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BMW aluminum sub frame repair #4519421
09/18/17 01:17 PM
09/18/17 01:17 PM
Joined: Jan 2009
Posts: 13,831
Illinois
tig1 Offline OP
tig1  Offline OP
Joined: Jan 2009
Posts: 13,831
Illinois
This is the same repair I did on a mid 2000 Bmw. This repair was the second one I have done on BMWs. Also did one on a front wheel drive Chevy.

http://www.peachparts.com/shopforum/open...repair-bmw.html

Last edited by tig1; 09/18/17 01:25 PM.

2007 Ford Fusion 232,000 miles
M1 0-20 EP
2017 Ford Fusion 55K
M1 0-20 EP
10,000 mile OCIs on both engines
M1 ATF and MC LV
M1 10-30 in all OPE
MC filters

Re: BMW aluminum sub frame repair [Re: tig1] #4519512
09/18/17 03:19 PM
09/18/17 03:19 PM
Joined: Dec 2014
Posts: 1,671
'murica
Ethan1 Offline
Ethan1  Offline
Joined: Dec 2014
Posts: 1,671
'murica
This car needs a cradle for the same reason that the Corvette was totalled over a 1" crack: every authority in the auto industry forbids welding cast aluminum structural members.

Re: BMW aluminum sub frame repair [Re: Ethan1] #4519519
09/18/17 03:32 PM
09/18/17 03:32 PM
Joined: Jan 2009
Posts: 13,831
Illinois
tig1 Offline OP
tig1  Offline OP
Joined: Jan 2009
Posts: 13,831
Illinois
Originally Posted By: Ethan1
This car needs a cradle for the same reason that the Corvette was totalled over a 1" crack: every authority in the auto industry forbids welding cast aluminum structural members.


Did you view the video I provided? If you did you will notice the factory welds the brackets to the sub frame, and they do a poor weld at that. It's there weld that fails.


2007 Ford Fusion 232,000 miles
M1 0-20 EP
2017 Ford Fusion 55K
M1 0-20 EP
10,000 mile OCIs on both engines
M1 ATF and MC LV
M1 10-30 in all OPE
MC filters

Re: BMW aluminum sub frame repair [Re: tig1] #4519526
09/18/17 03:41 PM
09/18/17 03:41 PM
Joined: Aug 2011
Posts: 9,560
Boston, MA
HerrStig Offline
HerrStig  Offline
Joined: Aug 2011
Posts: 9,560
Boston, MA
Didn't the Fast and Loud guys weld up a GT 40?

Re: BMW aluminum sub frame repair [Re: HerrStig] #4519528
09/18/17 03:43 PM
09/18/17 03:43 PM
Joined: Jan 2009
Posts: 13,831
Illinois
tig1 Offline OP
tig1  Offline OP
Joined: Jan 2009
Posts: 13,831
Illinois
Originally Posted By: HerrStig
Didn't the Fast and Loud guys weld up a GT 40?


Aaron tig welded it, and it appeared to be a very good job.


2007 Ford Fusion 232,000 miles
M1 0-20 EP
2017 Ford Fusion 55K
M1 0-20 EP
10,000 mile OCIs on both engines
M1 ATF and MC LV
M1 10-30 in all OPE
MC filters

Re: BMW aluminum sub frame repair [Re: tig1] #4519545
09/18/17 04:00 PM
09/18/17 04:00 PM
Joined: Aug 2003
Posts: 12,892
NE,Ohio
Rand Offline
Rand  Offline
Joined: Aug 2003
Posts: 12,892
NE,Ohio
Originally Posted By: tig1
Originally Posted By: Ethan1
This car needs a cradle for the same reason that the Corvette was totalled over a 1" crack: every authority in the auto industry forbids welding cast aluminum structural members.


Did you view the video I provided? If you did you will notice the factory welds the brackets to the sub frame, and they do a poor weld at that. It's there weld that fails.


What video? I see a link to a forum with 2 pictures?


2019 Jeep Cherokee Trailhawk 2.0T
Re: BMW aluminum sub frame repair [Re: Rand] #4519657
09/18/17 07:03 PM
09/18/17 07:03 PM
Joined: Jan 2009
Posts: 13,831
Illinois
tig1 Offline OP
tig1  Offline OP
Joined: Jan 2009
Posts: 13,831
Illinois
Originally Posted By: Rand
Originally Posted By: tig1
Originally Posted By: Ethan1
This car needs a cradle for the same reason that the Corvette was totalled over a 1" crack: every authority in the auto industry forbids welding cast aluminum structural members.


