Brakes not releasing on 83, any brake guru's?

[cowpuc]

Here's the scoop:

Edited April 20, 2009 by cowpuc

[Yammer Dan]

Too much fluid in rear Master. Bleed some out you should be OK

[buddy]

Yes you do have blockage somewhere,could be proportioning valve sticking which leads to front and rear brake hoses or return bleeder in master cylinder?

May have to remove rear master cylinder assembly unit and do a good cleaning.

Hang on more info. will be heading your way.

 

GoodLuck let us know what you find

 

buddy

[buddy]

Too much fluid in rear Master. Bleed some out you should be OK

 

Yes this too,Yammer sounds better plus easier to do.Do this first.

 

buddy

[Denden]

It could be what Yammer Dan said. there's another possibility...if the brake pedal is adjusted too high, it won't allow the master cylinder piston to return all the way, and that will block the tiny return hole in the master cylinder. There are 2 adjustments for the brake pedal...one is at the rear of the pedal itself, that adjusts the hieght of the pedal. There is another adjustment for the pedal free play. If you follow the pedal linkage where it pivots thru the frame, there is a bolt that is at an angle, just inside the frame. It will adjust the free play, so the piston can return all the way. I always adjust it by taking the black plastic side cover off, and adjust the bolt while looking at the master cylinder, where the linkage pushes the master cyl. piston upward. You want to make sure that the pedal moves slightly before it starts pushing the piston up.

[cowpuc]

Thanks for the FAST replies folks..

I am having the problem with the cap off the rear master, I also bled a bunch of fluid off at the caliper bleeder(s) so I am pretty sure its not an over filled master. Could it still be Yammer?

Wouldnt a sticking proportioning valve show up as not letting either the front or back - not both - release? As it is now, both front and rear stick the same and both release if I open the bleeder on either caliper..

I did check the "slack" in my pedal and it has plenty, another very good suggestion though. I thought that was it earlier today when working on it cause my pivot arm was very sticky and holding the pedal down a little.. I even pull up on the pedal and hold it up so I am pulling the actuator arm out of the master cylinder,, doesnt help..

Has anyone ever had a master apart and know if I can clean the return port orfice out without a complete tear down?? I dont want to open the system if I dont have to (remove lines)..

All great suggestions though!! THANKS AGAIN GUYS!!!!!

'Puc

[Denden]

You've covered a lot already. It sounds to me that it is time to pull the master cylinder out and give it a good cleaning. Probably that tiny return hole is plugged. It would be a good idea to put in a re-build kit while you're at it.

[Squeeze]

You've covered a lot already. It sounds to me that it is time to pull the master cylinder out and give it a good cleaning. Probably that tiny return hole is plugged. It would be a good idea to put in a re-build kit while you're at it.

 

 

I second that ...

[bongobobny]

If not, then the proportioning valve, which is a common failure, would be next in line for clean/rebuild followed last by the rear caliper. I agree with the other guys that a good place to start is the master cylander though...

 

A good flushing of the entire brake systems as well as the clutch system should be performed as peventative msaintenance every few years anyways to keep the systems in top operating condition. Every 3 to 4 years is good.

[Marcarl]

All good replies and I'm totally agreed with pulling the whole system apart. If your brakes fail to do what you expect if them, then you may have a lot of time to think about it later, along with the fact that another set of brakes on another scoot cost more than what you would spend now in time or money.

JMT Carl

[Guest timshosvt]

on it cause my pivot arm was very sticky and holding the pedal down a little.. I even pull up on the pedal and hold it up so I am pulling the actuator arm out of the master cylinder,, doesnt help..

'Puc

 

Before you decide to rebuild, if nothing is leaking....Make sure you do as Denden suggested. Adjust your pedal so the pedal isn't touching the actuator arm at all and flush/bleed again with the pedal in that position.

The calipers, as you saw, can hold loads of crud on the bottoms and I got lucky by cleaning them out, dumping the fluid from the master from the lid side, working the master cylinder piston back and forth (do this with fluid in)flushing and bleeding everything.

I ordered a new caliper seal kit for my rear but found that they are very durable and can be reused. Randya suggested that you can turn them inside out for a fresh seal surface. I had thought about doing that, but just put it back in the way I found it and it worked.

I also had too much fluid in the reservoir with the bike on the center stand and the fluid was touching the threads on the fill port. It was very, very full with the bike on the side stand.

I have no idea if my return orifce was ever plugged, but I know that while I was bleeding and fooling around with the caliper off the rear, I wasn't able to push the piston back with the pedal even slightly touching the actuator arm. I could have gotten lucky with pushing the pistons back by hand which blew the crud out of the return orifice.

