I looked at five 300zx's this weekend they all had rust there to varying degrees. I'm guessing some of the cracking looking stuff is undercoating but most look like the metal is rusting through/cracking from stress there.

The '84 I purchased has pretty much rusted through nex to the stay.

This must be common, besides the differential I would think this is all that holds the crossmember to the unibody.

So how bad is bad-if it is rusted/cracked next to the stays?

 

Holes = bad ... huge areas of rust = bad ...

If you want, get under there w/ a screwdriver or pocket knife & tap at the area. If it feels like it's going to break through, it's really bad.

 

Does anyone know if this is a common 300ZX problem like the Z rails and floors? From what I've seen so far this is the worst spot underneath.

Someone should make a weld plate kit to fix like the Z's.

 

Nissan started doing something about rust in 1984... so the Z31 slowly improved in rust control. The 84 - 86 still had bad rust probs, but the 87 - 89 was a bit better.

Yep... it has been done.

 

If you have any info on anyone selling a kit to fix let me know. That would make it a lot cheaper to repair-I would guess it would cost over a grand to weld both sides of mine here in NY. Don't know if I want to dump that much into it right now.