Front brake question

iahforgaming · Aug 1, 2022

Hello everyone,

My HS just return from the shop for a bad o2 sensor replacement. During the pick up process, the neutral switch started acting up, so the shop remove it and clean it will a brass brush and that seem to fix it.
If anyone have a neutral light problem, maybe try cleaning it if it is dirty before replacing.

Anyway, the main issue I would like to ask everyone is about the stock front master. I noticed that when the front brake is actuated, there is a swish sound and a lot of bubbles flying when view through the sight glass. Thought I have air leak or that I need to bleed the master but there is no valve for that and the level stop well before the half way point.
So I would like to ask if someone can check and see if this is the same on your HS or HM? Thanks.

uncle brad · Aug 2, 2022

i checked mine but the level is above the window which is what the maintenance manual calls for. I get no sound but can see the fluid moving and there may be a bubble or two. I think you're just low on fluid which makes me wonder if your brake pads are worn out as there should be no reason for the fluid to be that low unless someone had been monkeying with your brakes before you got the bike. Hope this helps.

iahforgaming · Aug 3, 2022

Thanks uncle brad, I will have to look over the brake system tomorrow. Fluid level, pads, leaks, et.

1-3-2-4 · Aug 6, 2022

I have had the same problem since I bought the bike in June. I did a complete flush on the fluid and zip tied overnight. No improvement. Still mushy, still get the sound, and still get the bubbles in the sight glass.

While bleeding, a quick inspection yielded a couple observations:

1. The bypass bleed hole is huge. This hole is used to allow fluid back up into the reservoir and also to tune the brake lever travel and feel. In my opinion, Ducati wanted to soften the lever on the Strada and they went overboard. This hole lets fluid shoot through it during the first ~25% of lever travel and that’s what causes the sound and the bubbles. But wait, there’s more!

2. There is no deflector shield over the bypass bleed hole. Most master cylinders have a little shield over that hole that stops the fluid from shooting up inside the reservoir.

Needless to say, I’ll be swapping a radial master cylinder this winter. Just need to see which one fits with the stock handguards since I want to keep them. I have an older R6 and newer R1 unit on the shelf. One of them should work and will have this thing stopping properly.

nickwst4 · Aug 8, 2022

I should check on mine first, but usually Brembo masters have an adjustment screw at the base of the lever. You can alter the setting of that to reduce lost motion, so long as you make absolutely sure that there is venting to the reservoir in the fully-released position. You need to see a tiny swirl of fluid in the first few mm of lever travel before the hydraulics pressurise. Go too far and the brakes will lock up as heat is generated by friction. There's really no need for the gusher you describe!

Nick

1-3-2-4 · Aug 8, 2022

This Brembo is a budget unit, so no adjustment like that. Heck, they didn’t even include the plastic washer that normally sits between the rubber diaphragm and reservoir lid. Many of them seep which eventually causes the powder coat to flake off around the edge.

To make these things worse, Ducati doesn’t believe we’re capable of servicing our own brakes. Unlike other OEMs, they don’t even sell rebuild kits!

nickwst4 · Aug 8, 2022

That's odd. Mine has the integral 'coffin' reservoir and the adjuster for the plunger, with locking spring. It's a 2013 821 HS, and I'm pretty sure the one previous owner hadn't changed it because he never modified anything else. Which model/market/year is yours?

appliance821 · Aug 8, 2022

1-3-2-4 said:
I have had the same problem since I bought the bike in June. I did a complete flush on the fluid and zip tied overnight. No improvement. Still mushy, still get the sound, and still get the bubbles in the sight glass.

While bleeding, a quick inspection yielded a couple observations:

1. The bypass bleed hole is huge. This hole is used to allow fluid back up into the reservoir and also to tune the brake lever travel and feel. In my opinion, Ducati wanted to soften the lever on the Strada and they went overboard. This hole lets fluid shoot through it during the first ~25% of lever travel and that’s what causes the sound and the bubbles. But wait, there’s more!

2. There is no deflector shield over the bypass bleed hole. Most master cylinders have a little shield over that hole that stops the fluid from shooting up inside the reservoir.

