Brake fade

[PastorCurt]

We were riding through the Bighorn Mountains in Wyoming today and when we were halfway down the rear brake decided that enough was enough and went away! I used front brake sparingly and a lower gear and made it safely to flat land! I have the organic brake pads on it, would semi- metallic have not faded?

[BlueSky]

It could have been caused by the brake fluid boiling.  Dot 3, 4, and 5.1 are compatible with our systems and can even be mixed.  The higher the Dot # the higher the boiling point but also the higher the number, the more likely it is to absorb water.  

[vzuden]

Have you changed the brake fluid lately?   Should changed every 2 years (clutch fluid too)

[djh3]

+1 on fluid flush with DOT4. I had same thing happen in NC years back. We were following a flatlander that evidently had not driven in mountain's and rode the brakes going down the mountain. I ran up on him because he was slowing in goofy places pretty hard. So I had to brake more than I had and I lost the rear brakes. When we got back to Fla I flush and filled and have never had an issue since. Every couple years I do this.

[Papa Fred]

Add me to the "probably brake fluid boiling" club.  Couple of years ago, I spent some quality time in a large parking lot working on basic ideas from Motorman Paladino's playbook I've practiced over the years.... low-speed stuff in the friction zone with light rear brake..u turns, tighter u turns, circles, high speed panic stops etc.  After a steady 5 minute session doing The Intersection turns, the rear brake took a holiday.  No pedal feel and no brake.  I let the bike sit for a few minutes then did a few brake-free trips around the parking lot.  Brake came back, and I flushed the brake line and Master when I got home.  Fresh, clear fluid makes for happy brakes (and clutch).

[saddlebum]

All of the above are true. I have switched to I switched to the  Bosch ES16 brake fluid and have noticed quite the difference. Even clutch and brake response has improved. It has a higher boiling point both wet and dry. Wet boiling point is the temperature boiling begins to occur when brake fluid icontains a certian amount of moisture. Dry boiling point is when there is no moisture present in the brake fluid. See attached link https://www.boschautoparts.ca/documents/101512/0/0/7c8c2217-78dd-0adc-c840-91edb62866a3

Also organic brake pads can be an issue as well because they have a greater tendency to glaze over at lower operating temperatures then other higher end friction materials.  Glazing is what causes brake failure  and once pads are glazed over they loose much of their friction ability and so stopping ability becomes compromised. Organic pads are easier on rotors and are very good for in town driving because initially they grab better than other materials. But in hard braking situations like riding hills or pulling a trailer they begin to glaze over and loose their braking effectiveness.

 

Edited September 10, 2021 by saddlebum

[PastorCurt]

Thank you all for the input! I had the missus on the back and she wasn’t a fan of mountain riding anyway! I did not tell her about the missing rear braking. When I got the brakes cooled they are back to the way they were and haven’t had any more problems. Will be changing the brake fluid when I get home!

[djh3]

Mine did same. I made it to a pull off at a parking area, sat 10-15 min and everything was fine the rest of the trip, although I did pay way more attention to my brake usage. I tried a carbon fiber pad and I actually had to learn to drag the brake to get heat to make them work well. Not conducive for most around town driving.

[saddlebum]

8 hours ago, djh3 said:

 I tried a carbon fiber pad and I actually had to learn to drag the brake to get heat to make them work well. Not conducive for most around town driving.

This is quite common. Often pads which withstand higher operating temperature quiet often need to heat up to a certain temperature before they become fully effective. This is why you will often see stock car drivers ride their brakes before a race in order to warm them up so they have maximum brake effectiveness  during the race also another reason why just because something is used on the track does not mean it is good for everyday driving. I have also known brake pads that have amazing stopping power but loose 50-70% of it when the rotors are wet and cold. When asked I generally tell people unless their vehicle is constantly heavily loaded, pulling a trailer or running hills constantly not to buy the high end pads but stick to something closer to the middle range and for that Sunday driver or the person who only gets out once or twice a week to do a bit of shopping the cheap organic pads are probably their best choice since at slow speeds softer pads stop better and there is little or no metal in the pads to rust from sitting and metallic pads do corrode even crumble and fall apart from lack of use due to a vehicle spending more time parked than driven. Believe me its no fun trying to convince a person that the brakes on their car are scrap even though they barely have any millage on them.

[Woody]

Amazon sells a brake fluid pen to check the moisture content of brake fluid. I got one because I lost my clutch on a ride last month I went ahead and flushed all fluids 

[Condor]

What's happening to a rear RSV brake with old DOT 3 is the moisture in the fluid is boiling at 212degs.  Far below the rated boiling point of new fluid.  This basically has the same result as air in the lines. With clean fluid you won't have the fade problem....