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mrbell321
Samba Member
Joined: December 15, 2017
Posts: 36
Location: TX
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 Posted: Sat Mar 17, 2018 7:26 am Post subject: brakes not completely releasing |
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I have a newly developed problem and I was hoping someone would know where to start.
Sometimes when releasing the brake pedal, the brakes don't completely release. The pedal also doesn't return to fully depressed either. I can pull the brake pedal up with my toe and that seems to release the brake. It probably only moves .5-1 inch.
it's a 72 w/ booster, discs up front and drums in the rear. I suspect that a drum spring might be bad/broken, but l wouldn't necessarily think pulling on the pedal would help. So it might be a MC problem?
I just drove about a 2k mile trip and this only developed in the last 300 miles or so.
Possibly related: the brake pressure sensors seem kind on non-sensitive. the brakes stop the car normally, but you have to be braking fairly hard for the brake lights to actually come on. Not emergency braking level, but harder than what I consider normal braking. Anyone else experienced this?
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1972 Type 2 (T2) mod. 221(1) |
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HelmutofBuffalo
Samba Member
Joined: August 22, 2005
Posts: 554
Location: West Coast of New York
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| Posted: Sat Mar 17, 2018 7:30 am Post subject: Re: brakes not completely releasing |
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flexible rubber brake lines deteriorate from the inside and fail causing your symptoms, they look good from outside.
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1979 Type I Convertible |
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Starbucket
Samba Member
Joined: April 30, 2007
Posts: 4025
Location: WA
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| Posted: Sat Mar 17, 2018 8:10 am Post subject: Re: brakes not completely releasing |
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| HelmutofBuffalo wrote: |
flexible rubber brake lines deteriorate from the inside and fail causing your symptoms, they look good from outside.
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2X, just replace all the rubber brake lines as the problem will just pop up again on other wheels. It's not the springs. Do one wheel at a time and bleed it before going to the next hose to save your self the headache of bleeding the whole system. If the brake fluid isn't clear replace it, its time. |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51128
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Sat Mar 17, 2018 8:48 am Post subject: Re: brakes not completely releasing |
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When was the last time you flushed the brake system and replaced the fluid?
Slow reacting switches is usually due to sediment buildup, non returning master cylinders could be due to the same or corrosion. Hoses can cause a wheel to drag but don't usually effect pedal return. Pushrod adjustment is also a possibility, but if you haven't done any work on the brakes before this started happening odds are good it didn't readjust itself.
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HelmutofBuffalo
Samba Member
Joined: August 22, 2005
Posts: 554
Location: West Coast of New York
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| Posted: Sat Mar 17, 2018 9:22 am Post subject: Re: brakes not completely releasing |
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"Hoses can cause a wheel to drag but don't usually effect pedal return. "
I disagree, not disrespecting BUSDADDY, but i have seen pinched off brake lines do this. Had a '72 Benz where a rear rotor was cut thru because brake pads would not retract. (EX was driving it and did not bother to tell me it was making noise till brakes failed and she hit back of school bus) 
I just realized I was wrong Busdaddy is correct
I was thinking pad or shoe return not pedal return.... MY BAD !
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1979 Type I Convertible
Last edited by HelmutofBuffalo on Sat Mar 17, 2018 9:36 am; edited 1 time in total |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50338
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| Posted: Sat Mar 17, 2018 9:33 am Post subject: Re: brakes not completely releasing |
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| Pull the pan from under the front and see if anything is blocking the levers and rod for the brake. Maybe a squirrel took up residence in there. I agree with BD that the pedal should come up no matter what else is or isn't wrong with the brakes. |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21513
Location: Oklahoma City
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| Posted: Sat Mar 17, 2018 9:49 am Post subject: Re: brakes not completely releasing |
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| HelmutofBuffalo wrote: |
"Hoses can cause a wheel to drag but don't usually effect pedal return. "
I disagree, not disrespecting BUSDADDY, but i have seen pinched off brake lines do this. Had a '72 Benz where a rear rotor was cut thru because brake pads would not retract. (EX was driving it and did not bother to tell me it was making noise till brakes failed and she hit back of school bus) |
No.
You need to think about how the brake master cylinder works....carefully.
A collapsed or pinched soft brake hose will keep fluid pressure from bleeding off...on the slave cylinder it is activating (meaning the wheel cylinder or caliper).
However the brake master cylinder pistons....CANNOT..."suction lock" from not being able to pull that fluid back up from a pinched hose.....BECAUSE....
...the master cylinder pistons have their own fluid supply from the reservoir.
When you let off the brake pedal and the spring returns the pistons to the at rest position.....as the pistons push through the fluid inside of the master cylinder the brass compensation port flap valves open. These act as a suction breaker so that the pedal cannot stay down.
