This sweet old GPZ 900 didn’t want to not stop… The brake calipers were hanging up because of the corrosion behind the seals of the piston. Brake fluid, whether it is Dot 3,4 or 5, acts as a sponge and absorbs water that builds up from the heating and cooling effect calipers undergo every time they are used. So, after the brake fluid becomes saturated (just like a sponge) it can no longer prevent the water molecules from etching the aluminum and necessitating expensive repairs if you want to continue riding your beloved motorcycle. Or you can simply perform some preventive maintenance, like flushing the brake system on a cold or rain filled weekend every couple of years. This is why most manufacturers recommend replacing your brake fluid every two years. Check your owner’s manual for other items that need attention every year or two that you can take care of or bring it by and I will see that it gets all the service it needs!
Hard to tell with all the bodywork off, but this is the same bike from “Top Gun”.
There really isn’t much crud in the caliper’s cylinder. Just enough to clearly see the brake fluid had absorbed all the water it possibly could.
Most of the crud was caused by water caught behind the seals of the caliper. As the moisture oxidized the aluminum, it pushed the o-ring seals outward until the caliper piston could no longer move freely .
Road grime on the outside and corrosion on the inside.
