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View Poll Results: What came first the Bend or the Crack ?
The Bend came first in my opinion 6 37.50%
The Crack came first in my opinion 7 43.75%
I don't know it is hard to tell 3 18.75%
Voters: 16. You may not vote on this poll

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      09-04-2010, 01:08 PM   #1
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What do you think came first ... a wheel bend or the crack?

I am attaching more close up photographs of the BMW Type 296 driver side rear wheel that has a 2.00" long crack approximately 0.031" (1/32") open at the very top.

I believe BMW runout check tolerance is 0.300 mm

Photos are in my garage on page 3 here

NOTE THE WHEEL IS CLEAN, ON THE OUTSIDE DIAMETER OF THE RIM THERE IS ABSOLUTELY NO MARKINGS OR EVIDENCE OF ANY IMPACT DAMAGE WHATSOEVER.

Thanks Fellow Forum Members for your Help
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Last edited by Mr. ///M3 RD; 09-04-2010 at 01:43 PM.. Reason: minor change ... ADDED NOTE ON WHEEL CONDITION
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      09-04-2010, 01:15 PM   #2
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Rolf, I assume it is bent at the crack?

Is there anyway you could show how it's bent - what direction, visually how much of a bent.

Other than the crack, the photo looks fairly normal to my eye. Am I missing something?
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      09-04-2010, 01:26 PM   #3
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I was hopping to check it this weekend in the vertical boring mill (my friend is gone to a wedding this weekend), it will have to wait till next weekend. I will perform a very careful TIR check once I've set up the wheel. Then I will check TIR on the outside diameter (spoke side of wheel and opposite spoke side).

I plan to indicate it from opposite the crack (180 degree) toward the crack going clockwise and counter clock wise (due to the crack).

I will know then the shape of out off roundness.
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      09-04-2010, 01:33 PM   #4
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Ok, the bend is a deviation in total roundness ( I think you did mention that).

I think logically the bend would have to come first. If the crack developed first, then I think further damage to the wheel (no assumption about how it occurred) would further aggravate the crack rather than form a symmetrical bend at the crack.

Would seem too coincidental to have a bend at the same location as the crack, if the bend occurred subsequent to the crack.
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      09-04-2010, 01:38 PM   #5
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There is no bend visible, It is BMW's way of telling me it is not running true.

Naturally with an open crack like this I expect the wheel to be sprang open at the crack therefore a dial reading starting from zero opposite the crack will show + some value at and near the crack.

I've added a note to my original post about the outside diameter condition, i.e. there are no impact marks from pothole damage etc, the wheel is clean smooth all around both sides on the outer diameter (spoke side and opposite spoke side).
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      09-04-2010, 02:21 PM   #6
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i believe the crack came first, and it's unrelated to road damage, it was probably stressed from it's manufacturing.
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      09-04-2010, 03:31 PM   #7
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Quote:
Originally Posted by Rolf-Dieter View Post
teagueAMX

There is no bend visible, It is BMW's way of telling me it is not running true.

Naturally with an open crack like this I expect the wheel to be sprang open at the crack therefore a dial reading starting from zero opposite the crack will show + some value at and near the crack.

I've added a note to my original post about the outside diameter condition, i.e. there are no impact marks from pothole damage etc, the wheel is clean smooth all around both sides on the outer diameter (spoke side and opposite spoke side).
OK, that helps.

If I read you correctly, BMW is saying the deviation is an indication of out-of-roundness, and hence you have a bend, regardless of the wheel being actually bent or not.

I thought the situation was different similar to another person reporting in another thread they had an actual bent rim that was cracked.

On the basis of that info, I'd have to say the crack came first.

Rolf, scratch my poll results as I voted the bend came 1st. Sorry for the misunderstanding.
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      09-04-2010, 05:41 PM   #8
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I remember you mentioned you hit some potholes on your roadtrip. Now it depends how big these potholes were and whether the damage was additive and progressive.

If the wheel impacted on the lip of one huge crater of a pothole then that naturally would have caused the damage immediately and shortly after pressure loss. There would also be some sort of bend and deviation in total roundness. But I am not sure how localised it would be, if you know what I mean. I have a 17inch cracked rim at home (went over curb) that I will take a look at and see how 'bent' it was in that area.

What's interesting would be the result of hitting the wheel multiple times on minor potholes. Has anyone done any testing of a BMW 19inch wheel with RFT like this to determine if such repeated stress will crack it at a single point??

The fact is that you only had the one, single crack in the rim which COULD indicate a weak spot in the manufacture of the rim. So it could be that you hit that single spot multiple times on a surface that was rough enough to cause stress (highly unlikely?) but not actually have enough penetrative force to damage (bend) the rim in one hit.

I am betting that the crack just appeared over time due to a stressor causing trauma in that particular area which set off a gradual weakening process in the material eventually leading to a crack.