Needless to say, I’ll be swapping a radial master cylinder this winter. Just need to see which one fits with the stock handguards since I want to keep them. I have an older R6 and newer R1 unit on the shelf. One of them should work and will have this thing stopping properly.

There are some threads on mushy brakes. The main problem, I think, is that you are bleeding the brake lines and caliper, but not the ABS pump. The air in the ABS pump then enters the system after the bleed. I bleed the calipers to put clean fluid in, then push the pads apart forcing fluid through the ABS pump into the master cylinder where I syphon off the fluid. I then refilll the calipers.

1-3-2-4 · Aug 8, 2022

nickwst4 said:
That's odd. Mine has the integral 'coffin' reservoir and the adjuster for the plunger, with locking spring. It's a 2013 821 HS, and I'm pretty sure the one previous owner hadn't changed it because he never modified anything else. Which model/market/year is yours?

Have a picture? Maybe you’re referring to the lever adjustment? Mine is a 2016.

appliance821 said:
There are some threads on mushy brakes. The main problem, I think, is that you are bleeding the brake lines and caliper, but not the ABS pump. The air in the ABS pump then enters the system after the bleed. I bleed the calipers to put clean fluid in, then push the pads apart forcing fluid through the ABS pump into the master cylinder where I syphon off the fluid. I then refilll the calipers.

Air in the abs pump would be terrible. But if the pump doesn’t cycle, that wouldn’t be an issue. The only way air would get into the abs pump (absent a leak) would be if an air bubble gets caught right before the pump and it cycled. Otherwise, the fluid inside the pump never mixes with the fluid in the lines. Back bleeding like you describe doesn’t push fluid into the pump, either. The only way to bleed the pump on an abs vehicle is to use the diagnostic tool to cycle the pump.

nickwst4 · Aug 9, 2022

"Have a picture? Maybe you’re referring to the lever adjustment? Mine is a 2016."

The piston-clearance adjuster is at the base of the lever and was common to previous Ducati/Brembo units on my various Monsters and my ST4. However, I must admit that I've put cheap-but-good Chinese adjustable-span aftermarket levers on the HS so possibly the original was as you say. Maybe someone else can comment?

Nick

uncle brad · Aug 9, 2022

If both Nick and the original poster are having issues with bikes that have been sitting for an extended period of time, it may be an issue with trapped air. My EXC 450 used to suffer from the same issue every spring. It was a common problem with these bikes. The solution was simple once you knew how to do it. The cause of the problem may make a lot of people scoff but i'm speaking from experience with my bike and friends KTM's also. The problem occurs when the vehicle sits for a lenght of time with the handlebars turned to the right (start scoffing now). Air somehow gets trapped near the banjo bolt on the master cylinder because the master cylinder is no longer the highest point of the system. Sometimes riding for a while will bring the lever back if it's not too spongey. What we used to do was back off the lever free play adjuster and cycle the piston with the wheel turned to the left. Normally this would cure the problem in a few seconds. No bleeding needed. I'll add this link which discusses the issue which is only one of many on the subject. Another problem i had with spongy brakes on an 1986 XT650 was that there was air trapped in the slave cylinder and i could only remove the air through bleeding if the piston in the slave cylinder was pushed all the way back in. You need to find a way of holding it there while bleeding the system. This may be part of your problems if your brakes are fairly worn. Some people suggest bleeding at the master cylinder banjo bolt. I've had no luck with that. Some suggest removing the master cylinder from the bars and lifting it so that it is the highest point. I've tried that and have had limited success. Conversely, i've flushed and bled both the front and rear brakes on the HS just for preventative maintenace with no issues afterwards.

I've also added pics of my stock brake lever and the free play adjustment from my 2016 HS.

nickwst4 · Aug 9, 2022

Uncle B;

Thanks for confirming my belief that Brembo levers should have that provision for adjusting free play in the hydraulics. Fortunately, it wasn't me having a problem!

