Topic: Front brake bleeding nightmare

[rebabal]

1976k with 78F front end for brakes.

I've tried to replace as much of the braking system as possible to get the best performance and less likelihood of death.

New master cylinder from eBay.  It says it's for dual front brakes but its piston may be too small?
New SS braided lines from the dude on the forums who makes them
New crush washers (Couldn't find new banjo bolts without ordering them, so I just cleaned out the old ones)
New seals in the calipers
New brake pistons
New Speedbleeder screws (I don't think these things are working, at all....)

The only things I'm reusing are the calipers (looked undamaged) and the junction splitter for the brake line to go to the front two wheels.

When putting the banjo bolts into each of their homes I put Teflon sealant on them to make sure nothing would get past.

Now to the pain: I've bleed through 3.5 large bottles of Dot3 brake fluid.  Sometimes I get it to where there's no air coming from the lines but there is absolutely 0% pressure from the handle.  I've let it sit overnight to let the foamyness settle down, no go.

What the hell am I doing wrong?  I've tried several methods of bleeding.  I also have a vacuum pump I got from Auto Zone that seems to pull out the air nicely, but the pressure never increases, the pistons just don't move.

I'm getting extremely frustrated.  I started the brakes last weekend, got upset because they wouldn't bleed - bought speedbleeders, went to work on them today and I spent all day troubleshooting it.

I can't see any leaks, all the seals are new, and I'm not getting any pressure.

The only thing I can think of next is to replace the junction splitter - looking on ebay I can't find any new ones so I don't know what to do - I'd rather not go used.

Any helpful advice?

[MCRider]

Don't have much to say here, someone will. I can't tell for sure from your post if you used new crush washers or reused the old ones? New are better. There was no need for thread sealer, the crushwashers furnish the seal.

But I don't think that could be your problem, really, just petty details.

[rebabal]

I have new crush washers, listed 3rd on my "new" list. 

I know it's pretty difficult to troubleshoot this from what I've written, but I've come to a complete halt (ran out of brake fluid haha) so I figured I'd ask around.

Is there something I'm doing wrong?  Is there some special trick to bleeding these dual brakes?

I am sad 

[MCRider]

I have new crush washers, listed 3rd on my "new" list. 

I know it's pretty difficult to troubleshoot this from what I've written, but I've come to a complete halt (ran out of brake fluid haha) so I figured I'd ask around.

Is there something I'm doing wrong?  Is there some special trick to bleeding these dual brakes?

I am sad 

Oh I see now, its the banjo bolts you used over. No problem.


Time to think... Going to a VJMC meeting. Hope someone can help you.

[crazypj]

Without watching you, I doubt anyone can say what your doing wrong.
 What size master cyl did you buy? (bore size)
 I've 'bled' brakes without bleed nipples and not had problems.
 you don't have a high point where air is 'stuck' do you? (I've also had to fit 'dummy' bars to get lever at 'correct' angle)

PJ

[rebabal]

I think the auction states it's a 14mm bore.  Too small?

I have the handlebars leveled out so the fluid is moderately close to being level in the canister.  As for a high point, the only thing that could come to mind is the line junction in the middle.  I try to tap it a few times to loosen up any bubbles but nothing i've done has made it any stiffer.

[750goes]

Basic Troubleshooting - process of elimination as follows:
- remove your brake hose from the master cyclinder and make sure your are getting pressure when exercising the brake lever - hold your finger over the end and pump - (make sure there is fluid in the resevoir) watch out for spraying droplets of fluid everywhere..
- if there is pressure that can push your finger off the outlet then good - reconnect your hose and do not put any teflon tape on the banjo bolt (also make sure the banjo bolt is clear of obstructions) - make sure the crush washers are on both sides of the banjo bolt
- go to the brake caliper - either one and loosen off the bleed nipple or take it out completely,
make sure the master cylinder has plenty of fluid in it and fluid should drip out of the nipple..
- if not back track to the junction splitter and undo the top hose and do the same pressure test here  - finger over end of hose while pumping - should have pressure  - if not top hose is rooted - replace and continue to check each link in the system -
KISS

let us know the results

[crazypj]

little small but should work fine.
 You probably have air trapped somewhere or an air leak.
 I use teflon tape around bleeder nipple threads
You may have to turn bars a little to get fully bled.
 I like to have M/C tilted slightly towards 'lever' side, seen air bubbles trapped in seal 'cup'
 I also 'tap' lever to 'loosen' bubbles.
Pull lever in slowly and let it 'flick' out also pulls air up line.
 Don't even waste time opening bleed nipple until line is filled.
 Just had a thought, Honda said don't pull lever all the way to bar (don't remember why?)

