O.Z. Racing AMG 3-piece Wheel Cracks - Page 9 - Mercedes-Benz Forum
Reply
 
LinkBack Thread Tools Display Modes
post #81 of 104 (permalink) Old 11-23-2017, 07:27 AM
BenzWorld Elite
 
Fonzi's Avatar
 
Date registered: Jun 2010
Vehicle: 450slc5.0cab 280sl5sp 280se4.5 500seAMG +250seStkW108 350sl4spdX3 500secEuro
Location: Philadelphia Area
Posts: 21,599
Mentioned: 50 Post(s)
Quoted: 2348 Post(s)
Garage
Thatís interesting. Trying to understand the physics behind this...

Letís say the tire pressure is low, but bumps in the road never cause direct contact between the road and the rim. Or the compressed tire never flattens to the point that the sidewall totally folds onto the rim. I could see how really low pressure with a direct hit on a pothole would cause higher stress on the wheel. Maybe this is why high pressure is required. But youíd think that the stress would usually get localized onto the lip or barrel of the wheel in this scenario.

But if you never hit a pothole, higher pressure would just make the whole wheel act more like a rock and vibrate that center that so commonly cracks. I would think that higher pressure would mean the tire absorbs less of the blow or vibration when you hit something in the road, transferring the blow all to the suspension of the car, through those crack-prone centers.

So Iím wondering if the purpose of the high pressure is to assure that you never get full compression of the tire onto the rim. Because if you donít get full compression of the tire ďbottoming outĒ on the rim, then the tire absorbs the energy. That would be good IMO.

So Iím confused.


Sent from my iPhone using Tapatalk

.


My signature:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
If, you want 70's-80's Mercedes tuner wheels, let me know.
Fonzi is offline  
Sponsored Links
Advertisement
 
post #82 of 104 (permalink) Old 11-23-2017, 10:30 AM
BenzWorld Elite
 
vdubpower's Avatar
 
Date registered: Nov 2003
Vehicle: 1985 500sel and 500sec 2012 E63 1989 Porsche 911
Location: So-Cal
Posts: 4,821
Mentioned: 13 Post(s)
Quoted: 552 Post(s)
I think I've run around 36 for past 12 yrs with no problems but I can add a few more lbs

1985 500SEL Euro Nautic Blue - A Classic Beauty
1985 500SEC Euro Nautic Blue
1989 Porsche 911 Carrera Silver Anniversary Edition
2012 E63 AMG Iridium Silver - Performance Package
vdubpower is offline  
post #83 of 104 (permalink) Old 11-23-2017, 03:51 PM
BenzWorld Veteran
 
Richter Rox's Avatar
 
Date registered: Aug 2016
Vehicle: 1988 560 sec
Location: Boston Ma
Posts: 667
Mentioned: 6 Post(s)
Quoted: 185 Post(s)
Low profile tires coupled with low pressure is a wheel killer . My feeling is that most rim damage and cracking comes from shock more so than from metal fatigue.

Aluminum is a great metal but it has limited ability to absorb impacts and when it fails compared to steel it fails catistrophicly .
Richter Rox is offline  
Sponsored Links
Advertisement
 
post #84 of 104 (permalink) Old 11-23-2017, 11:44 PM
BenzWorld Member
 
Evilaseq's Avatar
 
Date registered: Jun 2016
Vehicle: 1988 500 SEC
Location: Poland
Posts: 75
Mentioned: 0 Post(s)
Quoted: 5 Post(s)
Garage
Quote:
Originally Posted by Richter Rox View Post
Low profile tires coupled with low pressure is a wheel killer . My feeling is that most rim damage and cracking comes from shock more so than from metal fatigue.