Nick

1-3-2-4 · Aug 9, 2022

Thanks for the picture, that confirms it. My bike came with Evotech levers installed and the stockers were in a box that I didn’t even look at. However, I can confirm that my Multistrada 1200 and my Japanese Brembo-equipped bikes didn’t have that free play adjuster. Odd choice that they cheaper out on the master cylinder and gave this adjustment.

Regarding Uncle Brad’s EXC woes, I can unfortunately relate. Had a 2002 EXC250 with the same problem. To make matters worse, no amount of rebuilding would make those brakes any better. They were garbage from the get go and were destined to stay that way. The air would leak in, but fluid would not leak out. Very strange but indeed true.

Which also reminds me of my Concours 14 that drove me nuts last winter. Mushy brakes drove me crazy, and after nights of rebuilding, bleeding, and back bleeding, cursing, head scratching, and voodoo, I found the issue was the ABS pump. The unit corroded and leaked air in. The brakes were firm on the second sequential pump, but the first pump was god awful. The $1400 price tag drove me to remove the abs completely, and no surprise, the brakes never felt better. I mention this because as ABS bikes become more commonplace and people tend to do their own service, I’m concerned not using the diagnostic tool to cycle the pump while bleeding leaves old dirty, water-infused fluid in the pump, thus corroding it. If you feel so inclined, search for ABS failures on the Concours 14. The failures all involved the pump locking up - including the wheel.

That little sidetrack story aside, I’m not sure that the ABS pump is the issue here (yet). Maybe down the road those issues will pop up as the bikes age. But In my bike’s case, a full bleed, back bleed, and zip tie over night (several times) all yielded the same results. Air is getting in somewhere, and while I suspect the master cylinder, I cannot confirm it yet. Just a strong hunch that I intend to explore this winter when I swap to a radial master cylinder. If I don’t “double pump” every time I stop, the lever almost touches my fingers. Second pump is MUCH better.

If you do some searching on the various forums, you’ll find many stories of the same issue. Here are a couple:

Fixed my front Brakes.

Ducati Hyperstrada Fixed my front Brakes. Brembo 19 RCS Radial Brake Master Cylinder EBC Brake Pad - Sintered Double Spiegler Performance Parts - Motorcycle Performance Parts | Custom Motorcycle Accessories Brake line kit: EL-0102-002-710 Add a little more Bend to pad Cross...

hyperstrada.com

https://www.ducati.ms/threads/new-939-sp-brake-feel-issue.587209/

Google will give you more reading still. There is some talking about a bad caliper seal design, but short of changing calipers to the M50, there isn’t much you can do on that front. But as far as the original poster and the question, I can confirm the sound and the bubbles are the result of the master cylinder design. There may be competing, compounding issues here, but the master is surely one of them.

iahforgaming · Aug 10, 2022

Wow, thank you. A lot of good information. Will have to add greasing the pistons and bleeding the system on the to do list. Been thinking about getting an axial master cylinder. Sometime they show up on the used market for under $150 here in Japan.

nickwst4 · Aug 11, 2022

iahforgaming said:
Wow, thank you. A lot of good information. Will have to add greasing the pistons and bleeding the system on the to do list. Been thinking about getting an axial master cylinder. Sometime they show up on the used market for under $150 here in Japan.

That would be radial, I think? I've never seen axial used to describe old-style masters, but that would seem appropriate as they operate on the axis of the 'bars.

N4teTheGreat · Aug 11, 2022

Radial for sure. I went all in on a set of used Brembo M50 calipers paired with a new Brembo RCS17 MC. It gives more modulation but I can still lift the rear off the ground with one finger. I used th stok lines which was a little funky, so as soon as I stop being lazy I'll pull the tank and airbox and measure for custom lines with the correct fitting angles.

appliance821 · Aug 11, 2022

1-3-2-4 said:
Have a picture? Maybe you’re referring to the lever adjustment? Mine is a 2016.

Air in the abs pump would be terrible. But if the pump doesn’t cycle, that wouldn’t be an issue. The only way air would get into the abs pump (absent a leak) would be if an air bubble gets caught right before the pump and it cycled. Otherwise, the fluid inside the pump never mixes with the fluid in the lines. Back bleeding like you describe doesn’t push fluid into the pump, either. The only way to bleed the pump on an abs vehicle is to use the diagnostic tool to cycle the pump.

