Boler-to-frame fasteners -- I'd like advice on how to replace them

[Raya]

I'm seeking advice on replacing the screws fastening the Boler shell to the frame. Upon poking around in the forward compartment (under the couch), I found that the lag screws holding the front of the shell to the frame.... aren't. They just pulled straight out by hand.

Luckily, I made it all the way home from purchasing it in Winnipeg in ignorant bliss (and haven't towed since then), but with a trip coming up in about a week, well, it's time to make sure things are right. This is at the top of my list.

What's there now are lag screws (bolt-head/pointy-end), but obviously years of jiggling and what-not have caused them to lose their grip (the screws themselves are fine, and the butyl bedding is clean, but really, these screws seem a bit small!

Here is one screw and washer in the floor the storage bins under the front couch:





My first choice would be to replace them with bolts, however, I would have to drill holes in the bottom of the tubular framing member to do this, since the current holes only go through the top of the frame and then disappear inside. I understand how I-beams work, and on an I-beam I wouldn't want to drill a hole straight through this area. However I am not as clear on the way a tubular framing member gets its strength, and whether this would pose a problem. There is a strengthening web attached to the bottom of the frame starting just ahead of the second bolt of the pair (it is off to one side so wouldn't be in the way of a bolt coming through), and running back to the first wide, crosswise member (at the ankle edge of the couch).

My other choice would be to put in larger screws, so that they would get fresh "bite" on the frame where they pass through. I'm not as keen on this since you can't know how they are doing, but if bolts would weaken the frame too much, then maybe screws are better.

What say ye? I hope someone else has done this succesfully, and understands the physical properties of the tubular frame better than I do

The fasteners I'm talking about are both on the "V parts of the frame that are coming back on an angle from the hitch ball, on their way to meet the first cross-member, at the "where your ankles go" edge of the couch. The first photo here is taken looking rearwards. The forward fatener is between us and the support stand, and the second fastener is behind it. You can just see the beginning of the reinforcing web. behind the stand.





This photo is taken looking forward, and shows the gusset better. The two screws are forward, one just into the area of the small end of the gusset and one forward of the gusset altogether.




Thanks in advance for any help. I sure don't want the shell and the frame parting company on my trip!



Raya

[pjanits]

Raya,

I've never done it and maybe somebody here has a better idea but I would vote for some wider lag bolts and let them rebite into the frame.

While you're down there check out the frame where the "A" part meets the side frame. That is a notorious weak spot in Burro, Boler and older Scamps.

My old Burro and my current one both had "sistered" in angle iron plates to strengthen them.
My current Burro is ok but my old one looks like it had some cracks there before the repair.
I had it six years and never had a problem.

[Raya]

Thanks, Pete,

I did have a look at my trailer there and it looks just fine - no evidence of trouble. I had the feeling that the problem occurred more on trailers where the frame "dips" down to go under the body, which my Boler frame does not do -- it just goes straight from the coupler to the first cross-member under the "ankle" part of the couch. But thanks for mentioning it.

Raya

[pjanits]

Thanks, Pete,

I did have a look at my trailer there and it looks just fine - no evidence of trouble. I had the feeling that the problem occurred more on trailers where the frame "dips" down to go under the body, which my Boler frame does not do -- it just goes straight from the coupler to the first cross-member under the "ankle" part of the couch. But thanks for mentioning it.

Raya

My Burros were straight so I would keep an eye on them. Make it an 6 mo inspection. My new Burro has the "sistered" parts on the inside of the frame so you don't see them unless you're looking for them.

[Raya]

Pete,

I will keep an eye on the frame and running gear; they look good now, but it's always good to check. If I ever see a sign of trouble, I will have the frame reinforced there. Right now it looks good, and does not look to have the same sort of stress riser that my Trillium 1300 did in that area (a curve and a hole through for a fastener right in the same area - however fish plates were added).

Now, I just need to keep the shell attached to the frame on my Boler

I hope someone has made this repair and will have some insight for me!

Raya

[Raya]

Well, I received a helpful PM, which I'll summarize here for future reference. Apparently a box beam (such as the frame) is not so different from an I-beam, in that the top and bottom sides are the most highly stressed (top in compression and bottom in tension). So while one could use a bolt, the hole in the bottom of the frame is not so desireable.

Indeed, this is where I've seen Trilliums have frame issues -- the first bolt that holds the shell to the body has caused cracks in the frame (which can be remedied with fish plates, but which does point out that the area around the twin holes is stressed).

One idea that was suggested was to bolt angle brackets to the frame (thus the bolts would run horizontally through the less-important sidewall part of the frame), and then bolt the top leg of the bracket to the shell floor. This sounds like a plausible and good solution.

Right now my thought is to re-fasten using larger lag screws to "re-bite" the frame. With these it will be back to "good as original" strength, which did last 35 years. Then, I can add angle brackets later if I feel the need (in any case, the new screws will fill the existing holes in the top of the frame, which is good for the frame, structurally (in compression).

I'm still open to others' thoughts and experiences, but thought I'd write this down for future searchers.

