Got a customers car in this past week after she called and said she heard a loud noise after driving across a "crevice". Not sure what kind of crevice she went through but she needs something other than her 545I.

Anyway, thoughts, comments on how to repair it is appreciated. I've got a coworker that is capable of welding aluminum. Not sure I want to be responsible for someone welding on this car in my shop. I am considering sending her on to a body shop. Not sure I want to mess with it.

I've attached pics of the good side and the bad side.

Attached Thumbnails

   

__________________
Jim

I would guess from a liability perspective "replace the subframe" would probably be best.

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

x2

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Offer her two prices:
(1) Subframe replacement, fully guaranteed
(2) A verbal price to have the part welded back on. Cash under the table, no guarantees nor receipt.

The problem here is that kindness could be misconstrued as an attempt to avoid paying tax - it all gets nasty and complicated if you're not careful.

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

So if the repair under scenario (2) fails, and someone is injured or killed as a result, a little lying just might get the repairer out of a legal jam. Seems fair.

Just replace the subframe.

I wouldn't touch it. I believe you have to be certified by BMW for repairs like that.

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1979 Black on Black, 300CD (sold), 1990 Black 300SE, Silver 1989 Volvo 780, 1988 300CE (vanished by the hands of a girlfriend), 1992 300CE (Rescue).

Is that a swaybar bracket? Is it the only damaged/stressed area?

Oh please.... as far as BMW is concerned I'm guessing you'd also have to be certified to change the oil or replace a headlight bulb.

It's just a swaybar link, if the repair failed what's going to happen? It would be exactly like it was when she drove it into the shop. It's not like the sub-frame is going to fall off the uni-body.

I've got very limited experience with aluminum welding but I'll make 3 quick observations. Its much harder to control the weld-pool, aluminum weld-pools seem to have less surface tension than steel. Given the orientation of the car on the lift this could be an issue. Aluminum has to be really, really clean - much less tolerant of corrosion than steel welding and the heat input into the weld area is much higher, aluminum also transmits heat better than steel. Make sure there is no grease or oil anywhere near the weld area..... and make sure you've got a couple of fire extinguishers handy. You don't want a car on your lift on fire...... ya know the more I think about this the more I'm liking you're 'take it to a body shop idea'.

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98 Dodge-Cummins pickup (123k)
13 GLK250 (135k)
06 E320CDI (323K)
16 C300 (62K)
82 300GD Gelaendewagen (54K)

I'm not saying he can't do it, I'm sure his shop is capable of doing so. Liability, is another matter.

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1979 Black on Black, 300CD (sold), 1990 Black 300SE, Silver 1989 Volvo 780, 1988 300CE (vanished by the hands of a girlfriend), 1992 300CE (Rescue).

So if the repair failed and the sway-bar bracket broke (again) what would happen?

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98 Dodge-Cummins pickup (123k)
13 GLK250 (135k)
06 E320CDI (323K)
16 C300 (62K)
82 300GD Gelaendewagen (54K)

Verbal agreement cash under the table is very bad advice. I know Jim won't consider that option.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

As I was mowing the grass I remembered something from my welding classes..... some weldable aluminum alloys will get significantly weaker after welding is performed. Post welding heat treatments are require to restore full structural strength.

Here's a link from the Lincoln web-site that talks about the issues.

Aluminum Welding FAQs

Since the sub-frame is certainly a structural member you might have to be a little careful about weakening the main structure of the subframe if you did some welding on the sway-bar tab. Of course not all weldable AL alloys require treatment but since you don't know what type of alloy it is you wouldn't really know what was required. I might try it on my own car, on a customer's car no way.

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98 Dodge-Cummins pickup (123k)
13 GLK250 (135k)
06 E320CDI (323K)
16 C300 (62K)
82 300GD Gelaendewagen (54K)

Notify the press: Tim and I are in agreement. Aluminum welding is harrrrd to do well.

The pics are way different from my 325i (E30) but some years back I noticed an odd vibration, opened the hood with the engine running and noticed the fan wasn't turning. The front of the engine was supported on it bearing on the fan shroud. The subframe had cracked. I determined that the 318 for my series shared the same part and found one on a 318 with 180K on the odo, less than when I bought my car. I surmised that the smaller engine would mean less weight and torque on the subframe over its lifetime. Cost about thirty bucks. Thank you Pick n' Pull.

It was not an easy job but I lived to tell about it.

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1986 300SDL, 362K
1984 300D, 138K