Aluminum is a great metal but it has limited ability to absorb impacts and when it fails compared to steel it fails catistrophicly .
And if you add to this, that AMG/OZ are forged not casted, In my opinion You have the "recipe for destruction"
Evilaseq is offline  
post #85 of 104 (permalink) Old 11-24-2017, 12:22 AM
BenzWorld Elite
 
vdubpower's Avatar
 
Date registered: Nov 2003
Vehicle: 1985 500sel and 500sec 2012 E63 1989 Porsche 911
Location: So-Cal
Posts: 4,821
Mentioned: 13 Post(s)
Quoted: 552 Post(s)
everyone send me your sets, ill get rid of them for you

1985 500SEL Euro Nautic Blue - A Classic Beauty
1985 500SEC Euro Nautic Blue
1989 Porsche 911 Carrera Silver Anniversary Edition
2012 E63 AMG Iridium Silver - Performance Package
vdubpower is offline  
post #86 of 104 (permalink) Old 11-24-2017, 05:09 AM
BenzWorld Elite
 
Fonzi's Avatar
 
Date registered: Jun 2010
Vehicle: 450slc5.0cab 280sl5sp 280se4.5 500seAMG +250seStkW108 350sl4spdX3 500secEuro
Location: Philadelphia Area
Posts: 21,599
Mentioned: 50 Post(s)
Quoted: 2348 Post(s)
Garage
Quote:
Originally Posted by Evilaseq View Post
And if you add to this, that AMG/OZ are forged not casted, In my opinion You have the "recipe for destruction"


I could envision cast wheels with voids (spots where cracks that begin can stop) being less likely to have long cracks, but everything Iíve read on the internet says cast wheels are more likely to crack (in an accident) while forged is more likely to bend.

.


My signature:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
If, you want 70's-80's Mercedes tuner wheels, let me know.
Fonzi is offline  
post #87 of 104 (permalink) Old 11-24-2017, 11:13 AM
BenzWorld Member
 
Evilaseq's Avatar
 
Date registered: Jun 2016
Vehicle: 1988 500 SEC
Location: Poland
Posts: 75
Mentioned: 0 Post(s)
Quoted: 5 Post(s)
Garage
Quote:
Originally Posted by Fonzi View Post
I could envision cast wheels with voids (spots where cracks that begin can stop) being less likely to have long cracks, but everything Iíve read on the internet says cast wheels are more likely to crack (in an accident) while forged is more likely to bend.
Well I think that depends on direction and amount of force that affects the forging/ casting. I don't have any scientific evidence to prove that, but I think that in case of wheel disc, forged one would be more exposed for cracking than bending. Wheel lip will mostly bend but disc is a completely different thing - at least I suppose so.
Evilaseq is offline  
post #88 of 104 (permalink) Old 11-24-2017, 02:19 PM
KRH
Lifetime Premium Member
 
KRH's Avatar
 
Date registered: Nov 2009
Vehicle: 87 Euro500HVSEC. 88 Euro 560HVSEC. 89 Euro 560HVSEL
Location: Perth, Western Australia
Posts: 4,137
Mentioned: 26 Post(s)
Quoted: 539 Post(s)
Lifetime Premium Member
I have owned and dealt with very many of these AMG/Oz Racing 3 piece forged rims and never had one ever crack whilst on my W126 cars in the past 9yrs
At one point in time my collection topped well over 50 of these rims until i started selling them off in sets to same Merc enthusiasts across the globe.

Out of all those rims i purchased at opportunity from around the globe only 8 or so came cracked and most just with 1 lug hole wall cracked and a couple with 2 cracks. But the cracks were always only in the top half (about an inch) towards the face of the rim and never down the rear 2inches where the metal is a lot thicker. So the lug hole wall was never cracked all the way down.

These forged centres are a solid disc style unlike a modern rim with open centre design so the only weak spot in the centre is that top portion of the lug hole wall to centre bore.
So having that crack professionally repaired i don't see is a problem as the rear portion of the centre where it mounts to the hub and where there is plenty of metal and has never cracked in any centre i have seen is not affected or compromised.

The cracks seen on many other brand rims are usually serious cracks completely through a whole arm or completely through a whole centre hub front to rear.