[nitroeagle]

I also had a problem bleeding brakes. Turned out the hose was clogged, where the rubber meets the metal,
at each end. I was using the original hose. Makes me wonder about your crossover hose, believe you said it
was reused. After I cleared the hose(with a small piece of wire) I used a handheld vacuum pump with a brake bleeding attachment. I worked great. Hope this helps some.

[MCRider]

little small but should work fine.
 You probably have air trapped somewhere or an air leak.
 I use teflon tape around bleeder nipple threads
You may have to turn bars a little to get fully bled.
 I like to have M/C tilted slightly towards 'lever' side, seen air bubbles trapped in seal 'cup'
 I also 'tap' lever to 'loosen' bubbles.
Pull lever in slowly and let it 'flick' out also pulls air up line.
 Don't even waste time opening bleed nipple until line is filled.
 Just had a thought, Honda said don't pull lever all the way to bar (don't remember why?)

I don't remember exactly either but all the way was discouraged, I think it can suck some air somehow. 2/3 is fine.

[rebabal]

I've cleaned the junction splitter and fluid flows through it.  I have noticed that my left caliper doesn't flow as well as the other, but I don't know what that could be about. 

I'm not using teflon tape, i'm using teflon paste, just put a few dabs on the threads to make sure. 

I've tried tapping, but I haven't tried the pressure test, which I guess would be my next step.

Great news is I emailed the seller of the brake master cylinder and told him it was a piece of crap and he refunded my money, so I can get a different kind should this not get better.

[the technological J]

cover up your tank!!!!! that stuff is straight from hell and eats through paint like the things from the new the day the earth stood still movie (if you didnt see it its like sugar coated tank and acid water brake fluid!!!!)

[tomkimberly]

Try this, pump the brake lever a few times. Is there any pressure build up? If so, after you get pressure, tie off the brake lever after pumping the lever and go get a cold one. Come back and check in around 2 hours. If the lever is now soft, repeat until firm.


Tom

[xenoscr]

little small but should work fine.
 You probably have air trapped somewhere or an air leak.
 I use teflon tape around bleeder nipple threads
You may have to turn bars a little to get fully bled.
 I like to have M/C tilted slightly towards 'lever' side, seen air bubbles trapped in seal 'cup'
 I also 'tap' lever to 'loosen' bubbles.
Pull lever in slowly and let it 'flick' out also pulls air up line.
 Don't even waste time opening bleed nipple until line is filled.
 Just had a thought, Honda said don't pull lever all the way to bar (don't remember why?)

I don't remember exactly either but all the way was discouraged, I think it can suck some air somehow. 2/3 is fine.

I'm not sure if it's the reason or not but I just bled my brakes and when I pulled the lever all the way with the cap off the master cylinder it started to leak fluid from the handle. I'm guessing the plunger goes to far and pulls fluid back with it and pushes air in as a result.

XeNoSCR

[Kevin400F]

One reason why they tell you not too pull the lever all the way to the bar is that (on a master cylinder that hasn't been recently overhauled) is there's a good chance of having gunk or corrosion on the MC bore beyond where the piston cups normally travel.  When you pull the lever all the way to the bar you run the MC piston cup over this crap and risk a leak.

Kevin

[MCRider]

One reason why they tell you not too pull the lever all the way to the bar is that (on a master cylinder that hasn't been recently overhauled) is there's a good chance of having gunk or corrosion on the MC bore beyond where the piston cups normally travel.  When you pull the lever all the way to the bar you run the MC piston cup over this crap and risk a leak.

Kevin

Thank you I do remember that now that you've reminded us.

That would not be a problem on a new MC then, and shouldn't have affected the OP situation.

[rebabal]

Ok so I left it overnight and my dad took 5 minutes and bled them and now it's still and working well.

He bled it the same way I was doing it, so maybe it just took some settling of the bubbles.

Anyways, it's all gold now.

go figure?

[steamnjn23]

sure makes your dad feel needed huh?