Topic: Oil tank in swingarm?

[schmolze]

I'm in the middle of a 750 build, and want to leave the "triangle" area open. I'm toying with various ideas for a custom oil tank, including making a thin rectangular tank and sticking it in front of the rear wheel in the frame (I've seen that somewhere here), integrating it into a custom gas tank, oooorrr...grafting an oil tank onto the swing arm. The swing arms holds about 1L, so you'd have to expand the volume on the top or bottom or both.

I'm interested in people's thoughts on this idea. Has anyone done it? Do you think it would work?

Thanks!

[ekpent]

Have not read it but noticed it recently,might have your answers.  http://forums.sohc4.net/index.php?topic=70333.0

[Lostboy Steve]

That's where my Buell keeps the oil. I haven't looked into how it works as far as gravity is concerned. CB tanks are level if not above the head. I know that most evo engines (Buell Sportster older Harleys) only produce about 4 psi at idle. Not sure how much a CB engine pumps.

[schmolze]

The gravity issue is my main concern...but the oil pump is pretty strong from what I've read, and I think it should be up to the task. I think I should do it, just to know if it works 

[Kong]

What makes it a bad idea has nothing to do with the oil pump.  What you are doing is adding considerably to your unsprung weight at the rear wheel and that alone will turn your bike's handling to #$%*.  People spends hundreds and hundreds of dollars for shock absorbers to control the movement of that swing arm and here you are adding to its mass by a factor that probably approaches 50% if not more.  As far as your bike's suspension goes it would be pretty hard to think up a worse idea - except to make it a hard-tail I suppose.  There is another potential problem too.  You will need flexible lines to and from the swing arm if you try this and of course fittings in the arm to allow the oil in and out.  If any of these fail or leak the oil will dump right on your rear wheel.  Are you sure that is what you want?  And then there is this next problem.  How do you intend to remove the welding slag in the inside of wing arm or do you think its clean inside of those tubes?  Back in the early 70's Triumph started using the frame rails as an oil tank on their first Tridents.  The engines blew right and left because of welding impurities from inside the frame tubes that found their way into the oil and then into the engine.  Just thought you should know.

[schmolze]

Thanks Kong, everything you've said makes sense. I suppose if it worked well, everyone would be doing it. I guess I'll think about integrating it into the gas tank instead.

[strynboen]

can you not make a tank in the gas tank tunnel..or intigrade it in the frame tube..build a higer/bigger tube in..think the gas in the tank..are getting to hot if you build it in the gas tank

[Kong]

Well, as long as you're thinking about custom oil tanks (any machine shop can fab what you want for not much money) you might want to get inventive about it.  A pancake shaped tank could certainly be concocted to fit very low in the V or possibly up between the vertical frame tubes to act not only as an oil tank but also to be an inner fender could be done in a very attractive manner and if done well it could also hold the weight of the oil lower in the frame.  One mistake you don't want to make is to try and use the seat pan for an oil tank - not unless you ride on frozen roads a lot, because anywhere the roads aren't frozen your butt is gonna burn if you try that trick.  That's one of the problems with a 2-chamber gas-tank/oil-tank too.   That oil gets hot and it will heat the container its in.  That said many early Harley's had split tanks, oil tank on one side and fuel tank on the other side.   But then old Harlies had lots of idiotic crap on them.

[Retro Rocket]

What about something like this.?



Oil tank is at the front of the triangle.....

[RustyStuff]

Any way to go to a wet sump?

[strynboen]

if your return valve leak.. it already have it. ..750 is a bit different then the rest of the sohc serie..atleast you will have to build a cooler in instead..new problems to come

[schmolze]

What about something like this.?



Oil tank is at the front of the triangle.....

That's the build I was thinking of, and I think something like that might be the best way to go in terms of balancing aesthetics and practicality. Stay tuned...

[Kong]

That picture is more or less what I was referring to.  If I had made that oil tank it would have been mounted to the set of tubes that goes up to near the rear top shock mounts, not the more forward vertical tubes that terminate near the back of the tank.  That way it can act as a rear inner fender too and help keep road trash and spray off more of the back of the works and might make the bike a little easier to keep clean, particularly stuff like road tar.

As for the wet sump idea - which is somewhat amusing to contemplate - it could be done of course but you would have to construct some sort of oil pan, which of necessity would have to hang down below the engine.   Picture it in your mind.  Now picture the same bike trying to go over a speed bump, hitting a deep pothole, or simply trying to lean over going around a turn (and keep in mind how wide a Honda-4 engine is when you picture that last one).  The quality of the idea diminishes with the thought.

[Lostboy Steve]

Kong I disagree. Again all Buell motorcycles have oil in the swing arm and they are said to be some of the best cornering bikes on the market. The lines are stainless braided and haven't ever been a problem. Also the Ulysses is used for dual purpose and there are people with well over 60k on and off road with no issues, leaks, or catastrophic failures. You're talking about going from a steel swing arm to a hollow aluminum one. How much weight difference is that especially since Buell's hold about 2.5 qts of oil total. Plenty of bikes with swing arm oil tanks have won all different types and classes of races. Never have they been a problem. One guy even used half a Buell swing arm mated to a single sided Ducati and that thing is still out there rolling down the road.