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No rear brake, but do have left front brake


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I installed Speed Bleeders ™ on the clutch and on all brake bleeding points yesterday (perhaps I shouldn't have chosen Friday the Thirteenth) and flushed all clutch and brake fluids with new fresh DOT4. Everything was going swell until I replaced the last bleed valve on the rear caliper and could not get any fluid to come out of the bleeder when I attempted to bleed the rear brake line. I replaced the Speed Bleeder with the OEM and attempted to bleed as normal and again no fluid would emit. I removed the bleeder and depressed the brake foot pedal, but still no fluid at rear caliper. I can see that there is fluid in the open port where the bleeder fits, but none comes out when I depress the pedal. I have a very firm pedal and the left front brake works. I tried rebleeding the entire system and did not encounter any air at the front or at the metering bleeder near the steering head. I removed the plastic elbow with the reservoir fill hose attached to it and drained the reservoir. I examined the two ports inside the master cylinder that are visible when the elbow is removed and noted that the orifices were open as I depressed the pedal. I reinstalled the elbow, refilled the reservoir with fresh fluid and rebled the front left, the steering head metering bleed valve and attempted to bleed the rear once again without success. Same results, no fluid and no pressure at the pistons. Applying the pedal does not apply the brakes on the rear wheel but the front left brake works fine. It seems to me that the proportioning valve mounted on the master cylinder is stuck, perhaps, but I don't know enough about the internal plumbing of the master cylinder/proportioning valve to know if this is likely. It is not an easy task to remove the master cylinder and or the proportioning valve, so I am asking for guidance towards some other cause for me to have no pressure at the rear caliper. The last time I rode the bike a couple weeks ago, the brakes seemed to work fine, even two up. I only encountered a problem after I installed the Speed Bleeders™. (Thanks to your suggestion, Condor!) :whistling:

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You might very well have a pluged Compensator (??) valve on the back side of the master. With the rear brake not working and front OK you weren't missing much in braking power. Get in there and crack the banjo at the valve to see if fluid is coming out of the valve. If none, it's plugged.

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I was not able to crack the banjo bolt at the proportioning valve because it is not accessible behind the master cylinder and frame. To loosen that banjo bolt I had to dismount the master cylinder, loosen the banjo and remount the master cylinder and then depress the pedal. I decided to just remove everything. I removed the reservoir, the master cylinder with proportioning valve, the brake hose from the proportioning valve to the rear caliper and the rear caliper. I removed the proportioning valve from the master cylinder and removed the internal workings. Everything looked like new. I noted the position of the various parts and cleaned everything, even if it didn't look dirty. I used shop air and blew out all passages. I blew into the hose (by mouth, first) and found it open. I used shop air to blow it out real good, too. I used shop air on the caliper and all the pistons moved out. I pried the pistons back into the caliper body and again applied air and all four again moved out. I opened the reservoir and found it pristine as well. No deposits, nor crusty jello, nor sediment anywhere.

I am going to reassemble everything, but since I didn't find anything out of line, I am skeptical that the problem has been resolved.

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  • 2 months later...

I replaced the rear caliper with a freshly rebuilt unit from Earl (Skydoc_17) and installed a new master cylinder rebuild kit. Bled the system 'til I am sick of brake fluid and STILL I have no rear brake. Please read previous posts. All symptoms remain.

This is really starting to suck!

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If you are getting good brake on the front rotor, but nothing on the rear rotor, there are a couple of places to look at.

 

The attached pictures. shows the inside of the proportioning valve that is on the rear master cylinder on an 1st gen. This could be a source of the problem.

 

The only other place could be a bad rear brake hose. Have never seen on go bad and block pressure, but I have heard it is possible.

 

I'm sure Earl knows how to rebuild calipers and have confidence it is done right.

 

So no pressure between rear caliper and rear master leaves the two items above.

 

1st picture is internals of valve

 

2nd is with cap removed

 

3rd is looking through valve with internals removed, no obstruction.

 

4th is valve on top of master.

 

Something that has worked for me to get front brakes bled right is to push brake lever all the way down and tie in this position overnight. I have had this work several times on the front, but never had to do it to rear as I have delinked brakes and it has never been a problem to bleed rear.

