The rear brakes on my 08 TXC250 seem to not release pressure and drag badly after routine usage... This seems to be a daily random occurrence. I'm gonna check a few other things first but can anyone give me some pointers on checking \ cleaning the rear brake caliper? This s what I hope will be the last resort thing to fix my dragging brake issue ...
If the square cut seal the rides on the caliper piston gets rounded with wear it will drag. A caliper rebuild kit will have that seal as well as the dust boot. As long as the piston is smooth and the bore can be cleaned up you can rebuild a caliper many times.
If the flexible brake hose collapses inside it can act like a one way check valve and hold light pressure on the caliper, this too will cause drag. You can diagnose this by applying the brake a couple of times and then opening the bleeder, if it spurts fluid under pressure then there is a hose problem or the master cylinder is not releasing. If no pressure exists I would suspect the caliper piston dragging causing it to not return because of either a worn square cut seal or debris in the bore.
Yep, thanks for the help and process for checking the caliper ... It turned out that apparently the fluid had been boiled too often because after changing the fluid, the sticking has stopped ...
I usually change mine twice a season if I'm riding a lot of "wet" events. I think that the fluid picks up moisture and if it's not changed, I've seen it lock up the caliper and hence the wheel. I know during several events I stopped and told guys to open the bleeder on the caliper to free the wheel. They were like how did you know that, from experience from not changing the fluid frequently enough.Glad you got it fixed.
When DOT 4 brake fluid is new it is a light color but as it absorbs moisture it will become darker. DOT 4 brake fluid has a dry boiling point around 450 degrees F. but when you add moisture it's going to boil at about 320 which adds gas/air to the system. I change the fluid in the reservoir and bleed some new through the caliper every time it starts looking dark which is about twice a year. Fluid is cheap and keeping fresh fluid in the system will save you dollars and grief from boiling and corrosion.
