Repairing wheel well skirts

[Lonestar]

There seems to be a history of the screw holes on the ABS plastic fender skirts cracking, or the screw heads pulling through. Possibly from over tightening the attaching screw during the build process or flapping while going down the road. I have found a solution that might help.

1/8" ABS sheet material (found in Ebay) and JBWeld PlasticWeld. The ABS can be cut in small pieces and formed to fit the indentations of the screw holes. Then, a new hole drilled and attached with stainless steel machine screws, washers, and nylon lock nuts.

[familytruckster4]

I have replaced a few of these on my trailers over the years. Its my thought that the biggest problem with cracking is that they use a self drilling/self tapping screw through the skirt into the sidewall. There is no hole pre drilled through the skirt so the screw adds undue stress to the skirt while it pulls it towards the sidewall. The predrilling and addition of stainless screws usually prevents cracking as Lonestar points out.

[flyfshrockies]

Lonestar That makes a great looking repair and certainly adds strength to the location of the fastener. Every r.v. I ever had has developed cracks in a few of those spots over time as well as the screws working lose which has been stopped by adding silicone to the threads and a small washer helps distribute the load from the screw head. When viewed in the mirror the skirts vibrate and flap quite a lot while traveling, it is no wonder those skirts crack and the screws come lose.

Dave

[Lonestar]

I have replaced a few of these on my trailers over the years. Its my thought that the biggest problem with cracking is that they use a self drilling/self tapping screw through the skirt into the sidewall. There is no hole pre drilled through the skirt so the screw adds undue stress to the skirt while it pulls it towards the sidewall. The predrilling and addition of stainless screws usually prevents cracking as Lonestar points out.

That explains a lot as to why the cracks. I'm even thinking about filling all the screw cavities with the ABS inserts as a precaution. I feel it distributes the stress over a larger area than just a washer alone. Of course I will use a washer on top of the inserts.

I'm amazed as to how paper thin these ABS skirts are. If they could be supported at the bottom better to prevent the flapping, they would stand a better chance.

And the cost to replace them is outrageous. Now that I've found a suitable material I'll patch these things regardless of how they look!

[familytruckster4]

I replaced 3 of them on our previous Open range trailer. Two for the above reason (I got them to warranty the part and then installed them myself) and a third after a blow out. The one I had to buy after the blowout is a story in and of itself, a horror story about the supply chain issues for RV parts. Took me 2 months and one empty handed trip to Shipshewana (but I digress) One of the many reasons I like dealing with Grand design is that they work hard to get their customers what they need.

[Jlawles2]

I've repaired a couple on the first TT, seems that there is a small lip on the edge of the skirt leaving a gap between the skirt and the framing. If this gap were filled it would not put the stress on the ABS causing cracks.

Also like mentioned, the hole probably needs to be drilled properly to help reduce the lateral stresses caused by the self tapping threads and pilot on the end of the screws.

[Lonestar]

I've repaired a couple on the first TT, seems that there is a small lip on the edge of the skirt leaving a gap between the skirt and the framing. If this gap were filled it would not put the stress on the ABS causing cracks.

Also like mentioned, the hole probably needs to be drilled properly to help reduce the lateral stresses caused by the self tapping threads and pilot on the end of the screws.

You are correct. That lip limits the actual contact area between skirt and sheet metal framing where only about 5% of the surface of the skirt is making contact. This is a major factor and design flaw!

Before going with my current plan I was going to use a thin strip of wood to shim/space between the space created by the lip and the sheet metal and close the gap. Then drill new holes outside the current indentations. I know this would solve the problem but just more work.

If my present repair fails, that's my next step.

[Beachcamper]

After traveling all summer, I had to tighten several screws at rest stops as they would get so loose they would about be halfway out. I was wondering about using rubber washers and aluminum rivets on center and bottom ends (which are the ones coming loose). Would that be too much pressure and crack the plastic?

[Jlawles2]

Beachcamper Vivian, the bottom skirt screws coming loose is probably partly due to the thinness of the aluminum skirting. You may try replacing these with stainless screws and nylock nuts since they are the easiest to reach the back side on. As for the center ones, do you mean at the top in to the wall framing, or the one down by itself on the aluminum vibration brace that looks hand formed? If it's the latter, again nylock nut and stain less screw are what fixed the issue on my bumper pull.

You can also try silicone instead of rubber washers as the silicone will act more like a glue but still be removable.

[Beachcamper]

Beachcamper Vivian, the bottom skirt screws coming loose is probably partly due to the thinness of the aluminum skirting. You may try replacing these with stainless screws and nylock nuts since they are the easiest to reach the back side on. As for the center ones, do you mean at the top in to the wall framing, or the one down by itself on the aluminum vibration brace that looks hand formed? If it's the latter, again nylock nut and stain less screw are what fixed the issue on my bumper pull.

You can also try silicone instead of rubber washers as the silicone will act more like a glue but still be removable.

The ones that tend to vibrate loose are towards the bottom ends. Your idea was another option and probably what I will end up with. I was just wondering if rivets would not be more of a permanent solution in these areas. Just afraid of cracking the plastic with rivet gun.