Fuel Tank Welding

[davidd]

The owner has put fuel in this tank many times, but the last time fuel began leaking out the rear or the tank. I have seen this before and I found a crack near a seam and pried it of the tank. The holes you see in the photo are what I found. It had been filled with resin an body putty. Despite brazing the rear tab on both sides, no brazing or welding was attempted on the holes.

It seems that body putty or resin will last for a while under these conditions. Then, one day, there is a leak. It is difficult to explain why the holes are not repaired, but brazing is done and a nice paint job (usually). In this case it is an older restoration and I will just patch in the paint to match.

This is crash damage that if you look closely you can see that the tank tunnel is pushed to the left at the top. The rear mount had broken at both sides, but not the center. In order to remove all the braze and align it again it was easier to remove it and weld it back on. I also cut of the left front tank mount. It was not lined up with the bolt hole, much like Ron's was when he discovered that the steering head had been bent. In this case the UFM looks fine but that left front mount is noticeably bent. I thought it would be easier to cut it and bend it than to bend it in place. After a dry fit, it looks like it can be left alone and just welded back in place. I will fit the front then weld the rear mount in place.

I am not sure what the crash looked like. There is body putty in the rest of the tank, but it has been like this for a few decades. Getting rid of the leaks and stress relieving the tank is probably the best we can do right now.

It holds pressure now, but it will have to be tested again after the mount is welded on.

David

 

[davidd]

Leak testing kit:

David

 

[ogrilp400]

I'm doing this same same thing on a B tank.

 

[Bill Thomas]

How much pressure David ?, I have been told it does not take much to cause it to go Bang !, Cheers Bill.

 

[john998]

Hello, no more than 2 psi in my experience. I had a tank pop and wrinkle along the top at 5psi.
John.

 

[Tug Wilson]

Leak testing kit:

View attachment 3267

David

If successful I will attach some pictures of my tank repair 3 years ago. The previous owner had cut the base out to repair dents. I had the tank sand blasted and rolled on an "English wheel". Not my welding unfortunately!

 

[davidd]

How much pressure David ?, I have been told it does not take much to cause it to go Bang !, Cheers Bill.

Bill,

John is correct. No more than 2 lbs. You just need enough to make the soapy water bubble, which is not much. The mixture needs to be very soapy. I often do not seal the tank mechanically. I use masking tape on one of the holes, usually a petcock bung, and if it lets go I have used too much pressure. This is particularly true with alloy tanks. It is often difficult to find regulators that are this sensitive.

David

 

[davidd]

Tug,

Very nice job! I prefer to do the edge welding than making sheet metal, but that is a lot of welding. Sometimes if the sandblasting pressure it too high it re-shapes the metal. Sometimes it gets mis-shapen in the cutting and wheeling. This method or dent removal is pretty radical.

Oldhaven recently had a large deep dent repaired after the tank was painted and sealed. It was an amazing transformation, but I am not sure how it is done. Magic, I think.

David

 

[Oldhaven]

David is correct that I am chuffed about the tank repair. I am reserving complete judgement for when I get it back through the shipping ordeal. It arrives tomorrow, but from the picture the repair guy sent he did a terrific job. This was a mysterious dent and no one seems to know how it happened, but it wasn't there when I sent it off for tank lining. I was pretty sick about it when I opened up the box when itr was returned last month, since this was a nice Imron paint job that had survived about 30 years of storage unscathed. I found this fellow in California who says he pretty much invented motorcycle paintless dent repair (MPDR) in the 90's. I sent him this picture and he said he could do it for $185. Worth a try, right? Well the bad part was the shipping cost from Maine to California and back, but anyone closer would have found it a bargain considering the cost and effort of a new paint job, even one done yourself. So here is the result:

I hope it looks as good tomorrow. BTW, has anyone ever noticed all the tank selfies on the forum and elsewhere? I don't think the photo shooters are aware that they are forever preserved in the fun mirror of the tank paint job. Just make sure you have your pants on when photographing your Vincent. I seem to remember an old joke about taking your trousers off to start your bike to prevent catching the cuff on the gear indicator, which makes it hard to get away when the whole thing goes over..

 

[vibrac]

I read somewhere that with the latest cameras and software it is possible to 'see' the surroundings of the camera at the time of the photo by close blowups of the subjects eyes - developed in the war against terrorism....