BMW R90/6 Cafe

teazer said:
Just asking myself the same question. If there's no air in the pipes, it could work. I'd prefer to see it higher than the master though.
canyoncarver said:
Is the reservoir lower than the master cylinder? Will that work right?
Great question. A reservoir does not “need” to be above the master cylinder. In theory, there should be zero air in the system so it doesn’t matter. I believe that it is usually placed above as precaution, so if air were to get into the system it might make its way up to the master cylinder.

My reservoir is actually just about level, however the clear tygon hose loop is well above the master. If air were to get into the system, the highest point is that hose loop where it would be clearly visible.

I have a great motorcycle museum nearby, and I actually noticed several race bikes with a lower reservoir which made me consider the whole theory.

For an everyday rider just racking up miles between servicing, put the reservoir at the top.
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
ncologerojr said:
Great question. A reservoir does not “need” to be above the master cylinder. In theory, there should be zero air in the system so it doesn’t matter. I believe that it is usually placed above as precaution, so if air were to get into the system it might make its way up to the master cylinder.

My reservoir is actually just about level, however the clear tygon hose loop is well above the master. If air were to get into the system, the highest point is that hose loop where it would be clearly visible.

I have a great motorcycle museum nearby, and I actually noticed several race bikes with a lower reservoir which made me consider the whole theory.

For an everyday rider just racking up miles between servicing, put the reservoir at the top.
You're overlooking an extremely important point. Brake fluid is hygroscopic, which means it attracts water. Moisture in brake fluid creates gas bubbles when your rotors get hot. Those gas bubbles will get trapped in high points and cause your brakes to get soft. This is why a reservoir is above level and vented. Comparing it to a race bike is a mistake, since the systems have completely different maintenance cycles and engineered parameters.
 
irk miller said:
You're overlooking an extremely important point. Brake fluid is hygroscopic, which means it attracts water. Moisture in brake fluid creates gas bubbles when your rotors get hot. Those gas bubbles will get trapped in high points and cause your brakes to get soft. This is why a reservoir is above level and vented. Comparing it to a race bike is a mistake, since the systems have completely different maintenance cycles and engineered parameters.
Sorry, I didn’t overlook that point I just didn’t want to get too into the weeds while typing on my phone. I just simplified and said “if air gets into the system it makes its way up to the reservoir” I didn’t feel like I needed to address exactly how gas ends up in the system.

As I said above, a regular bike just racking up miles between servicing (maintenance cycles), put the reservoir above the master.

This is not a daily-rider bike, it will see few miles. It’s going to need regular servicing with those miles. This is a non-vented Brembo reservoir, and the clear tube serves as a high point in the system. Gas build up will be visible and easily managed.
 

Jimbonaut

Well-Known Member
DTT SUPPORTER
You missed a bit.

Just kidding.

Honestly, if I hadn't seen that photo with my own eyes I wouldn't have thought it possible to get a shine like that. Incredible - this bike is gonna be something when it's all said and done.
 
Jimbonaut said:
You missed a bit.

Just kidding.

Honestly, if I hadn't seen that photo with my own eyes I wouldn't have thought it possible to get a shine like that. Incredible - this bike is gonna be something when it's all said and done.
CrabsAndCylinders said:
Wow!, just wow!
Thanks guys!

Just to be clear, it’s not perfect. I don’t think you can get aluminum, especially this soft of an alloy, perfect. Microfiber towels scratch it.

It’s like a car with beautiful black paint. It looks stunning, but if you catch it at just the right angle/light you see all the ultra fine scratches.
 
TranceMachineVienna said:
Amazing fab skills!

Do you TIG or Gas weld youre alu work?
Thanks!

Both. I prefer gas for welds that are going to be planished and rolled thru the e-wheel. Everything else I tig. I’m also not as good at gas welding yet as I am tig.
 
This picture shows it a little better. If you get just the right light/angle you can see super fine scratches. Those are from the final hand buffing with a microfiber cloth. You can get better results with some of the firmer alloys, but those aren’t good for shaping.

Also different alloys will have different final colors. You can see the weld line here. That’s because the tank is 3003 aluminum and the weld is 1100.



 

cb360j

Member
I think if you spent to much time trying to get all those fine scratches out you'd go insane.
I remember back in this material sciences class I took in college, we were learning about metals and how the surfaces actually looked under a microscope. Well, we had these buffing and sanding tables that were made for polishing stones to look under a microscope and a few of us in the class made a bet for $20 that by the end of the semester (summer class) we would have the most shiny piece of steel out of the group. Well, I definitely lost but if you looked under the microscope, you could still see how imperfect the surface was.
 
cb360j said:
I think if you spent to much time trying to get all those fine scratches out you'd go insane.
I remember back in this material sciences class I took in college, we were learning about metals and how the surfaces actually looked under a microscope. Well, we had these buffing and sanding tables that were made for polishing stones to look under a microscope and a few of us in the class made a bet for $20 that by the end of the semester (summer class) we would have the most shiny piece of steel out of the group. Well, I definitely lost but if you looked under the microscope, you could still see how imperfect the surface was.
You’re absolutely right.

I always wondered what you guys did in college labs, polishing your rods eh?

Kidding aside, that’s a cool memory to share.
 

teazer

Well-Known Member
DTT BOTM WINNER
I can't weld for shit, but I used to think I was pretty good at polishing. And now you have blown that myth out of the water. :-(

Do you mind sharing how you managed to get that shine and what you used? I get that new 3000 series alloy is soft and easier to polish than old engine side covers but that shine is impressive.
 

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