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The dreaded 'rocks in the rocker panel to fender gap' finally got to me. I scoured the forum for the how-to's and sadly all the pictures are toast, however, with the description in hand, I headed out to the garage to give it a whirl. I removed the two screws per the instructions and rocks began falling out. I thought, "This is pretty easy, I'll be done with this in no time." Well, the more I tapped the body panels, the bigger the pile of rocks on the ground got. I became tired of this and knew that the only way to do this right was to pull the wheels and then the inner fender well. Plus, it would give me a chance to check out the back end of the car in detail, something I haven't done since we bought it back in April.
Let me warn you, what you are about to see may cause you to toss your cookies if you are a garage queen fan. If you are a daily driver kind of person, well, this may not surprise you. So what does 7 years of driving look like when it comes to poorly fitted inner fender wells?
How about 12.4 pounds of rocks, sand, and dust?
And what did that 12.4 pounds look like before I swept it all up?
I think GM included the weather stripping for the inner fenders in these bags that were stuffed inside the fenders just behind the brake duct intakes.
And what did I find behind those bags? Well, the driver side was far worse than the passenger side, but more gravel. It is up about half way toward the front of the car in the rocker panel. I was not wanting to drag the project out longer so I left it there. Sadly, my shop vac hose was just slightly too large in diameter to get around the seams and such in the rocker panel. It may be accessible from beneath the car, but that is a project for another day.
So, on to the fix. I looked at all of our big box stores and such and could not find any weather stripping thicker than 3/8". I had just about given up and stumbled upon this stuff in the metal roofing area at Home Depot. After reading the package, it sounded like it would do the job just fine. One roll did both sides with about 8" left over.
While you can do the entire inner fender/fender lip as I did, the only part that is required to keep rocks out of that gap is shown in the below photo. But, to get to that, you have to remove the inner fender, so you may as well do it all while you have it apart.
Here is the rest of the project if you made this this far. Each side was different as far as the size of the gaps. But since this stuff expanded, it didn't really matter. The worst and easiest gap to fill, without removing the inner fender, would be the notch at the top of each inner fender well (first pic below). On our car, the other areas that had a major gap was just in front of the tire, about 14" (essentially up from the gap the rocks like to get into, to the area where the curve of the opening starts towards the back of the car), and just behind the tire, a gap of about 6". I did have to add a piece to the passenger side on top of the existing foam as that gap was larger in depth.
And lastly, don't forget the areas around the triangular shaped part of the inner fender and just below the brake cooling duct. Yes, there were rocks in the brake cooling ducts. Thankfully they have a drain hole that helps some, but both of ours were clogged with...a rock.
We've driven about a hundred miles with no rocks, but we have a trip coming up that will net us about 1,300 miles and most likely some rain, so I'll report back after that trip on how the fix worked...or didn't.
Was your car a wide body mod or factory wide body?
My base does not have gaps like that. The rear diffuser does catch quite a bit of sand though. You can feel around by the reverse lights and feel it.
Yeah, those hollow "tunnel" rockers can really accumulate the road debris. I got some when I installed my BAP, but nothing like the volume you're seeing. My car is/was an AZ car its whole life and doesn't get the slop from driving on wet roads.
Wow, That is a lot of dirt and gravel. It must have spent a lot of its life on some back roads. I believe those black bags are the for reducing the road noise
Oh, I put them back. Funny though, that those were and are, or at least appear to be, the only sound deadening things back there. The wind noise from taking the top off is louder than any road noise, and to hear the radio over that, well, we're gonna need bigger bags of foam!
I wonder how bad my '08 base is - it was registered in Alaska, but lived in western Indiana - but I'm sure it made several trips to Alaska at some point - there's plenty of evidence - small rocks at the rocker panels - a million small chips in the windshield - very small rock chips at the leading door edges - so I'm curious what the " 2 screws to remove" are - I'm not ready to remove the wheels and inner fenders panels yet, but would like to at least see what's in there.
Thanks
Got to ask where you have been driving the car to get this much dirt in the areas.
Dirt oval tracking or trudging through farmer fields during date night for a place to get randy with strange maybe?
I pull mime from time to time when I'm in the car wrenching on something near it, and short of some dusting and may a small pebble of two, that is about it.
...so I'm curious what the " 2 screws to remove" are - I'm not ready to remove the wheels and inner fenders panels yet, but would like to at least see what's in there.
Thanks
One is located in the fender well on the leading side, first pic. The second screw is on the bottom side of the rocker panel, just forward of the fender well, second pic. You can also remove the three screws in the door jamb, but I chose not to do that. Hope that helps.
Got to ask where you have been driving the car to get this much dirt in the areas.
We've only owned the car about 6 months, so I can't speak for the previous two owners, but it isn't unusual to see this much road sand, pebbles, etc. Parking lots are full of the sand and such. You'd be surprised how much of that stuff there is when you actually look, but in most cases you can hear it being picked up by the tires and slung around the fender well.
As you can probably tell in the pics above, Annette is a filthy mess. We logged 1,570 on our road trip and I'm happy to report that there were not rocks in the fender to rocker panel gap! We endured tons of heavy rain and several parking lots and roads that were prime places to pick up road debris. So, the above process was a success! Now to give her a bath and tuck her away for the winter...
10-04-2018, 11:47 AM
Getting Rid of the Rocks
Wow that’s a lot sand,rocks, and gravel you pulled out. 
