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Jrh5r Samba Member
Joined: January 08, 2021 Posts: 33 Location: East coast
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Posted: Sun May 09, 2021 6:24 pm Post subject: Need expert advice. Cannot bleed front brakes. 73 bay. |
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Long time lurker, few time poster. I was given a 73 T2 by my folks and am on the last roadblock I think, aside from wasting more hours on how to put in the gd front roll up windows
I need help figuring out how to bleed the front disc brakes on this bus. The back brakes I have fluid to. The front brakes I cannot get a drop out of or even a sound of air. I bought a new Brazilian made master cylinder and a new brake servo, which I think Is an airtech, if I remember correctly. The manual is really vague as far as I remember reading today... I recall it saying 68-70 to leave a 1mm gap between the pushrod and mc. Beyond those years, I think it said to fine adjust by removing the Clevis pin and turning. I have the brake arm to the stop and I have nothing. I will note that the front half of the reservoir looks filled with fluid, as it appears to move around when I pump the brake arm and have a flashlight on it. That’s the side supplying the back brakes. The other chamber looks dead empty, or maybe it’s full and there’s no air?
I bought new master cylinder seals that connect to the reservoir. They were too large to fit in even with a lot of silicone and force and a small amount of heat. I reused the old ones off the original vw mc. The seemed to be fine. I have cracked the line at the mc supplying the front discs, and have nothing there.
All lines are brand new. Everything is tight. I have triple checked. No fluid coming from anywhere. No sounds of air escaping. Literally everything is new on this bus. Calipers are from O’riely. I cannot recall if the secondary reservoir on top of the mc is connected or not. I don’t think it is. The booster is not hooked up, as it seems that it should have no role in the bleeding portion.
I am thinking that this is either a clogged mc or defective out of the box mc. It’s hard to find quality parts. I tried to save a penny and bought the Brazilian made one. I am thinking to remove the mc and bench bleed it. I spent all day on this, and is my last roadblock to cruising.
Any advice appreciated.
TLDR; no front brake fluid |
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ImAddicted Samba Member
Joined: April 24, 2012 Posts: 1195 Location: Unorganized Territory, Maine
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Posted: Sun May 09, 2021 7:13 pm Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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Did you bench bleed the MC before installing it? _________________ 1979 Transporter (sold)
KC1MUR
strfish7 wrote: |
Original condition, which means something different on this forum than anywhere else! |
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skills@eurocarsplus Samba Peckerhead
Joined: January 01, 2007 Posts: 16865 Location: sticksville, ct.
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Posted: Sun May 09, 2021 7:17 pm Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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did you set the gap for the push rod?
when i say that, i mean the one between the booster and master. it is very possible that is wrong and adjusting the outer push rod (the one with the clevis) won't get you there.
beyond that, i'd say you have a bad master. never in my professional life have i ever bench bled a master. it's possible while fooling around you shaved a crumb off of the reservoir grommet and that's plugging the feed hole to the master _________________
gprudenciop wrote: |
my reason for switching to subaru is my german car was turning chinese so i said fuck it and went japanese....... |
Jake Raby wrote: |
Thanks for the correction. I used to be a nice guy, then I ruined it by exposing myself to the public. |
Brian wrote: |
Also the fact that people are agreeing with Skills, it's a turn of events for samba history |
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Jrh5r Samba Member
Joined: January 08, 2021 Posts: 33 Location: East coast
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Posted: Sun May 09, 2021 7:36 pm Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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ImAddicted wrote: |
Did you bench bleed the MC before installing it? |
I did not, as I didn’t think it was necessary. Probably going to do this tomorrow. Sounds like I’m removing the mc to see what’s going on |
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Jrh5r Samba Member
Joined: January 08, 2021 Posts: 33 Location: East coast
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Posted: Sun May 09, 2021 7:51 pm Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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skills@eurocarsplus wrote: |
did you set the gap for the push rod?
when i say that, i mean the one between the booster and master. it is very possible that is wrong and adjusting the outer push rod (the one with the clevis) won't get you there.
