This may be of use to anyone who wants to check:

Clicky

I'm sure there are others that are cheaper, but this was the first one I found.

For anyone interested Google dye penetrant testing. This only helps detect surface flaws. So is no guarantee.

Glad your ok.

I have come across cracked wheels 3 times in coupes now.

Noticed them whilst servicing.

I worry about my wheels as they have less surface area than these and I run 3 times the intended power.
A failure of this nature is the worst fear of any driver as it can't be predicted.
Lucky your ok,

Is powder coating an issue as mine have been coated?

Might also be worth getting the wheel inspected first by metal fatigue experts.
The last one a friend of mine did involved valve springs failing.
Comprehensive report done cheap as this is another paranoia scare for all of us.

Your wheels look immaculate and unmarked around the edge and your also using the bigger 50mm sidewalls which should cushion the wheel further.

Do you know the history of the wheel?

Thinking out loud as it were, johnnyk, baz76 and Hubby's failures have all been on the front wheels. That doesn't offer much solace, not least because I rotate my wheels with each change.

An alternate view is all the failures above have been on refurbed wheels, powder coated or sprayed. Do we know of any failures on original and not refurbished wheels?

Is there a common theme here?

Yes Chris, I've scrapped 2 rims with cracking that have never been sprayed or powder coated.

Personally I put these issues down to out crap roads and the age of the rims. We don't know there history or what abuse they've been given over the years.

I think the only way to be sure is have each rim tested by means of none destructive testing, either ultra sound or xray, it's the only way to be 100% sure they're no cracking or hidden horrors.

So pleased no one was injured.

I dont know the history of the wheel but i have owned the car for 5 years now.

I really dont think refurbishing the wheels can have an effect on the structure of the alloy

As the cars are about 15 years old now i think you will be hard pushed to find many original wheels (still in use) that havnt been refurbished

Fair enough, just throwing it out there.

For what it's worth mine have never been done and sadly it shows, but I will be checking them inside and out.

I'm in agreement.
Wheels are under resonance,frequency,thermal changes and forces in all directions.
Can't see how refurbishment can cause such a failure.


The ones I have seen fracture or crack are the Plus wheels.
There Made by speed line I think.

After market wheels suffer more from cracking especially multispoke.
Also Audi/BMW stock wheels are extremely prone for cracking on cars sub 5 years of age.

Was there any wheel wobble prior to failure or did it just happen very quickly without any symptoms?

You can tell if a rim is cracked by the noise it makes when you tap it with a plastic mallet, the tyre would need to be removed to perform this test though.

When struck it should have a ring about it if you get what I mean, cracks would dull that noise and make it more of a thud.

Hopefully fiat wont have the same mentality as ford

V.Scary indeed! Glad you are OK. Is that a date stamp in the 4th photo? (97) Worth a check against other failures for a potential bad batch perhaps?

Glad you're ok Hubby and glad you noticed and started slowing down

Another possibilty of the cracking could be down to the heat from the Brembo's maybe?

These worrying failures have all been front wheels and in the same area at the base of the spokes.
I'm wondering if 10 years of heat cycles from front brakes has caused the alloy to become britle in that area where the wheel will be exposed to the highest heat transfer from the brakes?

I'm not really sure what Fiat can do for a car that's been out of production for 10 years except to issue a warning to all current owners.

Do we have contact with any European owners clubs to see if they've seen similar failures?

Hmmm, interesting theory. I always swap front and rear wheels/tyres to equalise wear and buy new tyres in sets of 4, but most people don't, and so once a front wheel, always a front wheel...except when refurbished, they will likely all get swapped around randomly.

But presumably then, those people who have had one front wheel fail are likley to suffer another failure on the other side and should be checking very carefully. The close up on the last pic seems to show an inner dirty side to the crack, so it could have started on the inner side (closer to the disc) and grown larger and larger (and getting dirtier and dirtier) until the remaining half of the spoke arms could no longer hold up.

But also, some people use the brakes more heavily tnan others...and even though the discs get mightily hot, how hot are the wheel spokes likely to get?

Exactly what I'm aiming for, at least initially

Too hot to touch the wheel with bare hands, at least in the centre and part-way along the spokes

Yes, I PM'd the President of FCKP (Poland).

