Fuchs wheel center failure

[MrPerkles]

Teo bring the GT to brands next weekend !

[Geronimo '74]

That'll buff right out....

[911teo]

Originally Posted by MrPerkles

Teo bring the GT to brands next weekend !

The GT has the 118db exhaust set up on....

[911st]

I am not an expert but it seems a Fuchs wheel is a true forged wheel with the grains following its shape. Not a wheel carved from a forged blank. It is probably thicker and stronger than many light weight race wheel centers. Even if aged. If care is taken in selection, design, maintaince -- using it for a build should not keep it from having solid potential to make for a very usable and reliable road or race wheel.

Seems that even the best race wheels will sometimes fail.

One report is probably not enough to conclude that Lindsey's are not a safe road or race wheel.

How about just getting another wheel built and having them all xrayed or professionally inspect some way like the real race teams do.

A more important conclusion might be for all if us to inspect our race (and road) wheels front and back often no mater where they come from, how old they are, or how they were built.

We are lucky to have such fine quality Lindsey wheels for us to choose from.

[MrPerkles]

Originally Posted by 911teo

The GT has the 118db exhaust set up on....

dont worry I will bring a spare baked bean tin

[McLovin]

That wheel center is from what, a 16 x 6 inch wheel?

That wheel was designed as a lightweight wheel for a 205/55 street tire, but now its supporting a monster sized wheel welded around it, and a race tire, under race conditions, after being on the road for 20+ years.

I know Fuchs are a great, strong wheel, but this use seems to be rolling the dice a bit. I don't think there is any way to really know how safe or unsafe it is.

[Reaper930]

Go with a zuffenhaus wheel and you'll be happy when you can get them to take more orders

[rfloz]

Originally Posted by 911teo

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.

No, that doesn't sound like abuse. But who knows what happened in the previous 20-odd years.

When Jeff Alton was just starting to put his wheel deal together, I needed some wheels for auto-cross and DE in 9/11 x 17. I went with CCWs and have been very happy, as are many AX and track guys using them. I do hope to get some of the Alton wheels for street use eventually.

Nice catch, BTW. That could have been a real disaster.

Like many here, I have followed the build of your amazing car, as well as your post-build issues. Here's hoping for better luck to you in the future.

[911teo]

Just spoke with Zuffenhaus... They are working through the backlogs of the 1st wheels order and it all looks good...

Speaking to Keith we have come up with a different plan...

In 6 months the 1st centerlock 917/RSR wheels will be available....






In the meanwhile I have contacted BBS Motorsports and they can build me a set of these in 17's with a centerlock mount...

[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

[rsrfan]

[QUOTE=911teo;4980594]Just spoke with Zuffenhaus... They are working through the backlogs of the 1st wheels order and it all looks good...

Speaking to Keith we have come up with a different plan...

In 6 months the 1st centerlock 917/RSR wheels will be available....







Centerlock 917s are already available...hub conversions too.

JJR Products

I have seen these wheels and they are really nice

JP

[island911]

Originally Posted by Kurt V

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.

That is exactly right. ..well, except for that last part. That "period of time" is directly related (logarithmically) to the load. --it's not really time, but how many millions of cycles (rotations) can the aluminum take.

Notable: Not a bad failure mode. It's not like it shattered like some cast wheels do.

[vash]

Originally Posted by McLovin

That wheel center is from what, a 16 x 6 inch wheel?

That wheel was designed as a lightweight wheel for a 205/55 street tire, but now its supporting a monster sized wheel welded around it, and a race tire, under race conditions, after being on the road for 20+ years.

I know Fuchs are a great, strong wheel, but this use seems to be rolling the dice a bit. I don't think there is any way to really know how safe or unsafe it is.

i think this is some good stuff. sorta like taking your 3/8th ratchet, and putting a huge cheater bar on. you are taking the original design past the point it was built up for. those are some crazy cracks. glad it all ended safely.

[Wayne 962]

I've never been a huge fan of modifying Fuchs alloy wheels in this manner, for a variety of reasons. These are only my opinions on the design and use of this method, not necessarily any one manufacturer.

Firstly, I believe that the original wheel (maybe a deep dish or 16" SC wheel) was carefully designed to withstand the original loads that were to be placed upon it using the original design configuration. Taking a stock, small wheel and modifying it to be larger without beefing up the center seems unwise to me.

When you start with an "old Fuchs", you really don't know what you're dealing with. Was this wheel previously used in racing or heavy driving? Was it abused or well taken care of? Unless you bought the wheel brand new, then you don't know really where it came from. For street driving, used Fuchs are probably perfectly fine. But when you put them on a track, modify them, and then start driving very hard on them, you may be pushing your limits.

I'm not a high performance driver by any means, I don't race in the POC or anything more than weekend track events. But if I did, I would probably make sure that my track wheels were very fortified, if not brand new. Put the fancy Fuchs back on the car when driving it on the street, but save the strong stuff for the track.

-Wayne

[island911]

Just to be clear; we are seeing fatigue failure here. It is not just over-loading, but rather high loading AND high cycle.

Every cycled aluminum structure will (given enough cycles) fail this way. Aluminum has no 'endurance limit'. Steels, however, do. Steels can be designed to last an infinite number of loading/flexing cycles, whereas aluminum cannot.

[Jgordon]

Island, could you expand a little? From your post, I'd think that what you're saying is Aluminum does have an endurance limit (which Matteo clearly reached) while steel can be engineered with no limit.

Just curious.

Thanks.

[burgermeister]

As stress is reduced, the life gets longer. Very coarsely, a 10% reduction in stress (either by design change or by a 10% reduction in load) will double the life of the part. Conversely, a 10% increase will halve the life of the part.

For steel parts, there comes a point (the Endurance Limit) where the stress is low enough that the part will never break (usually somewhere just below 1/2 Ultimate Tensile Strength). With aluminum, there is no such point - no matter how low the stress, it will always break given enough cycles.

So VERY coarsely, going from a street tire with a lateral capability of 0.9g to a DOT-R with a capability of 1.2g (and assuming the capability is utilized) would cut the life expectancy of the wheel by a factor of 10.

Island makes a great point - the failure mode is pretty much ideal.

[JeremyD]

Originally Posted by island911

Just to be clear; we are seeing fatigue failure here. It is not just over-loading, but rather high loading AND high cycle.

Every cycled aluminum structure will (given enough cycles) fail this way. Aluminum has no 'endurance limit'. Steels, however, do. Steels can be designed to last an infinite number of loading/flexing cycles, whereas aluminum cannot.

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.

[Wavey]

More on the 917 style center locks:

http://www.pentamotorsports.com/pdfs/rim-flyer.pdf

[911teo]

They look similar but they are not "right" though, are they?

The spokes are much fatter in the original ones. And the 917s did not have a flat surface...