beyond that, i'd say you have a bad master. never in my professional life have i ever bench bled a master. it's possible while fooling around you shaved a crumb off of the reservoir grommet and that's plugging the feed hole to the master |
So I have followed the Bentley and am about to crash out for the night and just had to verify before responding. It gives numbers for 68-70 models, but then goes on to state that for models with brake servos, to just back off until no for is exerted on the mc. I might be misreading it, but sounds like the 1mm doesn’t apply here and I don’t even know how I’d measure it since it’s all so narrow and tucked up in there. I am also starting to think that that the that master port for the front must be clogged since there is no fluid or air being pushed out when I crack it at the connection to it. I backed the rod from the pedal to the servo all the way out and just barley put it back in.
After reading though, sounds like the servo to master arm could be too long and is maybe pushing the master cylinder just enough to block flow to that one side of the piston. I am going to tear apart tomorrow and see what I find. I do have the original vw master still. Hesitant to use it as the brake booster was full of brake fluid and the car sat for 30 plus years. Any suggestions on what to use to flush out the new mc? Carb cleaner or brake cleaner? I don’t want to destroy any rubber. I’m also assuming that the main reservoir tube to the one that sits on top of the master isn’t under any real pressure. I don’t think there is a leak there since I’m getting pressure to both rear drums.
Appreciate the advice. I’ll report back with findings and I need to post up some pics of my bay that’s been way too much time and money, but Im almost there. |
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ImAddicted Samba Member
Joined: April 24, 2012 Posts: 1195 Location: Unorganized Territory, Maine
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Posted: Sun May 09, 2021 8:01 pm Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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Chasing down things like this are a pain, I wish you luck. Bench bleeding isn’t necessary, typically, but I’ve been doing it on my daily as well as bus the last few times because of crappy quality aftermarket parts. While it won’t find every issue, it does help identify a dead player out of the box. Ray Greenwood has a post someplace on seals and prepping a Mc before installing, not sure if it will help you in this situation or not. _________________ 1979 Transporter (sold)
KC1MUR
strfish7 wrote: |
Original condition, which means something different on this forum than anywhere else! |
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Jrh5r Samba Member
Joined: January 08, 2021 Posts: 33 Location: East coast
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Posted: Sun May 09, 2021 8:04 pm Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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After watching this, https://youtu.be/Xeiml3VcuNo it makes more sense that the clevis adjustment won’t get me to where I need to be. I do recall a little force being needed to seat the master to the servo. I’m betting this is the issue, like skills said. The question now is how far in do I go? It sounds like just a trial and error and attempt to get close to 1mm. Sounds like the rod from the pedal lever to the mc can bring me home if I can get it close and get that preload off the master. I’ll update tomorrow just for follow ups sake. |
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kreemoweet Samba Member
Joined: March 13, 2008 Posts: 3898 Location: Seattle, WA
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Posted: Sun May 09, 2021 10:22 pm Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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Jrh5r wrote: |
I will note that the front half of the reservoir looks filled with fluid, as it appears to move around when I pump the brake arm and have a flashlight on it. That’s the side supplying the back brakes. The other chamber looks dead empty, or maybe it’s full and there’s no air? |
You need to make sure the lower reservoir is full, both chambers. And it should be full all the back up to the upper fill reservoir. _________________ '67 bug: seized by the authorities
'68 bug: seized by the authorities
'71 kombi: not yet seized by the authorities
Stop dead photo links! Post your photos to The Samba Gallery! |
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skills@eurocarsplus Samba Peckerhead
Joined: January 01, 2007 Posts: 16865 Location: sticksville, ct.
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Posted: Sun May 09, 2021 11:41 pm Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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Jrh5r wrote: |
I do recall a little force being needed to seat the master to the servo. I’m betting this is the issue, like skills said. |
there's your problem, or part of it.
