brake problems/ABS????

Hi there. Im on my first VFR, The 2010 1200f. I currently have 12600 on the odometer and i am experiencing a lack of braking power. (Almost rear ended a hard braking car this afternoon. I grabbed a hand full of brake and there was nothing there.) I have checked the pads and there is tons of material left. I am a very conservative commuter lots of down shifting so i am quite easy on the brakes. I have recently had occurrences where i was slowing to a stop and experienced an audible rapid knocking sound that i can also feel coming from the front of the bike also accompanied with a rapid pulsing in the front end. The ABS light is not illuminated nor is there any pulsing in the front or rear levers. Just putting this out there incase any one can help. Im sure this will be a dealership job in the end. Thanks for any and all replies.

 

the ABS system seems to be activating, under normal assistance the ABS light will not light, but if you go into full ABS control the light will come on and stay on until you power cycle the ECU.

if this is happening regularily then take it to a qualified mechanic that has papers on ABS systems- ask to see proof that he/she is qualified!

things you can check yourself that needs no special training or tools:

Break fluid levels, check both resivoirs
make sure your ABS wheel sensors are clean and do not have little peices of metal stuck on the end. The wheel sensor also depends on a notched ring on the wheel. it too must be clean(some dirt is ok but if you have lots of mud it will give false reading. check both wheels sensors.
Your ABS system is identical to the one on the 6th gens(same as my ABS), it uses three sensors and some information from the ECU and monitors the break light circuit, they work on a differential sensor loop. if one wheel says its going faster than the other and the spedo sensor can only confirm one speed then the ABS will activate as soon as you grab the break. There are some pressure sensors in the ABS unit that the ABS computer that monitor hydraulic pressures but you cant fix/adjust these.

Basically there is not much you can do with an ABS system without the proper tools as you do need the data reader for your bike to do the tests and to find out what the ABS unit thinks is going on.

Hope this helps

 

Thanks. I did check all those things to no avail. I left out that the bike has been doing this for the past 6K miles. But it has been so intermittent never could make the bike repeat the scenario and it never affected braking performance till now. I also figured out through some performance tests today that i can apply the front brake lever independently all the way to the brake stop and the bike will not lock trip the ABS nor will it lift the rear tire and braking performance is less than impressive at this point. The brakes on this bike was a feature that blew my mind coming over from sport bikes. I was amazed at the brake performance of this bike, not so much now... Thanks really.. Going to the dealer it looks like..

 

before going to the stealership, try bleeding the brakes, use a baby food jar and a bit of vacuum hose. bleed it a few times just to be sure you get the bubles out and make sure you keep the resivoir topped up during this process. there should also be a linked braking line, you will need the tech book for the vfr1200(might be the same as the vfr800 6th gen) to get the bleeding instructions for that, then do the back brakes.

its a simple and fairly painless thing to try, since the brake fade your experiencing has been happening for ~6k miles

If you rode through a puddle or in the rain you could have gotten oil on the pads, this will cause a similar effect as the ABS but will not be as effective. You would not be able to see a light oil contamination on the stock pads and the rotors can look clean even when throughly coated in oil. So if your planning to change to better pads(EBC? so worth the money IMO) then now would be the time to do so. try changing the pads and wash the rotors off with dish soap and water(lots of suds) then rise, dry and spray off with good quality brake clean(never use oil cleaners).

If all else fails then off to the stealership you go and make them try stoppies until it does it.

 

Yeah according to the service manual im up for a brake fluid replacement any way. Im a Diesel mech by trade so its not a difficult task. I have a good Vac Bleeder. Ill get on that in the morning. I have experienced no brake fade till today, thats the reason for so much concern now. But the pulsing and vibrating has been happening like once or twice every 1K miles and it was always for just a couple of seconds then it would stop. Thanks again...

 

I have some expeirence with automotive ABS sytems and it sounds like the system is working, just in unwanted conditions. Pulse ring is aboot the only thing that can cause this and not flag a ABS light. I may me dead wrong but would be looking at a blemish in the ring on one of the wheels myself.

 

the pulse ring is where I would start. as this ring causes the sensor to make an AC voltage at a frequency and voltage that is equal to the rotational speed, it would take a chunk missing or filled in to make the abs do weird things and not throw a light, the speed sensor works on a similar theory, but the ABS gets its speed signal from the ECU. you must have all three working to make the ABS work properly, a difference between the speed sensor and the rear wheel sensor will not always throw a light due to the mechanical link between them, but will cause the ABS to not work at all.

Another thought is that the computers on your bike only need to see half the signal, that is if one wire is broken on the sensor, any change in speed is a masive change in signal as there is no reference. you can check the sensors by lifting the wheel and using a good(read fluke 117 or better) VOM meter on AC voltage, expect anything up to 90vac as normal past 90vac is possible but not usually used. What is important in this test is that both wheels are the same +/- a few volts. If your VOM does frequency like mine does, then the frequency must be the same for each wheel for a given rotation speed. use a constant speed motor to drive the wheel during measurements. This is about the last test you can do without connecting to the computer. and if you dont know uch about how ABS actually works then going beyond this becomes difficult (and a liability issue if you kill your ABS).

I hope this points you in the right direction, just remember to take it one step at a time and make notes of what you see and of all measurements you make.

 

Good stuff to know there. I was out this morning and rode down a dirt road and intentionally tripped the ABS both front and rear independently and it functions without flaw. Quite seamless actually. Does the ABS light illuminate only when there is a fault in the system? Because it never even flickered while the bike was no doubt working to not lock either tire.

Another thing pertaining to the speed sensor.... I am running a 190/50 on the rear as opposed to the 190/55 that comes on the bike. Is this enough to make it act up?

 

Gravel roads are not enough to go into full ABS, it engages but not to 100%. if it did you'd be on your side or off the road. ABS is designed to provide more stopping traction under normal conditions on normal roads. To do that test you need to lock up only one wheel and watch the light. If it doesnt come on while in hard use then something is wrong.

you might need the computers wipes (full reset) as they learn what is normal. if you rode a while before the -5 (!!) swap then your computer would think its on the brink all the time. Note only dealers with an ABS qualified tech/mech can reset the ABS computer fully. If you have the old gears then swap back and see if the problem goes away. remember the speed sensor is on the drive gear shaft (small sprocket) and the ABS sensors are on the wheels, the rear wheel speed is double referenced with both the speed sensor and the wheel sensor. these are called constants, the computer can use these to know exactly what is going on.

 

Well im not sure any more. I removed the calipers and hosed the pads down with brake cleaner and proceeded to clean the crap out of the rotors with hot soapy dish detergent. I have since regained most of the bite the bike used to have but not quite like new. I checked out the rings and the sensors all clean and immaculate. Guess the pads just lose their effectiveness over mileage. I will take it in and have them flash or clear the ABS system and see if that fixes the pulsing, which by the way as not occured since we last talked and ive been on the bike all day in city traffic. Thanks for all the help thus far, it was much appreciated.

 

Hi
I have a Genuine workshop manual which shows how to get the bike to tell you what the problem is by putting a jumper lead across 2 pins. The ABS light flashes a sequence which you look up in the manual.

 

Hi
I have a Genuine workshop manual which shows how to get the bike to tell you what the problem is by putting a jumper lead across 2 pins. The ABS light flashes a sequence which you look up in the manual.

 

I've experienced this (lack of braking power) with contaminated pads. No matter what I did to clean them, even filed the surface, they never had the same bite that they once had. Installed a fresh set of EBC pads and it was like a new world.

 

Zombie thread, guys.