-Current set up on my 996
Brembo 19x20 radial master
OEM braided lines
Line configuration = one line exiting the master, breaking off into two lines, each to their own caliper.
OEM Brembo Mille 4pad calipers
Carbone Lorraine C44 race pads
Braketech iron rotors
Now I’ve seen a set up on the 999 where one line exits the master and goes to caliper one and then there is another line from caliper one to caliper two. I’m assuming that this offers the same performance as my current line configuration.
My question is, if I were to go to a different line configuration, meaning two lines exit the master, each going to their own caliper, how will lever feel, modulation and braking performance change given that all of the rest of the components remain the same? I’m guessing that the different configuration will react like this. The same lever travel will have less piston travel, effectively making me have to pull the lever more to get the same piston travel as my current configuration. I think this would provide more feel for what the brakes are doing, it would give the opportunity for better modulation and additionally enable more power in the end. This sounds like a decent alteration to the brakes but I’m concerned that there will be too much lever travel and I’ll be squeezing it to the bar.
Of course I could be missing something and be way off… Can anyone confirm this?
"Exercise restraint and discipline, only responding to posts from legit customers and those with constructive positive intent, you will find that the handgrenades explode harmlessly. You have many satisfied customers who are happy to have the parts you've made. My suggestion to you is keep making good parts, keep getting more customers, take care of them and let them speak for you."
Nope, both configurations will have the same caliper piston travel and the same master cylinder travel.
Think of it this way: since the fluid is incompressible, the master cylinder displaces a volume of hydraulic fluid equal to the volume of fluid needed to move the brake caliper pistons. (Volume of displaced fluid=area of piston X distance the piston moves X the number of pistons.)
The best brake line configuration will be the one having the shortest total length of tubing. Any tubing will expand slightly under pressure causing a spongy feel at the brake lever. The longer the tubing runs, the less direct the relationship between the lever pull force and the resulting braking force.
What about the force needed to pull the lever in order to move the fluid? You would think that the dual line set up would be an easier pull as there is more area for the fluid to pass through... wouldn't that make it easier to modulate the brake? And if the idea of decreased effort needed to pull the lever for the same piston travel is true, than you could squeeze the lever harder, transating into more brake power...
Maybe a bit off topic, but still brake pressure...
Would there be any difference, or measurable difference, if one used different brake hose sizes?
ie: -2 vs-3 line.
What about the force needed to pull the lever in order to move the fluid? You would think that the dual line set up would be an easier pull as there is more area for the fluid to pass through... wouldn't that make it easier to modulate the brake? And if the idea of decreased effort needed to pull the lever for the same piston travel is true, than you could squeeze the lever harder, transating into more brake power...
NO! the pwoer comes simply from the piston not the line. having stainless lines allows less flex in effect making the liston look stronger but it is not.
the fluid keep pressure on the piston(if bleed properly) so there is your taught
"Exercise restraint and discipline, only responding to posts from legit customers and those with constructive positive intent, you will find that the handgrenades explode harmlessly. You have many satisfied customers who are happy to have the parts you've made. My suggestion to you is keep making good parts, keep getting more customers, take care of them and let them speak for you."
Maybe a bit off topic, but still brake pressure...
Would there be any difference, or measurable difference, if one used different brake hose sizes?
ie: -2 vs-3 line.
"Exercise restraint and discipline, only responding to posts from legit customers and those with constructive positive intent, you will find that the handgrenades explode harmlessly. You have many satisfied customers who are happy to have the parts you've made. My suggestion to you is keep making good parts, keep getting more customers, take care of them and let them speak for you."
Think of it this way, you've got a coffee stir straw and a McDonlads shake straw, two very different diameters. Using each straw, fill your mouth completely with water and using the same force, see how long it takes to expel the water throught the straw. It probably takes more time for the coffee stir straw. ...with the McDonalds straw, what's it going to take... two seconds? Try pushing the water out of the coffee straw in two seconds, not going to happen.
I think the same theory applies, same amount of fluid through a smaller opening will require more force for the same amount of time.... and... same amount of fluid through a smaller opening will require more time for the same amount of force... lastly, directly comparing to the brake lines, it will require less force for the same amount of fluid over the same amount of time.
Think of it this way, you've got a coffee stir straw and a McDonlads shake straw, two very different diameters. Using each straw, fill your mouth completely with water and using the same force, see how long it takes to expel the water throught the straw. It probably takes more time for the coffee stir straw. ...with the McDonalds straw, what's it going to take... two seconds? Try pushing the water out of the coffee straw in two seconds, not going to happen.
I think the same theory applies, same amount of fluid through a smaller opening will require more force for the same amount of time.... and... same amount of fluid through a smaller opening will require more time for the same amount of force... lastly, directly comparing to the brake lines, it will require less force for the same amount of fluid over the same amount of time.
Make sense?
NO. you are no pushing it out, you are pushing against. if you take a 2" hose and line it up against the caliper piston as well as a tiny hose assuming they both are the same wall stainless and flex the same. fill and bleed taught. the same force applied to either on the caliper piston will be the same. if we were talking about fluid dynamics then it would be different as the larger pipe would allow higher flow speed. the piston the the master excerts the pressure no matter how large the tube is full and taught
"Exercise restraint and discipline, only responding to posts from legit customers and those with constructive positive intent, you will find that the handgrenades explode harmlessly. You have many satisfied customers who are happy to have the parts you've made. My suggestion to you is keep making good parts, keep getting more customers, take care of them and let them speak for you."
