Ducati Monster Forum

Hey all.

Woke up Jenn's 11 696 from an extra long winter slumber today for a ride together. She immediately noticed too much travel and lack of pressure in the rear brake.

~9k miles, new pads last year after dealer flushed and changed fluid.

So ABS error light, system initializes and light goes out as normal. Front brakes normal.

Fluid level at top.

Plenty of meat on pads.

No visible signs of leaks.

Can sorta get a little brake action at an extreme travel on the pedal, but never really get a firm pedal, definitely not normal.

First guess would be failure of the cups on the pistons in the MC?

UNLESS there's something in the ABS system that could do this without a code​light?


Any thoughts?


Kev


PS this is the bike you see occasionally with some of my RevZilla articles.

Just rebleed the rear brake . . .

I used to open the bleed nipple and pump about halfway thru the reservoir and then close the nipple, then I would pump 3 times and hold on the 4th . . . If your wife can help with pumping, even better

Might be worth a try. Jenn's used to helping me with bleeding.

But why would it work fine all last season and develop a problem in storage?

Also,  is there any problem bleeding ABS bikes without a scan tool to cycle the modulator?

No problems with bleeding an abs equipped bike

Sent from my SM-N9208 using Tapatalk

Good to know, sounds like I have diagnostic step 1!

Maybe humidity got to the fluid . . . Just saying and NO issues bleeding

Nah, I'm not buying that. Insulated garage with a bunch of other bikes and cars in it. Not the slightest problem on any other vehicle in there.

Can't see how moisture suddenly got in when we had no problem the first 5 years and no fluid change.

I'm still thinking master cylinder piston cups stuck over the winter and failed taking most pressure out of the stroke.

was just an opinion . . humidity here is to blame for way too many things .. .

No it's cool I appreciate the thoughts.

Around here we see little humidity until summer and even then...

This comment might seem off topic,the wall, which is fine by me...

but...

I have a condensing boiler in my house. All winter and spring the thing runs and you hear basically nothing other than fans and pumps whirring. Then...in the summer, when the heat doesn't run and things cool down, relatively, the thing starts banging away every time the hot water is called for. It goes away in the fall when the heat starts running again.

I think the fluid contracts over the winter and creates an airspace, which requires bleeding.

Carry on.

It's an interesting theory.

My question would be if that's true why didn't it happen the first 5 years of winters?

And why doesn't it happen to the rest of the fleet?

But I'm just thinking it through, I obviously don't KNOW yet.

I know little.

Doesn't make me wrong. ;D

Possibly some not-up-to-par fluid was used at the dealer.

Flush and bleed is first step, and nearly free.

Occam's razor.....

I know even less, and I'm usually wrong, just ask Jenn.

Then should I expect the clutch and front brake to fail next?

I like Occam's Razor, which is why I checked for leaks and checked pads first.  ;)

You were more easily convinced than I. ;)

Years of practice.  ;D

Well, that may be a bit of a jump, but not a bad idea to flush and bleed them too while you're at it.

I wonder if it's not something about that brake model.

My '13 796/ABS did the same thing last year.  It was fine all through the summer... then one day the pedal started to get a little mushy, a few weeks later it was done.  This was during the regular riding season, too, not in storage or anything.

I had my dealer flush and bleed it out and it seems OK now, but I think because of the way the system is plumbed... up to the ABS module, down to the swing arm, up through the loop and then back down to the caliper... it magnifies any shortcomings with the fluid or system.

796, and other models with the SSS and caliper on the bottom, tend to have issues with the system going soft.
I've concluded it's the hose routing and low-mount caliper that are the perpetrators.
Aided by many of those having the master cylinder mounted to the cases; 916 and later SBK, ST's and others.

ABS equipped models suffer from a soft lever and pedal, just due to the system volume and long lines, especially on the rear brake.

Some folks have fitted bleeder banjo bolts at the ABS unit with good results.

Normally I would suggest replacing the rear caliper.  You are correct Kev, it should not happen.  But it does with that caliper.  Bleeding seems to work most of the time.  It's the rear brake which many of us don't use anyway.  If bleeding doesn't work or last then worry.  Otherwise,  [Dolph]

Good explanation why this happens?  Beats me.

