You know the canyon road signs that say "beware of falling rocks"? So you know where this story is going.
The other day I'm heading alone a twisty 2 lane canyon road. Doing about 40-45 mph. There's another car ahead of me - I'm probably 1.5-2 car lengths back behind them. Suddenly between the 2 of us I see several small rocks - as well as one bigger one - fall from the rock wall, hit the shoulder of the road, and roll out into my lane. Of course at this exact same time, there's a bunch of cars heading the other way. There was no escape. I braked but rolled over the rocks doing probably about 30mph. As I drive over them I hear a loud bang and look in my rear view mirror to see the largest of the rocks bouncing around in the road.

At this time the car seems normal. No pull to one side or anything abnormal. At a turnout I stop and do a quick look under the car. No leaking fluids or anything like that. I drive on.

When I get home I put the car on ramps and discover the damage. The big rock appears to have been low enough to have missed the front bumper but it hit the openings in the aluminum tray under the engine. Also, more alarmingly, it put a fairly good dent in the welded aluminum sub frame that spans just behind the rear tires.

So of course my question is - what do you folks think? Anyone got any experience in dented sub frames? There doesn't appear to be any driving difference in the car. The sub frame is dented but it's not cracked. I'm thinking of getting an alignment done but outside of that I'm thinking it's probably okay. A dealer is not that close to me so I haven't taken it in and got it assessed there. Thoughts?

 

Man that sucks. If it were my car I would do exactly as you have suggested. I would get a four wheel alignment, and provided the alignment was within specs, leave the boxed sub-frame alone.
I would however bang out the aluminum tray so it looks decent.
Finally I would never drive down that road again

 

I would call my insurance adjuster ASAP. It looks like that sub frame might be tugging on the frame rail to bring it inwards.

 

That's terrible! That my friend is possibly frame damage. NAAA standards quantify any welded structural support that has a deflection greater than 1" as structural damage. It's hard to tell from the photos, but the cross member is welded and not able to be repaired or replaced without causing further frame damage. I would have your insurance company take a look at the car. I work in the auto industry and see this type of stuff almost everyday where motorists recall hitting a curb, speedbump or rock but never think about the consequences. Let us know what the results are...

 

That does look bad. I would find the closest A certified AM body shop to inspect that ASAP.

 

Thanks all for the replies and thoughts.

I've poured over the car and did some more looking online. While the sub frame took a good whack, I'm thinking it's unlikely there's any permanent damage to the bonded frame. I'm still planning on taking the car in and getting an alignment. I think depending on how that alignment comes in will be the tell on whether the sub frame has a bend to it or whether it's just dented. If it's too badly bent I'll unbolt the sub frame and replace it with a new part.