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[DonTom]

Several days ago, I noticed I had very little rear brake on my 2020 SS9-.  Pedal had to be all the way down to get just a little brake.


It was obvious to me that it needed bleeding very badly.


So I used a trick that I have been doing on my 1984 Yamaha Venture, where the rear brake always needed bleeding if the bike was not used for several weeks.


I discovered that when the bike is not used, if there is pressure left down on the brake pedal, it will bleed itself, but it could take a couple of days. On my Venture, whenever I am not using the bike I jam a thingy in there to hold the pedal down.  That keeps the rear brake like new at all times.


It was a little more tricky to find a way to keep the brake pedal down on the Energica, but I found a way to do it with small bungie cords going from the brake pedal to under the right brake foot peg to a vent  hole in  the rear brake  disk. But the idea is simple, keep the brake pedal down overnight or longer any way you can, with a little downward pressure and get all of the rear brake power back.


But be sure to remove all the stuff before riding!


I rode the Energica here to Auburn from Reno today (with a free CCS charge at the Donor  Summit  Rest Area) and the difference in the brake was very obvious, like new again.


Perhaps those who keep max regen don't use the rear brake much, but I prefer very little regen on most of my rides, so I get more use out of the rear brake. But IAC, you want the rear brake to work normally, and above did the trick for me.


-Don-  Auburn, CA

[staples]

This just sounds bad. Generally the reason brakes need to be bled is too remove compressible gases out of the enclosed hydrologic system. If it consistently needs to be bled that would lead me to believe that there is a way for new air to enter the system. Have you checked all the connections and components for signs of a leak?

It's also curious that you say by having the brake lever engaged it corrects this issue. Perhaps there is something wrong with the master cylinder.

[DonTom]

This just sounds bad. Generally the reason brakes need to be bled is too remove compressible gases out of the enclosed hydrologic system. If it consistently needs to be bled that would lead me to believe that there is a way for new air to enter the system. Have you checked all the connections and components for signs of a leak?

It's also curious that you say by having the brake lever engaged it corrects this issue. Perhaps there is something wrong with the master cylinder.

Of course if air can get out, it can also get in. But in my 1984 Venture, I rebuilt the entire rear brake system and it made no difference. Every seal was replaced in the master and slave cylinders. I first noticed the issue when the bike was still quite new. So I decided it was always that way, perhaps a design issue. 


It took me more than two years to have the same issue with my Energica. And so far, only one time.



Have others here noticed they needed their rear brakes bleed in their Energicas after a couple of years?


If it lasts another two years, IMO, it is not that big of a deal. Perhaps time to change the brake fluid by then anyway.


-Don-  Auburn, CA

[Crissa]

If you did that on my Mazda, the brakes would stop working.

I know this because I stupidly used the brakes with the engine off while in traffic one day.  After fifteen minutes, the brakes no longer worked.

-Crissa

[DonTom]

If you did that on my Mazda, the brakes would stop working.

I know this because I stupidly used the brakes with the engine off while in traffic one day.  After fifteen minutes, the brakes no longer worked.

-Crissa

I wonder what would cause that.  That even sounds dangerous, if your engine dies as you're driving, you cannot use the brakes?


 But what usually  happens is the brakes and steering become much more difficult as the engine helps provide power to both while it is running.


-Don-  Auburn, CA

[Crissa]

How often do you continue to drive for fifteen minutes constantly using the brake after the motor stops?

I can't imagine they thought of that use case.

-Crissa

[DonTom]

How often do you continue to drive for fifteen minutes constantly using the brake after the motor stops?

I can't imagine they thought of that use case.

-Crissa

I misinterpreted what you said.  But even after 15 minutes, are you sure the brake will not work if you press down very hard?  My guess is what is happening is you're losing the vacuum for the POWER brakes in 15 minutes. The brake should still work, but you would have to press down VERY hard, especially at a slow speed with the engine dead. It will brake better at a faster speed.


Much like what happens with the steering when the engine dies. It still works, but takes a lot more muscle, especially at slower speeds.


-Don-  Reno, NV

[Crissa]

Yes, the pressure was slowly released until the brake failed.  I had to resort to the parking brake and restart the car to get pressure restored.  Apparently they bleed themselves the opposite of your Venture - they can be weak, but will get stronger over time as the motor runs and they're pumped.

-Crissa

[Demoni]

Leaving a brake lever depressed for a few hours is a good trick to remove any micro air bubbles from the system.

If your brake pedal feels soft I would suggest flushing out the old fluid for fresh stuff. Brake fluid is hygroscopic and will absorb moisture over time. Brake fluid is non compressible but the water it absorbs is.

Quickest way to flush the rear brake system is to remove the cap on the master cylinder (22mm wrench) and suction out the fluid (normally use a syringe). Top the reservoir up with fresh fluid and do the standard: pump, pump, open caliper valve, close valve. Continue the process till the fluid flowing out the valve is clear. Just make sure you keep the reservoir topped up to prevent air from getting into the system.

[DonTom]

Yes, the pressure was slowly released until the brake failed.  I had to resort to the parking brake and restart the car to get pressure restored.  Apparently they bleed themselves the opposite of your Venture - they can be weak, but will get stronger over time as the motor runs and they're pumped.

-Crissa

But are you sure it failed? The norm would be a very hard brake pedal that will still work.


-Don-  Reno, NV

[Crissa]

Am I sure the car started rolling down the hill with a mushy pedal?

Yes, I'm sure.

It was just an anecdote, geez.

-Crissa

[DonTom]

Leaving a brake lever depressed for a few hours is a good trick to remove any micro air bubbles from the system.

If your brake pedal feels soft I would suggest flushing out the old fluid for fresh stuff. Brake fluid is hygroscopic and will absorb moisture over time. Brake fluid is non compressible but the water it absorbs is.

Quickest way to flush the rear brake system is to remove the cap on the master cylinder (22mm wrench) and suction out the fluid (normally use a syringe). Top the reservoir up with fresh fluid and do the standard: pump, pump, open caliper valve, close valve. Continue the process till the fluid flowing out the valve is clear. Just make sure you keep the reservoir topped up to prevent air from getting into the system.

Mine no longer feels soft after getting the air out by the simple method.


BTW, in some large  ICE touring bikes, the rear brake line runs over the engine to the front brake, as in my 1984 Venture.  The engine gets hot and makes those air bubbles expand. So it's possible for the brakes to get worse as the day warms up if there are  any air bubbles in the brake line. I just wanted to pass that on.


-Don-  Reno, NV

[tpproberts]

I, too, lost the rear brake on my SS9-.  I have a garage full of power bleed tools but took it to the dealership - thinking I was helping with a possible recall.  Nope - the charged me $100 to bleed that minuscule 20ml reservoir!  But I ride with maximum regen and rarely touch any brakes except at stop lights.

[DonTom]

I, too, lost the rear brake on my SS9-.  I have a garage full of power bleed tools but took it to the dealership - thinking I was helping with a possible recall.  Nope - the charged me $100 to bleed that minuscule 20ml reservoir!  But I ride with maximum regen and rarely touch any brakes except at stop lights.

That's the problem. If the rear brake isn't used much, it will accumulate more air. And with all the regen, it isn't used much.


-Don-  Ashland, OR (RV trip with my Zero DS)