Join Date: Aug 2010
Location: N-East Central USA
1. Tank(s) Sizing and Dimensions.
Primary consideration should be an ease of fabrication and installation. Measure each tank individually, do not assume that the left and right is a mirror image! You may be surprised what you’ll find out. Subtract ½” from the length and width. When it comes to the height, the bottom of the new tank will be where your old tank bottom flange edge is now (mine are 11.5"). The new top will be where the old top is. No flange at the top is required. Use a paint pen to mark all dimensions, datum points and notes directly on the surfaces of each tank.
Important dimensions are: grounding straps caged nut-to-floor (datum), x-pipe nipple-to tank floor [not the same LH to RH !], filler neck location and its incline.
There are a couple of excellent choices in corrosion-resistant materials. Primary concerns should be: formability, weldability and weight.
a) Easy-to-Weld Highly Corrosion-Resistant 5052 Aluminum, ( 0.090-0.100” thick)
Good combination of weldability and resistance to salt water. Commonly used for boats, buses, trucks, and trailers, as well as for chemical drums.
b) Highly Corrosion-Resistant 5086 Aluminum, ( 0.090-0.100” thick)
Excellent corrosion resistance with good formability. Commonly used in marine applications, such as in ships, oil rigs, tanks, and pressure vessels.
c) Super-Corrosion-Resistant 316 Stainless Steel, ( 0.048” thick ?)
Molybdenum gives 316 excellent corrosion resistance. Used in a variety of marine and chemical-processing applications.
Buying materials: Don't forget to check an eBay and Amazon also.
Tank surface: LH= 1260 sq in, RH= 1340 sq in
Baffles: LH= 345 sq in, RH= 309 sq in
Density: Aluminum = 0.098 lb/in^3
Stainless = 0.29 lb/in^3
If you choose aluminum, use 0.090”- 0.0100” thick sheet for walls and tops; 0.06” sheet for baffles
If you choose stainless, your primary consideration should be weight and “oil canning”/warping of the large flat surfaces (stiffening beads will be necessary).
One 48”x36”and one 36"x36" sheet will suffice for both tanks. Additional, smaller 0.06” sheet for baffles can be ordered at the same time.
OE tanks weigh RH=24 lbs, LH=22 lbs. Aluminum tanks: RH=15 lbs, LH=13.5 lbs
All bungs/pipes/nipples (including x-balance pipe), should have at least 0.120" wall and be made of the same corrosion resistant material as the tanks. Do NOT use any carbon steel components (ex: Time-serts, mounting bolts, etc.)
3. Tank details, modifications and improvements.
Material used: aluminum.
- Eliminate x-balance pipe extensions and instead, add a ¾”-14 NPT (thick wall) weld bung to the RH sump to accommodate a short 1”OD pipe/nipple, which will screw in after the tank installation.
- LH tank: add 2.5” ID small sump w/3/4”-14 NPT weld bung and drain plug.
- Use stainless Heli-coil or Time-sert type inserts (use stainless only! Corrosion!) at the fuel return nipple (M12x1.5mm), fuel sender ring (M5x0.7) and grounding bolt blocks (M8x1.25 upgraded to 3/8”-16 w/threaded inserts).
- Note: The fuel level gauge/sender ring has 5 holes (54mm CPD), forming an irregular pentagon with following dimensions between the holes (center to center): 30mm, 32mm, 32mm, 30mm and 35mm. The 35mm dimension faces the tank outboard wall, positively indexing the fuel sender and float orientation.
- New marine grade Neoprene or Viton gasket is required. VDO 226053 Replacement Fuel Sender Gasket•2-1/8" bolt circle (54mm).
- Replace the grounding point “cage” brackets with a solid aluminum blocks of the same geometry (6 degree incline). Heli-coiled holes are perpendicular to the 6 degree (outboard) surfaces of the "cages"/blocks.
- Replace OE foam pads: bottom one with 3/8”-1/2” closed cell poly foam cut to the OE size (Zoro tools.com). Top pad has to be thicker. Alternatively, aluminum L-shape hold downs fastened to the top board/shelf could be fabricated to add required lateral stability.
- Depending on the foam thickness used, the grounding block up/down location has to be adjusted. The easiest way to determine block location is to insert the tanks into the wells, line up the inlet tube with the filler neck end, canter the balance pipe bungs in the side wall (large) hole and project the grounding bolt hole location onto the tank side. Weld the blocks according to your markings.
Note: It is recommended that Heli-coils be installed w/red Loc-Tite. Loc-Tite de-bonds when the heat is applied, therefore do not install them until after all the welding is done.
* TO BE CONTINUED...
Last edited by MRDANGERUS; 11-07-2014 at 07:59 PM.