Once you get to a 3mm diameter brake line, the flow restriction you mention is inconsequential, so doubling the number of lines to the caliper pistons adds no improvement.
Remember we're talking about a maximum of only 3mm of fluid displacement in a one meter long 3mm internal diameter line to fully actuate the brakes.
Decreasing the line size will reduce the expansion of the line under pressure (which is desirable) but unfortunately will slow piston retraction time so 2mm is usually the practical limit to avoid unnecessary overheating. The pads retract only as the fluid flows back out of the caliper, through the brake lines, and back into the master cylinder. Some companies make 2.5mm lines to balance these effects. Brembo however, recommends 2.5mm or 3mm lines only.
Mrgrn, I don't know what the heck you're talking about.... ;-)
Quote:
Originally Posted by Shazaam!
Once you get to a 3mm diameter brake line, the flow restriction you mention is inconsequential
Coming from our resident expert I'll buy that but it's hard to believe that it won't make a difference. I still think that it will be easier to pull the lever with the two line setup.
Anyways, now that it's established that the configuration doesn't make a difference, why do people even bother running two separate lines. I mean, more cost, more mass, more brake fluid to bleed etc.... Given the explanation above, it seems like a waste to me.
Coming from our resident expert I'll buy that but it's hard to believe that it won't make a difference. Where's our physics guy?
Anyways, now that it's established that the configuration doesn't make a difference, why do people even bother running two separate lines. I mean, more cost, more mass, more brake fluid to bleed etc.... Given the explanation above, it seems like a waste to me.
easier for brake line makers to just make generic lines for applications then making the one down flip isolated to one bike
"Exercise restraint and discipline, only responding to posts from legit customers and those with constructive positive intent, you will find that the handgrenades explode harmlessly. You have many satisfied customers who are happy to have the parts you've made. My suggestion to you is keep making good parts, keep getting more customers, take care of them and let them speak for you."
Coming from our resident expert I'll buy that but it's hard to believe that it won't make a difference. I still think that it will be easier to pull the lever with the two line setup.
Anyways, now that it's established that the configuration doesn't make a difference, why do people even bother running two separate lines. I mean, more cost, more mass, more brake fluid to bleed etc.... Given the explanation above, it seems like a waste to me.
I can't comment on fluid dynamics and whatnot but there are a couple of reasons for running the two lines.
First a 996RS front brake line, which I have on the shelf, is a one into two sort of like stock. Except it splits closer to the m/c and is configured to run around the outside of the fork tubes. Look at any photo of RS bikes.
Either RS configuration or two lines routed around the outside of the fork tubes does tend to make caliper removal and hence wheel changes, particularly quick wheel changes, easier. Also since there is no upward looping part of the line going across the fender bleeding can be easier.
Another reason for two lines around the outside of the tubes is it lessens the chance that a tire can blister and throw a chunk that could cut the line. Or the tire could pick up a big hunk of something and cut the line.
I can't comment on fluid dynamics and whatnot but there are a couple of reasons for running the two lines.
First a 996RS front brake line, which I have on the shelf, is a one into two sort of like stock. Except it splits closer to the m/c and is configured to run around the outside of the fork tubes. Look at any photo of RS bikes.
Either RS configuration or two lines routed around the outside of the fork tubes does tend to make caliper removal and hence wheel changes, particularly quick wheel changes, easier. Also since there is no upward looping part of the line going across the fender bleeding can be easier.
Another reason for two lines around the outside of the tubes is it lessens the chance that a tire can blister and throw a chunk that could cut the line. Or the tire could pick up a big hunk of something and cut the line.
i think a big reason for the outside lines is they are using them as radiators and cooling the fluid by putting them out in the air and not behind the forks
i think a big reason for the outside lines is they are using them as radiators and cooling the fluid by putting them out in the air and not behind the forks
You think that there's much cooling to be had when the fluid molecules are only moving a few mm up and down the brake line?
it makes no difference how many or big the brake lines are (as long as they're not too small internally) - the pressure is defined by the ratio of master cylinder piston area to total caliper piston area, as is the amount of lever travel you need. the actual amount of fluid moved won't change either - the caliper pistons will still move the same amount no matter what is upstream.
however, the total volume of fluid in the system could effect how quickly it heats up, and the lines out the side could certainly influence that too. bigger would be better on both counts. i hadn't thought of the cooling thing before, but it make sense. especially in racing where every little bit helps.
and it's better than running two lines inside/behind the forks - look at any early 851 and you'll see two ovals of bent radiator fins where the brake lines hit the radiator on heavy braking and fork compression.
Spiegler? I still have an unused Spiegler front brake line for my 998R collecting dust somewhere. Even though the box is clearly marked "for 998R w/radial master cylinder and radial calipers" it still doesn't fit. It's simply too short
I'd consider Fren Tubo if I were you. At least they know what they're doing
Quote:
Originally Posted by Capt. Home Slice
Thanks everyone for your replies. Looking at getting a Speigler set up for my needs.
doing two lines down from the master uses more hose, more fittings so more cost
And more fluid......
I have two lines from 19x20 radial master to calipers, no difference in feel etc but is easier to bleed (no airlock in the 'loop' over the wheel), less chance of the 'loop' catching in the wheel (some race organisations require this) and, IMO looks better.
? - Effects of brake line configuration.
I still think that it will be easier to pull the lever with the two line setup.
i think a big reason for the outside lines is they are using them as radiators and cooling the fluid by putting them out in the air and not behind the forks
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