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83 Venture back brake issue

Yngbld14
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Yngbld14

Yngbld14

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Ok. I understand it's a pain in the ass to bleed the back brake. I'm having an issue with it after I bleed the system. In Lee the front with a mini vac and it seems I get all the air out relatively easy. I then work the back brake and get a decent pedal. So I think everything is great. I go to ride a day or so later and the pedal is weak again. Now I say to myself maybe there is still air in the system. So I go through and bleed it again. Again I get a decent pedal, next morning go to ride it and the pedal went soft again. I do it one more time and get a decent pedal, but it goes soft by morning. Is it really this hard to bleed these things? Totally lost now.

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cowpuc

cowpuc

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Ok. I understand it's a pain in the ass to bleed the back brake. I'm having an issue with it after I bleed the system. In Lee the front with a mini vac and it seems I get all the air out relatively easy. I then work the back brake and get a decent pedal. So I think everything is great. I go to ride a day or so later and the pedal is weak again. Now I say to myself maybe there is still air in the system. So I go through and bleed it again. Again I get a decent pedal, next morning go to ride it and the pedal went soft again. I do it one more time and get a decent pedal, but it goes soft by morning. Is it really this hard to bleed these things? Totally lost now.

 

I know this will sound strange but you gotta reach up on er neck and bleed off the proportioning valve up there as its it high spot in the system IMHO.. Not really a bad job,, just a matter of cracking the line at the valve, pressing down on the peddle and closing it off.. You might wanna hang around till one of our 1st Gen guru's speak to your situation but until then - if it were mine - I would do what I suggested above while I was waiting to hear back from others - never ever know,, might just be the solution!!

 

You need a short video pointing out that which I speak of?

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Yngbld14

Yngbld14

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Here ya go Blood!! Take a peek at this! Sometimes,, not always but sometimes,, I am easier to follow when I video stuff than when I write stuff.. Hope this is one of those times!!

Puc

 

 

This is great!! Thank you I will try this tomorrow. Thank you for your help.

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cowpuc

cowpuc

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This is great!! Thank you I will try this tomorrow. Thank you for your help.

 

You betcha,, you are more than welcome!!

Might wanna double check this thread again before you go to spinnin wrenches on er tomorrow,, got a few guru's on here that have forgotten more than I know about this stuff - maybe one of em will chime in with some advice that we can both learn from by then.. If not,, give er a shot and let me know how ya come out..

Puc

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Yngbld14

Yngbld14

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You betcha,, you are more than welcome!!

Might wanna double check this thread again before you go to spinnin wrenches on er tomorrow,, got a few guru's on here that have forgotten more than I know about this stuff - maybe one of em will chime in with some advice that we can both learn from by then.. If not,, give er a shot and let me know how ya come out..

Puc

 

Went with your idea seeing I had really nothing to lose and want to ride this week. Needless to say after I cracked it the first time my pedal got instantly stiffer. So I decided to go through all the procedures once again and bled it at the neck as well. Now it's time to wait and see if it goes soft again. It was a lot quicker this time. Thanks for your help!!!

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camos

camos

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Scratch that 45 minutes later pedal went soft again. Must be a leak somewhere, but there is no fluid on the ground or the bike anywhere I can see.
Have you cleaned out the caliper pistons and bores yet? There is an o-ring in each bore that could be bad. Also, the pistons can get crudded up and sticky so they do not release easily. The pistons and bores can be cleaned with a green Scotch pad.

 

If the o-rings are bad the re-build kits available are quite expensive and it is a better choice to spend the money on upgrading the calipers to Mk II or R1/R2 ones. Unfortunately, it is necessary to also upgrade the forks to Mk II for the newer calipers to fit.

 

There are a few places for air to get into the system, at each caliper and at the MC, loose connection or least likely, a split casting. Bleed the system then clean the area around the calipers and MC . Spray some baby powder everywhere a leak could be possible then pump the foot pedal until there is pressure and tie it off to keep pressure applied. The powder will easily show any leakage.

