ABS Question

[dave]

Some of our bikes have reached seven years old now, and working on a master cylinder yesterday that had been in storage in my garage for about ten years (that still had fluid in it) that had the piston seize in it made me think about this: What if a seven year old anti-lock brake system NEVER had the anti-lock feature activated - can it be depended on to function properly in an emergency? I do not understand the details of an anti-lock braking system, but I assume there must be some type of solenoid valve that acts to control the pressure and I am wondering if this valve could become stuck from non-use? I have deliberately tried out my front and rear anti-lock brakes just to see how they work, but how confident can we be that a system will function as designed if it is never activated over a course of seven (or more) years?

[Tev62]

It is a good point but I am not knowledgeable enough about ABS systems to be able to answer your question. Given that the master cylinder and caliper can suffer with old fluid and water contamination one would assume the ABS element must subject to the same corrosion.

But I never let my ABS system go unused and regularly test it on a dry day, it is very good practice and gives you a good feel for how far you can push the brakes and how the bike feels when they are in operation.

[the Ferret]

I've never been able to activate the ABS that I can feel and I've braked pretty darn hard a couple of times.

[max]

Same here Tev, the safest way to exercise my abs system is on a flat grassy park with enough room to maneuver safely, the system stops the wheel from slipping but does not prevent you losing balance and dropping the bike so i am careful in that way.
It is also a good opportunity to test the traction control.
testing the front and rear separately at low speed and in a straight line watching the abs light, in my case i can feel the action in the brake handle but have not felt it in the rear brake pedal which does however work, in the past i have used the rear brake on a damp surface and i could see the abs in and release marks in the track behind the rear wheel.

The abs unit has two "channels" one per wheel, ( a car has 4 channels ) each channel has a sensor, a spring loaded expansion chamber, 3 valves and a combined pump.
Briefly if the sensor sees a sudden drop in speed whilst the brake light is activated the first valve stops the flow from the brake handle whilst the second valve releases the pressure into the expansion chamber, when the wheel speed normalizes as a result the third valve re-applies pressure from the pump to slow the wheel down and the cycle continues until the wheel stops or the brake is released enough to allow sufficient traction to resume.

I have yet to convince myself that operating the abs system replaces the resident fluid in it, even with the manufaturer's method ( where would it emigrate to? ) so in the past i have cracked the bleed nipples and connected a clear hose to them in order to catch some fluid escaping the system which would replace the abs block's fluid, it worked but i am working on an easier way to do this by using a nipple with a very small hole in it to allow enough pressure to exist in the system to operate whilst slowly releasing fluid from the nipple into a clear hose during the pressurizing part.

Zam's channel has a 1,5 hr long video in which he completely dismantles an abs block;
https://www.youtube.com/watch?v=XIDuxA2cJiM

So i would advise to test the brakes and watch the abs light from time to time in a safe way for a start.

Bleeding the abs brakes can be done in the conventional way as long as no air is introduced in the lines, if that happens the fluid has to be replaced under constant pressure or vacuum to expel the air, in my case i used a pressure weed sprayer to produce a quick flow of fluid to clear the air out of the system ( plan b ) but i now have a vacuum bleeder to this with.

Just my thoughts.

[GoldOxide_imp]

My CB1100 ABS came on at times on the sandy side streets of metropolis Mississauga, Ontario, Canada. Just a reminder that the city takes their sweet time to clean-up after winter.

[Tev62]

I've never been able to activate the ABS that I can feel and I've braked pretty darn hard a couple of times.

I know what you are saying, with good tyres it takes some doing on the CB. It took me quite a few attempts. The brakes are not as sharp as some bikes and the action is quite nicely progessive.

[dave]

Same here Tev, the safest way to exercise my abs system is on a flat grassy park with enough room to maneuver safely, the system stops the wheel from slipping but does not prevent you losing balance and dropping the bike so i am careful in that way.
It is also a good opportunity to test the traction control.
testing the front and rear separately at low speed and in a straight line watching the abs light, in my case i can feel the action in the brake handle but have not felt it in the rear brake pedal which does however work, in the past i have used the rear brake on a damp surface and i could see the abs in and release marks in the track behind the rear wheel.

The abs unit has two "channels" one per wheel, ( a car has 4 channels ) each channel has a sensor, a spring loaded expansion chamber, 3 valves and a combined pump.
Briefly if the sensor sees a sudden drop in speed whilst the brake light is activated the first valve stops the flow from the brake handle whilst the second valve releases the pressure into the expansion chamber, when the wheel speed normalizes as a result the third valve re-applies pressure from the pump to slow the wheel down and the cycle continues until the wheel stops or the brake is released enough to allow sufficient traction to resume.

I have yet to convince myself that operating the abs system replaces the resident fluid in it, even with the manufaturer's method ( where would it emigrate to? ) so in the past i have cracked the bleed nipples and connected a clear hose to them in order to catch some fluid escaping the system which would replace the abs block's fluid, it worked but i am working on an easier way to do this by using a nipple with a very small hole in it to allow enough pressure to exist in the system to operate whilst slowly releasing fluid from the nipple into a clear hose during the pressurizing part.

Zam's channel has a 1,5 hr long video in which he completely dismantles an abs block;
https://www.youtube.com/watch?v=XIDuxA2cJiM

So i would advise to test the brakes and watch the abs light from time to time in a safe way for a start.

Bleeding the abs brakes can be done in the conventional way as long as no air is introduced in the lines, if that happens the fluid has to be replaced under constant pressure or vacuum to expel the air, in my case i used a pressure weed sprayer to produce a quick flow of fluid to clear the air out of the system ( plan b ) but i now have a vacuum bleeder to this with.

Just my thoughts.

Great write-up Max (as usual). Thank you.