Mushy front brake and no ABS after 3k miles

N4teTheGreat · Jul 2, 2018

Did some cursory searching but didn't find much beyond the usual complaints about brake feel.

Woke up yesterday to a slightly mushier front. At the same settings the lever would hit my middle finger under hard braking (still stops fine) whereas it didn't before. Being the nervous person I am I gave it a few test stops and discovered I can lock the front so whatever caused this appears to have taken the ABS down.

Didn't find any leaks, brake fluid levels and appearance are fine and the brake doesn't feel any worse this morning at 500 miles, several hours of which were in temps over 100 degrees Fahrenheit and sitting overnight.

I've never bled a motorcycle brake before and I don't think doing so in the middle of nowhere in Utah is a good idea. I'll probably just confirm all the fittings are snug and take it easy but it's concerning that somehow air likely has gotten into the system and that appears to have somehow disabled ABS. I suppose it could be a bad seal on one of the pistons?

appliance821 · Jul 2, 2018

Not good. Try ziptying the lever for a few hours/overnight and see of there are any changes.

Lack of ABS seems to point to the ABS pump.

I did post regarding my bleed method that clears the pump for a firm feel. But if this happened suddenly, it could be something besides bad fluid.

kuksul08 · Jul 2, 2018

What setting are you testing the abs at, and at what speed? It's normal for a tire to very briefly lock up even with abs but it should release to maintain grip. It also doesn't work as well at lower speed (under 8-10mph) because the sensors have less resolution to work with. It will be more chunky. Level 1 and 2 will be less invasive than 3 also.

I'm willing to bet it's just some air in the system, probably in the abs unit. Did you go up to altitude? You will need to do a proper bleed by pressing the pistons in the caliper in and bleeding the lever and both calipers. The front caliper jumper line is a little tricky to get the air out of.

Let us know how it goes. I suppose as long as the brakes work you're fine just take it easy. The visual check is a good idea.

appliance821 · Jul 2, 2018

I've found that pressing the pistons into the calipers - refreshing the fluid with a standard bleed, then pressing the calipers a second time, and siphoning fluid from the MC and then refilling the calipers works best. One press seems to just force the bad fluid in the calipers into the ABS circuit, 2 presses forces the new fresh caliper fluid into the circuit. Got solid results.

In a pinch - the zip tie method restores your brakes for a while to keep you on the road.

You could also ziptie overnight and bleed a little fluid out of the calipers the next day. I've never done this but they say it clears a lot of the system. Could be a quick roadside fix in a pinch.

kuksul08 · Jul 2, 2018

appliance821 said:
I've found that pressing the pistons into the calipers - refreshing the fluid with a standard bleed, then pressing the calipers a second time, and siphoning fluid from the MC and then refilling the calipers works best. One press seems to just force the bad fluid in the calipers into the ABS circuit, 2 presses forces the new fresh caliper fluid into the circuit. Got solid results.

In a pinch - the zip tie method restores your brakes for a while to keep you on the road.

You could also ziptie overnight and bleed a little fluid out of the calipers the next day. I've never done this but they say it clears a lot of the system. Could be a quick roadside fix in a pinch.

Good call on the ziptie. I have tried it before and it does work. A bungee or other clamp also works as long as its pulling pretty tightly.

gatdammit · Jul 2, 2018

Does it pass the ABS test on start up? In my experience, modern ABS test circuits are pretty good. Should see yellow ABS light until you accelerate beyond 5mph or so and it will extinguish.

N4teTheGreat · Jul 3, 2018

Rode it as is yesterday, brakes work, there just, ahem, lots of modulation. Honestly didn't really slow me down much as pretty much everything we did in Utah / Colorado followed rivers and canyons so lots and lots of nice sweepers. Considering it didn't get worse I plan to ride it as is to my destination for this trip (Grand Lake). There's a motocross / OHV shop there that can likely sell me the fluid and hoses I'll need to bleed it or, even better do it for me.

The first day took us over Sonora pass so the bike saw elevation changes as well as some high temps. I never ride the brakes however but I'm sure it was warmer than usual.

As for the ABS, there were plenty of gravel pull outs where I was able to confirm the wheel would just slide. I had to get on the brakes hard once on pavement and felt was was either ABS or me doing an exceptional job of threshold braking so it could just be the amount of air is limiting the effectiveness of the ABS, no warning lights on the dash.

Appreciate everyone's feedback, I'll try bleeding it, and if all else fails I should be able to ride it as is back to California to let Ducati deal with it.

appliance821 · Jul 3, 2018

Bind the brake lever overnight - not too tight. Your brakes will be firm the next day. Might have to repeat the next night. This is a dirt bike rider trick, and it works.

ferdi · Jul 3, 2018

appliance821 said:
Bind the brake lever overnight - not too tight. Your brakes will be firm the next day. Might have to repeat the next night. This is a dirt bike rider trick, and it works.

but this trick is to let stay brakepistons at brakepads and prevent that brakepistons get pulled back after each brake use.
it does not help if air is in the system.
but, if it does not help it will not harm ;-) .

gatdammit · Jul 3, 2018

Don't touch that rear brake on the road...nightmare even with a full set of tools.

ferdi · Jul 3, 2018

gatdammit said:
Don't touch that rear brake on the road...nightmare even with a full set of tools.

why ? i always use it, together with my frontbrake. if pressed too hard you feel ABS working, but no problem

dragoontwo · Jul 3, 2018

ferdi said:
why ? i always use it, together with my frontbrake. if pressed too hard you feel ABS working, but no problem

I think he means trying to bleed it on the road.

edgary · Jul 3, 2018

Yes, he meant working on it.

Do use it.

appliance821 · Jul 3, 2018

ferdi said:
but this trick is to let stay brakepistons at brakepads and prevent that brakepistons get pulled back after each brake use.
it does not help if air is in the system.
but, if it does not help it will not harm ;-) .

It's not a permanent fix, but if you're on the road and want firm brakes for a day or 2 - it works fine. It sure works better than double pumping mushy brakes. I've done it with very good success.

I've been told if you bleed at the calipers after a night of ziptie, you can clear the fluid pretty well, and pretty quickly.

Mushy front brake and no ABS after 3k miles

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