Early Model Tank Repair
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Early Model Tank Repair
Early Model Tank Repair
Early model Harley-Davidson gas tanks have a way of leaking around the rear mounting studs. I had the same stud/crack problem on my '58 Pan and at the shop there were many other tanks cracked in the same way. The problem comes from the tanks not being exactly flush when mounting and the fact that the area around the welded stud becomes brittle from the heat when it's welded. I don't like using products like Kreem to seal this because they eventually come loose and cause fuel problems and JB weld and expoxy products never seem to work on gas, so the best fix is to re-weld it and fit the tank properly. Re-welding the area requires removing all paint and primer in about a 2"x2" area around the stud. If you are REALLY careful sometimes it can be done without cooking the paint on the top of the tank, or maybe just a little so it can be covered up with a leather tank panel. Brazing, gas, and wire-feed put a lot of heat on the area and the metal expands causing it to re-crack when it cools. I use TIG (tungsten inert gas) welders because you can finely control the heat and just knit the metal back together without adding a lot of filler. I fashion a "heat dam" with a wet rag or commercial heat putty around the area to keep the heat from spreading and bubbling the paint. As with any gas tank welding, you should flush the tank thoroughly and in addition we sometimes flood the tank with CO2 gas to prevent fumes from igniting. Now, when the tank is welded and you have pressure tested it, the next step is to get it to fit the frame mounts without any stress being applied when it is tightened down. This is done with a combination of washers/shims and a slight bit of tweaking of the front upper and lower tabs. When the tank is laid up against the frame mounts they should all lay flat, so that when the bolts are tightened nothing is being pulled or pushed into place, it just clamps solid. Since the front top and bottom mounts can be tweaked and the rear studs can only be shimmed, work on getting the front mounts flush and laying flat, then check the rear studs. If when the front mounts are snug the rear studs will need to be pulled in, you can use a washer or two between the tank and mount (over the stud) to fill the gap. Once this is done the tanks will usually remain crack free for a long time.
Source" https://www.directparts.com/static/a...ank_repair.htm
Early model Harley-Davidson gas tanks have a way of leaking around the rear mounting studs. I had the same stud/crack problem on my '58 Pan and at the shop there were many other tanks cracked in the same way. The problem comes from the tanks not being exactly flush when mounting and the fact that the area around the welded stud becomes brittle from the heat when it's welded. I don't like using products like Kreem to seal this because they eventually come loose and cause fuel problems and JB weld and expoxy products never seem to work on gas, so the best fix is to re-weld it and fit the tank properly. Re-welding the area requires removing all paint and primer in about a 2"x2" area around the stud. If you are REALLY careful sometimes it can be done without cooking the paint on the top of the tank, or maybe just a little so it can be covered up with a leather tank panel. Brazing, gas, and wire-feed put a lot of heat on the area and the metal expands causing it to re-crack when it cools. I use TIG (tungsten inert gas) welders because you can finely control the heat and just knit the metal back together without adding a lot of filler. I fashion a "heat dam" with a wet rag or commercial heat putty around the area to keep the heat from spreading and bubbling the paint. As with any gas tank welding, you should flush the tank thoroughly and in addition we sometimes flood the tank with CO2 gas to prevent fumes from igniting. Now, when the tank is welded and you have pressure tested it, the next step is to get it to fit the frame mounts without any stress being applied when it is tightened down. This is done with a combination of washers/shims and a slight bit of tweaking of the front upper and lower tabs. When the tank is laid up against the frame mounts they should all lay flat, so that when the bolts are tightened nothing is being pulled or pushed into place, it just clamps solid. Since the front top and bottom mounts can be tweaked and the rear studs can only be shimmed, work on getting the front mounts flush and laying flat, then check the rear studs. If when the front mounts are snug the rear studs will need to be pulled in, you can use a washer or two between the tank and mount (over the stud) to fill the gap. Once this is done the tanks will usually remain crack free for a long time.
Source" https://www.directparts.com/static/a...ank_repair.htm
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