Help! Interior cracks in fiberglass

[Kortney M.]

John- thank you! looking for the splice after what you said and I’m not seeing one (which technically is a good thing right? Frame wise?) so I took two more pics angled toward front and then toward back of trailer in that area of the axle. Also attached floor pics from under dinette benches and from one angle see clearly an old crack that was patched at back of sink to wall of camper. So wondering now if an old problem....floors I think look okay?? I do not see where the plywood would be as the floors seem just straight fiberglass. Thank you for helping me!

[thrifty bill]

Originally Posted by Kortney M.

Huge thanks Bill! We will try and get it jacked up and check those bolts out hopefully before the weekend. We haven’t put too much distance on the camper and have kept it all to roads so far. Wanted to go out in it this long weekend! And now a little worried of course.

Checking them does nothing. They rot in the middle, the part you can't see. The part you can see will typically look just fine. Put a wrench on them and turn. Chances are, the nut will not move but instead the bolt will snap. Now in your case, some of them could have snapped off and are now missing. That is something you will see. Look for the tops of the bolts in your dinette benches and the gaucho bench. Depending on the year, you will have six or eight bolts.

[John in Michigan]

The plywood is sandwiched between the fiberglass floor and the bottom of the fiberglass outer shell, thus you can't see it, but water can get into it. Places to view and check the condition of plywood are the bottom of bench compartments and bottom of lower kitchenette cabinet, also bottom of the lower compartment below the closet if you can access it.

[John in Michigan]

Originally Posted by Kortney M.

John- thank you! looking for the splice after what you said and I’m not seeing one (which technically is a good thing right? Frame wise?) so I took two more pics angled toward front and then toward back of trailer in that area of the axle. Also attached floor pics from under dinette benches and from one angle see clearly an old crack that was patched at back of sink to wall of camper. So wondering now if an old problem....floors I think look okay?? I do not see where the plywood would be as the floors seem just straight fiberglass. Thank you for helping me!

Kortney, based on your pics, you don't have splices in the frame rails. That's a good thing.

[Kortney M.]

Thank you John and Bill! We will get those bolts replaced. You're help on the exact troubleshooting is extremely helpful because you are leading the blind here lol but it’s good to learn! So thank you. Nothing feels worse then watching something you love getting wrecked. Checked the back looking into the hole of axle and see that it’s almost what looks like just a nail down through? Or a bolt with no nut to hold it- which might be our problem...it’s the same on both sides of the axle.

[thrifty bill]

I'd see if that nail like thing lines up with the bolt head inside.


Your last inside picture looks like a prior owner tried to patch the fiberglass inside. Without eliminating the cause, any repair will be temporary. I'm guessing the back portion of your trailer is not attached, and the front may not be either.

[John in Michigan]

Originally Posted by Kortney M.

Thank you John and Bill! We will get those bolts replaced. You're help on the exact troubleshooting is extremely helpful because you are leading the blind here lol but it’s good to learn! So thank you. Nothing feels worse then watching something you love getting wrecked. Checked the back looking into the hole of axle and see that it’s almost what looks like just a nail down through? Or a bolt with no nut to hold it- which might be our problem...it’s the same on both sides of the axle.

Kortney, that looks more like a picture of a portion of the frame than the axle. Maybe if you back up and take another picture, then I could comprehend what it is. And as bill said, sure looks like a screw, not a nail.

[Kortney M.]

Originally Posted by John in Michigan

Kortney, that looks more like a picture of a portion of the frame than the axle. Maybe if you back up and take another picture, then I could comprehend what it is. And as bill said, sure looks like a screw, not a nail.

Sorry, yes I suppose it would be the frame- I’m at the very back of the trailer looking down the line of the frame. Where it is open at the back. There is not really any thread left to the screw except on the tip, so was hard to tell but there is definitely no nut to hold it on the frame side. I can get in and see if it lines up on the inside of the dinette benches when I get home. Definitely thinking it’s our problem now.

[Kortney M.]

Yes worried that’s exactly it. Since the patch work seems to be coming loose from the shifting. Not good not that it would of deterred us from buying the trailer likely, but wish we noticed it before.

[Kortney M.]

Hi guys- sorry to bother you again and this might be a stupid question but after locating the bolts...how do we go about tightening the new bolts if we can’t get on the inside of the frame? We can get those two end bolts but what about the ones more centrally located?

[John in Michigan]

Kortney, on the Trillium examples I've seen including my Trillium 4500, there should be 6 or 8 carriage bolts located inside front and rear benches. Look for carriage bolt curved heads and square washers that will be clearly visible inside the benches. After locating those carriage bolts inside the benches, then looking on the bottom of the camper frame, there are steel mounting tabs welded to the sides of the frame. The carriage bolts extend down through these tabs and are held by nuts. Post more pics if necessary.

