Rear wheel axle question


Well-Known Member
May 5, 2018
I placed the old pad into the caliper and squeezed the pistand back in.
yeah… it's how we've always done it. but if you look in this and other forums, you will see that there are a couple of users who had the same problem. they changed the rear pads (pushing the pistons in to insert the new ones)… and from there, they lost rear braking capacity, or they have recurrent air intake in the rear brake line. When you push the pistons, the liquid returns to the container, but first, it circulates "inside" the abs module. Apparently, this reverse circulation causes "something" in some internal seal of the abs that ends up generating the entry of air when in combined brake mode, the abs motor is activated to brake behind and thus reduce the sag of the front part.
Some tried eliminating the rear abs circuit (pipe bypass)… others by attaching the pump directly to the rear caliper. the air intake always went to the rear circuit (recurrently) ... and after changing the pads (the system was perfect before this) ... and other times the air intake manifested itself without mentioning at that time the change of rear pads ( but I do not know if they had been changed in a time close to failure by air) apparently, the electric rear braking assistance in combined mode, implies the actuation of the abs pump as a "pump", not as a flow switch (for the case of locking actuation) ... and this causes air to enter the rear line ..
The problem seems to appear when the rear pads are changed ... then "maybe" the pistons should be "pushed" by loosening the bleed screw, To avoid that back-flow ... those who realized the problem, it was through performing an "excellent" bleed and avoiding using the combined brake. while they were braking only behind, the brake worked perfectly for several stops. as soon as they used the combined brake, they again had air inlet to the rear circuit ...
I don't know, obviously the use of the combined brake brings about the excessive use of the abs pump, there are owners who even with many miles, have not presented problems air in the rear circuit. There are others who have had it… and others who have had it after changing rear pads …… I myself was wrong for a while, thinking that the air intake in the rear brake was due to the caliper pistons… ..with As time goes by, and reading a little more… ..I started to believe that the air intake was in the abs pump, but not because of the abs function, but because of the combined brake, that is, pumping electric braking.
So maybe I would "recommend" to myself that it would not be such a bad idea, to deactivate the combined brake (to avoid the permanent use of the abs pump) and secondly, every time the rear pads are changed, the push the pistons loosen the bleed screws to prevent back flow