Body Work…Rear

The rear section of this RV is molded fiberglass, as is the front, and a couple weeks ago I noticed that it was loose at two places. At the hinged engine access door, the outer fiberglass cover was loose all along the top where the hinges are. Lower down, the molded fiberglass that wraps around the lower section of the RV was also loose in the middle. These 3 fiberglass pieces, upper section, engine access door, and bottom section, are suppose to be epoxy glued to brackets to prevent flexing. There are a few bolts and screws here and there on the edges, but for the most part, the middles of the 3 fiberglass pieces are glued in place.

Over time, on-the-road vibration can cause the epoxy to break loose. The fiberglass sections then begin to get a bit wobbly. Here’s an overall shot of the back of my RV…

It happens that the middle fiberglass piece, the engine access door, is entirely glued. Unlike the other pieces, there are no screws holding it. Which means it could end up on the roadway and that meant I needed to address the problem quickly.

(Some of the following pics are of my friend Dawn’s RV. She caught the lower fiberglass section on something when she crossed the border and I got a few pics to have for reference since our RVs are almost identical).

You can see a couple of the brackets in this shot that were holding the lower fiberglass section on. Around on the sides, there are screws and bolts holding it on at the edges. But as I said, they only use glue at these middle sections. A big glob of glue is slopped onto the backside of the fiberglass part, that is slapped up onto the back of the RV and quickly bolted in place along the edges. Then I imagine it’s braced to hold it in place while the epoxy hardens. As it’s hardening, it oozes out of the brackets holes and my guess is that the ooze is expected to work like a screw. Same goes for the other pieces here in the end cap area. And up front on the front end cap as well there are places where the brackets are glued to the fiberglass.

The two areas of my rear fiberglass sections that came loose rattle and wobble while driving…I can hear through the backup camera’s mic. I didn’t want to leave it that way and have one of the pieces eventually become so loose that it damages something. Or worse yet, actually fall off onto a roadway somewhere.

I have read some forum postings where the owners had re-glued them to the brackets but that effort didn’t appeal to me. Lots of work with the possibility that it would come loose again. So what I planned to do was just replace that glue with a screw or two.

First the upper section, that part that lifts to allow access to the dip sticks and fluid reservoirs. It was loose in the middle but the lower epoxied brackets are still holding firm. But I thought that if I left it to wobble and shake too long, they would likely break loose too.

Here you can see the large gap that’s developed at the hinge.

Press on the fiberglass cover and it goes back to where it belongs. If a few more epoxy globs broke loose, this entire cover could end up on the roadway because there are no screws holding it at all.

While I was looking at where I could add a couple screws, I noticed there’s a 1/2″ square steel tube support making up a door frame accessible on either side of the door and along the edges. So I thought, why not just drill through the fiberglass on the edge, add some screws, and let the steel tube support it? So, that’s what I did as a proof of concept. Looks nice, feels nice and solid. Meaning the fiberglass part isn’t moving at all when you try to shake it. The screws are covered when the hatch is closed so they’re not visible.

I eventually changed this screw for a stainless steel flathead screw, 1 & 1/2″ long, 6-32 Phillips, with a plastic insert type lock nut. Used a countersink so the head of the screw is flush and won’t interfere with opening or closing the lid.

And here’s the left side. The fiberglass cover is 1/8″ thick so there’s plenty of thickness to hold the screw. And naturally, I didn’t tighten them too much so the screws will allow the cover to ‘float’ a bit, giving some flexibility to the assembly, hopefully to prevent cracking of the fiberglass where I’ve put the screws. The plastic insert lock nuts used will keep the screws in place. The fiberglass cover is very tight now after the addition of just those two screws so I doubt there’s much else I’ll need to do to it. I figured that putting the screws on the edge instead of the exposed face area will help prevent them from rusting, and of course, they aren’t visible on the edges when the cover is closed. Eventually, I’ll just have a dab of paint put on the screws to help them last.

---

The lower section had some access to the brackets from the back when the engine access cover is raised. Lucky the epoxy that gave way was right there at the two easily accessible brackets, so I made sure the broken off epoxy nub was flush with the metal bracket, center tapped and then drilled through the bracket holes from the back to the front. Countersunk the holes, and then mounted two more 1/2″ long 6-32 SS screws with lock nuts. The opening was just big enough to allow my 3/8″ Lithium battery drill in there. I know that a right angle drill would have worked better, but my regular drill worked good enough. Here’s a shot of the loose bracket on one side. Both of the epoxied on brackets had come loose in the middle of this section of fiberglass.

And here’s how one of the screws look when installed. It’s barely discernible unless you really look for it. I installed two screws but only one is visible in this picture. It’s so small that, in my opinion, it does not detract from appearance in the least. I can have it dabbed with paint when I get some paint work done too. Again, I used SS, Phillips flathead screws, 1/2″ long, and used plastic insert lock nuts. This section is now nice and tight. 

What the screws do is make it possible that in the event of an accident, like the type my friend had at the border, more damage will be done to the face of the fiberglass as the screws are pulled through the material. So that’s one reason why I used small 6-32 screws. The countersinking helps localize the damage if something like that ever happens as a countersunk screw head is more likely to pull through the material without damaging much around it. Even so, I’m confident that a good fiberglass repair person would have it all fixed up in a few minutes should an accident happen. I felt it was more likely that damage would be done by not having the fiberglass tight to the frame than the few tight screws I’ve installed would.

Update: 

When I was doing much needed maintenance to my basement heatpump, I removed the lower rear bumper (it’s not actually a bumper as it would split all over if anything hit it as it’s just a formed piece of fiberglass) for better access to part of the heatpump. Here’s what it looks like removed:

On the two ends, there are large 1/2″ bolts holding the bumper in place, then in 4 places there are the epoxied brackets that Winnebago likes. The brackets are screwed to the RV frame, the epoxy slathered on the business end and the bumper is pressed up against the epoxy, than held in place until it hardens and holds the bumper. I’d already had a couple of the epoxy joints break free so I’d installed SS screws and lock nuts.

But than I found while working on this that that wide piece of fiberglass was loose again, though lower down. And that 2 of the epoxied joints had let loose. I’d added two screws first back in 2017 and now in 2019, those were still holding fine, but I could tell that the bottom brackets with epoxy had also let loose. So I added another 2 screws through the brackets, than through the bumper fiberglass, so I now have a total of 4 stainless screws holding that rear bumper in place…along with the 4 large 1/2″ bolts on the edges. Should be fine for years to come. Barring any accidents.