1290 Brake maintenance question

problems . solutions . product reviews . tips
RyanD
Minimoto racer
 
Posts: 51
Joined: Thu Dec 24, 2015 11:29 pm

1290 Brake maintenance question

Postby RyanD » Sun Feb 04, 2018 12:12 am

I'm a very novice mechanic, but decided I should learn basic things about maintaining my bike. This week I decided to replace my front brake pads, possibly rotors, clean the calipers, and check my front wheel for any casting defects that others on this site have found. Its a good project to do, and I also really want to get rid of the goddamned whining/groaning front brake sound that has happened since day 1 with my bike.

I got everything undone, checked the wheel and didn't see any obvious casting problems on the rotor landing. I cleaned the rotors with brake cleaner and a scotch pad. I checked that all the bobbins can be spun using the bolt trick. I cleaned the calipers with warm soapy water and a toothbrush, then sprayed with non-soapy water, dried, then applied break cleaner and took the toothbrush back to them. They look great!

Finally, I wanted to check and see that all 4 of the pistons were working in unison. It doesn't appear that they are. I'm being careful to not allow the pistons to come out their bores when I hit the brake lever. When I squeeze the brake lever, 3 of the 4 pistons move at roughly the same distance, where one barely moves at all. Does this matter? The one that is hardly moving is on the same side as the brake line, and is the bottom of the 2. I squeeze the lever to the bar 10 times, and the other 3 are sticking out 4-5mm. I then push all of them back in (so I don't let them fall out), without pushing the slow one back in. Repeat 5 or 6 times, and the slow one is finally about 5mm out of its bore. Is this a problem, and how can I make it better? There is one very slow moving piston on both of the front calipers. They aren't frozen, I can move them. They just come out very, very slowly when I use the brake lever.

Thanks!

DaveNZ
Two wheeled terror
 
Posts: 156
Joined: Wed Jun 04, 2014 7:06 am
Location: Taranaki-New Zealand

Re: 1290 Brake maintenance question

Postby DaveNZ » Sun Feb 04, 2018 3:37 am

I doubt this will be a problem, the pistons generally sit about .5 of a mm away from the disc, as the pistons come under load from the master cylinder pressure, they move and take on the load to the disc, the stiff one will move once the pressure increases, also, the callipers get very hot, you may find the stiff piston moves easier then. you could try putting a packer between the 3 pistons that move freely, and working the stiff one in and out a few times. Im not surprised they all don't move evenly when theres no real load on them.
2005 640, full system, 18 litre tank, flatside carb. 2010 Black multistrada 1200 Ohlins-with SCU. 2016 1290 GT, Remus muffler and link pipe, Rottweiler plates, and dongles.


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