Anyone interested in Lab testing a real Fuch?
 

So, there has been lots of speculation on recent threads that wheel "A", "B" or "C" is not as strong as a Fuch. Lots of good theory has been passed around and debated. We have been shown pics of broken Fuchs and broken aftermarket wheels. The topic has been debated at length, but one key part of the debate has always been missing.....

Who knows what sort of load a real live Fuch can handle? We, collectively, seem to hold that wheel in such high regard, but have no true idea of the load test it can withstand. So, the group banters back and forth about this spec and that spec possibly not being high enough, all the while info has never been posted that shows what the Fuch will do. For all we know the new breed of wheels from the different makes and modifiers are as strong or stronger than the original, or maybe not!

Here is what I am willing to do. I have contacted a Lab that has tested wheels for GM, Ford, Chrysler, Alcoa, DOT etc. If enough interest is expressed I will coordinate the test and foot 20% of the bill. But, there are some things required and some agreement needs to reached as to what load the test should be carrired out to.

Here is what we need:

1. People willing to put a few dollars towards the project (the whole thing should cost less than 1K but once I have load specs etc, I will get a written estimate)

2. One or two real Fuch wheels, 16's preffered. (wheels not returned after testing for liability reasons.)

3. Tires, prefferably new, to be mounted on the wheel. They should be the same size as what is commonly run on the car. Ex. if we have a 16x7, we would need a 205/55/16. (or a 225/50/16)

4. Agreement on what load number we would like to see the wheel tested to on a CFT.

I do not want to get into a debate about the validity of the testing. These ARE the tests that car and wheel manufactures use. We can test more than the CFT, Radial fatigue (no side load) and impact testing can be done too.

Anyways, if I am off my rocker with this, let me know. If you are interested let me know.



Cheers

edited to add a tire size pointed out by a fellow poster

I'm interested. I think you meant 2225/50/16 on a 7". I can contribute a few $'s, but no wheel or new tires... When the time comes a PayPal addy would be good.

The only question is if the testing on a 7" will carry across the 6", 8", and 9" x 16 wheels??

As for loads, I think we should use track relevant loading. These cars are not grocery getters... :p

Have you attempted to get the original testing information from PAG? Might be something to think about even if it is 30 years old. Some people on this board have special connections they may be able to use to get it.

Best regards,

Michael

I'm in

fwiw, there can be a huge difference in failure modes. A bend or a break ... both are considered "failed" yet the bend keeps some composure, whereas the break is catastophic . . pieces of wheel all over the track/road . . car traveling on three wheels and a torn-up tire.

This is why landing gear on jets is usually made of steel (toughness/hanging-on even after the over spec hit & bend). Tho' their are exceptions. The SR-71 used (lower weight-specific toughness) titanium for it's gear. .... Forged titainium, btw.;)

You estimate a cost of around $1k, but new Fuchs will cost you nearly that for each one. And there is no real value to testing a 30 year old, used wheel since we would have no data regarding it's past stress exposure.

I'm in.
Island's an iconoclast.
You in Island?
Or you gonna be a loof?

Yes, but we do not need to test to failure. We can, but why not pick a load rating and see if it will pass?


Cheers

First, a 16x6 can be had used for about 125-150 dollars.

Second, I think it is very relevant to test a used wheel because the common sentiment is that "I would rather go to the track on my 25 year old fuchs then use a new wheel "A", "B" or "C".

Also, one maker of 17 inch fuchs uses old wheel centers. Have not heard too many questions about the quality of those wheels....

Yes, 1K should cover the testing and some of the additional costs (wheels and tires). I was hoping deep down in side that someone had a 16X6 they would sell maybe at 1/2 price (or at least a discount) and consider it their contribution........

Cheers

I'll chip in a few bucks...

Randy, Island and the others....

I realize that it may be apples to oranges as we do not know the exact method of testing used by others, only that it is a CFT, but we don't know the factors used to get the rating. Was it 1.5, 1.8 times the load rating to get it down to 100,000 cycles.

I would think we would want to use the SAE standards/table to figure out the factor.

Your thoughts?

Cheers

As one who wants to go back to a Fuchs-look with my car, and need to have a wheel that will hold up at the track several times a year, that is my primary interest here in that I'd probably be looking at "one maker who uses old wheel centers".

Unless of course, someone else developed a "faux Fuchs" using a forging process. :eek:

Interested; I've got some questions.

How are we going to use the data? It seems a bit useless in a vacuum, but very useful if we also test or have data for other track wheel options for comparison? Stock vs Rota vs blank (popular race wheel?), etc would be good, but is tougher. That's what I feel needs to be done to make this truly useful, though.

A few other thoughts-

1. What test would you use? Many tests would be effected by rim width, as the wider rims act with a larger lever arm on the hub, so using a 16x6 might not give you the same results as a 16x9. How could this be handled?

2. I'd suggest testing to failure in some way, perhaps with increasing load as cycles increase, so that we get a measure of strength rather than a pass/ fail.

