Half water half brake fluid in brakes?
06-03-20, 10:30 AM
#26
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I'll actually revisit this immediately.
A cute finnish couple did a youtube video about bicycle disc brake vs lathe. The fluid only boiled well after the rotor had been red hot (so around 1000 degrees celsius?) for quite some time. I've only ever gotten my rotor brown and my wife who has worse braking habits than me has gotten her rotors blue.
There's also the brake force one H2O brake system which uses a water and glycol mixture as fluid.
A cute finnish couple did a youtube video about bicycle disc brake vs lathe. The fluid only boiled well after the rotor had been red hot (so around 1000 degrees celsius?) for quite some time. I've only ever gotten my rotor brown and my wife who has worse braking habits than me has gotten her rotors blue.
There's also the brake force one H2O brake system which uses a water and glycol mixture as fluid.
Mineral Oil is hydrophobic. (And please don't add water or egg yolk to your mineral oil braking system.)
-mr. bill
06-03-20, 10:37 AM
#27
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Yeah true. The Brake Force One H2O uses 80% water 20% glycol and glycol functions as antifreeze. But to my understanding it doesn't significantly raise the boiling temperature.
06-03-20, 11:13 AM
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06-03-20, 11:19 AM
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Feel free to do a kitchen experiment. You will not get mayonnaise with water and oil, no matter how long you blend.
You also don’t need a blender to make mayonnaise.
A whisk will do quite nicely, though if determined enough a fork will do, or if really determined a spoon or chopsticks.
You do need an emulsifier such as lecithin found in egg yolk. A soluble thickener (such as the mucilage found in mustard) is wise too. Finally, lowering the pH with a bit of acid from lemon juice or vinegar helps too.
-mr. bill
You also don’t need a blender to make mayonnaise.
A whisk will do quite nicely, though if determined enough a fork will do, or if really determined a spoon or chopsticks.
You do need an emulsifier such as lecithin found in egg yolk. A soluble thickener (such as the mucilage found in mustard) is wise too. Finally, lowering the pH with a bit of acid from lemon juice or vinegar helps too.
-mr. bill
You tell me this now?
06-03-20, 12:17 PM
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Maybe OT - but in case the OP needed to flush their brake system, could they use alcohol? It's hygroscopic, so it will blend with the water?
06-03-20, 01:04 PM
#32
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The reality of the matter is, that it requires some serious work to get bicycle brakes boiling hot. Or rather, you'll easily hit hundreds of degrees celsius at the pads and rotor. However in order to transfer that heat through the caliper body into the fluid in large enough quantities and continuously enough to heat up enough fluid (a significant amount) to cause a boiling event even with water would require some monster hills and very irresponsible braking habits. I'm sure it'd be possible, but not with a dirt jumper in its natural habitat.
With water in the system and with the water phase separating at the bottom of the brake column, it wouldn’t take much heat to get the water to boil...i.e. convert to a vapor...which, as I pointed out above, introduces a gas into a system that abhors gases.
There is also a problem with residual water in the system which is why I said a full tear down and cleaning would be warranted. Residual water will expand a lot if the brakes get hot enough to boil the mineral oil and you are back to trying to compress a gas.
It may not be rocket science but it is not that simple.
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06-03-20, 01:07 PM
#33
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Yes, but as pointed out in the video the viscosity of the oil is unknown. I don’t know how important viscosity is to the brake operation but as also pointed out in the video, don’t go back to the manufacturer and try to put in a warranty claim.
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06-03-20, 01:11 PM
#34
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Ethanol, acetone, 20 year old Scotch, yes. But none of those are all that soluble in mineral oil. And, if you don’t dry out the system, you have something that has an even lower boiling point. Acetone would be a questionable choice as well because it could damage seals.
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06-03-20, 01:22 PM
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Mineral oil is unpleasant tasting and has a strong laxative effect.
Mayonnaise some find unpleasant tasting, but....
While there are food grade glycols, DOT brake fluid isn’t. POTUS might disagree, but if I were you avoid ingesting.
-mr. bill
Mayonnaise some find unpleasant tasting, but....
While there are food grade glycols, DOT brake fluid isn’t. POTUS might disagree, but if I were you avoid ingesting.
-mr. bill
06-03-20, 01:59 PM
#36
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I don’t know anything about the post you are referring to but mixing water with mineral oil is not the same as mixing water with glycol. I’m not sure what the benefit of mixing water with glycol would be for a brake system but putting water into an oil system is definitely going to change the characteristics of the braking system.
It’s difficult to get bicycle brakes to the point of boiling either DOT fluid or mineral oil but that’s because both have a boiling point of around 280°C. It would not be difficult to get the brakes to the boiling point of water at 100°C. 280°C is enough for a really good head of steam.