Hope this makes sense haha.
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      09-04-2010, 05:52 PM   #9
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Quote:
Originally Posted by Memphis1 View Post
i believe the crack came first, and it's unrelated to road damage, it was probably stressed from it's manufacturing.
Thanks for your post and vote Memphis, I am of the same frame of mind. The wheel is nice and smooth on the outer periphery on both the spoke side and opposite side of the wheel. No evidence whatsoever of making contact with any hard road surface.

Thanks again
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      09-04-2010, 05:56 PM   #10
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Quote:
Originally Posted by Alext View Post
I remember you mentioned you hit some potholes on your roadtrip. Now it depends how big these potholes were and whether the damage was additive and progressive.
Yes I did go thru a small pot hole also a step (road construction) in the road. However, there was no contact at all with the pothole or step in the road, they were both fairly small.

It must have been the RFT stiff sidewall exerting elevated stress, bending forces to the weaker side of the inner outer rim. My feelings anyway.

I ADDED ONE MORE PHOTO SHOWING THE INSIDE OF THE RIM, NOTE THERE ARE NO ROAD MARKS WHATSOEVER

For the photo click here

There are marks on the inside from the tire machine as the tire was removed by others. The small BMW Dealership in Idaho had n Tire Machine so they took me to another place. The bend that BMW is referring to might very well have been inflicted by the tire machine. As we well know it does not take much force to deflect a round alloy wheel. Go figure, this BMW Dealership can sell cars costing well over 100K however, cannot handle tire changes.

Thanks for your post and vote
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      09-04-2010, 08:10 PM   #11
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Here is a different tack.

If "they" determined that the wheel on the other side cracked because it was defectively manufactured.

And this wheel cracked in a similar orientation to that defectively manufactured wheel,
And this wheel is of the same date code and lot number as the defectively manufactured wheel,
It is reasonable to believe that this wheel cracked for the same reason as the other wheel..... and bent as a result.
Since "they" already determined defective manufacture of one wheel, I think the burden of proof would be on them, to prove that the other was not defective in the same way. This is how I think a small claims judge (or clerk) would see it.
No metallurgist or expert witnesses required. Just simple common sense based on "their" initial report of the other wheel. ...... So the bend occurred after ??? Impossible to prove or deny. But that wasn't a vote option so I had to abstain. My money is on you if it ever went to a small claims court.
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      09-04-2010, 08:16 PM   #12
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Quote:
Originally Posted by E89Tardis View Post
Here is a different tack.

If "they" determined that the wheel on the other side cracked because it was defectively manufactured.

And this wheel cracked in a similar orientation to that defectively manufactured wheel,
And this wheel is of the same date code and lot number as the defectively manufactured wheel,
It is reasonable to believe that this wheel cracked for the same reason as the other wheel..... and bent as a result.
Since "they" already determined defective manufacture of one wheel, I think the burden of proof would be on them, to prove that the other was not defective in the same way. This is how I think a small claims judge (or clerk) would see it.
No metallurgist or expert witnesses required. Just simple common sense based on "their" initial report of the other wheel. ...... So the bend occurred after ??? Impossible to prove or deny. But that wasn't a vote option so I had to abstain. My money is on you if it ever went to a small claims court.
Very good point indeed

There is a stamping inside the wheel (still have to take a photo of it) that shows the date of manufacture ... the year and a lot of DOTS for the month.

I will go to the dealer on Tuesday and take photos of the hairline cracks there locations etc as well as the production date. It will be very valuable information to have.

Thanks again, glad to see some input
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      09-04-2010, 08:31 PM   #13
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Good Luck to you... And anyone else experiencing cracks in the future might want to go to a rim shop and have the wheel checked for true and get a paper that says so, Before going to BMW.
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      09-04-2010, 09:18 PM   #14
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Wonder how much it would cost to have the rim material at the point of crack examined for porosity?
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      09-04-2010, 09:39 PM   #15
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Quote:
Originally Posted by Alext View Post
Wonder how much it would cost to have the rim material at the point of crack examined for porosity?
Properly more then the cost of a new wheel (then it is not the money that concerns me it is a matter of principal and safety in my mind). Once my report with my analysis has been mailed to BMW (sometime next week) I will give it some time for BMW to reply. If I receive a negative reply I will take other actions. I have a lot of resources and will call on them. Your point about porosity is well taken and will certainly be part of further tests and material analysis.

I will not take this issue lightly, you can properly imagine what my drive home was like (some additional 3000 KM) once I found out I have 2 more cracks in my passenger wheel and my rear tires had worn prematurely (see page 2 in my garage for photos). Every little bump my fear was I am loosing air pressure (like it did in the rear driver side) and my tire pressure warning light would come on. It was not a nice drive to say the least.