If a pinched or swelled hose does not allow fluid to "retract" as the master cylinder pistons are trying to return from the "pressurized" position.....fluid is pulled from the reservoir.....in compensation....for fluid that does not return from the wheel cylinders or calipers.
If your pedal is not retracting when you let off of it...and its not an internal or external return spring issue, not a pedal adjustment issue (which affects the compensation port position) or a booster diaphragm or pushrod bushing issue....then you either have compensation port flap valves that are gummed up or corroded or the ports are blocked by sludge or corrosion (very common)...or a piston seal cup that is starting to come apart or is gummed up or there is grit in the bore lodging the piston.
Also a common cause of pedal coming up not at all or slowly...on "some" ATE and FAG cylinders is the plastic elbows that connect the reservoir hoses to the MC being jammed down too hard in the rubber grommets.
This causes the flap open port on the end of the elbow to seal against the flat bottom of the well under the grommet. It seals off compensation fluid from the reservoir. This is why whenever I rebuild or install a master cylinder I cut two small notches in the elbow end with a round file.
You can see this in the end of this thread.
https://www.thesamba.com/vw/forum/viewtopic.php?t=679160
Its no doubt that you had bad hoses on your wifes 'Benz....that caused the PADS not to retract....but that does cause the pedal not to retract.
And...changing the hoses...fixed the problem...right?...and thats BECAUSE...you had to bleed the system right? 
Typically when the hoses are fubar...over time you get rubber debris up in the master cylinder and that is what plugs the fluid compensation ports....and can cause the pedal to stick or rise very slowly. Flushing the system for any reason....removes the debris blocking the return ports and generally fixes that.
Ray |
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mrbell321
Samba Member
Joined: December 15, 2017
Posts: 36
Location: TX
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| Posted: Sat Mar 17, 2018 2:32 pm Post subject: Re: brakes not completely releasing |
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Thanks for the replies.
It could be that pulling up on the pedal just gives the extra few seconds for the brake pad to release coincidentally.
I'll take a look & post when I find out more.
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1972 Type 2 (T2) mod. 221(1) |
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raygreenwood
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Joined: November 24, 2008
Posts: 21513
Location: Oklahoma City
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| Posted: Sat Mar 17, 2018 2:43 pm Post subject: Re: brakes not completely releasing |
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| mrbell321 wrote: |
Thanks for the replies.
It could be that pulling up on the pedal just gives the extra few seconds for the brake pad to release coincidentally.
I'll take a look & post when I find out more. |
If pulling up on the pedal releases the brakes.....that right there is telling you that pressure is not releasing on the system....from the master cylinder end.
If it were 100% only the brake hoses.....nothing you could do to the master cylinder would cause them to release.....if the master cylinder is working perfectly.
This wounds like what happens when the pedal is not being pulled all the way back either due to a grimy rusted brake pedal pivot or the same problem on the clevis pin that holds the pushrod onto the pedal or from grit or a sticking/swelled up piston seal. Ray |
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Jeff Geisen
Samba Chaplain
Joined: December 21, 2004
Posts: 1881
Location: N.W. Georgia
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| Posted: Sat Mar 17, 2018 5:18 pm Post subject: Re: brakes not completely releasing |
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This situation could be rectified by a simple push rod adjustment.
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SGKent 
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Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Sat Mar 17, 2018 5:43 pm Post subject: Re: brakes not completely releasing |
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this is a stupid answer that I apologize in advance for but make sure the rubber mat isn't folded in a way it is stopping the brake pedal from returning. Strange that you would go all those miles and it suddenly begin. There is also a return spring that could have failed. Part 211 721 163 C. The other answers from prior posters are also quite valid. It will take some investigation on your part.
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Wildthings
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Joined: March 13, 2005
Posts: 50338
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| Posted: Sat Mar 17, 2018 10:14 pm Post subject: Re: brakes not completely releasing |
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| Jeff Geisen wrote: |
| This situation could be rectified by a simple push rod adjustment. |
There is no reason the pushrod would be out of adjustment unless something broke or bent. Way more likely to be the return spring or something blocking the return of the pedal or rod. |
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ToolBox
Samba Member
Joined: January 27, 2004
Posts: 3439
Location: Detroit, where they don't jack parts off my ride in the parking lot of the 7-11
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| Posted: Mon Mar 19, 2018 9:46 am Post subject: Re: brakes not completely releasing |
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| Check that the pedal is operating freely. On my 59 and 78 the bushings on the brake pedal were dry and once cleaned and lubed fully returned on their own. Pull the booster push rod off and run the pedal through it's full travel and see how it feels. |
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Abscate
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Joined: October 05, 2014
Posts: 22641
Location: NYC/Upstate/ROW
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| Posted: Mon Mar 19, 2018 10:03 am Post subject: Re: brakes not completely releasing |
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| SGKent wrote: |
| this is a stupid answer that I apologize in advance for but make sure the rubber mat isn't folded in a way it is stopping the brake pedal from returning. Strange that you would go all those miles and it suddenly begin. There is also a return spring that could have failed. Part 211 721 163 C. The other answers from prior posters are also quite valid. It will take some investigation on your part. |
Yeah - its stupid until you spend three hours fault tracing a CANBUS electrical system to find out why the headlights don't work, then figure out both bulbs blew.
