hit biggest puddle on earth at 50 mph, now rattle in gear

[rtv900]

I know this is a total longshot but I'm stumped. Monday morning in the dark I hit a ridiculously gigantic puddle that took me from 50 down to
about 20 in a second. Ripped up those undercarriage aero panels, tore numerous mount point right through the bolts and ripped some pieces off.
So I repaired them as good as possible, cut off some pieces and used huge fender washers to secure the spots that were ripped clear through.

Thought those were causing the noise, and some of it was them.
But now I still have this insanely annoying very loud rattle at idle only, and also only in F or R. If I throw it in park or neutral it stops.
Mechanically the car runs and drives like new, there is zero mechanical issues at all.

Does anyone know if there's some external moving part that is engaged when the car is in gear?
I know internally the moving parts are actuated in gear even when not moving, but externally?
Obviously I need to get under there again and have someone sit in the car and hold the brake and move it in and out of gear, just wondering
if anybody had any experience with something finiky up there like a crappy heat shield or something?

 

[Snicklefritz]

Under held load, at a stand still in R or D, you are apparently creating a vibration that moves something now loose against something solid. That's my theory. Get the shreds of ruined undercarriage panels off and completely replace the lot. Look for anything else loose when you do this or have it done.

 

[Snowwhite]

check the belt tensioner. those really don't like water.

 

[rtv900]

found it last night. Finally had someone to sit in the car and hold the brake and put it in gear
On the exhausts right beside the trans there are heat shields attached to the underside of the body
That damn water must have hit under there with so much force it basically pulled them down and wrapped them
around the exhaust and one was basically touching the exhaust so it would ring against it when running.
Both sides were the same but one was worse. Simple fix, I just bent them back away up against the body like
they're supposed to be.
Man that water did a number on my undercarriage panels

 

[LordKOTL]

Glad it was an easy fix.

 

[Snicklefritz]

Cool. It feels good when I call it. And Ima glad too, that it was that quick and easy to see and fix. Now, new undercarriage panels. Don't wait.

 

[rtv900]

yeah I'm glad I found it, that was annoying as hell and it made the car sound like a piece of junk. I figured it would be something really easy since there was no true mechanical damage. Actually thought maybe a stick or something got lodged in a random spot from the water.
I still can't believe how much power that water had to rip those panels right out of the bolts and washers and bend both shields down.
Guess that's what happens when you hit a foot deep puddle at 50mph

 

[D.J.]

found it last night. Finally had someone to sit in the car and hold the brake and put it in gear
On the exhausts right beside the trans there are heat shields attached to the underside of the body
That damn water must have hit under there with so much force it basically pulled them down and wrapped them
around the exhaust and one was basically touching the exhaust so it would ring against it when running.
Both sides were the same but one was worse. Simple fix, I just bent them back away up against the body like
they're supposed to be.
Man that water did a number on my undercarriage panels

Hydroforming - Nice.

 

[rtv900]

Hydroforming - Nice.

yeah really
Once I saw all that damage I was worried the water might have mashed my intercooler fins all over. Thank god that was spared. The bumper probably broke the surface tension enough so it didn't trash my intercooler when I nailed that mofo

 

[Snowwhite]

Glad it was an easy fix!