Replace brake lines?

[klx678]

Vacuum bleeder from HF does the job fast and around $30.  Best $30 I've spent in years.   3 minutes to bleed out for a new brake line on the rear brake of my Zephyr.  Took longer on the double disc front, done first, because I was drawing too high a vacuum and sucking air in the bleeder thread.  Once that was figured out the job was fast.  Faster when I had my wife filling the master cylinder as it went down.

[ElGonzales]

With a little bit of brake piston grease applied around the bleeder thread you can seal this area against incoming air.

[FZWes]

On a FZ?

[Curious kid]

Which is better, OEM or alternative front brake line routing for steel braided lines?

[Subito]

1 hour ago, Curious kid said:

Which is better, OEM or alternative front brake line routing for steel braided lines?

That’s a good question, I’m wondering that as well. Intuitively I think running two lines directly from the master cylinder would be preferable to the OEM approach due to fewer junctions/connections in the lines, but I have no real-world evidence to back that up.

I do have personal experience in the improvements adding braided steel brakes lines and aftermarket pads can make; years ago I did that on my purchased-new 1991 Hawk GT a year or so after buying it, and the improvement in brake feel and power was massive. It was not a subtle difference. A single Russell line and some Ferodo pads, still the most cost-effective upgrade I’ve ever made.

After I’ve ridden my 2022 MT-07 for a year or so, I’ll probably go the Spiegler/EBC route.

Edited November 25, 2022 by Subito

[Curious kid]

1 hour ago, Subito said:

That’s a good question, I’m wondering that as well. Intuitively I think running two lines directly from the master cylinder would be preferable to the OEM approach due to fewer junctions/connections in the lines, but I have no real-world evidence to back that up.

I do have personal experience in the improvements adding braided steel brakes lines and aftermarket pads can make; years ago I did that on my purchased-new 1991 Hawk GT a year or so after buying it, and the improvement in brake feel and power was massive. It was not a subtle difference. A single Russell line and some Ferodo pads, still the most cost-effective upgrade I’ve ever made.

After I’ve ridden my 2022 MT-07 for a year or so, I’ll probably go the Spiegler/EBC route.

Thank you Subito! Looking to get some SB lines but have only been able to find the alternative front 2 line routing for my 2016 fz07.

[cornerslider]

On 11/25/2022 at 1:36 PM, Curious kid said:

Thank you Subito! Looking to get some SB lines but have only been able to find the alternative front 2 line routing for my 2016 fz07.

I personally run the 2 line system from the master. I can't remember if I went with Spiegler, or Galfer? I know which ever one I went with, I had the option of the 2-line system, or the one-line with a jumper (like OEM). I was told the 2-line system gives a slightly better feel at the lever? Either way, I'm very happy with the choice I made -

[Curious kid]

3 hours ago, cornerslider said:

I personally run the 2 line system from the master. I can't remember if I went with Spiegler, or Galfer? I know which ever one I went with, I had the option of the 2-line system, or the one-line with a jumper (like OEM). I was told the 2-line system gives a slightly better feel at the lever? Either was, I'm very happy with the choice I made ">-

Thanks Cornerslider! Looks like I'm going with the 2-line system. Do the lines basically follow the OEM route and is it held to the frame/forks the same way as well? Thanks again!

[sweetscience]

For ultimate braking feel, add to the mix a radial master cylinder like brembo RCS, Yam R6 or R7.

I'm gonna tweak my brakes come spring time.  Bypassing the ABS and replacing stock with Brembo RCS17 radial master, Core moto custom SS brake lines, and brembo pads.  I'll post an install and review.  

Since the "ready made" SS lines are fitted for a stock master, I wasn't 100% sure they would fit with a brembo setup.  So, I took measurements and I'll be fitting a custom made "T" junction setup for the front brake line.  This I think is the cleanest and simplest routing.  Went with Core moto instead of Spiegler because they never responded to my e-mails.    

Also, add some Stahlbus bleeder valves to make bleeding SOOO much easier.

[cornerslider]

10 hours ago, Curious kid said:

Thanks Cornerslider! Looks like I'm going with the 2-line system. Do the lines basically follow the OEM route and is it held to the frame/forks the same way as well? Thanks again!

Yes, it was a pretty straight forward install -

[klx678]

On 11/25/2022 at 8:29 PM, cornerslider said:

I personally run the 2 line system from the master. I can't remember if I went with Spiegler, or Galfer? I know which ever one I went with, I had the option of the 2-line system, or the one-line with a jumper (like OEM). I was told the 2-line system gives a slightly better feel at the lever? Either was, I'm very happy with the choice I made -

I used to think that, but then after having a fluid dynamics course in my mechanical engineering college classes I learned the facts.   Both line setups would have virtually identical feel if the lines don't have any give, expand.  If they do then the line and jumper would have a slight advantage since less line length is used.   

Once the lines are bled and full of fluid the system works on extremely small fluid movement, you squeeze the lever and the small piston movement is the fluid flow.  Maybe 20cc of fluid moving.   It is the pressure and in a full enclosed fluid system.  According to Pascal's law:

• Any force applied to a confined fluid is transmitted uniformly in all directions throughout the fluid regardless of the shape of the container.   - Just to give credibility and not just from "another guy on the internet", click here  to see Science Direct's site.

You squeeze the lever putting 100 psi against the piston and 100 psi is spread out through the entire brake system, brake lines and caliper pistons.   

So either line system should perform virtually identical and will.  The reason I say that is it follows the science of fluid dynamics and it seems almost every super sport is has the line and jumper over dual lines.  The set up is compact and clean, one line up to the master cylinder and a few ounces ligher using a shorter second line.  