 

Gary

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Thanks, Gary for taking the time to respond and post pics of the p-valve. I have disassembled the proportioning valve several times and find nothing out of the ordinary or anything that doesn't look like the pics that you posted. As noted above, the hose is clear to the rear caliper.

What would a FAULTY proportioning valve look like? Mine looks new, like the one you posted. What if there were a problem with air in the master cylinder that can't be bled out (Earl's theory) or a problem with pressure differential to the front caliper? A restriction in the metering block perhaps?

Many people are familiar with what the proportioning valve does when it's working properly, but no one has indicated what would cause a proportioning valve to NOT work properly.

The rear brake has worked in the past, what would have caused it to stop functioning?

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First thing I would suggest is to loosen the brake line at the rear caliper a little and depress the pedal to see if you get any fluid flow. This is a check to make sure the caliper is not blocking flow. If no flow at caliper line, do the same thing at the rear master where the line attaches, if none there, try loosening the banjo bolt that holds the proportioning valve on.

 

If none of these 3 places shows a flow, then internally, the rear master has to be blocked between the rear outlet & the front outlet on the master cylinder. This is based upon the premise that the front caliper is receiving pressure.

 

I don't think that the front metering valve is the cause of this problem. If you have good brake on the front rotor, that means the master is producing pressure. This pressure should be pushed through the master on both ports to the front and rear brake. If it was the other way around, and the rear was working, but not the front, the metering valve could be a suspect. This is not saying the metering valve is certainly operating flawlessly, but it is in good enough condition to allow flow through it.

 

Gary

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Yah! If your metering valve wass bad either you would have no front brake (clogged) or the front would lock up (too much volume of fluid). The metering valve is pretty much an oriface that limits the flow rate to the front brake. The proportioning valve, on the other hand primarily lets pressure build up to the rear brake before sending pressure to the front brake. That's what the spring in there is for, a "back pressure" has to build up and overcome the spring rate before fluid is allowed to be sent to the front brake. This prevents "nose dive" when the brake is applied.

 

Check the way Gary suggested by making sure you have flow to the caliper. Earl is an excellent mechanic and knows what he is doing, but sometimes defication occurs. Did the caliper bleed properly? What method of bleeding did you use? Vacuum pump works the best...

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And, I have good news! I have rear brake! Although I can't positively identify the exact cause of the misbehaving proportioning valve, I was finally able to get reliable rear brake application. For the past couple of days I have been trying to remove air WITHIN THE PROPORTIONING VALVE. It seemed to me that there must be some air SOMEWHERE causing the p-valve to block flow. Although the following didn't immediately fix the problem, it seems to have eventually accomplished the cure: I pumped (with the pump function of a Mity-Vac) brake fluid BACKWARDS through the rear bleeder until fluid came out the open reservoir fill hole. I did this several times, with the thought that vacuum sucking wasn't getting the air out of the prop valve as conventional pumping and bleeding wasn't opening the prop valve, so let's try pumping the air back into the reservoir. I also pumped the brake pedal and simultaneously loosened the big (19mm wrench) cap on the prop valve to evacuate air. I would get momentary application of the rear caliper, but then subsequent pedal depressions did NOT apply the brake. I persisted until suddenly, I had normal operation of the rear brake! Repeatedly.

For whatever reason, it appears the prop valve would close off the rear brake application pressure if there was any air within the proportioning valve body or rear caliper. At least that is what it seems to me. Apparently the trick is to remove the air, even when the p-valve is closed! I don't think you can bleed the proportioning valve conventionally, i.e. pumping fluid from the rear master cylinder to the rear caliper. Well, maybe if luck is siding with you.

Tomorrow morning will be the test. Will the brakes work correctly after sitting overnight?

Wish me luck!

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  • 1 month later...

During our Lake Superior Circle Tour I lost the rear brake AGAIN. After trying all the things I tried back in May, June and July to resolve the problem without positive effect, I gutted the proportioning valve of it's contents.

A short test ride including panic stops on pavement and gravel roads revealed no objectionable behavior from the rear brake as a result of having no proportioning valve.

I am running as is for now, but I don't like the idea. I like the idea of NO rear brake even less, though.

