I've searched a lot on the forum for the specific issue I have but haven't found anything similar, so I'm asking for your help in case anyone faced it or has any ideas:
- rear brake pads changed last week in a hurry due to late delivery from the dealer (and a long trip already scheduled for last weekend). Therefore I didn't have time to do it as per my previous procedures: open the bleeder, connect it to a hose and then to a small bottle of brake fluid, open the bleeder while pushing back the rear caliper piston in order to avoid old brake fluid going back in the master cylinder and ABS unit, causing potential damage. I use this practice after a nasty episode about 15 years ago when on a previous car the ABS unit got damaged due to the old brake fluid being pushed from the calipers to the unit;
- unfortunately, due to the rush, I didn't wash the visible part of the piston either (with a brush and brake fluid) for avoiding potential rings damage or piston seize due to dirty piston (though the exposed area of the piston looked somehow clean);
- and now the nasty part: during the 600 miles trip from the weekend the rear brake showed some abnormal behaviour. One of the issues is that the travel is longer than usual; initially if I pushed the pedal once more the travel seemded shorter, which could mean some air in the system. But after a few more miles the second/third push on the pedal didn't improve anything anymore. And, the most important, it seems that the proportional valve stopped working: while using both the front and the rear brakes I do not feel anymore the 'click' in the pedal which happened at every combined usage of the brakes. It clicks sometimes but randomly (every 6-8 usage of both brakes let's say) which makes me think the proportional valve in the ABS or some other valve got partially stuck/damaged.
I checked the rear ABS and it works properly under hard rear braking. Also while applying only the front brake the force in the lever but also the brake force itself are normal, so I assume the front/rear combined braking still works fine. I noticed no rear brake dragging (no heat issues).
As next action I'm planning a fluid change (~1 year old Motul currently) and use GS911 for additional bleeding but I doubt it will solve the problem. By default the GT seems to have an unusual long brake pedal travel (it can be slightly adjusted) but now, when it became even longer, it's disturbing. Even if I get used to the longer pedal travel I am not sure it will behave consistently (sometimes it still seems to 'bite' in a higher position) and it creates a feeling of 'not very safe' when I know it doesn't work as designed
. Most of my miles are hard-riding on curvy roads and I use heavily the rear brake, so I need to solve it somehow...
Thanks in advance for any ideas.