

+1
At work, we consider the HAZ to be 10mm either side of the weld for robotic welds. Tig might be a bit more ... still a big distance from any of these cracks.

[Kevin Stewart]

I am sure you have the right lugs, but they are ball seat correct. Sorry I had to ask, Kevin

if you have time can you post a complete picture of the wheel/tire, if not no biggy

[911teo]

I had to leave the car with a shop at Silverstone ( I drove there). So I cant take anymore pictures for a while...

sorry.

[palle7688]

island911,
I had the same on my cast replica, it broke just a little closer to the rim.

I've seen Original Fuchs welded up to a 11" wide, cracked at the same spot, the petals near the rim.

See also Bruce Andersons "performance handbook" he has a picture of a cast replica broken in the same spot.

911teo,
you have been very lucky, and vice to pull in when you heard something wrong.

[Green 912]

It has nothing to do with the HAZ. I have seen this same fail mode in unmodified 6X15 fuchs that were tracked. The cracks were bad in one wheel and just starting in another from the set. They were starting in the web between the lug holes almost as if the hub was pulling the center apart outward. Heat in the hub perhaps? Many aluminum alloys are sensitive to heat in the range seen in brakes and to some extent the hub the rotors are bolted to..