3. I'd use at least 1x new and 1x used, known history well used fuchs, as otherwise your results will always be open to questions regarding "getting a bad one", etc.

Could be good. I know I don't trust most of the existing wheel options at the track- the consequences of failure are just too high. New Fuchs or race wheels for me until proven otherwise...

All great points. Rota has posted their CFT ratings. And many other wheels will have it stamped right on the wheel itself.

1. I think the CFT is the most widely used test, so it may make sense to use it. Could also use Radial and impact testing, however finding data on other wheels may be more difficult for comparisons.

2. They can test to failure, in much the manner you suggest.

3. I see your point about using a new wheel, but how many people use new Fuchs? Especially in a narrow, say 6 or 7 inch front. But, none the less, good point. I like the idea of used wheels because this is what folks are saying they feel more comfortable with on the track. But, if someone wants to cough up a new one, I would test it!

Your are right, it "could be good" but it could also be a waste of time and energy. I just felt like maybe instead of speculating if Wheel "A or "B" is not a safe as a used fuch, we could find out!

Cheers

Wouldn't a letter to TUV be cheaper?

There ya go.

Someone here once got a response from Fuchs, regarding the alloy used. http://forums.pelicanparts.com/uploa...1182997952.jpg

If your're asking what r ota did, I have no idea. It strikes me that they added a few pounds to the wheel, and did some testing, because some PIA 911 guys were asking pointed questions. :cool:

btw, I think it's great that they beef'd the wheels. My biggest concern was that the "fit check" versions were perhaps less mass, on a size basis, than OE. That is, they weighed less than 17/16th of a 16" Fuchs. ...Taller structure, G-CAST, lower profile tire AND proportionately less material -- not a good combo.

I agree island, I had concerns about the weight of the prototypes too.

Can you translate that graph into english for us?? :) And is it for wheels or cylinders? Or does it matter?

John, yes maybe a letter to TUV would be cheaper. However, there is not a benchmark TUV standard a wheel needs to meet. They test, from my research anyways, to whatever a manufacturer requests. Now, I could be wrong on that as I did not get my info from TUV, but from a secondary testing facility.

Like I said, if I am off my rocker on this one, let me know.

But, to all the folks out there, myself included, concerned with the quality of different wheels we put on our cars, what load rating would satisfy you to deem them safe? What would YOU use a spec to say "I am comfortable using these on my car for the street and or track(if applicable)?

The point of the test and thread is to generate discussion about the topic. It comes up frequently and a few threads have been closed. This thread is a chance to put some real technical info into the BBS. Provided we do it right....... :)

Here are some questions to thing about. (feel free to add more)

Would you only accept a wheel that failed at the same point as a fuch?

What if the fuch failed before you thought it would while being tested?

Would you be satisfied with a wheel that tested as strong as one on a new Z06 vette?

What would you do about your wheels if the fuch failed at a load before what you stated would be acceptable?? Would you change your acceptable target, or think about updating to a newer wheel that is not 25+ years old.

Like I said, just trying to stimulate discussion. Lets do a test if it would provide info we could all use, but lets not bother if it won't.

Cheers

Is one or two wheels enough to get any kind of statistical significance? Especially with used wheels, the pre-existing stresses on them aren't known and one particular wheel could fail at much lower than expected load. Would a Fuchs that has visited a curb and was straightened and polished give reliable numbers? New wheels would remove that variable, but would be expensive. Not trying to rain on this parade, but if one Fuch wheel fails at 10,000MPa and the other fails at 18,000MPa ( I'm making numbers up here) what have we learned?

edit: this is kinda what petevb said, except I'm not sure just 1 of each wheel would be enough to be reliable. It would be fun to do, nonetheless!

Well, that is sort of the point. ......

Most folks on this board drive cars with Fuchs of unknown history. Who really knows the life their wheels have lived? Yet, the same people have no problem taking to the track or driving around town. YET, when a new wheel comes along, they say "no way I would run that wheel on the track, I will stick to my old Fuchs with an unknown history, because they are safer......."

Having said that, You are right, what if the one or two tested had a bad history? Skew the test results for sure. But what if the ones on your car were the same?

My point to those, me too, who question the safety of new wheels to hit the market " do you want to find out how safe your wheels are, or do you just want to continue to speculate?"

It just struck me as odd that we are totally comfortable (as a group) driving on the street and track with old wheels of untold history, and no knowledge of the tested strength, yet we will bash and question the strength/safety factor of some new or different wheels....

Here is a chance (random, true) to see if the concern about new products is justified. It may be that the a used old fuch is twice as strong as a new aftermarket wheel, but it may prove not to be......

Like I said, just trying to stimulate discussion.

So, feel free to post what you think a reasonable load rating would be for a wheel you would put on your car (for what ever you use your car for)

Cheers

Good question, mouth mechanic:D ! Yes who knows?

I keep getting stuck on the fact that a Fuchs WILL bend, whereas a cast wheel WILL break off a chunk. Could possibly make the difference between keeping the shiny side up and turning turtle if you slide into a curb, no?