Carry an 8mm wrench and a rag with you on test rides so you can let the pressure off the caliper to get home. Do you have a front brake that works while you are testing?

[cowpuc]

If your brakes fail to do what you expect if them, then you may have a lot of time to think about it later, along with the fact that another set of brakes on another scoot cost more than what you would spend now in time or money.

JMT Carl

 

and THAT is exactly why I am in the middle of all this.. I know from experience that right here in my own little garage with all the internet help (thanks again) and my tools and salvage parts and a place to sleep and shower is WAYYYYYYYYYYYYYYYYYYYYYYYYYY better then having this baby decide to lockup out in the middle of Moab/Utah in 128 degree temps!!!

Carl,, NO wiser words have ever been spoken!!

[cowpuc]

Carry an 8mm wrench and a rag with you on test rides so you can let the pressure off the caliper to get home. Do you have a front brake that works while you are testing?

 

BINGO TIM!!

That is exactly what I have been doing here. I also have a syringe with a hose that connects to my bleeders and its full of fresh fluid in it - PERFECT for "on the road testing"..

I am about to disconnect the pedal completely from the master and then try a c-clamp on the piston on the rear caliper and see if I can force fluid back thru the return orfice in the master without a complete tear down..

Anyone have any idea where the return orfice is located in the rear master??

You all are AWESOME!! Thanks again for the assist - all greatly appreciated!

'Puc

[Guest timshosvt]

All good replies and I'm totally agreed with pulling the whole system apart. If your brakes fail to do what you expect if them, then you may have a lot of time to think about it later, along with the fact that another set of brakes on another scoot cost more than what you would spend now in time or money.

JMT Carl

 

One of the wisest posts on this site. Two weeks ago, the person that taught my motorcycle safety class along with long time neighbor were killed in separate motorcycle accidents by cars that pulled in front of them. In both instances, better brakes wouldn't have made a difference, but safe and effective brakes are something I've been contemplating lately. Keep up the good work.

[Tupperj]

BINGO TIM!!

Anyone have any idea where the return orfice is located in the rear master??

You all are AWESOME!! Thanks again for the assist - all greatly appreciated!

'Puc

 

Puc,

 

if the Ventures are like the XS11's that I've torn into, the return or "spooge" (Don't ask me why folks call it that!) is located towards the banjo bolt in the bore of the cylinder. It's VERY small! Something one would clean out with the bristle of a wire brush kind of small. Doesn't take much to block it, and if you force the piston back you'll just wedge it in tighter. I'd recommend a tear down and clean/rebuild. Other posters are correct, most of the parts are reusable, but kits are cheap and you're not! I personally don't fool around with brakes or tires. Failures there can have swift and serious consequences.

 

One last hint: Many have problems getting the system to bleed air after a rebuild. I've had luck bleeding the master first by holding a finger over the banjo bolt hole and exercising the piston. You can feel just the slightest pressure build up on you finger until the "pump gets primed" and then it becomes easy to bleed out. SpeedBleeders are a help too.

 

Long winded, but hopefully helpful!

 

Paul

[rhncue]

My 83 does that about once or sometimes twice a year. My trouble is where the rear brake lever connects to the round bar going through the frame. Rust and dirt gets into the frame bushing at this point and makes the clearance to slight so that this bar binds. When the brakes are applied and then released, the return spring is not strong enough to fully release the rear brake. At first it is not severe enough to keep the brakes on hard but enough so that the bleed hole is not uncovered releasing the pressure. As time goes on it increasingly gets worse. To repair the brake lever needs to be removed, the master cylinder needs moved and the plate that the rear foot pegs are attached to needs removed and the rod worked out the back side. Once out it needs cleaned good and greased back up and reinstalled. Yesterday while riding mine I felt it not fully releasing again so tonight or tomorrow I'm going to tear it down, put in a grease fitting and some grooves so that I won't have to go through this again. If you just work some oil into the bushing it will loosen up but won't last long as the oil will wash away. As long as there is grease then water can't enter.

 

Dick

[cowpuc]

Hi Guys..

Just wanted to say THANKS again for ALL the great points on the brake issue!! Anyone reading this should take all the points made to heart. I got a chance to work on the scoot tonight and found the anwser... I am making a new thread - with pics - of what I found just in case someone else has these problems and wants a "quick fix" that may work...

'Puc

[Squeeze]

here's the new Thread ...

 

http://www.venturerider.org/forum/showthread.php?goto=newpost&t=12491