Fuchs wheels cracking?

[cstreit]

Two weeks ago I noticed that two of my Fuchs have cracks starting from teh hub lip heading toward the spkes and lug nuts... Both on one side... THe left side that receives most stress. 4-5 cracks!

No I didn't overtighten the lugs, yes they were snug (95 ft/lbs), no I never hit anything...

Then my buddy say an article in PCA racing talking about failing Fuchs...

Anyone else experiencing this?

Check your wheels...

[GeorgeK]

HI Chris,
A sad and little known fact of life. Yes Fuchs rims can crack. they are after all aluminum, and have a definite fatigue life just like any other material.
Funny thing yours cracked at the hub. EVERY one I have seen crack in the middle had a history of overtightening/using impact wrenches/having them mounted by people who dont know what they are (and yes I have seen a lot of fuchs rims, I now have about 40 in my basement...). they will not crack right after the episode, sometimes the crack would show years later, but in ALL cases some mishandling was established.
The other cracks, at the periphery, are mostly due to fatigue, shocks, and /or forging irregularities, that show after a long period of use. These can also be attributed to the wider, stickier tires available today, adding stress.
What to do with a cracked Fuchs?? There you have the world's most expensive garden hose hanger... They are shot, no if, and or buts. Unless you fancy being overtaken by your own wheel at speed.
GeorgeK

[carnut169]

thought they were magnesium....

[TRE Cup]

We second the experience. Original fuchs 7 x 15 cracked right from the lug nut areas on a new client's car. Pays to inspect your wheels regularly!

[cstreit]

Hmmm... I was thinking end-tables for the basement...

...but a hose hanger... Hmmmm

[Early_S_Man]

Chris,

Considering the age of most of the Fuchs that aren't recent 'new old stock' purchases ... X-raying or Zyglo testing might be a wise investment for wheels to be used on the track???

[Jdub]

Is the general opinion that FUCHs that have stress cracks are OK for mild street but not for track? Sorry for the dumb question...

John

[JWest]

Only ones that were magnesium were the Mahle gas burners and some rare 944 cup phone dials.

Fuchs are forged aluminum.

[Early_S_Man]

John,

Not if you value your life! George's coinlusion is the same as mine ... retire a cracked wheel to household ornamental duties!

[GeorgeK]

James,
There were also some 17 inch magnesium rims, in the Cup design, for the Carrera Cup, starting 1991. They are 8 and 9.5 inch wide. These are RARE, big time. The phone dial magnesium ones are sweet, 8 and 9 inch wide with a slightly different mold that the aluminum ones. VERY light, but don't take too kindly to potholes.
John,
I have a friend who had a cracked 8X16 Fuchs. He would watch it every week, then every other day, until the rim with tire actually overtook him. Not at high speed, but as the car put its butt on the road, the Turbo (930) got "redesigned" with direct air cooling to the turbine fins.
GeorgeK

[cstreit]

Regarding the overtightening of lugs, I would think if this were the cause, the cracks would radiate from the lugs outward. In this case the cracks start from the edge of the wheel and move inward toward the hub. I'll post a picture in a while...

[Jim T]

I had a cracked one - didn't crack near the hub, but more towards the outer part of one of the spokes.

But it had been chromed by the DPO, which probably didn't help.

[724doorE]

Chris, You never know what the PO did to those wheels before you got them.

End table hell!, They would make great legs for the table you should use to support that scalextric set you've been wanting!

Bad luck with you and rotating parts though, rotors and now rims, you go through em, not on purpose though!
At least your having fun wearing out those damn parts!

BTW, I've been practicing on the playstation, I won't be a walk over next time...

[cstreit]

Here are the pics... You'll notice that the cracks start from the edge, not the lug...

[6 Shooter]

Chris,
Just curious, what size Fuchs are cracking? On your 930 or 70 RS?

[6 Shooter]

Chris,
Sorry. I meant your 930 or your 70 RSR replica?

[Drago]

Were not some of the "cookie cutter" style wheels magnesium as well?

I remember reading somewhere that at a particular point they switch to aluminum.

Of course I could also be dead wrong....

[cstreit]

THe '70... They are 16x7 and 16x8. Cracks were only on the left side wheels... Side with the most stress on mostly clockwise tracks...

[TimT]

most of us are driving around on wheels that have micro-cracking that was built into the wheels when they left Fuchs. The forged wheel is a thing of beauty, but it did require machining to locate and finish part of the cavity for the lug nut, and to true the surfaces where the center cap is located, and true the bosses that bear on the hub, and to make an opening for the valve stem.

Unfortunately where the cutter parts the metal, micro cracks are present, In a similar fashion to the micro cracks in the root of every weld.

parts are relieved and polished to remove these stress risers. was that part of the fuchs manufacturing process? I dont know.

When you can visually see a crack as you have shown in your pics.... its time to make a coffee table from the wheels

If you get anothert set of fuchs you might want to give more radius to where the center cap goes break the edge with a file, then emory then crocus cloth

[GeorgeK]

Chris,
Agreed, these don't seem to come from the lugs. Could be stress from the force on the hub. They are toast anyways.
TimT has a point. I try to FULLY polish my Fuchs before anodising when I restore them. Every irregularity is a crack waiting to happen
GeorgeK