Thanks for your input and post, it is appreciated
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      09-04-2010, 10:52 PM   #16
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I emailed three different wheel repair organizations just to get some feedback from them on what they may have seen through the years. Soon as I get their info I'll type up the conversations and post them here.

Rolf, I know you did did research of your own concerning the BMW wheel cracks, and I did a little too and even through wheel cracking as we've been discussing is happening out there, for some reason, wheel cracking doesn't seem to be a widespread problem as the other type of wheel damage that repair shops fix.

One organization mention porosity as Alext mention, and often chrome plating alloy wheels can damage the surface area of the wheel and facilitate a slow process that allows cracks to develop where the spokes connect and that lug nut area.

Metro Wheels - wheel repair articles (Look about 3/4 down the page)
Quote:
Cracks can be Serious Business
Cracks are of particular importance, because they are the single most common type of damage that can leave a wheel beyond repair. When a wheel bends near the base of a spoke, haze marks in the finish can sometimes be seen and indicate cracks. Because repairing a wheel is not always best in a particular situation, it is important that the wheel is thoroughly examined.
  1. We value your safety above everything else and, for that reason, Metro Wheels considers a wheel to be irreparable if cracks appear: Near the base of a spoke
  2. Near the lug area
  3. On the inner lip of the wheel away from the spokes. (But if a crack is smaller in size, this type of damage is usually salvageable.)
Cracks are particularly common on chrome-plated wheels, where the chroming process tends to render the wheel more brittle than a standard-finish wheel. Sometimes, if a chrome wheel is bent severely, the chrome has to be removed because there can be cracks underneath the chrome. In the case of a cracked chrome wheel, Metro will grind the chrome out and re-weld it.
AutoMotix - Alloy Rim/Wheel Repair
Quote:
* Stress Cracks - Alloy wheels often suffer stress-cracks and air-pocket inclusions due to 'Hydrogen Embrittlement', which generally occur due to excessive heating. These cracks or inclusions can prove to be dangerous if it is not treated timely. This can be treated by filling the cracks with a suitable material. It is advised that these complicated issues should be handled by a qualified mechanic.
Apart from the links that you provided, I found only a couple of references to wheels cracking on the inside rim edge, but there was no reason mentioned for it.

One question that keeps burning a hole in my brain is this: are the other premium auto manufacture marques' wheels suffering the same issues as BMW's. I'm sure they use a common manufacture for their wheels, but is there any difference in the metallic alloy ratios or is there a difference in the thickness of the rim itself?
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      09-05-2010, 12:09 AM   #17
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Quote:
Originally Posted by Rolf-Dieter View Post
teagueAMX

Naturally with an open crack like this I expect the wheel to be sprang open at the crack therefore a dial reading starting from zero opposite the crack will show + some value at and near the crack. ...there are no impact marks from pothole damage etc, the wheel is clean smooth all around both sides on the outer diameter (spoke side and opposite spoke side).
The TIR reading will certainly help indicate the history of the rim. + Dial indicator nearing the crack will certainly indicate crack/fracture at that point and likely not related to impact bending at that location. However, (-) dial indicator reading elsewhere may indicate the rim took a hit at the (-) location and the fracture happened away from the point of impact. Be careful on assuming the 0 point being 180 deg opposite the crack. You may have to play around a little to find the true nominal diameter (0 location).
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      09-05-2010, 03:52 AM   #18
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Quote:
Originally Posted by Alext View Post
What's interesting would be the result of hitting the wheel multiple times on minor potholes. Has anyone done any testing of a BMW 19inch wheel with RFT like this to determine if such repeated stress will crack it at a single point??
Yes, I do test this almost daily, driving a road of 8 Km made of concrete slabs. The length of one slap is around 6 meters. The problem is that the change from one to the next slab is not quiet 'aligned'. Some of the slap changes are 3 - 4 cm’s higher, these ones are the bad ones who could damage the car because the edges are really sharp. There are also many that are more than 4 cm’s lower. But 'jumping' of one slap to the next one should be no problem beside the bad comfort.

I’m aware that this road can damage my cars. So I do keep the speed below the 60Km/hours and try to avoid the bad ones. But it is the long term effect were I’m afraid of. At the moment, my E89 has no problems after driven ~900 Km in 6 months on this prehistoric Belgium road.
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      09-05-2010, 07:29 AM   #19
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Quote:
Originally Posted by teagueAMX View Post
One question that keeps burning a hole in my brain is this: are the other premium auto manufacture marques' wheels suffering the same issues as BMW's. I'm sure they use a common manufacture for their wheels, but is there any difference in the metallic alloy ratios or is there a difference in the thickness of the rim itself?
Good question. Now as far are tires go, the Nissan GTR also uses Bridgestone RFTs as OEM, so do Ferrari etc. BMW - like these manufacturers - have developed a OEM tire with Bridgestone to suit their cars, so this makes me believe the issue is with the alloy. After reading people's experiences with cracked rims on BMWs in general it appears that more often than not it only occurs with certain styles of 19 inch rim. There are several reports I have read of cracked rims even with non-RFT tires.