Joe is an honorary member of the Wheeltapper's and Shunter's Social Club.

Quick reply from the President of FCKP in Poland - have not heard of any problems with wheels falling apart.

EDIT - most Coupes are imported to Poland from Germany or Italy.

Ok what about our other European Coupe clubs, can the board contact those as well?

I have been reading this thread with equal measures of interest and horror.

Also, I note that all failures are standard 20vt wheels, although I think JBT said that Plus wheels have also failed. Can someone confirm that Plus wheels have actually failed on the road? My car's a 20vt6 and has Plus wheels, so would be interested.

As for methods of checking your wheels, Joe's suggestion of tapping the wheel is very sensible. It's a time honoured method of checking for cracks in many different materials and happens to be a method used by some car manufacturers when checking body panels that have just come off of the press. Only problem, as Joe says, is that you have to take the tyres of first.

The use of dye penetrant has been suggested and I think that this is a good one. Over 30 years ago I used to use this method for checking aluminum castings when I was doing my apprenticeship. It's fairly simple as long as you can obtain the dye penetrant and the white powder spray that you spray on afterwards. It's not harmful in any way and will pick up any cracks on the surface.

Ultrasonic and X-Ray testing are not within the realm of the average user, however, although very effective.

OK, reasons for failure and why the right front in particular

The thermal cycle that the wheel goes through has been suggested as a potential contributor to the problem. I would agree with this and add that the difference in temperature across the wheel may also be a factor as the outside of the wheel will stay cool and the area around the hub may get very hot with heavy braking.

Thermal shock could also be a factor if after some heavy braking, you then have to drive through a flood, or a ford etc., and cool the wheel down suddenly. This might sound like grasping at straws, but the effect could be cumulative over time, so you might not associate this with a subsequent failure.

But, why the right front?

Look at the geometry of the wheel and it's asymmetrical design. Under braking, the forces acting through the wheel spokes act differently on left and right wheels. On the right, the force is acting across the spoke, almost like a shearing force. On the left the force acts in a different way, like the shear force is acting at an angle across the spoke, therefore sharing the force over a greater area (or more correctly volume) and to some extent the force on the left wheel is a combination of this more spread out shear and an element of tension.

The forces acting through the spokes are generally higher under braking than acceleration and much higher on front wheels as opposed to rears.

This is only my theory, but have a good look at the geometry of the wheel design and try to imagine the direction of the forces acting in the wheel and see if it makes sense to you.

If I'm right, there's no simple solution, as Fiat should have made different left and right wheels, where the spokes trailed in opposite directions. The other solution is to use aftermarket wheels that are strong enough for the job.

Yes. Under braking, the front right wheel is under compression along the spoke and over the centre; the front left is compressed along the spoke and under the centre. In both cases the weight of the car is acting down on the centre of the wheel and increasing as the braking force increases.

Which would mean though that there's a greater bending moment on the *left* wheel lowest spoke, not the right. But relative to the spoke, the bending is in a different direction.

(I am not a structural engineer)

I have contacted the French club management and posted on their forum.

glad your ok hubby, very scary,once happened to me in a bedford in the army!!!!!!

Bedford lorries have 20vt rims fitted, now that I gota see

I would try and post on the forum at fiatcoupe-freunde.de but can't get access at work Many of the other links to Coupe club web sites are no longer valid...

lol country cruising, knew as soon as i posted that some friendly forum banter would appear.

Scary stuff guys.

The 1st time it happened I remember checking my wheels thoroughly and giving them a darn good clean (they get very dirty on the inside!).

Sean_C owns my old wheels now, and they were never repainted or powder coated in 10 years of ownership.

Chris

I have a couple of thoughts. Sorry that they are a bit obvious.

Looking at the photos the crack appears to have started at the back of the wheel where there isn't a proper corrosion-resistant coating. Presumably all wheels are getting slowly eaten away at the back like this.

The wheels appear to fail at exactly the same "stress point" which might be down to some effort to get the wheel to clear the inner edge of the Brembo caliper.

To answer the above
They haven't failed I have just notices hairline fractured on checkovers.
If you tap them you can here the facture is across the wheel:

Not known one completely fail though.

Couldn't resist