[mcantar]

From searching it would seem that Ducati/Brembo has an issue with making rear brakes that actually brake. Unfortunately every thread I've found degenerated within the first few posts into "you shouldn't be on your rear brake so much" or "the rear brake isn't supposed to work, let me go back to jerking off on my Ducati Performance tube socks".

Anyway. The rear brake on my 1100S is absolutely worthless, won't even keep the bike from rolling down my driveway unless I have my full weight on it, let alone lock up the rear wheel for funsies which I sometimes like to do.
I've bled it a few times (and I use some high-dollar fluid), the pads aren't glazed over, calipers don't need rebuilt, etc. etc. etc. If it was some normal shit I'd have fixed it already.

Has anybody figured out what the common issue seems to be? Is the piston diameter or stoke too small/short or something? Are there Jap bikes with Nissin or Tokico brakes use the same bolt spacing for the master cylinder we could borrow from? What's the fix for this?

 

[Sheff928]

I agree with you that excuses are often made for poor rear brake performance - it ranges from it being a 'safety measure' and 'designed in to the system' to personal preference for using only trail braking... Me? I like things to work as they should.

On all of my bikes, very heavy application of the rear brake will lock up the wheel in motion. The most effective brake is on my 907ie, and it was a surprise when I found how good it was. It made me turn my attention to my ST4S which had the commonly experienced poor performance.

My remedy was to remove the caliper, clean it, and make sure the pistons were moving freely; remove any glaze and/or contamination on the rotor by cleaning it with emery tape, clean carefully afterwards; de-glaze the pads by scrubbing them in a circular motion on a rough surface until clean. Check adjustment at the lever and make sure that there is the correct amount of freeplay before engagement. I finished off with a fluid change.

Result: great performance, the wheel will lock up if I decide to make it do so. Obviously my overall braking performance has improved - and that was the object of the exercise.

 

[1198SP]

So far, the rear brakes on all 3 of my Ducati's has had the same issue. The solution for me was to remove the rear caliper and flip it so the bleed nipple is on top. Then I place a piece of old bar stock that's about the same thickness as the rotor, in between the pistons and then I flush/bleed the brake system as usual. I can lock up the rear brake on both my 1198 and Diavel without any issue whatsoever.

 

[Spex]

Yup, what @1198SP said.

There's nothing wrong with the rear caliper, but the mounting is flawed. Once there's air in it, there is literally no way to bleed it out with the caliper in place because the bleed nipple isn't the highest point in the system.

I went through this same journey of discovery when I first switched over from sensibly-put-together Japanese bikes, but since I started doing it right my rear brake has been lock-at-will.

So my process with the rear brake:

1) Don't get air in the system. I use a pressure bleeder, which I find has less scope for me to stuff it up.

2) If you do get air in the system, then take off the caliper and bleed it upside down so the nipple is at the highest point. You can do this by elevating it (wedge something between the pads like 1198SP suggests) or even just mount it at the top of the rotor. Tap the line to make sure all the air gets to the nipple, bleed, reinstall.

3) You might also get a bubble near the top of the MC. It has no bleed nipple as stock, but you can bleed it by pumping the pedal and cracking the banjo bolt open just long enough to get the bubble out. Pack the surrounding area with rags to catch the fluid.

You don't have to do all of this, but hopefully you get an idea of how easily air gets trapped into this setup and how you might go about getting it out.

 

[rob1botes]

I was never overly happy with my rear brake on the Hyper. Two weeks ago I switched from the stock Brembo pads to EBC HH pads. Well for me it is like night & day...I actually have a rear brake again...& It will lock up very easily. The Brembo pads had great longevity, but for me that's all. When the stock Brembos up front wear out, I think I'll go the EBC route with them too.
Cheers Rob

 

[jahjah]

From searching it would seem that Ducati/Brembo has an issue with making rear brakes that actually brake. Unfortunately every thread I've found degenerated within the first few posts into "you shouldn't be on your rear brake so much" or "the rear brake isn't supposed to work, let me go back to jerking off on my Ducati Performance tube socks".

Anyway. The rear brake on my 1100S is absolutely worthless, won't even keep the bike from rolling down my driveway unless I have my full weight on it, let alone lock up the rear wheel for funsies which I sometimes like to do.
I've bled it a few times (and I use some high-dollar fluid), the pads aren't glazed over, calipers don't need rebuilt, etc. etc. etc. If it was some normal shit I'd have fixed it already.

Has anybody figured out what the common issue seems to be? Is the piston diameter or stoke too small/short or something? Are there Jap bikes with Nissin or Tokico brakes use the same bolt spacing for the master cylinder we could borrow from? What's the fix for this?

Yes, it is a circle jerk. If you can stand on the brake without bottoming the pedal out, you are getting the force to the pad, regardless of air pockets. The air bubble just acts like a spring, the spring still has to be grounded. Since bottoming out should be obvious to you, sounds like you have defective or contaminated pads. If you are bottoming the pedal out, obviously you are not applying the force to the pads and you need to follow the bleeding suggestions that have accompanied every previous discussion. Personally I would just hoist the front of the bike up until the nipple is high. If you have race pads installed, they will need to build heat before they become effective.