Oh yeah - check out the "Forged Fuchs Replicas' thread here. Jeff's posted some great info and pics!

DARISC, brings up a good point. Most times (most) when a forged wheel fails, it bends. Now real fuchs have cracked, we have seem pics posting evidence of that here.

When a high quality three piece wheel fails, *usually* the failure is a bent wheel half, but the wheel hold air. This usually happens in the heat of battle. Some folks have posted pics where the center of a wheel has cracked (BBS Mg) but I think that is rare.

Cheers

I know little about metallurgy, but i do remember that repeatedly bending a ductile alloy will cause work hardening. That's the same principle behind being able to break a wire by bending it back and forth repeatedly. Perhaps the Fuchs that cracked (without hitting a curb) finally reached that point, where instead of bending a crack began to propagate. Age of the wheel and stress history I'm sure will play a significant role.

It would be interesting to find out that an old Fuch was still stronger than a new Japanese cast!

I agree,

Is an old fuch stronger than a new Japanese/Philipeanese replica?? Who knows, the point of the thread/ question was to find out, and if so, how much stronger?

THere is so much anectdotal heresay on the internet... everything from "failure of a 16x9 fuch is well documented" to "cast fuchs will all fail" to "these are tested to "X" load" that it becomes hard to tell what is real.

Fact is, folks always want to critique based on knowledge and not facts. Ideology and not testing. Nothing wrong with that, I do it too, provided it is taken in context.

cheers

Me too. If I was a bettin' man I'd be putting big money on the Fuchs.

Given odds on that money? :)

Cheers

Yeah, but you're really pushing my disclaimer. http://www.pelicanparts.com/support/...ool_shades.gif

That graph says a LOT. But the skinny is, forged can take 3x more load, than cast, for any given number of cycles.

fwiw, Rota sez they tested at 100,000 cycles (that's 10⁵) . .about 113 miles of travel. To make that 113,000 miles, we would be looking at 10⁸. This is past the "knee" of the "curve" ... and while there is no endurance limit, it doesnt drop as quickly. And note this is a log scale --10⁹ would be over [Dr Evil] One Million Miles[/Dr Evil].

But of course wheel loads on our cars is fluctuating, and not at max for all those cycles. There are engineering models for this too, but really, that's not needed here. The bottom line is, for a given average stress level, the cast version is not going to last nearly as long as the forged. The difference in life is magnitudes . . many.

Q: What is more likely to fail at the track, the wheel or the tire?

Aside from not having torqued the lugnuts recently, my greater worry at speed is a tire failure. Are wheel failures that common? My suspicion is that even the weakest wheel will out-endure a tire. But on the other hand, a given wheel may have seen a dozen sets of tires over 30 yrs. Opinions anyone?

A tire. BUT, a slow tire leak is not nearly as memorable an event as a fast breaking wheel. ;)

Too much pseudo science ( or partial-view correct science) floating around in this thread.

IMHO... testing *one* (or a few) old Fuchs and saying you'd get meaningful results that would translate to what other people might see...is not valid. As someone here mentioned, the statistical relevence is lacking unless there is a large test sampling used.

Also... the prior history of the particular used Fuchs comes into play. This was also discussed. How do you translate that to the next user?

Next...the graph indeed shows some information, but people used it incorrectly here on this post. Yes...the forging is stronger and more fatigue resistant ( on the *same* psi basis), but that's the point. Key words..."on the same psi basis". That means....on the basis * IF * the cast component was designed using the forged component's sizing parameters..which usually isn't the case. Meaning?..designers who knowingly design a cast wheel will purposely use thicker load bearing sections than the equivalent forged piece. This is where some of the "fake Fuchs" went off the deep end. The copy-cat Fuch clones in some cases were not made thicker in critical areas to compensate for the cast piece's reduced strength and reduced bending/fatigue resistence. Modern cast wheels that are of different design (than Fuchs) should be designed properly ( made thicker, heavier, unfortunately..in some areas of the wheel) and should be "safe" for any road purpose. However, there are caveats here too. If we don't know the design basis of the new cast wheel...and what regultory agency it was built and designd to comply with ( TUV, etc)...we can only guess on how adequate it is for track purposes.

Nice attempt guys..but this approach to testing an old Fuchs will lead you toward a dead end unless all these other factors are blended into the testing mix.

- Wil

Looks like Subydude is offering to find out if Rota will do the testing.

I read that as 100k load cycles not revolutions, ie: 100k corners... Testing 113 mi seems ridiculously small for a wheel. that's about enough to see if it rolls straight and thats it. 100k corners is a real test and seems to make more sense. But I have no facts to back up this assumption of mine. Do you know their definition of 'cycle'?

Best regards,

Michael

A cycle is one rotation. The wheel sees the load constant for the given number of rotations.

Cheers

There is interesting discussion going on relating to this thread at http://forums.pelicanparts.com/showthread.php?s=&threadid=354765&perpage=20&pagen umber=1