So my theory is these AMG/Oz Racing 3 piece rims are +25yrs old and seen plenty of road use and stood the test of time so finding a low percentage with a minor crack issue that is still not compromising the rim integrity is no big deal when it can easily be repaired.
I would have no doubt the ones that have cracked have taken some repeated abuse during the test of time over those 25yrs whether it be incorrect tire pressure, incorrect lug bolt torque, incorrect lug nuts (not ball seat lugs) and taking many bone jarring hits in those +25yrs from pot holes,speed bumps, kerbside swiping etc etc

So all the paranoia of a small crack is no big deal in my eyes with these rims as it can be repaired - unless you came across one that had multiple cracks in the bore of which i have never seen myself with my past rim collection
Fonzi, karmann_20v and Evilaseq like this.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
by
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
, on Flickr" border="0" />
87 White Euro 500 "ECE" 265hp SEC
88 Black Euro 560 "RUF"300hp SEC
89 Blue Euro 560 "RUF" 300hp Hydro SEL

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Last edited by KRH; 11-24-2017 at 02:23 PM.
KRH is offline  
post #89 of 104 (permalink) Old 12-12-2017, 02:57 PM
KRH
Lifetime Premium Member
 
KRH's Avatar
 
Date registered: Nov 2009
Vehicle: 87 Euro500HVSEC. 88 Euro 560HVSEC. 89 Euro 560HVSEL
Location: Perth, Western Australia
Posts: 4,137
Mentioned: 26 Post(s)
Quoted: 539 Post(s)
Lifetime Premium Member
Ok i was down at my local Pro engine machining shop yesterday and he has just about finished repairing those cracked lug hole spare rims i had separated out of my collection of these rims some yrs ago.
The Shop owner has been repairing alloy engine blocks & heads for many years and knows his stuff when it comes to repairing stress fractures in alloy.
After examining my centres and working on them and repairing the cracks his belief is over-torquing the lugs is the main culprit as to the design of the centre.

I was surprised at the way he tackled the repair work on each centre and managed to capture some pics on one of the last centre he was in the middle of repairing that had two fractures in the lug holes.
Despite the cracks only appearing down half the lug hole from the face of the rim he has taken a lot more metal out ready for the tig welding process.
The centre is heated up to required temp before welding and cooled down in the correct sequence.
When the rim is tidied up by me later at home there will be a lot of the raised weld left untouched in the bore hole and just blended in the lug hole and on the face

When i collect the centres at the end of this week i will post up more pics of the final repair work after the welding was completed.
He feels the repair work is solid and they wont crack again where they have been repaired. He said the alloy metal is good quality.

Anyway here are the pics after machining and before the welding is done
Attached Thumbnails
Click image for larger version

Name:	IMG_1523.jpg
Views:	47
Size:	82.7 KB
ID:	2332090   Click image for larger version

Name:	IMG_1524.jpg
Views:	44
Size:	71.2 KB
ID:	2332098   Click image for larger version

Name:	IMG_1525.jpg
Views:	33
Size:	74.8 KB
ID:	2332106   Click image for larger version

Name:	IMG_1526.jpg
Views:	40
Size:	79.0 KB
ID:	2332114  
bsclifton likes this.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
by
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
, on Flickr" border="0" />
87 White Euro 500 "ECE" 265hp SEC
88 Black Euro 560 "RUF"300hp SEC
89 Blue Euro 560 "RUF" 300hp Hydro SEL

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Last edited by KRH; 12-12-2017 at 03:13 PM.
KRH is offline  
post #90 of 104 (permalink) Old 12-12-2017, 07:24 PM
BenzWorld Member
 
sleauxdaddy's Avatar
 
Date registered: May 2010
Vehicle: 99 SL500R Sport Pkg Pano roof
Location: Southlake, TX
Posts: 132
Mentioned: 1 Post(s)
Quoted: 14 Post(s)
Wow!!!

Kim,

Great to see that you've found someone competent to tackle these! Pretty amazing to see how much metal he decided to take out in order to do it correctly.

Any chance we could get contact info for him to see if he'd be willing to tackle any of the rest of ours? Thanks to your kindness I'm rolling in style but now I have two cracked centers taking up room in my garage. I know it's a long way down there, but after two years of trying I still haven't found anyone here in the DFW metro area that is willing to take on this job. Probably too many lawyers here in the good ole USA.

Can't wait to see some pics of them after he gets done with them.

Lowen
sleauxdaddy is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > Mercedes-Benz Sedan Forums > W126 S,SE,SEC,SEL,SD,SDL Class

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 

Title goes here

close
video goes here
description goes here. Read Full Story
For the best viewing experience please update your browser to Google Chrome