Bleeding Rear Brake

[Jakub]

Hello,

I working an 83 Venture XVZ12.  I recently purchased a master cylinder rebuild kit and replaced the the components.  Now I'm trying to bleed the rear brake but it seems that I'm not not making any progress.  I have read numerous post on this site and feel that I'm doing this correctly, but my pedal is not getting any harder nor am i getting fluid at the back l caliper.  I loosened the bolts (i cant remember the name of this bolts going to the front and rear caliper at the MC and i have fluid coming out of both.  I did notice a small tear (picture attached) in a rubber seal in the proportioning valve.  Im wondering if that tear is causing some of my issue. 

Also, i checked the valve at the steering stem but a cannot get it lose.  I have been spraying blaster at it for days but it will not let loose.  Any suggestions would be greatly appreciated on how to loosen that bolt.

Lastly, I don't have a vacuum pump, I'm trying to bleed these using the old fashioned way just like in cars.

 

 

[Chaharly]

That torn boot might be part of your problem, maybe the proportioning valve is not allowing fluid through, but to be honest I've never tore one apart.  So far I've been really lucky with bleeding my brake system. Sorry I can't be any more help to you

[Marcarl]

If memory serves me correct there is no bleeder at the steering head on an 83, those weren't installed until 86. That doesn't mean you don't have one, but it would be aftermarket.

If the proportioning valve is compromised then you'll have fun getting things to work right if at all. That needs to be fixed first.

[saddlebum]

That torn cup will definitely affect your ability to bleed the brakes. If you have the bleeder screw at the steering head get a can of wurth rost-off ice  penetrating spray  If memory services me blaster also make an ice version. Using a small butane torch heat the bleeder screw (Not red hot you do not want to ignite the spray) than hit it with the spray keep the spray on it till it gets cold (may have to do it a few times) but the bleeder should break loose. Once you loosen it it remove it completely and either clean it well making sure the hole in it is clear or replace it. 

To bleed the system:

Option 1 

Bleed 1st at this bleeder then the left front brake and finally the rear brake.

Option 2

Completely drain the brake of all fluid. Get a new windshield washer pump. and some clear hose connect to pump. place the suction hose in a new bottle of brake fluid. connect the other end to the left front brake caliper (NOTE: you may want to add a restriction in this second hose as the pump may move too much fluid at once or a rheostat to slow the pump down). with the line connected to the open bleeder of left front caliper and the bleed screw at the steering head open run the pump. Close the bleeder screw as soon as fluid comes out and turn the pump off as soon as the fluid gets into the master. You should now be able to bleed the rear caliper the conventional way.

[Jakub]

Thank you all for responding!!  I was able to find a used MC from a salvage yard with the rubber cup in the proportion valve intact.  I do have a bleeder in the steering column and I cant get the bolt loose.  I will be trying your advise on getting that loose.  

As for the bleeding part, I'm going to try the conventional way first.  With that said I have bleed my car brakes many times over the years.  Are motorcycles basically same way, push on the rear brake pedal, hold, loosen bleeder screw, tighten bleeder screw, release rear brake pedal (Repeat, repeat, repeat)? 

One dumb question: If I pump the brake pedal multiple times does the fluid travel up the line or am i just pushing it back and forth with every pump?

Thanks guys!!

Jakub

[saddlebum]

16 hours ago, Jakub said:

Thank you all for responding!!  I was able to find a used MC from a salvage yard with the rubber cup in the proportion valve intact.  I do have a bleeder in the steering column and I cant get the bolt loose.  I will be trying your advise on getting that loose.  

As for the bleeding part, I'm going to try the conventional way first.  With that said I have bleed my car brakes many times over the years.  Are motorcycles basically same way, push on the rear brake pedal, hold, loosen bleeder screw, tighten bleeder screw, release rear brake pedal (Repeat, repeat, repeat)? 

One dumb question: If I pump the brake pedal multiple times does the fluid travel up the line or am i just pushing it back and forth with every pump?

Thanks guys!!

Jakub

Yes bleeding the conentional way will work though these bikes can sometimes not be as co-operative as when bleeding car brakes. Back bleeding by feeding the fluid under pressure in through the bleeder screw until the master. Is full is more effective. On many hydraulic systems I have worked on which includes cars, heavy trucks and tow motors as well as hydraulic clutches, I have found back bleeding is sometimes the only method that works and is also the quickest.

Edited 3 hours ago by saddlebum