Mercedes-Benz Forum banner

1 - 20 of 108 Posts

·
Moderator
Mercedes
Joined
·
9,039 Posts
Discussion Starter #1
By now, many of you know that one of the downside of these beautiful wheels is the tendency for cracks to develop between the lug holes and the center bore hole. Overall consensus is that using a pneumatic tool to screw in lugs and over-torquing will lead to cracks developing. However, I feel that there is more to that than just over-torquing. I strongly believe that these cracks are multi-factorial, with over-torquing being secondary to a variety of different fracture-leading causes.

Instead of having another thread to complain about the cracks, I thought of starting a controversial one on the repair of these cracked inner faces. Many posts in the past have stated that once a crack is developed, then the wheel is no longer repairable and is junk (only worth its weight in scrap price). My question to you all is, is it really?

I bought my set requiring a refurbishment in 2006. I spent a year tracking down a set that was not cracked. I've had seen several sets during my year of searching that had various degrees of cracks. Luckily, I found one complete set that just needed paint and polish -- no cracks. If you're interested in the full details of that whole ordeal, its in my old thread found here: http://www.benzworld.org/forums/w126-s-se-sec-sel-sd/1285099-amg-3-piece-wheels-revisited.html

Now, back to the question. Can the cracks be safely repaired? Many say no.
I would be curious to hear why those who say no believe that. I must say that I am also from the camp that says that its difficult to repair these cracks in a safe manner. However, I'm hesitant to flat out say NO, it cannot be repaired in a safe manner. I just don't know how just yet.

In my field of work, I deal with components made out various metals, alloys and ceramics. I have to be familiar with the properties (tensile and yield strengths, hardness, fatigue, etc) of these materials to minimize any risk of failure as it can be cata$trophic when it does. Sometimes we have to modify components or make them when manufacturers stop production of an item. If we have to cut metals and weld them, we use laser welding. I never thought of this method being used in repairs of cracks in wheels. So I started to investigate and looked into this a little more and sure enough, I found publications on use of laser welding in repairs of aluminum and steel wheels.

This brings up questions to those who say "no, that once these wheels have cracks, they can no longer be repaired". Obviously, not all welding processes are the same. There are different techniques and ways of welding metals and alloys. Some are more precise than others. So I would like to hear some opinions and thoughts on this topic. Everyone can have an opinion, but I would like to hear thoughts that can be backed up with science and facts.

Oh by the way, I realized I reached 8000 posts. It only took me 11.5 years to get there ;-)

For those interested in reading more on this issue, here are some good links:
Crack Repair
Materials Research - Cracking susceptibility of aluminum alloys during laser welding
http://www.microjoining.com/docs/1366134548_microtip_weld_cracking.pdf
http://www.aws.org/rwma/docs/winter13/RWMA_.pdf
 

·
Premium Member
1991 560 SEC Black on Grey
Joined
·
1,890 Posts
You might be on to something there. Now it is just a matter of trying it and finding a guinea pig to test it. Even if you could fix them I would imagine selling them would be an issue as most people, myself included, wouldn't ever feel comfortable knowing disaster was a real possibility any time I went around a corner.
 

·
Registered
'82 Euro 500SEL, '85 Euro 500SEC AMG WB Cabriolet,'86 Euro 500SEC RUF
Joined
·
9,487 Posts
I wonder, out loud, if the cracks can be stopped by the way cracks are stopped in Aluminum and other materials. If one drills a small hole that encompasses the crack end, the crack does not extend in length because the hole relieves the stress. I know this works on water jackets in automobile and truck engines. The cracks and holes are then filled by welding. A heat sink of some type can be used to localize the heat.
This might be a possible fix for cracked wheels also?????
 

·
Registered
'82 500sec euro, '95 Ford F150
Joined
·
1,581 Posts
"Oh by the way, I realized I reached 8000 posts. It only took me 11.5 years to get there ;-)"

Congrats Doc! I'm Green with envy. Just wondering how many posts some others will have in 11.5 years:)
 

·
Premium Member
2012 CL550 4MATIC Coupe
Joined
·
9,990 Posts
I am having two centers repaired as we speak.

