How to Install a High Top
By Sandy (as told to Bob)
Sandy is a great guy I met through the Vandwellers Yahoo group. He is one of those guys who can do just about anything with a set of tools. He had this 1986 GMC 1/2 ton Vandura (picture #1) but really to take pictures and share with me the details of how he installed it. You may be thinking, “I could never do a project that hard!” But Sandy breaks it down into smaller steps and really, anyone with a modicum of skills with tools could probably do it themselves. Let’s get started.
First, Sandy found this 1985 Chevy van with a high top to be the donor van. He paid $350 for the van and sold the tires off it for $150, so the van only cost him $200. The first thing he did was loosen the top off the donor van so he see how much of the roof he needed to cut off his van.
Removing the old top was straight forward. There is an extruded aluminum frame that holds it down. The first step is to remove the black trim molding on top of it. Start at a joint and pry off the molding. If it is in good shape you can reuse it, if not, buy a new one at any RV parts store, it is a standard item. Under the trim you will see the screws that attach the roof. Remove all those. The caulking they used will still hold the roof on, so no worries about it just falling off. Using a putty knife, very gently cut through the caulking and then pry the top off. You can see in picture #3 that Sandy put 2X4 lumber on the corners to keep it elevated. The next job is to cut the roof off the receiving van, but before you can do that you need to know how much old roof to leave on for the new roof to screw down onto. So, with the donor roof elevated, you need to look to see how much the roof extends in from the sides.
Next he marks where he is going to cut. Using the measurements he took from the donor van, he measured in from the gutter and used a straight edge to make the long lines. For the curved lines he drilled holes to follow the curve and hand marked the curved lines.
In pictures 5 and 6, he cuts the roof off his van. This is something of a dramatic moment, the moment of no turning back! Everything you have done up to now can be reversed, but once you start cutting that roof off, you are committed. So take a deep breath, and let’s go!
Most people will tell you to use a sawzall, reciprocating saw, jig saw, or even a skill saw to cut the roof off with. And they will get the job done, but they are all going to create a lot of sparks and vibration, and will probably destroy some expensive blades. The tool Sandy used is an air chisel. It worked super well and he had the roof off in about 15 minutes without even the slightest problem. They can be bought for around $20 from WalMart or Harbour Freight. They do require an air compressor which you can rent if you don’t own one or can’t borrow one from a friend.
It has three fingers, with the middle one lower than the outside ones. The middle one goes down into one of the holes you pre-drilled. The fingers are forced forward like a chisel by the hammer action of the tool. It goes trough the roof like butter. You can see the long, thin piece of metal it leaves behind as it cuts. It reminded Sandy of the old ham cans or Spam cans that used a key to turn and cut the lid off. The red stuff on the ribs is a foam applied at the factory that acts as a glue and sound deadener. So once you have made the cut on the roof, you have to go back inside and push the roof up and push a knife over the ribs and under the roof to cut through the red foam, then remove the roof. You still have to cut out the ribs. They are spot welded onto the body, so just use a mini-grinder or small angle-grinder to cut off the welds and then pop the ribs off (picture #8).
With the roof off your van, you are ready to transfer the high-top from the donor van. First, you want to get the roof of your van very clean, and then clean the bottom of the high-top as well. Next, park the two vans close to each other, and run two planks across between them, then, just slide it over. Although the top is fairly heavy, Sandy was able to do this alone. Once it is across and on top of your van, get it where it needs to go and put boards under the corners so it is still up in the air.
You will need two rolls of RV Mastic, one to go under the high-top, the second to go around the outside of the high-top. You can buy them at any RV parts store. It looks like a roll of flat putty tape about an inch wide. Buy the best quality they sell. With the high-top on blocks over your van, start to unroll the mastic and press it onto the bottom of the high-top. When you come to one of the blocks holding the top up, you will have to move the blocks to where you have already rolled the mastic. You don’t want the mastic to stick to the block so put wax paper between the mastic and the block. When you are ready to drop the high-top, first put a centering mark on the high-top and the van roof. Do this on the front and back so that you know the high-top is centered when it comes down. Once you know it is centered, work your way around removing blocks and let the high-top down onto your van. It’s weight will seal the mastic.
Next, push the second roll of mastic into the joint where the high-top meets the top of the van roof. Then place the extruded aluminum frame around the base of the high-top. You will see all the holes where you removed the screws holding it onto the donor van. Screw through those holes using #8, one inch stainless steel screw, through the mastic, and into the roof of your van. Then push the black molding into place (picture #12). This should be good enough, but just to be on the very safe side, Sandy used a very high quality caulking on the inside of the joint as well. Finally, take the van to a self-serve car wash and blast away with the high-pressure hose to see if there are any leaks. There shouldn’t be, but if there are, caulk around them really well.
The upholstery on Sandy’s high-top was old and ugly, so he removed it (pictures 13 and 14). He used a wire brush, knives and a heat gun. It is tedious work, but you just keep at it till the old stuff is all gone.
He reupholstered half the roof with cheap carpet he bought from WalMart. He used contact cement to glue it on. On the rest of the roof and the sidewalls he used one inch pieces of Styrofoam that he cut into 5 sections and covered with upholstery he bought at WalMart. He glued the upholstery to the Styrofoam using Borden’s Foam and Fabric Glue, also bought at WalMart. Part of his roof already had plywood attached to the high-top, so that is the part he covered with Styrofoam. He just used screws and washers to attach the Styrofoam.
We hope you are inspired to consider doing it yourself. Sometimes the idea of a project seems so daunting that we don’t even consider it a possibility. Hopefully, seeing it broken down into small, easy, steps will show you that it is within the average person’s ability. So, if you are sick of stooping down in your van home, start searching junk yards for a donor van. Hopefully you will find just the right one!