Bleeding rear brake system -> Am I doing something wrong?

colind · 08-10-2016, 01:48 PM

So, first off, I appreciate all the help I’ve gotten thus far from these forums. The information and helpfulness of people on here really has given a breath of new life for a lot of these bikes, that would be otherwise unsupported, so once again, thanks in advance for the clarification I’m about to seek.

The subject in question -> rear brake bleeding. Never in my life have I had difficulties bleeding any sort of hydraulic brake system until I got a couple of chinese pit/dirt bikes. So that being said, I just want to reach out, for sanity’s sake, to ensure there is nothing I’m missing in how I’m bleeding my rear brake systems. The symptoms I’m experiencing are a completely lack of pressure from the rear brake. The pistons/pads BARELY move when the rear pedal is depressed. I’ve even gone so far as to replace the brake pads, and replace the rear caliper on one of the bikes, but to my dismay, I’m still running into the same end result -> rear brakes that don’t work on either bike. Anyway, here’s what I’m doing:

1 - Hook up the brake bleed tube and bottle to the bleed nipple on the caliper
2 - Open the rear brake master cylinder to ensure that it has ample fluid in it, and close it back up.
3- Pump the sh*t out of the rear brake to build some pressure i the line.
4- WHILE KEEPING THE BRAKE PEDAL FULLY PRESSED, I crack the bleed nipple open just enough to let fluid (and subsequent air bubbles) to flow up the tube, and into the bottle
5- Close the nipple, release the pedal
6- Repeats steps 3-5 two or three times until fluid starts to get a little low in the cylinder
7- Refill the master cylinder, and start the whole process over again until no air bubbles are seen in the bleed line.

I swear to god, I’ve done this at least 10-15 times PER BIKE, to the point where no air bubbles have been seen for 2-3 cycles of this process, and still, the caliper pistons barely move at all. I’ve never had issues with the front brakes on motorcycles, but I’m starting to wonder if I’m doing something wrong as the symptoms are the same on both bikes, and for the life of me I can’t figure out what’s going on. I’m not seeing any leaks on the nipple or the cylinder, so I’m not sure where to go at this point.

Thanks again for the help!

08-10-2016, 01:48 PM	#1
colind Join Date: May 2016 Posts: 16	Bleeding rear brake system -> Am I doing something wrong? So, first off, I appreciate all the help I’ve gotten thus far from these forums. The information and helpfulness of people on here really has given a breath of new life for a lot of these bikes, that would be otherwise unsupported, so once again, thanks in advance for the clarification I’m about to seek. The subject in question -> rear brake bleeding. Never in my life have I had difficulties bleeding any sort of hydraulic brake system until I got a couple of chinese pit/dirt bikes. So that being said, I just want to reach out, for sanity’s sake, to ensure there is nothing I’m missing in how I’m bleeding my rear brake systems. The symptoms I’m experiencing are a completely lack of pressure from the rear brake. The pistons/pads BARELY move when the rear pedal is depressed. I’ve even gone so far as to replace the brake pads, and replace the rear caliper on one of the bikes, but to my dismay, I’m still running into the same end result -> rear brakes that don’t work on either bike. Anyway, here’s what I’m doing: 1 - Hook up the brake bleed tube and bottle to the bleed nipple on the caliper 2 - Open the rear brake master cylinder to ensure that it has ample fluid in it, and close it back up. 3- Pump the sh*t out of the rear brake to build some pressure i the line. 4- WHILE KEEPING THE BRAKE PEDAL FULLY PRESSED, I crack the bleed nipple open just enough to let fluid (and subsequent air bubbles) to flow up the tube, and into the bottle 5- Close the nipple, release the pedal 6- Repeats steps 3-5 two or three times until fluid starts to get a little low in the cylinder 7- Refill the master cylinder, and start the whole process over again until no air bubbles are seen in the bleed line. I swear to god, I’ve done this at least 10-15 times PER BIKE, to the point where no air bubbles have been seen for 2-3 cycles of this process, and still, the caliper pistons barely move at all. I’ve never had issues with the front brakes on motorcycles, but I’m starting to wonder if I’m doing something wrong as the symptoms are the same on both bikes, and for the life of me I can’t figure out what’s going on. I’m not seeing any leaks on the nipple or the cylinder, so I’m not sure where to go at this point. Thanks again for the help!
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