Hey guys glad to be a part of the forum!

I just recently bought a 2004 G35X for $2,000 with 130k miles. The car looks great from the interior and the exterior looks pretty darn good also. It ran without any issue and the underside of the car looked pretty rust free for the most part. I jumped on it and bought the car. Everything was awesome at first. No issues at all. A couple weeks passed and I decided to replace the passenger side fender since it had a small rust hole towards the bottom. That's when I noticed some pretty heavy rust behind the fender.



A bunch of mud had collected behind the fender for god knows how long. I started poking around at the rusted metal and eventually opened up a pretty big hole. Didn't think much of it since the thick subframe steel was still perfectly intact. I decided to fiber glass the hole properly by cutting away the rusted steel.





This is where it all started going downhill. I needed to take the door and side skirts off in order to fix the hole correctly. I patched the fender hole without any issue but under the side skirts was so much rust that it practically started disintegrating. My heart started to sink when I saw the extent of the damage.





With the side skirt on the car looked imaculate but underneath the plastic was barely any metal. The sideskirt metal didn't bother me to much since I could always fiberglass the shape and or weld a sheet of metal to fix it. What is really bothering me is this particular area right here. Not sure what this part is called nor what it's for but I'm pretty sure it's part of the rear suspension.




It looks eaten up. I genuenly don't see how to fix this without welding huge chunks of metal around the damaged area. Is this car gone or is there a way to fix this? I'm actually pretty bummed out about it. Everything was looking so good now I don't know what to do :/

 

Holy crap thats a lot of rust.

I would clean off as much of the rust as I can. Then seal it with some galvanizing spray. I dont think the rust has eaten through the thicker “suspension” metal u posted. Looks like its just the top layer.

 

I'll try to do that and post some pictures of how it looks afterwards. I'm just scared the damage has transfered deep into the frame of the car where that suspension part is at. If anyone knows what that part is called/ what it's for it would be great help!

The thick frame steel feels super brittle and is rusted on both ends. I'll post more pictures later today. 🥲

 

Basically the question is how long are you planning on keeping the car.

If this is just a disposable vehicle that you plan on owning for 5 years or so then I wouldn't even bother trying to fix any rust, make it look pretty on the outside and spend zero time whatsoever trying to fix these issues. If you don't like the color then spray it all down with black rustoleum paint underneath.

If this is a car you were hoping to own for 10+ years or more and something you wanted to fix up, that rust is too far gone, find another chassis. You will probably spend the rest of your life fighting rust unless you literally strip the ENTIRE car down to the chassis for a FULL restoration

It looks like someone drove that car through the ocean on a regular basis, probably a winter daily driver in an area where they salt the roads. You probably have a ton of rust in other areas that would need to be repaired as well, that's a very significant amount of work, probably 500 hours of work for a full chassis rust restoration. That's if you already have the proper tools, angle grinder, drill, die grinder, sawzall, metal brake, welder, and the knowledge of how to do a repair like that.

I can't see that project being one that you would want to tackle for an '04 X sedan unless you had some serious emotional attachment to the car. If that's the case then YES all the rust can be fixed with the proper tools, methods, and a LOT of work.

 

The plan was to keep this car for a few years only then down the line buy a newer nicer G35/37. I needed a cheap AWD car for wisconsin snows. I'm not attached to the car but I also don't want the rear suspension to break off on me while driving her on the freeway. I'm more so concerned for the integraty of the car. Not really sure what the brace does in the back but I'm sure it has to be there for a reason. I wanted to patch up/clean up as much of the rust as possible so she would last me a few years. I just got kinda scared when I saw that one suspension piece looked all gnarly. I'm cleaning her up right now. I'll post some picture later today after I hit it with the angle grinder/wire brush. Hopefully it doesn't all disintegrate on me.

 

So I've been trying to sand the rust down for the past few hours to very minimal success. After sanding down the bolts from the underside I was feeling a bit more optimistic. The bolt from the underside of the car actually looks in pretty good shape with some of the surface rust removed.


I then started to sand the inside of the hole when I came across this atrocity.

FML, try to replace or pray they don't break?

The inside section where the bolt goes through has so much rust I bet the whole bolt could crumble if I keep sanding it down. Should I try to replace the bolts or just pray they don't snap on me while driving?

Would adding some rust converter even do anything at this point? I want to slow down the rust as much as possible. I know repairing this requires way to much money and effort. Just need her to last me a few more winters. SMH I was hoping to get some new tires mounted this weekend now I'm stuck dealing with this bs

 

Take a can of expanding foam insulation and fill any holes, no air = no further oxidation/rust.

Everything on the suspension/powertrain is bolted to aluminum components (except the engine cradle) and the rear has an aluminum subframe. There are only a few places where it bolts to chassis steel like behind the rear tire for the suspension transverse link (traction arm). Same with the front.

I can't tell exactly where on the car you're digging around on the rust but those subframe braces just help stiffen up the chassis, they aren't not critical for holding the car together. Here's what the front and rear subframe brace looks like, there are also a stay bars that is also non-critical. They just make the chassis super stiff so it won't flex because it's a sport sedan.

Yours may look different due to sedan awd but they should be very similar. You could literally take these 3 components off the car and it would be fine, just have more chassis flex.

 

Thanks for the idea dude. It actually worked pretty awesome. Been messing around with the car for the past couple days. Here's the progess so far. It's actually not looking too bad. Put some rust reformer on with 2 layers of enamel over it. Just need to put some fiberglass over the foam and it should hold up for some time.






That's a relief, thanks for the tips man. Just need her to last me a few more years. I'm much more optimistic now. Everything is looking a whole lot better!