I spent yesterday building the starboard side fuel tank mount frames. I'm using the three holes holding one of the crossmembers to the frame for the forward attachment point. This will locate the fuel tanks as close forward as possible while clearing spring hangers and such and still allow mounting stabilizer jacks on the front of the fuel tank frames. Since the crossmember is held in place with 1/2" bolts and my fuel tank mounts are held in place with 3/4" the first thing to do was drill out the holes to accept the 3/4" bolts. As it turned out it wasn't as bad as thought it would be. A little cutting oil here and there and we made it through just fine. I tacked the down tubes to the angle brackets first and got them squared up, a longitudinal tube tacked in place and then an angle 6" above that to mount strap anchors to as well as add some strength to the overall frame. I'm dropping the skirts to 20" below the floor frames and with 1/2" clearance on top will give me a 17.5" deep tank. This still gives me 17" of ground clearance while filling up the space much better than the factory fuel tank mount that, while way overkill as far as strength, took up way too much empty space. I'm doing this on both sides with tie bars between the frames on bottom for added support. Each tank will be 80 gallons. I was hoping to build 100 gallon tanks but ran into too many other issues with understorage placement, side door location and such. This way the predrilled holes in the frame are used making life a lot simpler. The plan is, once the framework for everything under the floor is finished (understorage frames, LPG and battery compartments, etc...) I'll remove all of them, sandblast and have hot dipped galvanized. The fuel tanks will be made of aluminum with isolation straps (rubber) between the aluminum contact with the galvanized frames.
Here's a pic of the frame on the bench just after welding it together:
A front on shot:
I have a bunch of leftover mobile home strapping and anchor material from a previous project and am going to use them as the tiedowns to secure the tanks in the frames. In case anyone is interested, mobile home tiedown hardware is rated at around 3500 psi. I don't think I'll see 7000 lbs of uplift on the fuel tanks. If I ever do, that'll be the least of my problems (Gimel landed on it's top after falling off a cliff).
Here's a pic of the anchor mechanisms. A square shouldered bolt goes partially through the hole, strapping is fed through a slot in the bolt and the bolt is turned to tighten things up. When the proper tension is reached, the square shoulder is tapped into place and the nut tightened to secure it.
The other side of the frame basically has through bolts that will hold a strap loop:
This is what it looks like installed (and yes Bansil, I used my tractor
Next weekend, the port side!!