Uneven break pad wear

[goose111]

I heard some squeaking from the front brake on a ride and I checked my brake pads in the front. 3 have about 4 mm of pad left and one has only 2 mm of pad left. what could cause this uneven wear to happen? all four should be wearing evenly +-.5 mm or so. I know some cars have guide pins that the calipers sit on so that the caliper finds center when under breaking so this doesn't happen. Does the fz6 have some sort of thing? The calipers seem hard mounted to the fork. Anyway the bike has been sitting outside for its entire life so corrosion might be a factor, But I dont know what would cause this to happen

 

[Gary in NJ]

If one or more of the caliper pistons is frozen you will get uneven pad wear. I would remove the pistons and inspect them for any pitting or signs of corrosion. A corroded piston must be replaced. I would also replace the seals as a seal that is no longer pliable will restrict the movement of a piston.

 

[TownsendsFJR1300]

What year bike is it?

Clean and re-grease the slide pins as they will gum up over time.

Also, the seals (caliper) tend to harden up over time and not release.
Yamaha recommends they be replaced every TWO years..

Checking brake drag will also give you an idea how much their sticking:

After new seals, S2 (and yes, pads are in the operating position).

https://flic.kr/p/24gHvHC

.

 

[goose111]

The year of the bike is 2009. The pin which holds the pads in was a little rusty and gummed up. the pistons look OK, If I were to remove the pistons from the caliper I would have to bleed the brakes right?
I cleaned and lubed the pin and will try the dragging test soon.

 

[Gary in NJ]

Yes, if you remove the caliper you will need to bleed the brakes. Anytime you introduce air into the system you need to bleed the brakes.

But don't let that stop you from doing proper maintenance. To that point, the brake fluid should be changed every few years. The FZ6 brakes are easy to fill and bleed. If filling from the reservoir (a top fill) be sure to leave the bleeder valves open as you fill - this helps to push air out of the system. If you see fluid leaking as you are filling - feel overjoyed that gravity is doing the hard work for you. I usually use a large 1" x 8" syringe and fill the system from the bleeder valves (a bottom fill) with the cap off the reservoir. With this method there is typically no bleeding (unless you don't get all of the air out of your filler hose when moving to the second caliper.

 

[TownsendsFJR1300]

The S2 bikes have 4 pistons on each side.

Their notorious for sticking. The S1 bikes have HALF the # of pistons

As yours are likely original, just clean the caliper and replace the seals..

(I tried cleaning and re-installing, that lasted a month, maybe)..

My 04 FJR used the same calipers and suffered the exact same issue...
With that said, you can get way many more years of use (much more than 2 years).