Cracks in Rim or ??

I cant comment on the marks your looking at, but thats an enormous amount of balance weight.

 

Ditto!

 

The cracks are probably there because the wheel took a big hit once, cracked the wheel and now it needs 400 grams of stategically placed weights to "balance" the wheel again.



Seriously though Johnny.......I cannot really provide a worthwhile comment on those that appear to be cracks as it is very hard to diagnose looking at pics. But, if they ARE indeed cracks, I would certainly not put them back on the car. (I am sure you are well aware as to why. )

I suggest taking the wheels to a wheel repair expert in your area and get them to have a look. They may be able to repair them or at the very least give you some closure.

Could they be casting marks/blemishes when they were cast at the factory perhaps?

You are VERY lucky that you noticed this now mate. God knows what may have happened on your next drive. Serious injury or death. Glad you are ok.

 

Seriously, I pointed out the weight because idealy you want none or very little. Good wheels are precision balanced, and if you have good tires they shouldnt need much correcting.

 

When you need that much weight that far appart on the rim, the wheel is toast, or they where not balanced correctly. As for the cracks, get new wheels.

 

I agree this wheel clearly has some serious issues and I do think it smacked into something. I have never seen that much weight used to balance any wheel before. You may have set some kind of record here. =(

Best Regards,

Thomas Carey

 

Hi, looking at the pictures I would say they appear to be marks from the casting of the wheel.
Try to clean them real well and with a file or with some sand paper rub the surface to see if they are simply superficial marks where the dirt has gone in or if the run deep.
As for the amount of weights, I would agree that it appears to be excessive, but that could be due to the tire and not to the wheel.

 

Having the wheel balanced without the tyre will tell you if it is the rim or the tyre

 

This I think would be a very wise thing to do. I believe it could well be a unseen defect in the tire itself. Although I don't know if it would have required that much weight to balance.

Best Regards,

Thomas Carey

 

It's hard to tell what's going on in 3-D from 2-D photos...

Those could be cracks, or they could be ridges / flags from the casting moulds. If you take a piece of fine grit emery paper and rub them a bit, they will either disappear (if they are casting ridges) or not (if they are cracks). You can also put a good magnifying lens on them and see if you can probe into them with a needle (or something equally sharp).

They look suspicious for being cracks from here... but, photos can be misleading...

Obviously, if they are cracks, they are serious... and the wheel is no good. BTW, don't waste your time and money trying to have someone weld it --- it's next to impossible to create a good, structural weld in sand-cast Aluminum. The welding process will anneal the material and weaken it significantly below its original yield strength. If the wheel were forged Aluminum, welding can be possible --- but these earlier Ferrari wheels were cast .

 

The wheels are not aluminum, they are magnesium.

 

...not on the 328 wheel, my friend... note the casting ID's "Al" and "Si" ---

 

Typically you would expect that cracks would propagate across the spokes of the wheel. Most of the stress in a wheel comes as a result of cornering and results from "bending" across the spokes. In this case the defects are radial, and if you were creating a lot of spoke stress that would result in a radial crack it would be happening near the edge of the spoke and not in the area where these are. Stress that would come from a radial crack would also be near the edge of the spoke and not where these are.

In the first photo, on the left, as well as in the other photos, the defects appear to be what is called a "shrinkage" defect. That occurs when the metal cools and solidifies on the outer parts of a thick section, and then, as the interior cools it shrinks more and pulls open a defect. If the wheels had that much of a defect in them they should have never left the factory.

The longer, worst of the defects looks like it was originally a shrink defect, but it has "opened" up due to stress and use and become longer. This is a reasult of the stress concentration effect that occurs at the edge of a defect. Moreover, it is on the edge of the spoke and is in the higher stress area, and most importantly, it appears that the crack has "turned the corner" and is now starting to propagate across the spoke (as you would expect it to in response to the spoke stress field).

In short that wheel is done, you should not dream of putting it back on your car other than to hold the car up while you are looking for a new wheel.

While you can try to have them welded up, it depends on the wheel heat treat as to wether or not cracks will come back. While these are cast wheels, they may have been heat treated to a higher hardness, and if that is the case, welding on them will result in a "heat affected zone" and may not be as strong as the original material. The only way to know that is to do a hardness test on the wheel and, if you had a good idea what the material was you could make a guess as to the strength and have a good idea as to the heat treated condition.

Were it my car I would start looking for a set of wheels.

 

My mistake, I thought they were the same as the 308 (I have owned both).

Dave

 

John,

We can check the balance at the Tech session. We do not have a good selection of stick-on weights. So if you are interested we will need to get some. PM me and let me know.