Possibly embarrassingly ignorant brake question.

[Canyon Runner]

Hello.

32K, 2005 R1150R, Non ABS.

A couple of times recently, I am starting to brake and the front brake lever travels farther in its range of motion than normal before engaging. Once I get into the brake, it seems all there, just as sure footed and efficient as always, but instead of engaging at the beginning of the lever travel, it is engaging at midway into the travel. Intermitant symptom. The brakes will function in the familiar way and then once in a while I will get the lever pull with increased travel.

Dealer did an annual at 31 K (Last service on a service program).

Is this what is sometimes referred to as "spongy" brake behavior? Is this consistent with a braking system that is need of bleeding? (Could this be cause by air in the lines?)

I have checked the brake fluid per Owners manual and service guide, nothing seems abnormal there. And the fluids should be new, per the annual.

Long story short, I am taking it in for service, because brakes are nothing to trifle with and I am not yet confident enough to jump in. But in the interest of being able to "interpret the interretation" that I get from the dealer, I am hoping that maybe someone on here might be able to educate me a bit about possible causes of this type of behavior.

Cheers, all!!

-Kyle

[MIXR]

Kyle,

My R1150R (2001 non-ABS 100,000 miles) did that from a very early age. Sponginess is genearally air in the system. The softness you feel could be that, or it could be just the softness in the non-braided brake hoses. Worn pads will also give you more lever travel as the fluid level drops and more 'space' is created in the reservoir. There was nothing wrong with my brakes, so I lived with it. I never liked that aspect, but it wasn't worth chasing a fix at great expense when the brakes actually worked fine, particularly in the hills where they were always pumped up. What I have noticed on my R1150 GS Adventure is that the braided brake lines have no 'give' and that the brakes are far more positive. Again, it's a non-ABS model.

By all means go ahead and check your pad wear, do a brake bleed (easy process), and check your rubber brake lines for any deterioration, but otherwise, .................

When you check your brake lines, do it with help. Let the bike 'rest' for a while, so everything is relaxed in the brake system. Have a helper do a single hard pull on the brake lever and hold it. You need to grab the rubber hoses on the brakes and feel for any ballooning of the hose. That means the pressure exerted by the brake system is being expended on the least line of resistance and trying to stretch weak hoses rather than operate the brake pistons. Result is a soft feel to the brakes, and extended lever travel. The ballooning will be very slight.

Also check your brake pistons and calipers for free and easy operation (with pads in place!!!!!!!). Sticky or binding calipers/piston slides will also mean that the brake pressure will go elsewhere. Or try too. Same result - Pressure is 'used' on things other than actual brake operation.

That's as good as I can get on this. Good luck, Mick.

[towerworker]

A very good and descriptive response from Mick.

Wayne

[iowabeakster]

Rubber brake lines might feel a tiny bit spongier (most people would not notice), compared to steel brake lines, but they should always be consistent. The real benefit to the steel brake lines, is they don't allow as much water to absorb into the fluid (less frequent fluid changes), they are less prone to splitting or rupture, and they last longer.

The sometimes-there-sometimes-not sponginess is almost certainly some air in the brakes. Possibly, there could be something wrong with the master cylinder.

I would bet on air.

I (respectfully) disagree with MIXR about the brake pad thickness idea. The pistons extend to compensate for the loss of brake pad material. The pistons don't retract when the brakes are released. They simply stop pushing. They never retract. That is why you hear the light rubbing noise (pads against rotors) when you spin the wheel, when the bike is on the center stand. The pads should always be in contact with the rotor, however new or old they may be.

Assuming that it is air (I'm risking making the ass out of myself)...

The thing that would worry me, is how or why the air got into the brakes to begin with. I hope the dealer fully investigates. They can bleed the air out easily, but is it going to happen again next year? I would ask questions at the dealer to find out what they did to investigate. I would start the conversation, "how did I get air in my brakes, in the first place?" Hopefully, they will describe what they did to answer that question.

[sweatmark]

Rubber brake lines might feel a tiny bit spongier (most people would not notice), compared to steel brake lines, but they should always be consistent.