One from my original set with three of the lugs both hogged out and cracked. And one that Kim gave me with a single crack.

He is going to repair Kim's first since it has a lot less damage, a single crack and no hogging. If that is successful, he will then do my wheel, the one that departed controlled flight three years ago. That one has far more extensive damage with three of the lug holes "Hogged" out, or ovaled out.
 

·
Premium Member
87 Euro500HVSEC. 88 Euro 560HVSEC. 89 Euro 560HVSEL
Joined
·
4,266 Posts
The centre i gave Mclare is going to be a good test.
His rim guy has analyzed the crack and as well as weld up the crack is also going to mill a solid alloy disk that is going to fit into the bore (still allow the centre cap to clip on as normal) and it is going to be welded in place for added strength/bracing.
He is aware of the hub grease cap and is going to do all the clearance measuring/milling required to ensure a straight bolt up again

Sounds a good plan and Mclare is going to post up shots as the repair process is undertaken.
 

·
Registered
1985 500sel and 500sec 2012 E63 1989 Porsche 911
Joined
·
5,266 Posts
i tried talking to the HRE guys to make a homage version of these....not too much interest
 

·
Registered
560SL,380SL
Joined
·
4,012 Posts
I had a W208 wheel crack repaired by a specialist in Cincinnati. It was one of those lightweight "modern Bundt" wheels, which I like very much. It was claimed that the wheel was better than new in that area. They had various presses, a colossal water-cooled aluminum TIG welding and a wheel lathe setup. After doing 10,000 wheels, they have probably developed some skills in this area. I do know that "serious" aluminum TIG welding takes very, very high powered equipment, due to the great heat dissipation of aluminum. It's very difficult to get just one area extremely hot, quickly. It may even be beyond any 220V equipment to weld aluminum as large and thick as a wheel center quickly.
 

·
Registered
Joined
·
4 Posts
cracked rim wheel

If helps anyOne !!??
I repaired my cracked wheel or rim in Brooklyn NY 11206,
the address was 113 troutman st.
I think the name was or is Master Repair, the price was right 65.00 welded with a laser Tig machine. it took like 40 minutes.
He number is 718386-4747 he name i think is Karl, very professional. and guaranteed work.
and i was driving like new. that was 2 year and 3 month and is it still holding strong.
 

·
Registered
560SEC, 1988; 500SE, 1984; 500SL, 1983
Joined
·
1,880 Posts
If helps anyOne !!??
I repaired my cracked wheel or rim in Brooklyn NY 11206,
the address was 113 troutman st.
I think the name was or is Master Repair, the price was right 65.00 welded with a laser Tig machine. it took like 40 minutes.
He number is 718386-4747 he name i think is Karl, very professional. and guaranteed work.
and i was driving like new. that was 2 year and 3 month and is it still holding strong.
that's crazy, I used to live on Troutman St, Brooklyn and have owned cracked OZ wheels. If only I'd known. :thumbsup:
 

·
Premium Member
87 Euro500HVSEC. 88 Euro 560HVSEC. 89 Euro 560HVSEL
Joined
·
4,266 Posts
I took a cracked rim last year to welding shop that specialized in high end welding - "Aerospace Welding" as he has an aircraft Engineering background and does a lot of work with alloy. Yes his shop has some serious equipment and is spotless like a hospital operating room.
He was telling me to weld alloy it requires a meticulous clean working area

And yes he said welding the cracks up was not a problem except i had to remove all paint from around the radius of the weld area and he would cut a thin slice through the crack first and relieve it before welding it up to as good a new in his words.
 

·
Registered
W126 500 SEL 9/85 W124 E320T Brabus
Joined
·
2,068 Posts
I´ve been going through that process and it failed. As Kim stated, it takes an abspolutely clean surface to weld the cracks. Untill one recognices, that his centers are cracked, lots of water and dirt get into the crack and that makes it impossible to weld it as is.