 

[mcantar]

I agree with you that excuses are often made for poor rear brake performance - it ranges from it being a 'safety measure' and 'designed in to the system' to personal preference for using only trail braking... Me? I like things to work as they should.

On all of my bikes, very heavy application of the rear brake will lock up the wheel in motion. The most effective brake is on my 907ie, and it was a surprise when I found how good it was. It made me turn my attention to my ST4S which had the commonly experienced poor performance.

My remedy was to remove the caliper, clean it, and make sure the pistons were moving freely; remove any glaze and/or contamination on the rotor by cleaning it with emery tape, clean carefully afterwards; de-glaze the pads by scrubbing them in a circular motion on a rough surface until clean. Check adjustment at the lever and make sure that there is the correct amount of freeplay before engagement. I finished off with a fluid change.

Result: great performance, the wheel will lock up if I decide to make it do so. Obviously my overall braking performance has improved - and that was the object of the exercise.

Thanks for the input. Hopefully it won't come to rebuilding the caliper but if it does, is there anything odd about these that I should be aware of?

So far, the rear brakes on all 3 of my Ducati's has had the same issue. The solution for me was to remove the rear caliper and flip it so the bleed nipple is on top. Then I place a piece of old bar stock that's about the same thickness as the rotor, in between the pistons and then I flush/bleed the brake system as usual. I can lock up the rear brake on both my 1198 and Diavel without any issue whatsoever.

Yeah I'd noticed the less-than-ideal bleed nipple positioning, and reverse-bled the system with a syringe in order to prevent it being an issue. Do you think it'd be worth positioning the caliper as you did and bleeding it the "normal" way after doing that?

Yup, what @1198SP said.

There's nothing wrong with the rear caliper, but the mounting is flawed. Once there's air in it, there is literally no way to bleed it out with the caliper in place because the bleed nipple isn't the highest point in the system.

I went through this same journey of discovery when I first switched over from sensibly-put-together Japanese bikes, but since I started doing it right my rear brake has been lock-at-will.

So my process with the rear brake:

1) Don't get air in the system. I use a pressure bleeder, which I find has less scope for me to stuff it up.

2) If you do get air in the system, then take off the caliper and bleed it upside down so the nipple is at the highest point. You can do this by elevating it (wedge something between the pads like 1198SP suggests) or even just mount it at the top of the rotor. Tap the line to make sure all the air gets to the nipple, bleed, reinstall.

3) You might also get a bubble near the top of the MC. It has no bleed nipple as stock, but you can bleed it by pumping the pedal and cracking the banjo bolt open just long enough to get the bubble out. Pack the surrounding area with rags to catch the fluid.

You don't have to do all of this, but hopefully you get an idea of how easily air gets trapped into this setup and how you might go about getting it out.

As I mentioned I reverse-bled the rears with a syringe, forcing the fluid from the bleed nipple upstream to the master... was hoping this would prevent air bring trapped in any high points, but maybe it didn't? Good idea with cracking the banjo bolt at the top, I've been meaning to install a pressure switch there for the brake light anyway so I suppose I may as well just get that done.

I was never overly happy with my rear brake on the Hyper. Two weeks ago I switched from the stock Brembo pads to EBC HH pads. Well for me it is like night & day...I actually have a rear brake again...& It will lock up very easily. The Brembo pads had great longevity, but for me that's all. When the stock Brembos up front wear out, I think I'll go the EBC route with them too.
Cheers Rob

Already running HH pads, throw em on all my bikes. Definitely a great product.

Yes, it is a circle jerk. If you can stand on the brake without bottoming the pedal out, you are getting the force to the pad, regardless of air pockets. The air bubble just acts like a spring, the spring still has to be grounded. Since bottoming out should be obvious to you, sounds like you have defective or contaminated pads. If you are bottoming the pedal out, obviously you are not applying the force to the pads and you need to follow the bleeding suggestions that have accompanied every previous discussion. Personally I would just hoist the front of the bike up until the nipple is high. If you have race pads installed, they will need to build heat before they become effective.

Pedal doesn't bottom out, and force DOES get to the pad... just not very effectively. It bites just fine on a paddock stand and will *kind of* slow the bike a little bit on the road. I had pushed the pistons/pads out a bit and working the pedal by hand, they seem to move as smoothly as any other caliper I've played with.



I did notice another thing today when I had the front stand under it cleaning the wheel. The front brakes make a sort of clanking noise when they release after biting (even with extremely light force), almost as if something is loose and being pushed forward/backward (happens both directions) when it bites and then springs back into place when the brakes are released. Checked the caliper mount bolts, the pads, the brake disc bolts and rivets, and it's all tight. Very confused on this one. I can post a video if need be.

 

[Spex]

As I mentioned I reverse-bled the rears with a syringe, forcing the fluid from the bleed nipple upstream to the master... was hoping this would prevent air bring trapped in any high points, but maybe it didn't?

It probably wouldn't, since the reverse bleed would just have fluid moving past the bubble trapped air. It may not be enough to stop force getting to the pads, but it would increase your travel markedly. When I had issues with mine, it wasn't bottoming out but I had to stand on the pedal to get any kind of braking. After proper bleeding, it locks on command.

Honestly, try bleeding the caliper unmounted. It's a known issue with these calipers and it's a pretty easy fix.