2019 V4 air in rear brake

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Joined
Apr 21, 2022
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320
Location
san antonio texas
have you guys ever gone to ride ...and find your rear brake lever is much...then bleed the brakes and tons of air comes out.
it say for a week, we got 2 cold snaps nothing lower then 50, i go to ride and the lever is poop..
i did find that the brake pads had only a bit over 1/16inch per pad, so i replaced them..
rebled and all is well again, but i purchased another obstar after that debacle with my ex buddy sold mine.
and im gonna rebleed with the abs bleed feature just to be sure, front as well..
have you guys experienced anything like this on yours...
was it the worn pads let the pistons out too far and broke the seal (there was no brake fluid leaking out)
the brake fluid coming out was very milky so it had moisture in it, lots of it.
i bleed all my bikes every six months to flush out the fluid and air anyway,
but i have never had a master just be mushy from sitting from one week to the next even with really worn pads
 
Take the caliper off make sure its higher than the MC
Upside down
Hang a weight from the rear brake lever.

Now take a piece of silicone hose attach to the bleed nipple. Run the other end into a fresh can of brake fluid submerged.
Slowly loosen the bleed nipple.
Repeat as needed. Found this is the best way to bleed.

You can also crack the other end that runs into the ABS module to bleed air out there as well.
 
My 1199 is the only bike I own that has a problem like this, and it's with both fronts and rear, but usually the front. If I let it sit for 2-3 weeks I get a mushy front and there is always air in the calipers, and sometimes up at the master cylinder. Brembos are great calipers, but I think they make a compromise in the seal area to reduce drag on the pistons to give you smoother operation, at the cost of more permeability and the possibility of water or air seeping past due to temperature changes or high humidity levels. The only time I can consistently just jump on the bike without checking the front brakes for mushiness is during the Summer. Spring, Fall and Winter all get a little degradation to the front. I've noticed it a couple of times with the rear, and a quick bleed solves it, but it's less often.

I just stepped outside and grabbed the brakes to check them. The front took one pull to remove clearance on the pads, then firmed up, but it's a tad mushy as well. The Rear definitely needs a bleed. Too much play for sure. It's been sitting for about 2 weeks due to the cold and wet weather, but if memory serves me correctly the last ride it was a little soft and I just ignored it because I hadn't ridden it in a month. So figure 6-8 weeks and it needs a bleed out. I have two other bikes (V-Strom 1000 and C650gt) that are my around town and grocery getter bikes respectively, so the Ducati doesn't get much play time during these miserable months.

Maybe it's time for seals?

How many miles are on the bike?
 
it has 8k on it..
this is what i was looking for, i was not aware of an update to the rear line..ill do the update for sure if it needs, i checked the vin to look for service bulletin or recalls and it did not show rear brake line.

i just wanted to know if others had a similar experience with unexplained air in the rear brake. i thought maybe cuz the pads got down to far but thats never been a problem...
bleeding the rear is not a problem at all. i just found it strange cuz ive never had this happen on any bike ive ever owned before, i just found it strange.

i had similar problems with my front brakes always feeling mushy.. i still live it, plenty of power just mushy, even after trying 6 or 7 different masters, including aftermarket but i just live with it, leaking front valve cover.. this bike is the biggest drama queen ive ever owned. come to think of it so was the 748

just making sure im not insane. thank you guys for sharing, ill keep an eye on it, if it happens again, somethings definitely off, as mentioned it might need caliper seals, i cant imagine why, but meh... if air continues to come out then its getting in somewhere, i suspect its the abs pump..but im not willing to remove it if the cost is only bleeding brakes flushing fluid every 6 to eight months, which is something i do anyway.

no biggee it doesnt get ridden in the wet or cold much.. believe it or not i bought cfmoto 800mt and it has had less problems than the v4. and it gets ridden more, 3k in the first month i owned,, but make no mistake ill never let go of the v4 and im looking for a streetfighter version or maybe a superduke(but thats not looking llike a good idea lately) LOL, it does get aggravating when the little problems come up and theres no apparent fix.. but its a labor of love, you guys know what i mean. i enjoy working on them
 
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I typically tie off the front brake the night before I go riding. When traveling I rebleed ever couple of days 1000-1500 miles. Both front brake and clutch. This behavior showed up with the radial brakes as I cannot remember having to do this before that on street bikes. One thing I sure of is that with ABS the levers get more mushy. I put stylema's and the stock matching master (so now like a panigale) on my 1098 and those brakes are stunning (two finger stoppies but will not suffer fools). I went to a stock Brembo 18/19 on the clowncar (21 V4SF) to get sort of the same feel but still feels mushier. The new calipers, Hypure?, are claimed to provide better feel.
 
Again...so happy to hear im not fing insane..i never had this problem with the old brembo axial masters..even the 800mt with its .... j juan brakes and axial master have a better feel than the v4..i put a NOS brembo axial master and the 800mt and the feel improved even more..with fully warmed up HH galfer pads it will 1 finger stoppie..looks hilarious im sure

.the v4 will too now that i used an aftermarket master with adjustable ratio...its a monster even with the inherent mush...1 finger at over 130mph...the back tire came off the ground..its not something that scares me as im used to the back tire comng off the ground approaching turns..but the extra ratio really surprised me..with full heat in the pads its downright nastyon the front brakes but it suits my riding style.
( one handed..early downshifts using slipper.very late braking)

I just wish i could get rid of that damn mush at the beginning of the squeeze you know..i think it jas to do with where the piston sits at its resting position in relation to the bypass port in the cylinder ..(and the abs pump) something im still exploring but ive just gotten where i just want to enjoy the ride..still a helluva missile to sit on though..

Btw...this rear brake problem never happens in anything other than cold weather ...here the coldest its seen in the garage is 35f...but i hesitate to even start it at those temperatures..i wait till the themps are above 60 if im gonna start it..i do it once a week..not good to let it sit....i know thats kinda stupid but i dont want to start it when the oil is that thick.and i dont like letting them just sit.

Again thanks fellas..i doubt the bleed procedure will change anything but well see..
 
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