Ah, so it's a known problem.

I'm not sure if that makes me feel better or not lol.

Ok, just have to pick up some fresh fluid.

So I have had (and still have) this same problem on my 1100

Did you just have any service done recently? Specifically a valve adjustment or timing belt service?

The reason I ask is since the exhaust from the front header needs to be taken off to get to the belts, sometimes the slip fit exhaust connections get installed slightly mis-aligned and the header gets too close to the abs brake lines that are generally routed directly below the header and up to the front of the bike.

The heat from the bike literally starts cooking the fluid inside the lines.

The routing on the 696 is probably a little bit better than the SSS my 1100 variant  which is just poorly designed but the impact may still be there. Just throwing it out there for you to look at.

Interesting... I'll have to look at mine.  I'm fixing to pull my Y-pipe off, anyway.

And, duh, I forgot the routing would be different with the 696 vs 796/1100 because of the SSS.

Actually sorta.

So at the beginning of last season we had a complete service:

Valves/Belts
Flush and refill of clutch and brakes
Fork oil changes
Etc.

But then we went through the whole season, only maybe 2k miles or so, but including a track day all with no problems.

Put her to bed around Dec, and woke her up kinda late this year (yesterday) thanks to a broken wrist but suddenly a brake problem seemingly out of no where after sitting.

<shrugs>

I'll report back after bleeding.

Ok, I'm a slug (actually bought another new bike after this thread and been busy).

So today I finally check to see what I need for bleeding and noticed something weird.

The clutch and front MC reservoirs call for Dot 3 or 5, but the REAR calls got Dot 4?

Is that right?

you can you anything not less than DOT4 or if you feel spendy, DOT5.1

I used to use DOT4 and DOT5.1 at the dealership's shop and at home I still use DOT4/5.1[5.1 for newer vehicles with ABS] that for some reason make the later vehicles work better

never put in dot 5 if you have already used dot 3 or 4. you want dot 5.1

You can always use a higher DOT number as long as it is polyglycol based.  Silicone brake fluid was the first brake fluid to earn the DOT 5 rating.  It is not compatable with polyglycol fluids as originally thought so polyglycol has the 5.1 designation.

Sorry, took way to long to get to this. Father's day spent the afternoon riding all the bikes in the fleet.

Ended with the 696 and threw it on the lift for an oil change and brake bleed.

Went through the capacity of the tiny reservoir about 3-4 times, was getting lots of air at first, but eventually firmed up.

I still need to test ride it, but I'm thinking that will fix it.

But man I'm freaked. From where the heck did all that air come?

(https://uploads.tapatalk-cdn.com/20170627/6c01f32a182cd4614ddc4053bcbc81a0.jpg)(https://uploads.tapatalk-cdn.com/20170627/e1db15e7a722665a37f675c40b80edff.jpg)

More than likely either of three scenarios, least likely first:

1) The air was always there  but didn't cause a problem until it moved around. 
2) Air got in through the caliper upon release of the bake lever.
3) The reservoir was low enough to allow the master to intake some air at an angle.

Well all logical suggestions. But let's see:

1. It had been hundreds of miles since the dealer had flushed and refilled the brake and clutch fluids. And that included a track day. Though Jenn is particularly smooth and may not have pushed it that hard on the track she does use the rear a lot in conjunction with the front, enough to wear the rear pads out in about 7k miles.

2. Bleed screw was tight and tightly capped, but I guess it's still possible.

3. I'd replaced the brake pads after the dealer had done the fluid with a complete service (I didn't realize they were getting low before hand or I would have done them). So reservoir was completely full. But now that you mention it I think the bladder was extended. I don't recall taking fluid out when I pushed the caliper pistons back in and I don't recall it overflowing, but maybe I'm just remembering wrong.


I still think it is weird that it was fine all last year and this just showed itself only after winter storage.

On item 2 I was thinking air getting past the seal, they can pass air but be tight enough to hold fluid.  Since the bike was in storage we can rule that out.  I think (hopefully) it will remain a mystery.

Ah gotcha. Yeah I'm with you, hopefully it stays away and we never know.

Thanks for all the suggestions!

Btw, the brake was good all year. Thanks all.