Quote: |
The question now is how far in do I go? It sounds like just a trial and error and attempt to get close to 1mm.. |
if i am replacing all this shit at once and it's on the bench i do it then.
basically i put it all together and push the push rod. if there is no play i adjust it (inside the booster). you can usually feel the play or listen for a little metallic 'click'
it can be fidgety for sure. _________________
gprudenciop wrote: |
my reason for switching to subaru is my german car was turning chinese so i said fuck it and went japanese....... |
Jake Raby wrote: |
Thanks for the correction. I used to be a nice guy, then I ruined it by exposing myself to the public. |
Brian wrote: |
Also the fact that people are agreeing with Skills, it's a turn of events for samba history |
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timvw7476 Samba Member
Joined: June 03, 2013 Posts: 2201 Location: seattle
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Posted: Sun May 09, 2021 11:43 pm Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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it's a real grind. bench bleeding. I went with a 1 quart milk container cut open & enough brake fluid to immerse my new MC in it. Yeah, it seemed to work, but I also took out my caliper bleed screws, made sure they were clean at their tips & wrapped teflon tape around their threads. THEN I could get some fluid movement. The new grommets were useless for me too, had to rely on the oldies. Good Luck with it. |
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Jrh5r Samba Member
Joined: January 08, 2021 Posts: 33 Location: East coast
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Posted: Mon May 10, 2021 6:13 am Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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skills@eurocarsplus wrote: |
Jrh5r wrote: |
I do recall a little force being needed to seat the master to the servo. I’m betting this is the issue, like skills said. |
there's your problem, or part of it.
Quote: |
The question now is how far in do I go? It sounds like just a trial and error and attempt to get close to 1mm.. |
if i am replacing all this shit at once and it's on the bench i do it then.
basically i put it all together and push the push rod. if there is no play i adjust it (inside the booster). you can usually feel the play or listen for a little metallic 'click'
it can be fidgety for sure. |
I’m underneath it now. Def seems like it was the issue. Do I make the booster adjustment with brake pushrod adjusted to the stop? Do I want to just back off the servo pushrod until there is just a little click when I activate the brake arm? |
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skills@eurocarsplus Samba Peckerhead
Joined: January 01, 2007 Posts: 16865 Location: sticksville, ct.
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Posted: Mon May 10, 2021 7:49 am Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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not sure i understand....
you want to adjust it with no pressure on the pedal or rod, as in the brake pedal isn't being activated.
adjust it from the master cylinder side inside the booster itself
when you say "adjust with the brake pushrod to the stop" i think you mean with the pedal up and the arm against the rubber buffer on the floor. that is the way you want to do it.
basically do NOT depress the brake pedal while doing this adjustment _________________
gprudenciop wrote: |
my reason for switching to subaru is my german car was turning chinese so i said fuck it and went japanese....... |
Jake Raby wrote: |
Thanks for the correction. I used to be a nice guy, then I ruined it by exposing myself to the public. |
Brian wrote: |
Also the fact that people are agreeing with Skills, it's a turn of events for samba history |
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Abscate Samba Member
Joined: October 05, 2014 Posts: 22648 Location: NYC/Upstate/ROW
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Posted: Mon May 10, 2021 8:13 am Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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It’s probably a 1mm pitch thread on the pushrod( you can measure it easily )
You can unscrew until it touches, the retract it 1 turn to get the clearance, Clarence. _________________ .ssS! |
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kreemoweet Samba Member
Joined: March 13, 2008 Posts: 3898 Location: Seattle, WA
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Posted: Mon May 10, 2021 8:35 am Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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The pushrod in the booster (or the one in the pedal linkage) being misadjusted is not going to affect the ability of the m/c to push fluid thru the lines to the caliper. It's either a bad m/c, empty reservoir (see OP's first post), or blocked fluid passage somewhere. _________________ '67 bug: seized by the authorities
'68 bug: seized by the authorities
'71 kombi: not yet seized by the authorities
Stop dead photo links! Post your photos to The Samba Gallery! |
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skills@eurocarsplus Samba Peckerhead
Joined: January 01, 2007 Posts: 16865 Location: sticksville, ct.