Here is Honda's set up, essentially doing the jumper at the lower triple clamp.  Talk about hardware...

It's almost like the old three line setup using the manifold mounted on the lower triple clamp.   If they could get better feel from two lines down from the master cylinder they certainly wouldn't use this set up.  

So another braking myth put to rest.

Edited November 28, 2022 by klx678

[klx678]

In my previous post just above I neglected to mention the piston relationships in size, because that wasn't really the point of the thread or my post.  But for what it's worth here is the story... and I aced physics class...

 

Force at large piston = 100 pounds.

Pascal’s principle states that any pressure applied to a contained fluid will be experienced at all points throughout that fluid. Thus, pressure generated by the 25 lb of force on the small piston creates a pressure (2.5 PSI) distributed throughout the fluid’s volume which is experienced in full at the large piston to create the 100 lb force there.

Fluid pressure = 2.5 PSI. 

take the  25 lb / 10 sq in = 2.5 lb/sq in      (labels are built like the math, lb/sq in)  

then 40 sq in X 2.5 lb/sq in = 100 lb           (Square inches cancels the label, because the label builds as lb/sq in X sq in/ -  the square inches cancel leaving lb )

That's about the best I can explain it.   

There is more relating to fluid movement, the small piston has to travel four units to move the large piston one unit.  So to move the large piston one inch higher the small piston must move four inches downward.  the small piston displaces 10 ci (cubic inches) for every inch it moves downward and since fluid can't compress the other piston will rise at the ratio of 1:4 which would be .25 movement of the small piston.  so 4" for the small piston would be 4"/4 for the large piston.

The reason why this is important is to realize to increase pressure on the brake calipers of your motorcycle - stronger brakes - doesn't requre a bigger piston, but rather a smaller one since your hand pressure with the lever will be distributed over a smaller area, increasing the pressure you apply.  The negative to this is with the better smaller piston the fluid moved is reduced so more lever travel (piston travel) is required to make the change.  Sounds kinda nuts, but that's the facts jack. 

Now that we have that we suddenly find that not all master cylinders of equal piston size are equal in pressure applied.  It seems wrong that a 17mm piston Brembo master cylinder would work when the stock one is a 14mm.  The difference is in the mechanical leverage of the lever against the piston.  Pretty simple once you realize what's going on.

Now, if you can't fall asleep after that wad of information, go read a physics book.  

Edited November 28, 2022 by klx678

[Triple Jim]

Funny... I just posted a very concise version of that on another board.  A guy had installed a master cylinder with a larger piston and claimed his brakes worked better.  I wondered why he liked the higher lever force for the same braking.  I'm pretty sure the 5/8" master cylinder is giving a terrible feel for his single disk front brake.

[cornerslider]

Okay.... I never claimed to be a fluid dynamics expert . I just posted my thoughts? I'm personally glad that I got the two-line system. My bike is now my dedicated track-only/race bike. With frequent wheel/tire changes, the two-line system is easier to manage. I can remove either caliper very easily, and remove the front fender easily, without the "jumper" line running over the front fender. The brakes on the FZ-07 are built to a price point.... I'm still running a stock master cylinder & calipers on track. I've invested in the best brake pads available, and it suits my needs at the moment. I can appreciate the math/science behind fluid dynamics.  I think on stock/OEM components the math might be a bit "overkill".... For most riders, I think either the 2-line system, or the "jumper" system will work fantastic with upgraded steel-braided lines -

[klx678]

1 hour ago, cornerslider said:

Okay.... I never claimed to be a fluid dynamics expert . I just posted my thoughts? I'm personally glad that I got the two-line system. My bike is now my dedicated track-only/race bike. With frequent wheel/tire changes, the two-line system is easier to manage. I can remove either caliper very easily, and remove the front fender easily, without the "jumper" line running over the front fender. The brakes on the FZ-07 are built to a price point.... I'm still running a stock master cylinder & calipers on track. I've invested in the best brake pads available, and it suits my needs at the moment. I can appreciate the math/science behind fluid dynamics.  I think on stock/OEM components the math might be a bit "overkill".... For most riders, I think either the 2-line system, or the "jumper" system will work fantastic with upgraded steel-braided lines -

I think that's why Honda used the setup they did.  The two lower lines allow caliper removal easer than the jumper line that loops over the fender.   So you score one for the dual lines for racing.   The nice part is knowing both work equally well.

The math was really an explanation how a system works if someone wants to go to a radial master cylinder or the like.  Plus the fact that where a 14mm master cylinder works in one case, but to do a Brembo RCS 17 is what is used in the same situation.   

 

[klx678]

13 hours ago, Triple Jim said:

Funny... I just posted a very concise version of that on another board.  A guy had installed a master cylinder with a larger piston and claimed his brakes worked better.  I wondered why he liked the higher lever force for the same braking.  I'm pretty sure the 5/8" master cylinder is giving a terrible feel for his single disk front brake.

He may want less brake lever travel and doesn't mind less feel or having to squeeze harder with the caliper he has.   It also may depend on which master cylinder he got.  If a Brembo RCS 17 works for the dual calipers a 16 or 15 would possibly work for a single caliper, where a 14mm like the one on the MT or XSR would be too big.  The reason to research.  The information I have on the Brembo RCS I got directly from Brembo when I asked why would I use a 17 on a bike that has a 14.    

Or maybe you're right, he may have screwed up.  Some people are stubborn enough to not admit they made a mistake or just don't have a clue.   For the latter I wrote all that stuff.  And when in doubt contact the manufacturer and ask.

Edited November 29, 2022 by klx678
keying error

[Triple Jim]

He screwed up.