I'm also not sure it is that easy to get bicycle brakes so hot that the fluid inside is at 100 C. Parts of the brake? sure. Rotor and pads? Most certainly. Pistons? Well, maybe part of the piston. However, getting enough heat transferred to get the fluid to reach 100 C is going to take some doing. I mean there is on the market a bicycle hydraulic brake system that uses water as brake fluid. I also know that it used to be done with Shimano hydraulic brakes. Water laced with glycol doesn't freeze easily. Granted mineral oil doesn't either, but I used to suffer from the mineral oil turning solid thus making braking a bit difficult.
With water in the system and with the water phase separating at the bottom of the brake column, it wouldn’t take much heat to get the water to boil...i.e. convert to a vapor...which, as I pointed out above, introduces a gas into a system that abhors gases.
I do not know a single person who has ever had a boil event. I haven't had a boil event and I used to do DH with mineral oil brakes. And I was bad at it so I was on the brakes a lot. The routes I did were easily long enough to overheat brakes, which I did etc etc. Really the only place I could imagine a boil even could occur would be with a loaded touring bike, kilometers of fast descent and abhorrent brake practices.
Hydraulic systems have a lot of nooks and crannies that can hold up water at the bottom of the system as well as other places in the system. The water at the bottom is the most concerning. Are you certain that draining the system would remove all the fluid from the pistons? I’m not. The bleed valve is on top of the piston and any oil injected would just force out any water that is around that valve. There’s nothing driving emptying the piston itself, especially if just mineral oil is used. The oil will just flow over the top of the water in the bottom of the piston.
There is also a problem with residual water in the system which is why I said a full tear down and cleaning would be warranted. Residual water will expand a lot if the brakes get hot enough to boil the mineral oil and you are back to trying to compress a gas.
It may not be rocket science but it is not that simple.
i did mention in my other comment the youtube video where they put a bicycle brake on a lathe. The fluid boils only after the rotor has been glowing red hot for fifteen seconds.
06-03-20, 02:08 PM
#37
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Feel free to do a kitchen experiment. You will not get mayonnaise with water and oil, no matter how long you blend.
You also don’t need a blender to make mayonnaise.
A whisk will do quite nicely, though if determined enough a fork will do, or if really determined a spoon or chopsticks.
You do need an emulsifier such as lecithin found in egg yolk. A soluble thickener (such as the mucilage found in mustard) is wise too. Finally, lowering the pH with a bit of acid from lemon juice or vinegar helps too.
-mr. bill
You also don’t need a blender to make mayonnaise.
A whisk will do quite nicely, though if determined enough a fork will do, or if really determined a spoon or chopsticks.
You do need an emulsifier such as lecithin found in egg yolk. A soluble thickener (such as the mucilage found in mustard) is wise too. Finally, lowering the pH with a bit of acid from lemon juice or vinegar helps too.
-mr. bill
Take one jar of Hellman's. Open it.
06-04-20, 08:21 AM
#38
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The interesting thing is though, that compared to mineral oil, water has almost three times the thermal capacity. So getting to a hundred centrigrade is going to take far longer than with mineral oil. With Glycol (DOT) water still has the advantage with almost double the thermal capacity.
Mineral oil won’t hold heat like water can. The heat radiates away and the brakes cool more quickly.
I'm also not sure it is that easy to get bicycle brakes so hot that the fluid inside is at 100 C. Parts of the brake? sure. Rotor and pads? Most certainly. Pistons? Well, maybe part of the piston. However, getting enough heat transferred to get the fluid to reach 100 C is going to take some doing. I mean there is on the market a bicycle hydraulic brake system that uses water as brake fluid. I also know that it used to be done with Shimano hydraulic brakes. Water laced with glycol doesn't freeze easily. Granted mineral oil doesn't either, but I used to suffer from the mineral oil turning solid thus making braking a bit difficult.
Mineral oil freezing is another good argument for using DOT fluid (or mechanicals
). DOT doesn’t freeze until -40°F. Water suffers from the same problem.Try it. Try to boil you brakes. Actually I might try it. I have enough stuff in my parts bin to give water brake a go. I wonder if I should even do a preheated test where I preheat the whole system so I'd get better info on how much dragging brakes on steep descents really heats up the fluid.
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06-04-20, 08:23 AM
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Ethanol, acetone, 20 year old Scotch, yes. But none of those are all that soluble in mineral oil. And, if you don’t dry out the system, you have something that has an even lower boiling point. Acetone would be a questionable choice as well because it could damage seals.
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