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Posted: Mon May 10, 2021 8:51 am Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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kreemoweet wrote: |
The pushrod in the booster (or the one in the pedal linkage) being misadjusted is not going to affect the ability of the m/c to push fluid thru the lines to the caliper. It's either a bad m/c, empty reservoir (see OP's first post), or blocked fluid passage somewhere. |
if it's misadjusted it sure will not let you bleed it, btdt...especially if it's a mm or 3 pressed into the bore blocking the ports _________________
gprudenciop wrote: |
my reason for switching to subaru is my german car was turning chinese so i said fuck it and went japanese....... |
Jake Raby wrote: |
Thanks for the correction. I used to be a nice guy, then I ruined it by exposing myself to the public. |
Brian wrote: |
Also the fact that people are agreeing with Skills, it's a turn of events for samba history |
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Jrh5r Samba Member
Joined: January 08, 2021 Posts: 33 Location: East coast
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Posted: Mon May 10, 2021 9:26 am Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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kreemoweet wrote: |
The pushrod in the booster (or the one in the pedal linkage) being misadjusted is not going to affect the ability of the m/c to push fluid thru the lines to the caliper. It's either a bad m/c, empty reservoir (see OP's first post), or blocked fluid passage somewhere. |
It 100% will not let you bleed both the front and the rear, if the booster rod isn’t adjusted properly. If the piston is already pushed in from the get go then it won’t retract to let fluid flow into the other side of the master. That’s why the manual specifies that 1mm adjustment. Readjusting resolved the issue and I have fluid at all corners |
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Jrh5r Samba Member
Joined: January 08, 2021 Posts: 33 Location: East coast
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Posted: Mon May 10, 2021 9:33 am Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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skills@eurocarsplus wrote: |
not sure i understand....
you want to adjust it with no pressure on the pedal or rod, as in the brake pedal isn't being activated.
adjust it from the master cylinder side inside the booster itself
when you say "adjust with the brake pushrod to the stop" i think you mean with the pedal up and the arm against the rubber buffer on the floor. that is the way you want to do it.
basically do NOT depress the brake pedal while doing this adjustment |
Ok, that’s what I did and was asking. Sorry for the poor wording. Basically adjusted the brake lever arm just to where it rested on the stop and then the booster pushrod to where it was just barely backed off the master. Pedal is firm. Have not started and tested it yet. Got fluid to all corners easily.
Total pain in the ass job, but what can you do. Didn’t do a bench bleed either, just disconnected the lines going to the master and tried to fine tune that booster adjustment. Seems to have worked well |
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kreemoweet Samba Member
Joined: March 13, 2008 Posts: 3898 Location: Seattle, WA
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Posted: Mon May 10, 2021 10:32 am Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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Jrh5r wrote: |
It 100% will not let you bleed both the front and the rear, if the booster rod isn’t adjusted properly. If the piston is already pushed in from the get go then it won’t retract to let fluid flow into the other side of the master. That’s why the manual specifies that 1mm adjustment. Readjusting resolved the issue and I have fluid at all corners |
It seems some folks need to look at a diagram showing how a m/c works. There is no "1 mm" spec for anything in the late bay disk brakes. The purpose of that spec in other models
was to ensure the compensating ports are not blocked. Those ports have nothing to do with refilling the m/c chambers when the pistons retract to rest position, and they have
nothing to do with bleeding. If yours were blocked (and both front and rear will normally be blocked together), it apparently had no effect on bleeding the rear circuit, according to your
tale. The front and rear circuits are independent, and there should never be any fluid exchange between the two. The fact that you got your system bled after fiddling with the
push rods does not mean that fiddling was the cause of your success. _________________ '67 bug: seized by the authorities
'68 bug: seized by the authorities
'71 kombi: not yet seized by the authorities
Stop dead photo links! Post your photos to The Samba Gallery! |
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Abscate Samba Member
Joined: October 05, 2014 Posts: 22648 Location: NYC/Upstate/ROW
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Posted: Mon May 10, 2021 4:50 pm Post subject: Re: Need expert advice. Cannot bleed front brakes. 73 bay. |
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The front and back are nearly hydraulically independent.
They are not mechanically independent and are in fact mechanically linked. _________________ .ssS! |
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