After the Challenger is built, removing the fuel tank for maintenance or modification in the tank area requires that the front tank brace cross tube be removed before the tank will come out. With the cross tube installed per factory directions, you have to drill out rivets that are located right next to the skin, and then replace those rivets when the tube is put back. This modification will make tank removal after the skin is on very easy.
1. Use one bolt at each end of the cross tube instead of the rivets called for by the factory. With the tank in place to align the location of the hole, drill straight through the flattened ends of the cross tube and the supporting tube at each end. You will use a washer and a nyloc nut under the tube between the two gussets when you permanently install the tube. It’s hard to access the area between the gussets to get the washer and nut installed, but it can be done before the skin goes on – use needle nose pliers, surgical forceps, or a magnetized tool to hold the washer and nut while you start the bolt. Magnet works best. Once installed, this nut and bolt need never be removed again.
2. Before permanently installing the two bolts, cut the cross tube in half somewhat offset from the middle to accommodate a sliding sleeve. After cutting, pivot the two pieces around the end bolts and use a felt tip to mark the ends and grind the corners so that the skin will not be touched when the tube is pivoted after the skin is on.
3. Fabricate an 8~10 inch piece of next-larger-size tubing to use as a sleeve over the cut tube. Install it and drill a vertical hole through the sleeve and the cross tube and use a small AN bolt to hold the sleeve in place. You also could use electrician's tape or duct tape or hose clamps at both ends to hold the sleeve in place if you don't want to drill the assembly. With the sleeve in place, this cut tube should be plenty strong.
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Now, when you need to remove the tank, you can simply remove the bolt, slide the sleeve to one side, and swing the two halves of the tube out and away from the tank, and the tank lifts right out. Works well, and it's so easy that you can remove the tank for routine maintenance like visual checks for contamination or suctioning the bottom of the tank as needed.
Additionally, with the cross tube made “movable” you can build a box in front of the tank that can hold the battery or other large object that normally could not be placed there because the cross tube prevents full access to the area.