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Hey Kevin,

The progressive engagement technology of the FJR caliper you purchased removes the need for the proportioning valve. The bike that caliper came from does not have a proportioning valve, and that is why the caliper functioned as well as it did for you after you gutted the valve. I offer progressive engagement calipers for the front as well. This mod would require the delink of the front and rear calipers. I realize you are not too keen on that, but thought I would mention it.

I am glad to hear that you have solved that issue with the rear brake, once and for all.

Good Job,:thumbsup2:

Earl

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Hi, Earl

Does the FJR have linked brakes? If not, that would be the reason for it (FJR) not having a proportioning valve, correct?

I left the proportioning valve body on the master cylinder and had quite a long session removing the air from the vacant valve body. The pedal seems a bit soft yet, but I can live with it until I change over to stainless steel braided lines this winter, where upon I'll remove the prop valve body and plug the passage with the appropriate bolt.

 

Earl? How is your '87 trunk repair coming? You aren't the guy who is bidding against me for the Ventureline trunk rack on ebay, are you? It is already past my limit and besides I bought a new one (not Yamaha) for a Buy it Now of $45 and free shipping. I haven't got it yet but it looks identical to a Drag Specialties rack I had on my first 1983.

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Hey Kevin,

The FJR that caliper was from does not have linked brakes. As far as my 87'VR goes, I have replaced the side bags with used ones, I have a used tail light installed, used trunk rack, but am having trouble finding a usable trunk in the Elegant/Birch Brown for the 87' model. I did ride the bike to the WNY meet and eat a few weeks ago, and was glad to discover there appears to be no frame damage. I do have some noise in the Final Drive, but have another to replace it with. I dearly miss the extra storage space the trunk provided. I am not bidding on that trunk rack on Ebay, I am not quite there yet. The removal of that proportioning valve will help with the bleeding of the rear brake.:thumbsup2:

Earl

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  • 2 weeks later...

You guys sure seem to know your way around these big bikes.I'm having a time getting the brakes to work on my 1985 venture royal.I have front hand brake but no rear or left front.I was at a friends place trying to bleed the front but couldn't get more than a tea spoon or so out with a mighty vac and then trying the conventional way same thing. I have read just about every post on bleeding brakes on the sight but I'm not sure what I should try next .Thanks in advance , Bill

Edited by bill in mn
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You should post a new thread when you have a somewhat new question. Often people don't look at old threads even when there is a new post in it.

 

Go to link below & click on New Thread in somewhat upper left to start a new thread in the 1st Gen Tech Forum.

 

http://www.venturerider.org/forum/forumdisplay.php?f=8

 

Most always, you will get some sort of help from one of us.

 

Gary

Edited by dingy
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  • 7 months later...

Since I don't see where to make a new thread I have decided to reply to this thread. Since its an older thread I trust I have not cut anyone off in their communication.

 

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)

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Hi! To start a new thread you hit the "New Thread" button at the top of the forum listings for that particular forum.

 

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...

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The proportioning valve is bolted to the rear master cylinder. It's job is to reduce the braking force to the back brake when you are slowing down (so that the rear wheel does not lock up.) You can see above what problems Prairehammer had with his last September. It might be possible to reverse a seal in the mechanism, but that wouldn't explain why one would suddenly stop working, so maybe an air lock around the weight would cause a problem. Generally people can forget these things and just ride, though.

 

You can try using a syringe full of brake fluid and pump fluid through from the bleed nipple, possibly just loosening the banjo as you do so in the hope of forcing air out through another orifice.

 

Me, I took the thing off and threw it away years ago. The bolt that holds it on is the same thread as a banjo bolt. The metering valve is still there to stop you over-pressurising the front.

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Anybody have a picture of the "banjo" bolt is and where it is located ? I haven't been able to successfully bleed the rear and front of my 87. When I get back in town, that will be my #1 goal on the 87. Next to installing new carb diaphragms.

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Since I don't see where to make a new thread I have decided to reply to this thread. Since its an older thread I trust I have not cut anyone off in their communication.

 

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)

Unless modified, LEFT FRONT brake is attached to the REAR master cylinder (linked brakes), and also needs to be bleed. Tons of air in the front half could be you problem.

Your hand brake is attached to the RIGHT FRONT brake and would from your description to be OK.

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