rear brake bleeding?

i just replaced my rear tire and i has to push the pistons in on the brake caliper to get it back on....

i did like i would on any car and remove the cap and press the pistons in then put the cap back on....

well now the rear brake "goes to the floor" and doesnt operate the rear caliper, i tried bleeding like i would a car, pumping it a bunch then holding it down and opening the bleeder valve on the caliper...

still there is no pedal...

did i do something wrong or what do i need to do to correct it?

thanks

84 vf700 btw

 

Does anybody know what's going on or what I screwed up?

 

I would go back and do it over again see if I missed something..

 

Doesn't sound like you did anything wrong. Sometimes air gets in the brake system when you manipulate it, specially if the parts are being pushed to places they haven't been for a long time. If it's that difficult to bleed, the air is probably trapped up around the master cylinder. The easiest way to fix it is to use a vacuum tool, such as a mity vac to assist the bleeding procedure. The cheap and dirty way you could try is to leave the cap off the reservoir, and figure out a way to compress the pedal and just leave it for several hours, then rebleed...sometimes that works. If you have puddle of brake fluid under the master cylinder you'll know you should rebuild that. Oh...and when you pump the lever to bleed, slow and deliberate works best as opposed to pumping like crazy.

 

i actually have a nice vacuum pump and i just tried that, ran a hole bottle of fluid through it, clear lines so no air bubbles basically from the start...

i then tried the standard method of bleeding again...

and after all that i still have no pedal....

ill try strapping the pedal down for a couple hours but the pistons havent moved out even a mm since i pushed them in, im kinda wondering if they are stuck, but even at that if they are stuck you would thing the pedal would be impossible to push down...

 

Leaving the pedal all the way down did nothing... anyone know how to get stuck pistons out?

 

Usually you take the brake hose off the caliper and put compressed air to the port on the caliper. Make sure to use a rag/piece of wood to catch the piston's flying out so as to prevent damage to them. No, don't use your hand, it WILL hurt like hell. But, if you're getting hydraulic pressure to the caliper it should be pushing them out, me thinks something else may be wrong. How old is the rear brake hose???

Edit: Wait, scratch that, by what you've said you ARE getting fluid to the caliper. Maybe check the rear master cylinder for flipped seals as a result of pushing fluid back into it. I've never had it happen to me personally, but I've heared of it happening, for whatever that's worth.

 

I hadn't even considered the hose collapsing until u mentioned it... and its stock 27k miles....

Just weird how it was perfectly fine and when I push in the pistons they get locked up..... I'm gonna pull it off tomorrow and see what's up

 

OH, also, make sure you didn't accidentaly twist the hose when re-installing the caliper. That may give you just enough restriction to allow fluid through @ low pressure when bleeding, but when high pressure is applied it may further twist the hose thereby pinching it off without there actually being a failure. Good luck!!

 

The hose may have gotten twistedwhen I was doing.g it, thanks for the help ill try it later

 

On some really stubborn ones, I found it helps to remove the caliper and heat it to about 175 F, or just hot enough so you wouldn't want to pick it up without light gloves. I use a trashed griddle on it's lowest settings.

Also, I've had similar thing happen to me on a GL1100...the problem ended up being a clogged brake line. Apparently compressing the pistons pushed some sediement around. 25 year old brake systems that (maybe) haven't seen real frequent fluid changes can be temperamental. You may have a combination of things going on. Sometimes it's best to just be real thorough...rebuild master cylinder, blow out brake lines, clean caliper/pistons/sliding pins and replace piston seals. Really, the parts to do all that aren't very expensive...but it can be a bit time consuming.

 

i started a new thread concerning just the master cylinder.... i took the hose off and can blow through it easily, the caliper pistons are "stuck" in there and i have no way to get them out... how am i going to put compressed air to it?

id rebuild it all but idk how the hell im gonna get them out of there...

 

Edit: Wait, scratch that, by what you've said you ARE getting fluid to the caliper. Maybe check the rear master cylinder for flipped seals as a result of pushing fluid back into it. I've never had it happen to me personally, but I've heared of it happening, for whatever that's worth.

just noticed that so ill try taking it apart

i also heated the caliper up in my oven, pistons still wouldnt budge

right now im thinking it is the master cylinder

edit:
I figured out how the master cylinder comes apart, i took it all apart, cleaned it up real good, reassembled and now its working good

thanks for the help everyone

 

So glad to hear I've helped someone, good stuff man, now go ride the brakes offa her!!

 

I rode her to work tonight, nice to beback on the road...