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Jeff Geisen
Samba Chaplain
Joined: December 21, 2004
Posts: 1881
Location: N.W. Georgia
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| Posted: Mon Mar 19, 2018 2:08 pm Post subject: Re: brakes not completely releasing |
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| Wildthings wrote: |
| Jeff Geisen wrote: |
| This situation could be rectified by a simple push rod adjustment. |
There is no reason the pushrod would be out of adjustment unless something broke or bent. Way more likely to be the return spring or something blocking the return of the pedal or rod. |
Most bus drivers don’t check parts like push rod length. Mine just tightened for some reason, however my bus is a daily driver.
Besides, I wrote it ‘could be’ the problem. Sheez.
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TomWesty
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Joined: November 23, 2007
Posts: 3482
Location: Wyoming,USA
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| Posted: Mon Mar 19, 2018 8:29 pm Post subject: Re: brakes not completely releasing |
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| Abscate wrote: |
| SGKent wrote: |
| this is a stupid answer that I apologize in advance for but make sure the rubber mat isn't folded in a way it is stopping the brake pedal from returning. Strange that you would go all those miles and it suddenly begin. There is also a return spring that could have failed. Part 211 721 163 C. The other answers from prior posters are also quite valid. It will take some investigation on your part. |
Yeah - its stupid until you spend three hours fault tracing a CANBUS electrical system to find out why the headlights don't work, then figure out both bulbs blew. |
I’ll give you that one, the likelyhood of 2 bulbs dying at the same time is pretty low....
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50338
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| Posted: Mon Mar 19, 2018 8:40 pm Post subject: Re: brakes not completely releasing |
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| TomWesty wrote: |
| Abscate wrote: |
| SGKent wrote: |
| this is a stupid answer that I apologize in advance for but make sure the rubber mat isn't folded in a way it is stopping the brake pedal from returning. Strange that you would go all those miles and it suddenly begin. There is also a return spring that could have failed. Part 211 721 163 C. The other answers from prior posters are also quite valid. It will take some investigation on your part. |
Yeah - its stupid until you spend three hours fault tracing a CANBUS electrical system to find out why the headlights don't work, then figure out both bulbs blew. |
I’ll give you that one, the likelyhood of 2 bulbs dying at the same time is pretty low.... |
Decades back, I had a pair of friends spend a couple of days trying to figure out why none of the lights worked on one of their aging cars. They wanted me to come over and figure it out for them, which I did. My diagnosis was that every last bulb was bad, EVERY ONE, headlights, tail lights, turn signals, brake lights. The car had been in a minor fender bender and the shock had busted every one of the old filaments. |
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Abscate
Samba Member
Joined: October 05, 2014
Posts: 22641
Location: NYC/Upstate/ROW
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| Posted: Tue Mar 20, 2018 4:09 am Post subject: Re: brakes not completely releasing |
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| TomWesty wrote: |
| Abscate wrote: |
| SGKent wrote: |
| this is a stupid answer that I apologize in advance for but make sure the rubber mat isn't folded in a way it is stopping the brake pedal from returning. Strange that you would go all those miles and it suddenly begin. There is also a return spring that could have failed. Part 211 721 163 C. The other answers from prior posters are also quite valid. It will take some investigation on your part. |
Yeah - its stupid until you spend three hours fault tracing a CANBUS electrical system to find out why the headlights don't work, then figure out both bulbs blew. |
I’ll give you that one, the likelyhood of 2 bulbs dying at the same time is pretty low.... |
Except we had replaced a faulty alternator the week before, so an over voltage condition almost certainly took them both out.
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Pastelweis
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Joined: June 02, 2010
Posts: 92
Location: Stockholm / Los Angeles
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| Posted: Mon Sep 30, 2019 5:03 am Post subject: Re: brakes not completely releasing |
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I am replacing my front brake discs and ran into a similar problem. At first I thought the Remsa break pads were too thick to fit, but then as I pumped the break I noticed the piston did not retract, now making it impossible to fit the new pads back in. My break pedal retracts however. Greatful if OP could respond to how he solved the issue.
Thank you!
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50338
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| Posted: Mon Sep 30, 2019 5:21 am Post subject: Re: brakes not completely releasing |
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| You have to take a bar and pry them back in, as there is no return mechanism like the springs used in drum brakes. Opening the bleeder may help. |
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