EDIT: The square washers are about 2"x2".

[thrifty bill]

Yes, you can see it in my pictures. The inside plate has a square cutout, made for a carriage bolt, 5/16 inch as I recall. Take the plate with you to the place you buy the bolt. I used galvanized bolts, not the zinc plated and not stainless either.

[Kortney M.]

Originally Posted by John in Michigan

Kortney, on the Trillium examples I've seen including my Trillium 4500, there should be 6 or 8 carriage bolts located inside front and rear benches. Look for carriage bolt curved heads and square washers that will be clearly visible inside the benches. After locating those carriage bolts inside the benches, then looking on the bottom of the camper frame, there are steel mounting tabs welded to the sides of the frame. The carriage bolts extend down through these tabs and are held by nuts. Post more pics if necessary.

EDIT: The square washers are about 2"x2".

Ok thanks John- so someone has clearly taken those carriage bolts out and replaced them with straight screws. We’ve taken them out and there’s no nuts or washers. And the screws go straight down into the middle of the frames which is weird. Like the picture I sent of the back of the frame. That was one of the screws. So I guess we will improvise with trying to get washers like the old 2x2 ones...

[John in Michigan]

Yep I used Unistrut square washers available in electrical department of home building stores.

Sure if you can get a nut (maybe a nylock nut) inside the frame onto bottom of the bolt, that would work. Here are pics of the two different ways the bolts are secured on my Trillium 4500 (1) angle iron tab welded to frame, (2) angle iron cross member of the frame itself.

[Kortney M.]

Originally Posted by John in Michigan

Yep I used Unistrut square washers available in electrical department of home building stores.

Sure if you can get a nut (maybe a nylock nut) inside the frame onto bottom of the bolt, that would work. Here are pics of the two different ways the bolts are secured on my Trillium 4500 (1) angle iron tab welded to frame, (2) angle iron cross member of the frame itself.

These pics are very helpful thank you! Helps us understand what we’re missing. Just went down to our small homehardware and they didn’t have unistrut washers there of course so we will still have to get them- thank you for the guidance. This was clearly our problem. Can’t thank you enough!

[Kortney M.]

And thank you thrifty Bill as well helping us sort this out.

[John in Michigan]

Kortney here is a pic of one that I replaced. Washer brand is actually superstrut, and its about 1 and a half inch square. The bolts are stainless 3/8" diameter. I used nylock nuts so that the bolts can be tightened just snug to reduce probably of cracking the fiberglass. Can always tighten more later. Also I coated underside of bolt head and washer with butyl tape. Many people coat the inside of the drilled hole with a surface sealant.

[Kortney M.]

Originally Posted by John in Michigan

Kortney here is a pic of one that I replaced. Washer brand is actually superstrut, and its about 1 and a half inch square. The bolts are stainless 3/8" diameter. I used nylock nuts so that the bolts can be tightened just snug to reduce probably of cracking the fiberglass. Can always tighten more later. Also I coated underside of bolt head and washer with butyl tape. Many people coat the inside of the drilled hole with a surface sealant.

John- here are the three screws instead of bolts. This is down a pic from behind looking down the frame. When I look at every part of our frame there’s no black tabs like what you have to attach the bolts to- so wondering if this trillium was put on this aftermarket frame? Hence the screws? Also a pic of under a dinette bench (and front bench) with plywood they’ve got between the screws and the floor which goes under the floor of the dinette so they must have added that when they did it. So hard part now is getting deep into frame to get to new bolts to tighten them....or maybe we can drill hole all the way through frame and attach (if we can get bolts that long)...? Since we’ve got nothing else to attach it to? Especially hard at the front of the frame when it’s all sealed off.

[thrifty bill]

My understanding that the tabs came after the Trillium recall. Prior to that, front and rear bolts all went through the entire frame vertically. After Trillium had frames cracking on the front attachment, they went with angle iron tabs. Since your trailer is a 1973, I would not expect any tabs, and you should only have 6 total mounting bolts, rather than 8.

A traditional bolt will work fine, it just becomes a two person job. Use a large washer inside the trailer to spread the load.

[John in Michigan]

Kortney, lacking any tabs or angle iron integral to the frame, another option is to use U bolts. This solution has been posted in other threads on this forum. I imagine the "U" portion of the bolt would extend below the bottom of the frame and the two nuts and flat metal piece would rest on top of the floor. The advantage of the U bolt solution is to avoid putting bolts through the frame which would weaken the frame.