The first problem is, to get there with a cutting or grinding tool , especially in the bolt hole there is no room to cut as much as needed. And after one faced this problem, the second one comes on - how to get there with the welding unit? One cant get deep enough into the crack to weld it in his complete depth!

I´m pretty shure, that no one here would like to drive a car, whichs centers have been only welded on the surface and not colmpletely.

And even if it would work anyway, i wouldn´t drive this centers anymore. Each weld weakens the material immediately adjacent the weld. Therefore they will crack again not at the weld, but they will break left and right of the weld due to the heat in its composition altered material.

Happy easter :D
 

·
Registered
84 500SEL AMG, 90 560SEC AMG, 85 500SEC AMG Widebody
Joined
·
1,784 Posts
I own a set of these wheels (on my wife's R129 SL) that are crack free and hope they stay that way. With all of the past discussion on OZ wheel cracks, has anyone actually seen a wheel that broke apart because of the cracks? I haven't and have read about every thread written about this subject. Please understand, I am not advocating driving on cracked wheels and I would not drive on cracked wheels, but I really wonder if anyone has ever seen one fail.

Al
 

·
Premium Member
2012 CL550 4MATIC Coupe
Joined
·
9,990 Posts
Al,

I saw a pic of a wheel, not these wheels, but a slightly different design, that failed due to cracking. Mark showed me pics of it because he did the research into it to repair mine. Those wheels that cracked were cracked in a different manner. Our wheels crack along the lug trough to the centerbore. Mark took my wheel to another M/E to confirm his thoughts, and they both agreed that our wheels crack in a different manner. They also identified the cause of the cracking, and it is due to a bad design. In the centerbore where they machined the bore to accept the canter cap, there is a sharp edge and it is milled a bit too thin there. Had they not milled it in that manner, this whole thread and issue would be non-existent.

Mark says that the wheel I got from Kim will be ready this week, and the other one will take longer because it needs more attention.

I will post pics up when I get the wheel back.
 

·
Moderator
Mercedes
Joined
·
9,039 Posts
Discussion Starter #17
Interesting replies, as usual, some more informative than others.

Regarding the points made:

Having an aftermarket run of these wheels will be costly and difficult to do. A member has attempted this path and he can summarize exactly what that entails and the costs involved.

These wheels, may even still be available at your local dealership. I do know they have a HWA number which a dealer can provide you with availability and price. However, do not expect the cost to be anywhere near the "market" value. I do not have the part number for these handy, but am 100% certain it has a part number that a dealership can determine whether its NLA and its cost.

It is true, a clean surface is critical, but that is not really an issue as the crack must be enlarged in order to weld properly. Access may be challenging to do it properly, but with the right equipment should be manageable.

True, the welds can be actually stronger than the aluminum of the wheel. The area directly to the sides can be weaker from the heat generated from the weld. With that said, it should be looked into further to determine if the tolerance is still safe enough to be used. Just because its "weaker" does not necessarily mean its still not strong enough to withstand daily use. This should be tested, and I would imagine there would be publications out there on metal hardness strengths of certain alloys after heat treatment.

Sounds as though someone used a laser TIG welding on a wheel already. I would love to hear feedback on this. How long ago has the wheel been repaired? Length of use? Has it been rechecked to see if anything is going on at the site of repair?


They also identified the cause of the cracking, and it is due to a bad design.
The above line is interesting. I agree the design of the area where the cracks typically occur may be flawed (thin material that can lead to a weak point), but that is not the actual cause of the cracks. Cracks occur due to stress and fatigue. Why it occurred would be the real cause.

No matter how much we can say that these wheels are weak and terrible, they were extensively tested in order to receive its TUV certification at the time and were deemed safe enough to be used on public roads. Had it been really that bad of a wheel design, I strongly feel these cracks would have developed early on and almost right away. There are torquing guidelines for wheels, but most shops from what I've seen that replace wheels/tires use a pneumatic tool that just puts a tremendous amount of stress which unsurprisingly can and will induce cracks.

Mike, you had a very unfortunate experience with one of your wheels. You mentioned the term "hogged out" which I assume means "removed or cut out". Were the lug hole damage noticeable or is it subtle that its not seen?

