Bulb Seal Placement

Hey Friends- I am planning a self reinstall of my camper, which I had to remove for truck repair. With this comes a new bulb seal install.

I’ve noticed that most toppers have the bulb seal attached to the bottom of the topper, while Go Fast opted to attach the bulb seal to the truck bed rail. To me it seems it would be easier and less error prone to put the bulb on the camper before install, but assuming I’m missing something that explains why they do it the other way…I am not the professional afterall.

Anyone know what the logic is?

Whichever way you install it (and I guess I would probably do it like they do because there is likely method to the madness), take the opportunity to seal between the seal parts - these are leaky in the rain and if you have it all off the truck, may as well. I have been using either of these products with reasonable luck:

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Yeah I had to seal those spots with silicone originally. This time, I plan to keep as a continuous seal by cutting out a little v shape to make the 90 degree turn, so there’s no seam.

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That’s what I was going to recommend. I need to ask how that has worked out with my buddy who got my damaged camper. But, I was told that is how canopy installation places do it.

I asked about why GFC doesn’t attach it directly to the camper and they told me then the ‘bulb’ wouldn’t be oriented the right way because of the shape of the space frame. I thought a guy could just put strategically placed VHB 1/4” or 1/2” in between the bulb and try it that way. It’s worth a shot :wink:

The bulb seal’s purpose is to be a mediator between two hard surfaces: the bedrail and space frame. Given that the space frame is rounded, you want a seal that will cradle and wrap around the frame. This is why we use the kind of bulb seal that we do. In short, this creates the best seal possible given the profile of the space frame. If you do the inverse and apply the seal on the bottom of the space frame, you lose the benefit of the seal cradling the frame, while also creating an opening for debris to accumulate inside the channel of the bulb seal. Sure, you can run VHB (or something similar) to fill the opening, but you are creating more work for yourself by being a rebel :wink:

One of the benefits not mentioned is that the space frame and seal form a tight suction once the mounting brackets are tightened. Yes, water can still work itself through, but the suction can be very difficult to break once you unbolt the mounting brackets and try to move/slide your camper. I removed my camper from my vehicle recently and both my bed rail caps came off my bed when the camper was lifted by a crane lol.

Since the bulb seal’s main function is to be a mediator between two hard surfaces, we do not guarantee that the bulb seal will prevent water intrusion. So you may need to add sealant along the bulb seal, while also doing the kinds of things that @the_philxx noted since bed rail caps and bulkheads are known to create openings for water intrusion.


Yeah! What I’m talking about is in addition to the normal pre-installation bed rail seal and whatnot.

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