No back brakes

[chrislemon]

Since I have found the button to make a "new thread" I will copy what was said before I ask my next question....

 

chrislemon

I had no back brakes and so I replaced all the cylinders in my rear caliper in the fall. Now that it is spring I see I still don't have rear brakes. Upon further investigation it looks like I am getting lots of air when bleeding the back brakes but still no pressure on the back brakes and yet the front is doing great and the fluid reservoir burbs when I apply the front brakes.

When I cracked the line going into my rear calipers and apply the back brake I did not get a surge of fluid coming out.

What should I check now?

PS I can't seem to find where the metering valve is located either (how to get to it)

 

bongobobny

Now, chances are you probably have a plugged up proportioning valve which is attached to the rear of the rear master cylinder. The metering valve, on the other hand is attached to the frame towards the front by the battery along with another bleeder as there is a high point in the lines and air can get trapped there. Due to the fact you are saying the front brake works fine there should be nothing wrong with that as the metering valve only works with the front brakes...

 

chrislemon

Now my question is "where is the rear master cylinder"? I would think its the brake reservoir on the handlebars but I don't have anything attached to it. If it is in another location than that tells me I am also bleeding my rear brakes and filling the front brake reservoir. Sometimes its just better to leave things to a mechanic(go ahead and have a good laugh at my expense).

PS When I do find this proportioning valve, do I just blow it out to unplug it?

Thanks

Newbie

[GeorgeS]

Do you have a service manual ???

If not.

 

From Home page, down left side, see, " VR Tech " Click on that.

and find the Link to the Service manual for the 2nd gen bikes,

 

You can find the brake section, all the information you need is there.

 

However it sounds. like you just need to Bleed the Brakes, These systems

are not easy to get all the air out the systems,

 

A tool, call the " My T Vac " tool is very usefull for bleeding out the brake

systems on these bikes.

 

Also, its good to use "Synthectic Brake Fluid " Do not use the old DOT-3 stuff.

 

Basicly, on the rear, and left front, you need to bleed the back, then the front, then the back then the front , maby several times to get the air out.

 

It helps to have a Second set of hands

[Venturous Randy]

From Home page, down left side, see, " VR Tech " Click on that.

and find the Link to the Service manual for the 2nd gen bikes,

 

 

Basicly, on the rear, and left front, you need to bleed the back, then the front, then the back then the front , maby several times to get the air out.

 

It helps to have a Second set of hands

 

George, his profile says he has a 1st gen 87, but I had to look.

Chrislemon, the rear master is located behind the side cover on the right side, just above the passenger foot rest. Be careful taking the plug out as these housings can be broken. As George noted, the rear master feeds the left front caliper and the rear. If you have no fluid movement, you may have to do a lot of pumping before you get it flowing good. The reservoir is small, so it does not take many pumps to empty it and you will again be filling the system with air. Once you have the system properly bled, make sure you do not have it too full when you go for a ride or your brakes may start locking up. Make sure you take a 8mm wrench with you.

RandyA

[gscbertrand]

I don't think I would change to synthetic brake fluid until I'm ready to change my brake hoses and rebuild kits for the master cylinders and calipers. In the mean time I did switch to DOT4 which is a little better than DOT3. I just received my SS brake lines from a company in Quebec, all 8 hoses in red covers for $170.00 delivered to my home. Now for the kits.

[paysaw]

When I had my 83 I changed and bled all my brakes.It was a bit tricky but when you figure out how to do it, it only takes minutes.I used a hand bleeder to do my front left brake.Once I cleared out all the old fluid, it was a snap.

[chrislemon]

I appreciate hearing it takes a lot to get all the air out. I have gone thru almost a full bottle of dot 3 and am no closer to building pressure than when I first started.

Its almost like the actuator that is going into the bellows portion on the proportionate valve is inserting air into the system.

Is there a systematic approach to fault finding the cause of not building pressure?

[reddevilmedic]

from what i understand, air gets trapped in that valve. i couldnt get my pedal to fully disengage. after a dozen times bleeding it, with speedbleeders, still the problem. i decided to go delink and stainless. just waiting on parts...

[rstacy]

I appreciate hearing it takes a lot to get all the air out. I have gone thru almost a full bottle of dot 3 and am no closer to building pressure than when I first started.

Its almost like the actuator that is going into the bellows portion on the proportionate valve is inserting air into the system.

Is there a systematic approach to fault finding the cause of not building pressure?

 

Chrislemon,

This is what I have picked up from this thread.

You may have been trying to bleed the rear brakes by filling the the front brake master cylinder. The front brake master cylinder only works on the front right caliber. This system is probably good and why the front brakes appear to work.

As mentioned, the rear brake/front left brake master cylinder is down on the right side behind a panel.

 

I had the same problem on an 89 that I picked up.

The problem was the bleeder that BongoBob mentioned.

It mounted right in front of the false tank cover. It is actually very easy to see.

Its the high point for the rear brake and front left brake and air collects there.

Edited April 24, 2012 by rstacy

[dingy]

Pictures of valve I mentioned in your PM

 

Not in a logical order though.

 

Gary

[chrislemon]

Pictures of valve I mentioned in your PM

 

Not in a logical order though.

 

Gary

 

Is there anything I can do to make the job easier when removing the proportion valve?

[bongobobny]

You mean besides pay someone else to do it???

[dingy]

Is there anything I can do to make the job easier when removing the proportion valve?

 

Remove the one screw at the bottom of the reservoir, this will free it up. Remove brake line banjo bolts. Then remove the 2 screws holding master in and it should fall out.

 

Gary