DIY Van High Top Installation Questions

[akoehne]

Hey y’all!
I ripped a high top off an old van at the junkyard, got my roof cut, and am now deciding how to install. There is little to no info online and I would love some opinions. Its a 99 extended 4x4 E350 and the top came off the same -4th gen extended ford van. The fiberglass top doesn't have a lip which makes it a bit harder to install. So far my plan is to clean the area, drill in long self drilling metal screws, and then silicone the in and outside. Should I utilize weatherstripping at all? Should I utilize wood and install in some way between the fiberglass and metal for added stability? Do you think just the screws and silicone will be enough to safely secure it? Ideally I would use bolts and nuts but I cannot access the underside to apply a nut. When I pulled it off of the van at the junkyard, it appeared to be held on with just screws and silicone so Im assuming it will work but want to make sure it will hold and that water will not leak in/sit in the gutters. I’m not high maintenance and it by no means needs to be professional, just trying to make it secure and avoid leaks/pooling. Any info or advice is greatly appreciated!

Also as you can see in the photo, there’s an opening above the doors. The van it came off of was an old handicap van with the large bus-style doors. I plan to build and install a custom window there.

 

[javajoe79]

Don’t use silicone. Use a urethane like Sikaflex 252 to bond the top to the van. If done right, you won’t need any hardware

 

[SquirrelZ]

Yes, a top quality adhesive like Sikaflex 252 or 3M 5200 should be more than enough to hold it in place. I'd also use something like fiberglass angle stock to get more contact area. With 6 to 10 feet of 1/4 x 2" fiberglass angle stock spaced out along the edges, the top would be very well bonded to the van (assuming you go good prep work on the surfaces.)

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[akoehne]

Thank you so much for your replies! Good to know about the silicone - that was the main thing I saw other people doing so that’s very good to know! It may not have been silicone on the old top, just some type of adhesive. I scraped and sanded it all clean though so should be good.
The fiberglass angle is a great idea! J guess my question now is what order should I do it all? Clean/prep of course, lay fiberglass angle stock, screw in angle stock to the top and into van, then layer the 3m 5200 inside and out? Or should I do a layer of adhesive, put the top with fiberglass angles attached on, screw on, layer adhesive in and out?

 

[akoehne]

And this may be a dumb question, but which way should I lay the fiberglass angle stock? Outside on the edge of the high top and the gutter of the van? Or the edge of the high top running under the high top, securing on the inside? Or on the inside entirely? Im assuming the first one but wanted to clarify

 

[akoehne]

And just to be sure before I return it - the adhesive I had bought was dynaflex ultra weather max advanced exterior sealant for window, door, siding, & trim - this is no good, correct? I should instead use one of the two mentioned above?

 

[SquirrelZ]

I'd put the fiberglass angle stock on the inside for a cleaner look if possible. Mechanical fasteners are usually overkill with 5200.... assuming you do good prep work and the adhesive is bonding solidly to both surfaces. Look at the data sheet for 5200, its an extremely good adhesive. Its pretty much the gold standard for marine adhesives. If you do use mechanical fasteners, make sure you don't tighten them too much and force out the adhesive. I'd get the top situated exactly how you want it, then secure the angles and finish up with sealing the gaps. 5200 is more challenging to work with than regular caulk. If you want a clean look, I'd use blue painters tape to delineate the edges of the sealant line on the roof and the fiberglass top. Once you have the 5200 applied and rounded over, carefully peel off the tape before the 5200 sets up. 5200 takes a full week to cure so the good news is that you have plenty of time to do things correctly when applying it. The bad news is that you'll have to wait a while for it to cure before its at full strength.

Looks like you'll have a great setup- good luck!

 

[SquirrelZ]

One other thought. Since you already have holes in the fiberglass top, it seems likely you'll use mechanical fasteners. If so, it would be a good idea to slightly oversize the holes for the fasteners to ensure there is adequate room for the sealant. For instance, if you're going to use 1/4" fasteners, use a 3/8" bit for the holes.

 

[akoehne]

I truly cant thank you all enough for all this great feedback! I appreciate it so much!

 

[GlennA]

Perhaps you could use VHB to bond the high top to the van, then use 5200 to seal any gaps.

I guess it would depend on the profile of the van compared to the hightop.