Oil tank fixing rubbers

Thanks for that Keith, I think I may have to pay a little more attention to the bottom mount. The top alignment is about 1/4" out when sitting on the bottom rubber alone. I am having to push the tank back to align holes, putting stress on the top fixings straight away. I may drill out and put a larger soft mount on the base so less stress at the top. Or slot the top holes and let it sit where it is, which would be easier. Are you saying that brackets welded to the tank itself break off with stress and vibration? I don't fancy taking the oil tank off for re-welding every 1500 miles.

Thanks for info Keith, I will make sure the whole thing is stress free in position. I was concerned about pushing the tank back into position before your comments. Now I'm sure I need to do something other than just fit new rubber mounts. Ta again.

Thanks Keith, have just discovered that my rear bracket was bent in so far that it was stretching the rear rubber mount.

Just spent another happy hour in the garage with my oil tank. Two observations.

1. With the top fixings in line, the oil tank is hard up against the battery compartment. Sort of defeats the point of rubber mounting.

2. With a little re-drilling there is probably room to move the tank top mounts sideways 1/8" or so and use the waisted exhaust rubber mounts that are more substantial. This would move tank away from battery compartment also.

In light of point 1. I wonder what would happen if the oil tank was rigidly mounted? It is attached to the frame after all and all the connections to the vibrating engine are rubber.

Decided in the end to make some rubber spacers and go with a semi rigid fixing. (picture attached i think) Made each end the dimension required to allow the tank to sit without stress. I re-made the top breather tube with a slightly longer small section rubber hose and bent the rear mount back to shape; the whole assembly then sat a lot better. Didn't go with standard rubber as the gaps between the brackets and the frame were about 20mm and the rubbers are only 15mm long; too much stretch/stress for me.(although I could have spaced those) There is now a 1mm gap to the battery housing also.

Feels good and solid but with a little flex. I'll let you know.

Thanks for advice Keith, I did have to replace the bottom rubber, 20 years in a shed and all the rubber on the bike was in a pretty sad state. The front roadrunner has some nice cracks in the wall also, I will have to replace that before I take it out. That's another thread for later. i.e. a Dunlop/Avon debate.

Hi Tony this is a nice thought and an interesting calculation. I have no idea how hot the oil tank gets, however:-

Assuming the oil tank is about 200mm high and the temperature would rise from an ambient 20 - 150 degs c then the linear expansion of steel would be approximately 0.0004mm. I hope this will not affect my semi rigid mounts that seem to give about 0.5 mm movement. Can't believe I looked and found a web site where you can work that out. Good job they had a calculator because the last time I did a differential equation was 30 years ago.

Has anyone tried a rigid mount?

Rubbish web site, not sure now. Just recalculated substituting inches and degs f and it worked out an expansion of .030 ins over 8, significantly more. I'll stick to embroidery. May try another web site and see what that gives.

Just been on another web site that worked it out closer to the first metric calculation. No way am I doing this longhand. That's that unless we have a mathematician that wants to join in.