Did you view the video I provided? If you did you will notice the factory welds the brackets to the sub frame, and they do a poor weld at that. It's there weld that fails.


What video? I see a link to a forum with 2 pictures?


Video was a typo. Sorry. The two pics shows the brackets that broke from the sub-frame.


2007 Ford Fusion 232,000 miles
M1 0-20 EP
2017 Ford Fusion 55K
M1 0-20 EP
10,000 mile OCIs on both engines
M1 ATF and MC LV
M1 10-30 in all OPE
MC filters

Re: BMW aluminum sub frame repair [Re: tig1] #4519790
09/18/17 09:14 PM
09/18/17 09:14 PM
Joined: Dec 2011
Posts: 4,729
North Carolina
rooflessVW Offline
rooflessVW  Offline
Joined: Dec 2011
Posts: 4,729
North Carolina
Do you have photos of your repair?


"Zed's dead baby, Zed's dead."
Re: BMW aluminum sub frame repair [Re: rooflessVW] #4519840
09/18/17 10:30 PM
09/18/17 10:30 PM
Joined: Jan 2009
Posts: 13,831
Illinois
tig1 Offline OP
tig1  Offline OP
Joined: Jan 2009
Posts: 13,831
Illinois
Originally Posted By: rooflessVW
Do you have photos of your repair?


No I don't. Even if I did, since Photo Bucket went south I can't seem to figure how to use a different system.


2007 Ford Fusion 232,000 miles
M1 0-20 EP
2017 Ford Fusion 55K
M1 0-20 EP
10,000 mile OCIs on both engines
M1 ATF and MC LV
M1 10-30 in all OPE
MC filters

Re: BMW aluminum sub frame repair [Re: Ethan1] #4519947
09/19/17 01:46 AM
09/19/17 01:46 AM
Joined: Nov 2006
Posts: 19,890
MA, Mittelfranken.de
Trav Offline
Trav  Offline
Joined: Nov 2006
Posts: 19,890
MA, Mittelfranken.de
Originally Posted By: Ethan1
This car needs a cradle for the same reason that the Corvette was totalled over a 1" crack: every authority in the auto industry forbids welding cast aluminum structural members.


I wouldn't buy into that Corvette story too much, there is more to that story IMO than is being told.
The part tunnel cost almost 8K and even if the labor was 3x that its still not enough to total a 60K new car.
I cant see why the insurance company would pay 2x the money out when the don't have to.

I can see not welding a control arm or its mounting parts on the cradle but a sway bar bracket is not really a high stress part in comparison, the bar itself takes most of the stress if the form of torsion just look at the brackets and the small diameter bolts that hold them, they are very low strength parts.


ASE L1, Master. Deutsch Meisterbrief.
Re: BMW aluminum sub frame repair [Re: tig1] #4519955
09/19/17 02:09 AM
09/19/17 02:09 AM
Joined: Dec 2011
Posts: 4,729
North Carolina
rooflessVW Offline
rooflessVW  Offline
Joined: Dec 2011
Posts: 4,729
North Carolina
Sure, don't weld cast aluminum. However, I'm fairly certain that the cross member is an extruded aluminum piece. The brackets that broke would be aluminum bar stock welded on. The Corvette chassis would have been stamped aluminum... Shouldn't have been to difficult to repair.

Only the outer mounts themselves should be cast aluminum here, and they're cheap enough to replace. Was this a car with active sway bars? Looks like it.


"Zed's dead baby, Zed's dead."
Re: BMW aluminum sub frame repair [Re: Trav] #4520093
09/19/17 08:34 AM
09/19/17 08:34 AM
Joined: Jan 2009
Posts: 13,831
Illinois
tig1 Offline OP
tig1  Offline OP
Joined: Jan 2009
Posts: 13,831
Illinois
Originally Posted By: Trav
Originally Posted By: Ethan1
This car needs a cradle for the same reason that the Corvette was totalled over a 1" crack: every authority in the auto industry forbids welding cast aluminum structural members.