I need to reiterate that I am just wanting to bring out a discussion on the possibility of repairing these wheels that many have said is not possible atleast in a safe manner. I personally would not want a cracked or previously-cracked set (personal preference), but would like to hear how repairs can be done to safely allow these beautiful wheels to be used again.
 

·
Premium Member
2012 CL550 4MATIC Coupe
Joined
·
9,990 Posts
Interesting replies, as usual, some more informative than others.

Regarding the points made:

Having an aftermarket run of these wheels will be costly and difficult to do. A member has attempted this path and he can summarize exactly what that entails and the costs involved.
I believe that was me, and yes, the cost would have been prohibitive for only 20 or so sets. 100 sets or more would make is cost effective.

These wheels, may even still be available at your local dealership. I do know they have a HWA number which a dealer can provide you with availability and price. However, do not expect the cost to be anywhere near the "market" value. I do not have the part number for these handy, but am 100% certain it has a part number that a dealership can determine whether its NLA and its cost.
Possible, but HIGHLY unlikely. I believe there are some sets in Germany at the factory, but this is only my belief and I have no hard evidence.

It is true, a clean surface is critical, but that is not really an issue as the crack must be enlarged in order to weld properly. Access may be challenging to do it properly, but with the right equipment should be manageable.

True, the welds can be actually stronger than the aluminum of the wheel. The area directly to the sides can be weaker from the heat generated from the weld. With that said, it should be looked into further to determine if the tolerance is still safe enough to be used. Just because its "weaker" does not necessarily mean its still not strong enough to withstand daily use. This should be tested, and I would imagine there would be publications out there on metal hardness strengths of certain alloys after heat treatment.
This I don't believe will be true in the case of this type of wheel design, because the material gets substantially thicker very quickly as you move away from the cracked area. These wheels are not cracking the way that my guys have seen other wheels crack. They are saying that they are cracking in a different place and manner.

Sounds as though someone used a laser TIG welding on a wheel already. I would love to hear feedback on this. How long ago has the wheel been repaired? Length of use? Has it been rechecked to see if anything is going on at the site of repair?
I will have my wheel back any day now and I will fully document his repairs.

The above line is interesting. I agree the design of the area where the cracks typically occur may be flawed (thin material that can lead to a weak point), but that is not the actual cause of the cracks. Cracks occur due to stress and fatigue. Why it occurred would be the real cause.
Mark and his ME buddy both agree that the wheels are a good design with one bad flaw, too thin where the MB cap snaps in. They say a simple change in the milling would have prevented this.

No matter how much we can say that these wheels are weak and terrible, they were extensively tested in order to receive its TUV certification at the time and were deemed safe enough to be used on public roads. Had it been really that bad of a wheel design, I strongly feel these cracks would have developed early on and almost right away. There are torquing guidelines for wheels, but most shops from what I've seen that replace wheels/tires use a pneumatic tool that just puts a tremendous amount of stress which unsurprisingly can and will induce cracks.
I personally don't believe they are weak, but they do have a design flaw and are cracking. From what Mark and his buddy said, the "typical" cracking is due to over-torquing. However, my cracking happened during the departure of the wheel on the freeway when I was driving it home from the new engine install.

Mike, you had a very unfortunate experience with one of your wheels. You mentioned the term "hogged out" which I assume means "removed or cut out". Were the lug hole damage noticeable or is it subtle that its not seen?
The "hogging" was very visible Sharif. I took pics and posted them up in my thread. The three lug holes that had the cracking were oval in shape. This probably happened in the last few seconds that the wheel was clinging to life, and not from over-torquing, though it's possible.

I need to reiterate that I am just wanting to bring out a discussion on the possibility of repairing these wheels that many have said is not possible at least in a safe manner. I personally would not want a cracked or previously-cracked set (personal preference), but would like to hear how repairs can be done to safely allow these beautiful wheels to be used again.
The "fix" according to Mark , will be stronger than the original wheel because it will have an added sleeve to shore up that wall. We'll see?
 
1 - 20 of 108 Posts
Top