Raya

[Raya]

Hmmm, what does it mean if I'm making most of the posts in my own thread

I was just looking at photos of a 1973 Boler frame, and I see that it doesn't have the gussets mine does (which run through the potentially weak area Pete mentioned). Mine look original, but I don't really know if they were a developmental upgrade, or if they were retrofitted.

There were "stub" versions of the gussets on the 1973 frame, which you can see here, right in front of the couch cross-member:





They show up as little triangles on the far right of this second photo:





The ones on my boler begin in the same place, by the couch cross-member, but are much longer, extending forward and then tapering up to meet the frame (maybe 16" long, off the top of my head). Not that this has anything to do with the thread topic, but I was looking at them when I was looking at the frame, and they relate to what Pete mentioned.

This is a repeat of a photo from above, but shows aforementioned gusset on the frame of my trailer:





Raya

PS: Okay, someone else's turn!

[Larry&Carrie]

Raya---- another option would be to drill a hole thru the floor on either side of the frame and run two bolts (1/4 inch would do-would be stronger than a lagbolt) and then a flat plate under the frame. Sort of a u-bolt the way springs are attached to an axle... Larry

[Raya]

Aha, that's a good idea for the forwardmost fastener. The one aft of that would have the gusset in the way (see photo just at the end of my last post).

I'll have to see how much further forward I would have to go to avoid the gusset.

Alternatively, maybe with the gusset there, I don't have to worry as much about bolting straight through (but something tells me I won't do that).

Alternatively alternatively, I could use your idea for the forward bolts on either side (no gusset) and then larger screws for the pair behind them (where the gusset is).

Thanks,

Raya

[pjanits]

Upon closer inspection that gusset looks exactly like a sistered in 1/4 iron plate.
The reinforcement I was talking about. Mine runs even with the frame whereas yours extends under the frame somewhat.

I still wouldn't bolt all the way through though, just a wider lag bolt. Possibly coated with some die-electric paste to inhibit corrosion.

[Lizbeth]

We have plans to U bolt our Boler with the bolt on the outside and the plate inside. As rusty as our screws look I'm surprised the body is still attached to the frame. We were going to do at least the front compartment area and the back under dinette screw area.

[Raya]

Thanks for all the input, folks. I've decided to use new, larger-diameter lag screws. I figure if those wimpy little things lasted 30 years, some newer, beefier ones with fresh "bite" should do well. If theres any doubt as they go in, Ill use U-bolts around the frame rail on the forward set (where there is no gusset in the way).



Raya

(And folks might want to take a close look at their shell-to-frame connectors.)

[curtis c]

i would weld 6 tabs on the frame and use an 8 grade or better bolt thought the fiberglass into the tab. and above the fiberglass i would use a plate so the bolt is clamping the plates together. if you really wanted to go crazy you could add a bit of rubber matting in between the bottom of the fiberglass shell and the new frame plate. and I'm sure you know this but don't use self tapping screws if you already have holes. i would also look and see if you can find a high grade screw for cement or metals, usually blue powder coated. they re a lot better and stronger than the normal screws you get at any hardware store. u bolt will work good but put a plate or really big washers across the top to prevent the bolts from breaking the fiberglass.

[Victor Benz]

In my rebuild, I replaced the small carriage bolts with elevator bolts. Worked just fine! The have a square shank below the bolt with a perfectly flat top. They are not generally available at hardware stores, but any bolt supply house should have them.


Vic

[Dana T]

If you use U-bolts you should have a saddle on the frame to keep the U-bolt from crushing it. Because the part of the U-bolt that actually touches the tubular frame member is very narrow it is easy to crush the tube.

Also, unlike screws or bolts into the frame, a U-bolt only holds the two items together, but does allow them to slide along the length of the tube.

Finally, for those thinking of drilling all the way through the frame and using a bolt, tightening the bolt will tend to crush the tube, squeezing it like a soft drink can. That's why they used screws in the first place -- tightening the screw does not significantly distort the tube.

[carlosperez]

Has anyone used new larger screws to replace old/loose ones? If so what size is recommended? Do you just go in the same spots as the old ones?

[bullfrogeh]

I've just today retrieved my '73 Boler frame from the 'sandblasting and paint' shop. Mine (Earlton built) was originally fastened to the fibreglass body with 14 'lag-type screws'. I have also welded four secure angle brackets, one near each 'corner' of the overall body-to-frame mounting areas, and will thus 'bolt' the body to the frame, using appropriate large weight bearing washers. I will also replace most; but not all, of the mounting screws, for additional security.

Am I on the right track ? further advice would be graciously appreciated !

[bullfrogeh]

I have welded on four pieces of 1/4 inch angle-iron to the frame. one near each body-supporting corner, each with a drilled bolt hole. I now plan to 'bolt' the fibreglass body to the frame. I will also replace most of the original 'screws'. I am also leaning towards 'Lisbeth's concept of a 'U-bolt' structure for further security at each corner.

I sincerely appreciate the 'advice' and ideas I've gleaned from this site. Tanksalot !
And, of course, further advice is always appreciated !