I wouldn't buy into that Corvette story too much, there is more to that story IMO than is being told.
The part tunnel cost almost 8K and even if the labor was 3x that its still not enough to total a 60K new car.
I cant see why the insurance company would pay 2x the money out when the don't have to.

I can see not welding a control arm or its mounting parts on the cradle but a sway bar bracket is not really a high stress part in comparison, the bar itself takes most of the stress if the form of torsion just look at the brackets and the small diameter bolts that hold them, they are very low strength parts.





Trav,
What breaks the swaybar bracket is a jolt to the suspension. My customers wife hit a large pot hole going about 45MPH. The other customer drove over a concrete wheel stop in a parking lot. There couldn't be much stress on the welded bracket because of how poorly the factory weld is. It's been 2-3 years since I welded these and I haven't heard back from them. However my weld was much stronger so I didn't expect to hear from them.


2007 Ford Fusion 232,000 miles
M1 0-20 EP
2017 Ford Fusion 55K
M1 0-20 EP
10,000 mile OCIs on both engines
M1 ATF and MC LV
M1 10-30 in all OPE
MC filters

Re: BMW aluminum sub frame repair [Re: Trav] #4520241
09/19/17 12:01 PM
09/19/17 12:01 PM
Joined: Dec 2014
Posts: 1,671
'murica
Ethan1 Offline
Ethan1  Offline
Joined: Dec 2014
Posts: 1,671
'murica
Originally Posted By: Trav
Originally Posted By: Ethan1
This car needs a cradle for the same reason that the Corvette was totalled over a 1" crack: every authority in the auto industry forbids welding cast aluminum structural members.


I wouldn't buy into that Corvette story too much, there is more to that story IMO than is being told.
The part tunnel cost almost 8K and even if the labor was 3x that its still not enough to total a 60K new car.
I cant see why the insurance company would pay 2x the money out when the don't have to.

I can see not welding a control arm or its mounting parts on the cradle but a sway bar bracket is not really a high stress part in comparison, the bar itself takes most of the stress if the form of torsion just look at the brackets and the small diameter bolts that hold them, they are very low strength parts.





The other repairs were $8k, plus it needed the trans tunnel which GM does not offer. GM stated that replacement would compromise the vehicle.

Re: BMW aluminum sub frame repair [Re: tig1] #4520868
09/20/17 01:49 AM
09/20/17 01:49 AM
Joined: Apr 2005
Posts: 583
Under the hood
Carmudgeon Offline
Carmudgeon  Offline
Joined: Apr 2005
Posts: 583
Under the hood
I've seen this happen to an E63 6-series with active roll. I don't know if it was a road hazard impact or the stress of the system that caused the right side sway attachment to fracture from the subframe, though it was relatively mild compared to the one pictured.

Dealer and indy shop both quoted thousands for replacement of the front subframe, even for a junkyard part in the case of the latter.

I directed them to a local welder/race car fabricator who repaired it for a fraction of the cost. I didn't hear of any issues with the repair before the car was traded in for another.

Last edited by Carmudgeon; 09/20/17 01:50 AM.
Re: BMW aluminum sub frame repair [Re: Carmudgeon] #4521008
09/20/17 08:25 AM
09/20/17 08:25 AM
Joined: Jan 2009
Posts: 13,831
Illinois
tig1 Offline OP
tig1  Offline OP
Joined: Jan 2009
Posts: 13,831
Illinois
Originally Posted By: Carmudgeon
I've seen this happen to an E63 6-series with active roll. I don't know if it was a road hazard impact or the stress of the system that caused the right side sway attachment to fracture from the subframe, though it was relatively mild compared to the one pictured.

Dealer and indy shop both quoted thousands for replacement of the front subframe, even for a junkyard part in the case of the latter.

I directed them to a local welder/race car fabricator who repaired it for a fraction of the cost. I didn't hear of any issues with the repair before the car was traded in for another.


Both of my customers also told me the sub frame cost would be in the 5K+ range to replace. Paying that kind of money to get another sub frame with poorly welded brackets.


2007 Ford Fusion 232,000 miles
M1 0-20 EP
2017 Ford Fusion 55K
M1 0-20 EP
10,000 mile OCIs on both engines
M1 ATF and MC LV
M1 10-30 in all OPE
MC filters


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