I agree with this, based on years of riding R1150R Roadster (with rubber brake lines), and then more years riding Rockster (with steel shrounded lines, with and without iABS)... both systems provide solid brake feel at the lever as long as there's no air in the system.

[MIXR]

Iowa - I don't particularly disagree with your comments either, but one of the functions of a floating disk rotor is to float. The R has thin wave washers that allow this, unlike most race bikes as some other performance rotors where the rotor can just clang around with no restriction (no wave washers). The subtle flexing of the rotor on the wave washers allows for some piston retraction. I agree absolutely that they do not forcibly 'retract', but they do get pushed slightly back into the caliper as the floating disk rotates. All I am saying is the slight initial movement that takes up the 'slack' generated by the spring in the wave washers can be percieved as 'air', or something else. I bled my brakes many times to remove what I thought could be air. It wasn't. It was just old hoses 'giving' a bit under pressure and a bit of tightness in old and tired slide pins and pistons. They still do that, many tens of thousands of kilometres later, but far less evident after a good clean and re-grease of the slides. You are correct - You should not be able to pick this, but if you can, then it may be an old or weak hose or just some stickiness.

It's a bit like tapping on the top of the kitchen table. If you have a hand underneath, you won't feel much (if any) movement, but you will still feel the tap. Holding the soft rubber hoses is similar. You will (or may) feel the initial pulse of a hard brake application. Nothing sinister here, but I've spend a lot of time chasing 'brake' problems with my bike over the years. I still think that it's not air and would be checking the slides and pistons, even if that means forcibly retracting the pads a few mm and then operating the brake lever. Do the pistons all move together with no delay on both sides? If they don't, look for something binding. If nothing is binding, look for a soft hose. If nothing is wrong with the hose, look at the master cylinder (which is a much bigger deal).

Cheers mate, Mick.

[iowabeakster]

Mick,

I agree with that, and most all the above advice. If the rotors' wave washers are missing/broken, or the rotors warped, the wobbling rotors could wiggle the pads and pistons back. That could cause increased lever travel before engagement. We are on the same page here. I originally wrote something about the rotors, then changed my mind and deleted it.

I deleted it because he did not describe any typical symptoms pointing to the rotors (noises, pulsation). I thought by mentioning the rotors, I might be heading into territory that didn't need to be explored. Who knows? That could certainly be it. He might not hear any noises due to earplugs, wind, etc.

I was just trying to keep my suggestions strictly confined to the symptoms that were given. If the rotors were causing the problem, I figured he would have noticed and mentioned some symptom to point along that path.

The normal inherent "float" of our rotors, however, should never cause the engagement point to be altered, at least not in any way the rider should feel the difference.


What I disagreed with was this statement.

Worn pads will also give you more lever travel as the fluid level drops and more 'space' is created in the reservoir.

Respectfully, I still maintain worn pads do not affect the engagement point. I am only being persistent about this, because he said he wanted to better understand how these things work.

The fluid level in the reservoir will drop as the pads wear, as MIXR said. That is true. As the pads wear, more fluid is now going to be down in the caliper, and less in the reservoir. That is because the pistons, in the calipers, will be extended farther to compensate for the worn pads. That lower level of fluid has absolutely no bearing on braking, or the engagement point. The reservoir was designed to be big enough, to accommodate the drop in fluid (from pad wear), and still keep the master cylinder and piston fully submerged.

The master cylinder and piston (which are underneath the reservoir) are always fully submerged in the brake fluid (as long as it was filled to the proper mark). It is the pressurized brake fluid, created in the master cylinder, that makes the brakes work. This pressurized fluid is created by squeezing the lever (thusly moving the piston in the master cylinder). The amount of fluid (or "space") in the reservoir, up above, has no bearing on this fluid pressure created the master cylinder. Whether there is 1oz or 2oz or 3oz (or corresponding amount of "space") of unused fluid above in the reservoir, it makes no difference to what is happening in the master cylinder.

[momentman]

To the question of air in the lines of a non abs 1150r would be worth noting Canyon Runner that its worth checking the bleed point at the (redundant) ABS connection point near the head stem RHS ( ie where the upper and lower main hoses join) i have found trapped air at this point causing sponginess. You will find a bleed point there. Its a pain to get at, is easy with tank off.


re mixr beakster discussion, i would agree with beakster, this was the main innovation of hydraulics after all, self adjusting.

