Fuchs wheel center failure

[911teo]

Yesterday I had a close call at Silverstone.

I was out in the 74 RSR/IROC Blue 911 when I heard a funny noise coming from the rears when under lateral load (Club, Bridge, Luffield etc)...

I thought the tyre was rubbing against the fender (strange as it had never done it before). So I went into the pit lane...

As I am checking everything I notice something that make eyes pop...

The rear wheel (11x17 Fuch wheel made using original Fuch centre and BBS outer rim) has cracked in at least 7-8 points. The shears are basically going through the spokes (petals in a Fuch wheel) and also across the centre (in between the holes for the studs)







The noise we were hearing was the wheel (deformed) hitting the brake caliper on the inside.

Saying it was a close call and we were super lucky is a gross understatement.

I checked the other wheels and there is no sign of cracks or anything, but these wheels are coming off my car straight away.

I guess the wheels have reached the end of their life and using super sticky rubber certainly does not help.

Anyway moving on.... I want to buy a new set of wheels.

First thoughts went to the Zuffenhaus wheels.

The sizes I used to have were 9.5x17 and 11x17

I am thinking of getting to sets....

Zuffenhaus 17" and something else in 18" just for the track (track day tyres are getting difficult to find here in the UK).

What do you think?

Suggestions are welcome.

But please check your Fuchs, especially if you are tracking your car and are using super sticky rubber.

[ERH]

I can't stop looking at those pictures..... very scary stuff.

You are so lucky.....

New Zuffenhaus wheels are an easy call for the 17s. I'm not sure what to suggest for 18s.

Ed

[WPOZZZ]

Glad you caught it in time, Matteo.

[JeremyD]

Glad you are OK Matteo - and glad that didn't result in a spin

[Bill Verburg]

Just goes to show that anything will break if you abuse it hard and long enogh

[jpnovak]

Looks more like a Fuchs center failure. I am glad to see that there appears to be no issues at the weld bead or outer rim where Lindsey makes the 17" wheel.

Glad you caught it before there were no other resulting issues.

[B18CXr]

Saying it was a close call and we were super lucky is a gross understatement.

So true, glad you had the mind to pit and inspect

[jjwood]

Thanks for the post Matteo ... I'll now be extra vigilant with my Lindsey's. I think they'll become 'street only'

[911teo]

Originally Posted by jpnovak

Looks more like a Fuchs center failure. I am glad to see that there appears to be no issues at the weld bead or outer rim where Lindsey makes the 17" wheel.

Glad you caught it before there were no other resulting issues.

I agree.... I need to change the title of the thread. The welds Mike Lindsey made held perfectly!

PS
I cannot seem to be able to change the title as it appears on the forum. Bill can u help?

[911teo]

Originally Posted by Bill Verburg

Just goes to show that anything will break if you abuse it hard and long enogh

I do not think I "abused" the wheels long and hard.

These wheels have probably seen 7-8 track days in total and 6k miles since they are in my possession.

I just believe it would be wise to rethink one's strategy when tracking a 20yr wheel with modern track day/race rubber.

[dtxscott]

Not to add fuel to the fire...... But adding an extra half inch in radius to the wheel may have contributed to its failure. The wheel was probably originally designed as a system of wheel/tire based on a 16in diameter. When you remove flexible material and add rigid material a longer moment arm is created and more lateral torque is transferred to the wheel center.

I'm sure for street applications the modified 16" wheels are fine. For track applications I would be skeptical as your results show show the physics may hold true.

[Rot 911]

This has been discussed on the board in the past. Even a forged wheel can only sustain "X" amount of stress of a period of time before failure. Just that no one knows what that period of time is.

[Noah930]

Glad to hear that there was no comprehensive catastrophic failure. You might not be posting, had there been. Fortunately, it sounds as if Zuffenhaus is finally coming around to accept further orders for their 17" wheels. Supposedly they've fulfilled about 40 of their original 50 or so "pre-production" orders.

[175K911]

First- glad you and the car are OK
Second- I'm always gratified to hear someone who can tell by sound or feel when something's wrong with their car, and then backs out of the throttle and comes into the pits to check it out. I don't understand the logic of someone saying "it didn't feel right" immediatedly after they're pulled out of a tire wall.
Third- I've never been a fan of cutting a 20 or 30 yr old center out of a 6" wheel and welding it into a 9, 10, 11" wheel. The centers were never designed for the extreme loads that are being exerted laterally, longitudinally and radially on those centers and yours certainly shows what can happen.
Finally- Love my Jeff Alton (Zuffenhaus) wheels. I have the first set delivered and have done 20 track days on mine with no issues at all. I've gone through 2.5 sets of R-comp tires and the wheels still balance up almost perfectly.

And FWIW- even the factory Fuchs will crack. I cracked a 16x9 wheel on my previous 911 after two seasons of track use. Fortunately I caught it early and it was able to be repaired albeit as a street wheel only. The shop that fixed it said they'd seen several 16x9 and just as many 951 offset 16x8 Fuchs that were cracked across a spoke.

[johndglynn]

Originally Posted by 911teo

I do not think I "abused" the wheels long and hard.

I love you man but I would lean away from 100% agreement. Your car is the fastest thing I have been in with big bumpers on and you can pedal it. You are using super sticky tyres which are placing lots of stress on that centre with the big rims.

I think at my pace I'd probably be happy to keep using the Lyndseys but at yours - I dunno!

The Zuffenhaus wheels are an A1 idea, perfect for your car IMO

[Dantilla]

My 7 & 9 x 16 Fuchs see only street tires. The sticky 17" Hoosiers go on the Fikse wheels.

I guess now I know why.

[GaryR]

Matteo -

Glad to see what could have been a really bad situation wasn't.. If you need wheels in the near future I would go with CCW. The wheels from Zuffenhaus will be great once they are actually in production but that isn't now. They are just about at the point where they are delivering the first 50+ sets of their prototype run now (I'm #40, ordered in April, still no wheels). Once they start pumping out a "standard wheel" special orders like yours may get fit in but again, if you need wheels now.... CCW. Fikse is gone AFAIK, and were a lot more expensive. Anyone make racing wheels in the UK?

[Noah930]

Good point by Gary. If you need wheels NOW, Zuffenhaus is not an option. I'd lean towards CCW in that case. If you can wait a couple/few months, Zuffenhaus will offer a period-correct look in an excellent product.

[gsmith660]

+1 on the CCW wheels

[911teo]

Weather has turned bad.... This was my last track day for the year. The car is tucked away in a nice Porsche Specialist garage at Silverstone (Fearnsport.... great guys).

So I can wait on the Zuffenhaus wheels....

Not 1 year tough