K0Kid
"No Detail Too Small Not To Obsess Over"
Bevelheadmhr said:The oil tank mounting caused some head scratching. The mounts at the top our obvious, but how to use the grooved bosses on the lower sides wasn't clear. Original Tritons used rubber loops to pull the oil tank down against the top of the gearbox, with a rubber pad sandwiched between to try absorb the vibes. On the Ace Café Norley they used the same method, but with the oil tank sat on a T piece welded to the rear engine mount. My frame didn't have this T piece, I did Email Norley to ask about this, but got no reply.
So before the frame went for powder coat I had a couple of hooks welded to the inside of the frame, to be used to hang the oil tank via rubber O rings, or some other suitable loop. I prefer my method as it better isolates the tank from engine vibes.
This is how the Ace Café Norley mounted their tank, notice the upright tube supporting the tank from beneath, which my frame doesn't have, and my bike pictured beneath
Let me make an observation about the oil tank for a future revision. My oil bag (stock steel tank) on my Triumph 650 would tear the tabs off the tank and open a hole on the back side even though the tank was suspended from 2 straps with tubes at the end and 2 isolastic rubber bushes. The oil tank was so heavy that over time the mounting tabs just couldn't carry the load even with a supporting L(90 degree) bracket at bottom of tank also rubber bushed, we all know there was concern for vibration especially in a Triumph. A good engineering practice is the support the weight of the tank on something solid. It seems the way Norley did it is one way but it does illustrate the notion the tank should sit on something. A single post or tube would make me think eventually the weight will punch a hole in the bottom of the tank.
A better way might be to let tank rest against the small diameter cross tube you have on your frame about 2" above the swing axle. I notice so far you are not running a rear fender or a flat panel just ahead of the tire. Instead you have created a curve in the tank itself that I'm sure you matched to the radius of the tire. But similar to the issue with the radius of the front fender the radius of the rear tire although it may be the same as the tire doesn't ever match the radius ( not concentric ) of the tank except at one finite point of the swing of the axle and becasue it is so short draws attention to itself. This is visually competitive. The way you have mounted the top of the tank with an addditional tab (horizontal or some angle ) that will tend to change as tank pulls the tab downward at an angle again visually too busy, if the tab on the frame was bigger and tank thru bolted thru side of tank using your bung feature it would still support the tank (a straight downward hanging load even if the bolt loosened at the top it would still carry the load but the way it is now the tank wants to rotate into the rear wheel with the tanks rear bottom edge coming into contact with tire.
Also your use of the orings aren't really doing their job. My suggestion is to make a thinner, longer tank maybe wider tank that would fit againts the rear of frame to act as fender shield. Although for safety reasons and cleanliness (you will ride in the rain over there, no? I would run a shaped or flat plate to protect oil tank from rocks kicked up by tire and as an innner fender against water. Most Jap bikes have a plastic liner here and use a separate fender above the wheel. I know the cafe look is to throw all this crap away but without a liner you will be cleaning the crap off your oil bag all the time. Making a different shape to the oil tank will do 2 things open up the visual space between the rear cylinder and head and allow easier mounting perch for the oil bag. Currently it looks crowded with tank up against engine and /or hanging out in mid air not to mention its trapezoidal flowing shape. A simpler tank more rectangiular like a flat box of tissues, longer, wider and only 2.5 inches thick, you could still radius the back side but the longer it is, the less curious it will look.
Now finally the piece d'resistance the proper use of the o-rings as rubber bands. The current tabs will tend to cut the o-rings. See attached Norton solution or aftermarket Norton race solution on a revised Norton, simple and elegant. Love your circular bungs at side of tank and with the orings doubled over but around the lower crossover tube just above the swing arm which would hold tank firmly against that tube with a thin strip of rubber in between as anti chafe to anchor tank against frame at bottom and load of tank carried above thru the 2 lugs and tabs on the frame.
An alternative is to use small angle iron as a cup on the same lower crossover rail so the tank rests on it carrrying all the load but also anchored to it by the o-rings. Otherwise Bevelhead, a masterful project so far.
PS
I recieved my Cali II Guzzi from snow country and have a line on the bottom Tonti frame tubes for the conversion, can't wait to see this finished and a restart on your Guzzi project. The race is on !