Again respectfully, my opinion is that the brake pads withdraw infinitesimally on the basis of the elasticity of the piston seals after the brakes are released

Reg

[MIXR]

Agreed guys - Bad choice of words by me. I hope that hasn't muddied the waters too much with all the explanations.

[AirForceDirt]

Since no one seems to have paid attention to the first line of the original post, the bike is a 2005 roadster, so there are no rubber brake hoses, they are all braided steel, on all the 1150Rs after the 2004 model year. Bulging lines is nearly impossible, pad wear wouldn't lead to an as noticeable condition as what was described, so somehow, the brake system is getting air in it, so bleed it, get new pads if they didn't get done at the dealership, and see if it happens again. My guess would be, the fluid didn't get bled at the dealership if they didn't do anything on the brake system, brake fluid, I believe, is a bi-annual thing.

[Canyon Runner]

Very educational stuff, all. Thank you so much for taking the time. Regardless of what I learn about what needs to be fixed this time around, I have learned a lot about the system from reading your responses and experience. Thanks!

I was pausing a bit on response, and maybe should hold off a bit longer, as I am waiting in line to get it into the shop. I am crossing my fingers for the air in the line scenario, but I do have a bit more information, and possibly a follow up questioon.

First of all, the lines are, indeed, the braided metal variety, so I think I can cross off hose flex from the list. The pads do bear investigation, but the fact that the behavior of the lever and point of engagement varies noticeably between a normal pull, and an abnormal pull, often occuring immediately after one another, I am not sure I can wrap my head around the pad status changing signficantly between the two brake lever pulls.

But I did end up getting out on a ride (albeit a cautious one) and noticed the symptom again. Again, wasn't on every engagement of the front brake (by a long shot), but when the lever behaved "abnormally", the brake system did not engage until noticeably later in the travel of the lever, just as I mentioned before. The new piece of information is that, without exception, simply releasing the lever and reengaging it seemed to return the lever and braking systems to normal functionality. Is this also a characteristic of brakes with air in the line, this "pumping" of the lever seemingly correcting the issue?

Seems strange to me , really, in that there didn't seem to be a meaningful relationship between the time between brakings and the abnormal behavior (in other words, it wasn't an issue where the abnormal behavior happened more or less often after an extended period of time with no brake activity...it just seems "random", like, all of a sudden, I'll reach for the lever and it will travel a lot father before engaging, sometimes soon after a previous occurance, sometimes after several normal engagements, soetimes after a pretty long time). Can air in the line be sort of "ghost in the machine" like this, or is this description starting to sound like something else? Also, can it show up after a while (for example, if the Dealer (I will check) replaced the fluid about 1K ago, is it reasonable to assume that the symptom might have "slept" until now? I have been closely monitoring the bike (fittings, reservoir, etc) and the floor of the garage below it and have not noticed any leak or bleed, at least in its home position.

Anyway, and primarily, thanks for all the help and advice. I should be able to get the bike into a shop soon and will certainly post about what I learn. Until then, all speculation welcome!

Cheers!

-Kyle

(P.S. If it provides any additional clues, I have not experienced any other ancillary symtoms (pulsing, noise, etc etc) from the braking system, only the abnormal brake lever behavior.)

[iowabeakster]

Is this also a characteristic of brakes with air in the line, this "pumping" of the lever seemingly correcting the issue?

Yes. That is the most defining characteristic of air in brakes.

When I was in college, I bought a 1982 corolla (300 bucks!). It was a total junker. I didn't have any place to work on it myself, and had no money to pay a shop. I sometimes had to pump 3 or 4 times to make the brakes engage. Sometimes they engaged on the first pump, that would happen quickly after a 3-4 pump application.

I drove the car for a year, and got 500 bucks when I traded it in. I did not spend one cent on maintaining it (not even an oil change). It was the best car value I ever encountered.

[Canyon Runner]

Sweet! Thanks for all the patient explanation, all. You guys are truly gems!

Cheers!