DIY POPTOP IN CHEVY EXPRESS AWD

desertweaver

New member
I'm not sure if this is where I'm supposed to answer you or not Steve ... but how could be offended if we hijack a thread that was inactive for 4 years? If this isn't proper etiquette, I apologize.

Short answer on leaks is my top is sealed up very well. Unfortunately, I am not as efficient and through as the rest of this expedition portal crew and do not have a build thread so show for it. However, I can say that I did my installation quite a bit differently than the one shown in this thread. Three major differences with my install compared to this one are a) I retained the front fixed portion of the Vanagon top (lots of modification required), b) fit the movable portion to the top to the fore-aft contour of the GM van (Vanagon's are flat), and finally c) added an additional seal across the forward edge of the movable top that contacts the original van roof.

Here's my reasons for each;
a) The fixed front portion of the Vanagon top does an excellent job of deflection the 70 mph wind up and over the top. This I believe reduces the opportunity for rain or air to be forced under the forward edge of the top under the seal (photo 1).
b) The standard uncut Vanagon top fits surprisingly well for-aft in it's uncut form, particularly if you push the top farther back on the top of the GM van (which is what it looks like was done in this thread). The reason I didn't like the mounting the top rearward is the opening in the roof also has to move backwards and you end up with the stand up opening too far behind the front seats to be as useful as I wanted it too be. Once you commit to moving the top forward, the flat bottom of the uncut Vanagon top cause the front of the top to ride up off the surface of the van ... making sealing it up near impossible. To fix this I scribed the contour of the GM van roof on the Vanagon top and got out my saber saw. Fits very nice and tight now (photo 2).
c) I did several tests with the wife driving up I-5 at 70mph and me running around with a mirror and flashlight to see where all the leaking wind noise/lack of contact was on the movable top seal. What I learned was the aerodynamic forces are signifiant on the front of the movable top and the outside front corners can actually lift enough to allow leakage under the parameter seal. To help this situation, I put a stiffener across the front of the movable top that not only stiffened the front but provided a location for an additional seal on the front bottom edge of the movable top (photo3).

Ok, way too much info ... probably could have stopped after the first sentence. I spend 25 years as an engineer working on door sealing of class 8 trucks and I know too much about what makes automotive environmental seals leak!
Good info. Thank you. Can I ask what year Vanagon your top came off of? Also, did you modify front fixed piece? I thought they all had a recessed luggage tray. -Ross
 

Roamin' Chariot

New member
The top I used for the Savanagon was of an 84ish Vanagon, as far as I know all the factory bread-box Vanagon's pretty much have the same top. They are pretty easy to track down where I live in the Pacific Northwest on Craigs. As I stated above the front box was modified significantly primarily because of the for aft location I chose for movable top ... I think answer b) above lays it out pretty well. Anyhow, it ended up being easier to just put a solid top over the chopped up recess luggage tray since I had to cut about 7" from it's length to make if fit in from of my movable tops location.

Let me know if you're not clear on this one and I'll show you some more pictures ... and thanks for the interest ... I'm really happy how this project is turning out.

Roamin' Chariot
 

scottrinne

Member
Nice work! I was looking for ideas from people who did this and there was limited info at the time. We grafted a pop top from an older g-van about a year ago. I think your top looks better and easier to use than ours.

 

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