I'm a pragmatist - after doing this method, which is partially alluded to in the workshop manual, but not detailed, I have not had mushy brakes.

iahforgaming · Aug 11, 2022

Ahh, yes. Got to make sure to search for radial master cylinder.

appliance821 · Aug 15, 2022

1-3-2-4 said:
Thanks for the picture, that confirms it. My bike came with Evotech levers installed and the stockers were in a box that I didn’t even look at. However, I can confirm that my Multistrada 1200 and my Japanese Brembo-equipped bikes didn’t have that free play adjuster. Odd choice that they cheaper out on the master cylinder and gave this adjustment.

Regarding Uncle Brad’s EXC woes, I can unfortunately relate. Had a 2002 EXC250 with the same problem. To make matters worse, no amount of rebuilding would make those brakes any better. They were garbage from the get go and were destined to stay that way. The air would leak in, but fluid would not leak out. Very strange but indeed true.

Which also reminds me of my Concours 14 that drove me nuts last winter. Mushy brakes drove me crazy, and after nights of rebuilding, bleeding, and back bleeding, cursing, head scratching, and voodoo, I found the issue was the ABS pump. The unit corroded and leaked air in. The brakes were firm on the second sequential pump, but the first pump was god awful. The $1400 price tag drove me to remove the abs completely, and no surprise, the brakes never felt better. I mention this because as ABS bikes become more commonplace and people tend to do their own service, I’m concerned not using the diagnostic tool to cycle the pump while bleeding leaves old dirty, water-infused fluid in the pump, thus corroding it. If you feel so inclined, search for ABS failures on the Concours 14. The failures all involved the pump locking up - including the wheel.

That little sidetrack story aside, I’m not sure that the ABS pump is the issue here (yet). Maybe down the road those issues will pop up as the bikes age. But In my bike’s case, a full bleed, back bleed, and zip tie over night (several times) all yielded the same results. Air is getting in somewhere, and while I suspect the master cylinder, I cannot confirm it yet. Just a strong hunch that I intend to explore this winter when I swap to a radial master cylinder. If I don’t “double pump” every time I stop, the lever almost touches my fingers. Second pump is MUCH better.

If you do some searching on the various forums, you’ll find many stories of the same issue. Here are a couple:

Fixed my front Brakes.

Ducati Hyperstrada Fixed my front Brakes. Brembo 19 RCS Radial Brake Master Cylinder EBC Brake Pad - Sintered Double Spiegler Performance Parts - Motorcycle Performance Parts | Custom Motorcycle Accessories Brake line kit: EL-0102-002-710 Add a little more Bend to pad Cross...

hyperstrada.com

https://www.ducati.ms/threads/new-939-sp-brake-feel-issue.587209/

Google will give you more reading still. There is some talking about a bad caliper seal design, but short of changing calipers to the M50, there isn’t much you can do on that front. But as far as the original poster and the question, I can confirm the sound and the bubbles are the result of the master cylinder design. There may be competing, compounding issues here, but the master is surely one of them.

It is probably the ABS pump. It can be bled by pressurizing clean fluid through it up to the MC where the fluid can be siphoned off. I know you dismiss this out of hand but for others reading this, I have detailed the process in another thread, and have not had mushy brakes since. You can throw money at the issue, read google until the cows come home, or just do a thorough system bleed and ride your bike.

1-3-2-4 · Aug 16, 2022

No doubt, some people experience mushiness from air in the system. As elaborated as nauseum above, that’s worth pursuing, as you say, before throwing money at it. What I offered was simply that the stock master cylinder suffers from a subpar design and will never deliver the feel or performance of a quality master cylinder. Radial or axial. We can all make informed decisions about the courses of action. And depending how the bike is used, each remedy has its merits. Fact is that Ducati skimped on the master cylinder - as they did on the suspension. The expense of adding the touring bits eliminated the performance parts.

Front brake question

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