The G isn't my daily driver so I'm in no hurry to get rid of it below market /kbb value. I'm sure I will find a buyer who appreciate the car for what it is and will to pay fair market / bluebook value one day.

 

what you looking at there is an Aluminium Cross member. The reason the welds look so bad simply cuz that's how aluminium welds, I even think that it is welded by hand, it's too complicated for bot to weld.


G37 cross member looks to be made out of steel, if it was aluminium there would be no need painting it.

 

mine looks the same way on the frame rails. front section toward the cats

 

I think that's a normal weld for this car.
Get the alignment and a wheel balance, and you wil probably be okay.

 

Got a chance to inspect my G the other day when the new tires were being installed. My welds look the same. I did not realize that the frame was aluminum. These welds are not necesarily abnormal for aluminum. When I first saw your post, I assumed it was steel. I don't think it's anything to worry about.

 

Ok who has a magnet!

 

looks like the factory welds to me O_o
I thought mine was like that too but its normal they all look like that
look at the whole cross membrane (the whole piece) and you will see it all looks like that

 

G37 is heavier, Why?


More rigid suspension (STEEL Components)


The difference between the G37 and G35 undercarriage is the parts used differentiate. The G35 uses Aluminum as abundant as possible. Where the G37 has more steel.


Aluminum takes a different welding process than Cold Rolled Steel. Dealerships have to use T.I.G. welding for Aluminum, where Cold Rolled Steel is quickly bonded with M.I.G. The difference is precisely why lots of people have a misconception as to why the welds look the way they do.

That "red substance" IS NOT bondo. It is SPRAY undercoat. "surpresses NVH and protects from the elements"

I've seen some vehicles drip as the pictures posted all due to the fact that sometimes a car or two pass on the sprayers too slowly, or the sprayers were not calibrated correctly thus overspraying. Therefore the spray "drips".

Aluminum with a slow pass process looks like a "nickel roll" on a quick pass using a heavy coating of filler looks like smeared chrome $hit. Regardless as long as the metal does NOT warp, and penetrates to BOND the two surfaces. It will be a solid weld. Many of these welds look like a machine was feeding lots of filler and a high rate of speed.

If your vehicle was involved in an undercarriage accident and Aluminum was damaged you would damn near NEVER know.(explaination below) All due to the properties of aluminum.

There are many forms of Aluminum but the two that are mainly used in motor vehicles is 5052 and 6061.


6061 is used mostly for aerospace material. You can bend it easier as it won't make "spider cracks" thus making the material weak. It's an alloy that tends to lose its strength when welded as it's a much SOFTER material.

5052 is used mostly used where strength, high levels of vibration, and when a post-weld strength is of upmost concern.


The material used in our undercarriage is 5052. The problem with 5052 is simple. IT DOES NOT LIKE TO BEND. Once you bend this material you've basically killed it. The only fix is to replace it.

So if your car was damaged, it would have BRAND NEW parts.


This is why nearly ALL respectable shops will replace the part instead of just attempting to repair it. If it were steel, that wouldn't be so much so an issue because Cold Rolled Steel can be repaired using various techniques all the while retaining its stength. With all actuality the more you weld steel the stronger it gets. Aluminum is backwards, the more you weld it. The less it's strength gets as you are annealing the material thus softening it. The only way to make aluminum stronger, you HAVE TO FORGE IT.

 

^Good info sir