Then in your case, the problem is not related to the abs pump, but to the rear caliper or master cylinder 😯I bled the rear brake circuit on my '16 TV several times. The pedal would be firm for a few months but eventually it would get soft. Even bleeding per the MV service bulletin resulted in the same outcome, over time.
No problems with air in the system, since installing a brake line from the master to the caliper.
The ABS pump is no longer connected to the rear master cylinder or caliper.Then in your case, the problem is not related to the abs pump, but to the rear caliper or master cylinder 😯
I will come back to the ABS unit later, but first I tried bleeding the system again but that did not work for a very long time (I have made it easier by installing banjo bolts with bleed nipple on top of the ABS unit). My MV dealer suggested to install a rear brake master cylinder from a known good bike and guess what, the same problem came back after a few weeks so my attention was back to the ABS unit where, during standstill, on the rear brake side there is a small vacuum at the ABS unit due to the difference in height between the reservoir and ABS unit. For the front brakes the reservoir is above the ABS unit so there is always a small overpressure at the front brake side of the ABS unit and that has no issues. The problems with loss of rear brakes also happens a lot to Ducati's and guess what they also use the Bosch ABS unit installed above the reservoir.My rear brake was gradually losing firmness and after a period of standstill of several weeks, waiting for MV parts (don't ask....), the rear brake was gone and the lever went all the way down. Bleeding the system only worked for a short period and eventually the rear master cylinder was replaced by the dealer under warranty. It was perfect after that but slowly the lever lost a bit bit of firmness and now that the bike is under cover during the winter I checked after a few weeks and guess what........no rear brake. I put the bike on my lift and checked but could not detect any leakage whatsoever so I'm also slowly moving my attention towards the ABS unit as this is the highest point in the system and a leak in this unit might not show as an oil leak as air could enter at the highest point, the ABS unit, without showing as an external oil leak. Haven't had the time to look further. Was thinking about bleeding it again and keeping it pressurised by hanging a weight from the lever and perhaps I can detect a possible leak. Problem of course is that the direction of sealing is different for something going out (oil) and air going in.
So I moved the rear brake reservoir to the tail section of the bike and above the ABS unit. I used brake fluid resistant hose and a small clutch fluid reservoir and made a bracket for this. See below pictures.
I posted about my rear brake issues a long time ago and, at least for my bike, it appears I found a solution that fixed it and that Iwould like to share.
I will come back to the ABS unit later, but first I tried bleeding the system again but that did not work for a very long time (I have made it easier by installing banjo bolts with bleed nipple on top of the ABS unit). My MV dealer suggested to install a rear brake master cylinder from a known good bike and guess what, the same problem came back after a few weeks so my attention was back to the ABS unit where, during standstill, on the rear brake side there is a small vacuum at the ABS unit due to the difference in height between the reservoir and ABS unit. For the front brakes the reservoir is above the ABS unit so there is always a small overpressure at the front brake side of the ABS unit and that has no issues. The problems with loss of rear brakes also happens a lot to Ducati's and guess what they also use the Bosch ABS unit installed above the reservoir.
I never had the problem of the rear brake, and my bike has 35.000 km(Brutale B3 2017).Did that work for you?
hi I read as much as I can find on the subject of rear brakes Ive got a dragster and a f3 both have the same problem also a cbr600rr with abs. The Honda doesn’t have a problem with the rear brakes and the rear reservoir is higher than the abs unit and has lots of heat shielding around the master cylinder and reservoir. So comparing all installations and mods from yourselve and Sparks I could aply yours to my F3 question is after a couple of months have past by how is the rear brake now and can you show me the the route taken by the new pipe would be great. The dragster will have its reservoir raise and I wil take some temperate readings with my infrared thermometer before and after.I posted about my rear brake issues a long time ago and, at least for my bike, it appears I found a solution that fixed it and that Iwould like to share.
I will come back to the ABS unit later, but first I tried bleeding the system again but that did not work for a very long time (I have made it easier by installing banjo bolts with bleed nipple on top of the ABS unit). My MV dealer suggested to install a rear brake master cylinder from a known good bike and guess what, the same problem came back after a few weeks so my attention was back to the ABS unit where, during standstill, on the rear brake side there is a small vacuum at the ABS unit due to the difference in height between the reservoir and ABS unit. For the front brakes the reservoir is above the ABS unit so there is always a small overpressure at the front brake side of the ABS unit and that has no issues. The problems with loss of rear brakes also happens a lot to Ducati's and guess what they also use the Bosch ABS unit installed above the reservoir.
View attachment 483656
So I moved the rear brake reservoir to the tail section of the bike and above the ABS unit. I used brake fluid resistant hose and a small clutch fluid reservoir and made a bracket for this. See below pictures.
View attachment 483662
View attachment 483663
View attachment 483664
The hose fits closely underneath the fairing and you see nothing of this modification.
I installed this the 20th of July 2020 and the bike has been ridden a few times, stood still for extended periods of time and the rear brake is still perfect today. I spoke with my MV dealer as he was very interested in what I did and if it worked and he suggested I keep it like this as it was unlikely that MV would come up with a solution.................
I'm not saying what is right or wrong but after a very long time this has fixed it for me...........on to the next problem.
Rear brake is still in perfect working order after I relocated the reservoir above the ABS unit. No leakage anywhere and solid braking power. So the original problem must be air either entering the system via the ABS unit itself or via the crimped banjo couplings if this crimping wasn't done correctly. I have owned CBR600RR's with ABS and currently own a 2018 Yamaha R6 and this has the ABS unit above the reservoir but these Japanese bikes do not have the problems that MV, Ducati and Aprilia have, but the ABS units on the CBR600RR and R6 are not manufactured by Bosch and the brake lines are Japanese made. The relocation solved it for me it won't solve a defective master cylinder or caliper.hi I read as much as I can find on the subject of rear brakes Ive got a dragster and a f3 both have the same problem also a cbr600rr with abs. The Honda doesn’t have a problem with the rear brakes and the rear reservoir is higher than the abs unit and has lots of heat shielding around the master cylinder and reservoir. So comparing all installations and mods from yourselve and Sparks I could aply yours to my F3 question is after a couple of months have past by how is the rear brake now and can you show me the the route taken by the new pipe would be great. The dragster will have its reservoir raise and I wil take some temperate readings with my infrared thermometer before and after.