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snyper316

snyper316

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Hey young blood have you checked or possibly kept it quiet in the garage where you are working this and maybe here funny little noise coming out from the neck area that could also be your valve I had the same issue but I was hearing a little noise and also there should be a rubber cap I'm sure you seen that in Scott video you might want to check that out. Which is why I ended up having to replace mine and I went ahead and upgraded mine to an MK II line because it had the bleeder valve at the neck the one old Scott saying that we cheat with. Because what you're describing sounds like it's allowing air to enter your brake lines which is basically what mine was doing. Due to my little rubber cap missing...

 

Sent from my LG-K371 using Tapatalk

Who asked for wine need to say line...

Edited by snyper316
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skydoc_17

skydoc_17

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Hey Dave,

Congrats on your "new to you" scoot!

If you are not seeing brake fluid at the left front caliper, the rear caliper, or dripping off of the frame from the proportioning valve, then I am afraid the Rear Master Cylinder needs to be rebuilt. The seals once worn, allow air to be reintroduced into the closed brake system. After the rebuild of the rear master, this kit will improve the bleeding process, and brake performance:

 

http://www.venturerider.org/forum/photopost/showproduct.php?product=316&title=6-line-first-gen-ss-brake-line-delink-kit-with-both-clutch-lines&cat=17

 

Earl

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Yngbld14

Yngbld14

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After watching the video closely I did notice I do not have a cap on the proportioning valve. When I bleed the system I see fluid everywhere I'm suppose to. I get a great pedal then after a short period of time the pedal goes soft. I see the upgrades you guys are doing, but where do I find them? And master cylinder was rebuilt once, but who knows if it was done correctly. I don't see fluid around it at all. You guys are great everything and everyone has been helpful. Thank you!

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cowpuc

cowpuc

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After watching the video closely I did notice I do not have a cap on the proportioning valve. When I bleed the system I see fluid everywhere I'm suppose to. I get a great pedal then after a short period of time the pedal goes soft. I see the upgrades you guys are doing, but where do I find them? And master cylinder was rebuilt once, but who knows if it was done correctly. I don't see fluid around it at all. You guys are great everything and everyone has been helpful. Thank you!

 

I am not exactly sure how missing that rubber cap could cause a leak because it would seem that that rubber could in no way hold back hydraulic pressure.. I would guess that the cap is just a cover over some form of an adjustment or something for the metering of the fluid going thru the device.. Just doesnt make sense in my pea brain of how air could get thru there and there not be fluid leaking out,,, probably wrong,, been wrong many times over..

On the same token though,, having that cap missing could easily be a sign that someone else had problems with that system and was playing around with the metering/proportioning valve,, maybe,, maybe not..

Just thinking out loud..

Bottom line on a hydraulic system IMHO.. If there is a leak ANYWHERE in the system you can easily find it (if you are working on brakes) just by holding down on the pedal or pulling real hard on the lever for a couple minutes.. If its leaking,, even slightly you will loose "pedal" = meaning the pedal will go down or the lever will travel in - when you sqeeze that lever hydraulic fluid will not compress and if air can get in = fluid can get out...

As mentioned,, almost sounds like you do have a master going south IMHO..

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  • 3 weeks later...
Wingzz

Wingzz

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I just did this mod on my 83, made the rear super easy to get working, my fronts work pretty good but I'm planning on rebuilding the MC over the winter as my lever goes soft after holding it on for a few min. already rebuilt the calipers. Good luck with your project, they are a fun bike to work on and very satisfying to get running and riding

 

Hey Dave,

Congrats on your "new to you" scoot!

If you are not seeing brake fluid at the left front caliper, the rear caliper, or dripping off of the frame from the proportioning valve, then I am afraid the Rear Master Cylinder needs to be rebuilt. The seals once worn, allow air to be reintroduced into the closed brake system. After the rebuild of the rear master, this kit will improve the bleeding process, and brake performance:

 

http://www.venturerider.org/forum/photopost/showproduct.php?product=316&title=6-line-first-gen-ss-brake-line-delink-kit-with-both-clutch-lines&cat=17

 

Earl

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