Thoughts on this subframe weld job?

[artbun]

I’m finally having my subframe mounting points reinforced and welded. I work at my family’s body shop and one of the bodymen is doing the welds for me, he’s a great welder and does great work, but I’m unsure if these welds would deemed adequate for this kind of job. I’m not a professional welder, but I’m worried that the welds are kinda hot and if they’re solid enough by most standards. Also curious for those who have done this job if seam sealer (after welding and before paint) is required or just recommended.

For additional context this is an ‘02 E46 M3 with ~115k miles and SMG to Manual converted (it’s a California car too). The car is also my daily and I plan to do track days in the future when I feel the car is ready.

After all is said and done I’m throwing on PSS10s, Powerflex Street Subframe Bushings, New OEM RTABS + Limiters, Monoball Rear Shock Mounts, Rear Spring Perch Reinforcement Plates, and Front Tower Reinforcement Plates.

I’d love to hear y’all’s thoughts. Btw the welder in question is a Lincoln 220V MIG welder, unsure on what wire gauge was used. I appreciate any feedback.

[bigjae46]

Its hard to tell on two of them since they're primered. But the other two look pretty good. What you are looking at is the silver region which is the heat affected zone and porosity in the weld. The HAZ is relatively small so he didn't blow through the sheet metal or weaken a large area by putting a lot of heat in one spot and there's no porosity so the puddle was relatively clean and shielded. This minimizes the likelihood of corrosion.

[cobra]

The appearance of a weld is not necessarily indicative of its strength. An "ugly" weld can be much stronger than neatly stacked dimes.

That said, I don't know how to weld myself and so I asked a welder friend of mine. He said they are not good, for the following reasons:

"Inconsistent width and height
Stop and start tie-ins are bad
Insufficient material prep (evident by black smoke)
Settings were wrong for clean penetration
Plug welds are not fully plugged"

That said, are they good enough for this application? The stress isn't really trying to pull the welds apart, it's more about distributing the force on a broader area. And the weakness in the heat affected zone will now be the weak point - not the plate or the welds themselves.

[bigjae46]

The appearance of a weld is not necessarily indicative of its strength. An "ugly" weld can be much stronger than neatly stacked dimes.

That said, I don't know how to weld myself and so I asked a welder friend of mine. He said they are not good, for the following reasons:

"Inconsistent width and height
Stop and start tie-ins are bad
Insufficient material prep (evident by black smoke)
Settings were wrong for clean penetration
Plug welds are not fully plugged"

That said, are they good enough for this application? The stress isn't really trying to pull the welds apart, it's more about distributing the force on a broader area. And the weakness in the heat affected zone will now be the weak point - not the plate or the welds themselves.

Not an expert but you'll get black smoke because there's no way to prep the backside of the weld. I found this out the hard way and it involved a fire extinguisher...hahaha. But its MIG so not as big of a deal. It is far more important to get it clean with TIG welding.

The other stuff...I'd defer to the welder friend. I didn't see the gap in the plug welds...definitely want to fill those in.

[Slideways]

Those look average (there is worse out there), but should hold up just fine. The other main concern should be the drivers rear arch and tying the frame rails to the RACP inside the trunk - either the new Redish kit, Vincebar or something like the 4 point brace that connects the two rear RACP mounts to the rear shock towers.

[bmwfnatic]

Horrible job that accomplished absolutely nothing.

I think cobra already provided accurate comments on the welding itself, and I feel like I don’t need to add much there.

The guy who did this probably has trouble with the vertical and overhead processes. There’s indeed a proper lack of consistency, which shows immediately on the first picture with the left most bead lying completely on top and showing poor penetration, and the vertical one next to it lying much flatter and seems to be welded with much more heat.

But it doesn’t stop at the welding itself.

The overal prep is just done poorly and lazily, not removing enough original sealer near the weld zone, causing it to burn and drip into the weld. which ultimately leads to contamination.

Directly welding onto the factory e-coat without stripping to bare metal? Not 100% sure on this one but it seems the case.

Instead the entire area and a bit more should have been stripped to bare squeaky clean metal, and then treated with either a copper or zinc based weld thru primer, as well as the back side of the plates.

And then we come to the biggest issue with this job, the plate design, I am just going to say it, whoever designed these plates, has absolutely no clue about this car and just made them physically fit.

The rear plates are extremely small, and because of that they put the most common location for cracks (the most extreme folded corner) right into the heat affected zone of the weld, making it even weaker than before, especially if welded with excessive heat.

The locations for the plug welds on the rear plates are also placed in seemingly random and meaningless locations, the original idea of these was to use them as guides to drill trough the outer layer, into the base of the threaded receiver, and then start the plug weld from there, connecting all 3 layers of metal (the base, the outer layer and the new plate) together, to provide stability for the base within.

After so many copycat manufacturers, it seems that this intended function of the holes was lost and we just add many of them in random locations so it looks good, right?

Then moving on to the front plates, the front left plate is exceptionally large, why? This is the area that has to deal with the least amount of forces and I often see this one with very little or no cracks at all. So why is this plate so huge…

Lastly the first picture you have a spot weld that let go in the top right corner (dirty area, away from the plate) which is another good example to prove that plates do nothing…

To sum it all up, if this is your car OP, start saving for a Vincebar or alike system to hold your car together, because this wont…

[K-Dawg]

Despite all of the comments above, that job is probably no worse than most others out there. Most people suck. And why I think that a "reinforced" car without good documentation is not worth anything more than a factory original car.

artbun Go ahead and drill your holes for a Vincebar while you have the subframe removed.

[bigjae46]

BMW E46 Rear Subframe Reinforcement | BimmerWorld

My only comment on this is the rosette welds look like a butthole. haha

[oceansize]

BMW E46 Rear Subframe Reinforcement | BimmerWorld

My only comment on this is the rosette welds look like a butthole. haha

Checks out... (scans bigjae46's South Park avatar).