I checked an old chrome rim I saved from years back and it actually has a similar crack in the same spot as Rolfs. It was done by going over a 4 inch Kerb at around 40km/h. Tires at the time were non-runflat Falken FK451 205/40/17 I think.
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      09-05-2010, 07:32 AM   #20
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ZedEP - that sounds quite harsh. Want to test at 100km/h? Haha
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      09-05-2010, 09:09 AM   #21
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teagueAMX, E89Tardis & HerrK

Thank you all again for your excellent feedback!

The additional information provided by you all got me thinking that the runout check in the vertical boring mill is properly not a good idea (unless I set it up in the same way as BMW, wheel repair shops or tire shops do). BMW may reject my report if the check is not done in the same way they do there’s.

So Tuesday I will go to my dealership (while I check the manufacturing date of the passenger wheel that has the 2 hairline cracks) and find out how they do the runout check also see if I can get a copy of the report from the wheel with the open crack that was not warranted.

After reading thru the repair and tire mounting procedures I reflected back to the tire shop in Idaho USA (not naming the town at this point). The boys were quite rough removing my tire from the wheel with the crack. In fact they ended up making gauge marks in two places with the tire machine and or method of removal on the inside of the inner rim (see photos 1 and 2 below).

Photo 1 of 2

Photo 2 of 2

The heavy markings may very well have caused the out of round condition that was measured here in the BMW shop in my home town.

Combined with your feedback and the excellent post made by E89Tardis my thinking has somehow changed as follows;

A) If the BMW Idaho shop sub-contracts his tire mounting work to a tire shop that mishandles the tire removal why should I as a customer be blamed as having gone thru potholes or the like having bend a wheel. The excessive force as used by the tire shop was most likely enough to bend the wheel (exceeding the 0.300 mm [0.012”] BMW tolerance for roundness) leaving marks like shown in the above photos.

B) Why would this BMW dealership not invest in equipment and manpower to handle such delicate tasks as removing and mounting tires on these so soft and delicate alloy wheels (did I mention expensive I paid $606- US in Canada I am told the wheel is $900- CDN).

C) I am almost convinced that I will find the wheel now at BMW (with 2 hairline cracks) having the same manufacturing date as the one with the crack I have here at home.

Based on A, B and C above I will forgo the roundness checks of my cracked wheel at this time since it is very likely just useless information since the damage may very well has been inflicted in the tire shop by removing the tire in the first place.

I will write to BMW first arguing points A to C before I will take further steps. What do you think fellow? Or am I not thinking clearly here?

Thanks as always for your input.
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      09-05-2010, 09:10 AM   #22
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Quote:
Originally Posted by Alext View Post
Good question. Now as far are tires go, the Nissan GTR also uses Bridgestone RFTs as OEM, so do Ferrari etc. BMW - like these manufacturers - have developed a OEM tire with Bridgestone to suit their cars, so this makes me believe the issue is with the alloy. After reading people's experiences with cracked rims on BMWs in general it appears that more often than not it only occurs with certain styles of 19 inch rim. There are several reports I have read of cracked rims even with non-RFT tires.

I checked an old chrome rim I saved from years back and it actually has a similar crack in the same spot as Rolfs. It was done by going over a 4 inch Kerb at around 40km/h. Tires at the time were non-runflat Falken FK451 205/40/17 I think.
We're focusing on BMW here, but are we absolutely sure this is a BMW problem, per se?

As an example, it was my understanding years ago that Enkei produced alloy wheels for the US auto manufactures. No doubt another company produces all the alloy wheels for the Germany manufactures as well. I’d suggest that BMW produces a design sketch or possible even a clay model. They then sent that information to _________ (place company name here) who then actually produces the molds, dies, whatever. No doubt the rim component of the wheel is standard for each wheel and only the spoke design, hub and offset changes according to BMW specs. And remember, we’re talking about the inside rim design failure and not the portion of the rim that attaches to the spokes.

Here’s my basic point: Years ago, this company would have developed wheel standard design practices for metallurgy, strength of materials, standard dimensions, final production, etc. For these guys, prototyping a rim with spokes and a hub is child’s play – they’ve done it a million times. No doubt they use the same procedures and methodology for BMW, Volkswagen big ten marquees, etc. If that’s true, why aren’t the other marquees' wheels produced by this same company having the same issues as BMWs? Although I believe the RFT are a component of this problem, I’m sure that there is also consistency in the RFT design Bridgestone is producing across the board, as well.
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Last edited by teagueAMX; 09-05-2010 at 12:32 PM..
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