2 line vs 3 line brake pressure, performance topic- 98valk, (aka CA) & mellodude

[mello dude]

Just a follow thread to keep this tech discussion separate...
Copying from Spiegler thread...
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98Valk...

the two-line set up? That's what I want but I need custom length due to taller risers.  OEM setup causes the right side pads to wear faster than the left indicating reduced braking performance. Two lines will increase stopping power.

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mello dude..

Cant see how you can say 2 line increases stopping power or 3 reduces... etc.  Pressure is pressure and it will be the same thru out the lines.... Maybe you have a sticky piston or ?

You can get any length lines built by Speigler.  Their standard kit for the Valk is a 2 line. (I believe)
Typically the best way to figure it out is to, grab some plastic tube from Lowes and route it the way you want and then figure the length.
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98Valk....

I have custom SS lines from Viking when they were active, look like OEM, but longer for the deuce risers.  The OEM right side has a shorter hose, less restriction due to the straight run so caliper sees pressure sooner and a little more pressure. the right side has to make a 90 degree turn at the tee fitting before it goes to the left side via a longer hose. 62k miles and I've seen increased wear of right pads vs left pads both times.  All of the top road racer bikes use two direct hoses to the front calipers. much written on it.


 

[WintrSol]

Pressure loss is a function of fluid flow against the resistance to that flow. So, I guess it depends on how much motion there is in the pads before they are hard against the rotor, and how much resistance there is to fluid flow through the two junctions to the LH caliper. Once that occurs, the pressure on both sides equalizes, so all else being equal, braking performance would be the same on both sides. I can see that, over the miles, the small difference in initial contact time could cause some increased wear on the pads that stop moving first, and the initial braking force would be slightly less than the steady state force. That time has to be in the micro- to millisecond range, depending on how much initial pressure is applied to the lever, IOW, squeezing vs grabbing the brakes. Larger bore lines would reduce the difference, but then they would be heavier and less flexible.

[gordonv]

My engineering goes back closer to 40 years ago, Industrial Eng with my drafting course. Pressure is pressure, it's equal everywhere the fluid is (we aren't talking air here).

Movement on a piston is based upon the volume of the fluid. If you had 2 different dia lines, or restrictions (elbows/connectors), it doesn't affect the piston movement, as long as there is fluid in the lines (1 oz in, 1 oz out, no matter the dia, as long as it's full to start, this is why SS doesn't flex [as much] as other lines, so you don't lose volume).

If you have a sticking piston, it takes some of the psi away from the pad to overcome the resistance, which leaves less for the pad.

If I remembered correctly, this is basic hydraulics.

As for brakes, I don't think I've removed one pair that had not been worn un-evenly. I'm not a mechanic, so I'm talking 20-30 pairs of disc.


How about this 2 line question? What's it's purpose, cosmetic? The h style design of our dual calipered front wheel is not an issue.

[WintrSol]

When the fluid is moving through a restriction, there is a drop in pressure, proportional to the rate of flow. Once the motion drops low enough, the pressure drop disappears. The theory is that there is enough restriction through the two right angles and the extra length of line, along with the inertia of the extra amount of fluid, that there is a small differential pressure while the pistons advance, delaying the advance of the side with the extra line restriction. Granted, that is a very small motion, so any pressure drop would also be small, and very brief. With a smooth squeeze, the flow rate is so low that any pressure drop is likely un-measurable, if present. A very quick application may yield a small differential pressure due to the higher flow rate, however brief. Again, this may not be measurable. Using two lines directly from the MC would equalize any of these small pressure difference.

There are plenty of mechanical reasons, IMO, for there to be a difference in wear, which could easily overcome any differences from brief differential pressure losses. I'd have to see verifiable differences in application rates of the pads to really buy the two-line argument.

[mello dude]

Thanks guys for keeping up the discussion.. I'm a mechanical engineer by trade and you make the same exact points that have been spinning thru my brain..... 

[mello dude]

How about this 2 line question? What's it's purpose, cosmetic? The h style design of our dual calipered front wheel is not an issue.

Generally in the sport bike and racing world, the 2 line off the master cylinder is generally standard stuff for its simplicity....

[gordonv]

How about this 2 line question? What's it's purpose, cosmetic? The h style design of our dual calipered front wheel is not an issue.

Generally in the sport bike and racing world, the 2 line off the master cylinder is generally standard stuff for its simplicity....

Not having a sport bike, or one in front of me to look at, are we talking a longer bango bolt with 2 sets of holes, so you can place it thru 2 lines of the same MC? Run from there to each caliper than. One line then might be longer than the other, or in my case with the fairing, equal length, but the closer one would be coiled up in the fairing out of sight.

[mello dude]

How about this 2 line question? What's it's purpose, cosmetic? The h style design of our dual calipered front wheel is not an issue.

Generally in the sport bike and racing world, the 2 line off the master cylinder is generally standard stuff for its simplicity....

Not having a sport bike, or one in front of me to look at, are we talking a longer bango bolt with 2 sets of holes, so you can place it thru 2 lines of the same MC? Run from there to each caliper than. One line then might be longer than the other, or in my case with the fairing, equal length, but the closer one would be coiled up in the fairing out of sight.

Qualifying my statement a bit, there's multiple ways to do it, but generally for aftermarket and racing --
-.  Two individual lines, one is longer and then 2 banjo fittings bolt directly to the master cylinder and one goes to each caliper.

I suppose you could make them identical length and do the coil thing, your the first person I have heard that from. It's more typical one line is a bit longer than the other..

[98valk]

Why do your front sportbike line kits not follow the stock routing?

Almost all of our front line kits are 2 line systems that have both lines exiting from the master cylinder and then going down to their respective calipers.

We have found that this type of routing allows for shorter lines, which allows for a firmer brake feel.
https://galferusa.com/technical/faq#wave

two lines are lower cost also
http://www.helperformance.us/motorcycle/honda-en/valkryie/


my viking lines have one tee and then a flex SS brake line from each tee branch to each caliper.