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Cptn. Calzone
Samba Member
Joined: June 27, 2007
Posts: 1855
Location: S>E>Alabama
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 Posted: Sun Mar 26, 2017 9:38 am Post subject: emergency brake shoes sticking |
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More brake drama! After successfullyb bleeding and a new ATE MSTRCYLN. in my 912 I drove and smiled  Then after a stop at the accountant(tax season) and setting bthe oarking brake, I noticed the car dragging a bit.Down to the shop and on the lift, the fronts have a minimal amount of drag which I understand is normal after a PMB rebuild.The rears however had a noticable amount, as if the emergency shoes were not releasing!! Any one ever expireence this or have any tips or clues as to a remedy?Search mission and pull the rears down .....again...!! 
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71 westfalia
67 912 Porsche Quintilla
67 Single Cab aka my work horse |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21513
Location: Oklahoma City
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| Posted: Sun Mar 26, 2017 10:27 am Post subject: Re: emergency brake shoes sticking |
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| Cptn. Calzone wrote: |
| More brake drama! After successfullyb bleeding and a new ATE MSTRCYLN. in my 912 I drove and smiled Then after a stop at the accountant(tax season) and setting bthe oarking brake, I noticed the car dragging a bit.Down to the shop and on the lift, the fronts have a minimal amount of drag which I understand is normal after a PMB rebuild.The rears however had a noticable amount, as if the emergency shoes were not releasing!! Any one ever expireence this or have any tips or clues as to a remedy?Search mission and pull the rears down .....again...!! |
Sorry I meant to get back to your PM.
Things that can cause this:
1. As you suspect....its possible you have crud or grease build up in the E-brake cable tubes. For this problem....I got away from grease totally in E-brake cable tubes where I could.
Over time ...grease is a rust magnet....because...Grease...virtually all grease but a few synthetics...changes and hardens over time and becomes acidic or caustic. This is from a combination of the oil used in it, the metals in it oxidizing and the fact that as a paste it entrains water vapor in it as the cable is dragged through it in an open use environment like the cable tube. After a long period with the right/wrong kind of grease....the tube begins rusting from the inside out.
This next step also prevents them from rusting.
I first totally cleaned out the tubes of old grease by stringing a wire through the tube...flushing with a hot solvent like MEK...and pulling a plug of cloth through several times. you would not believe the crap that comes out.
Then...lube the cable and tube by pumping Automatic transmission fluid through it...which is heavy in anti-oxidization additives. Drain out the excess...feed in the cable lubed with ATF and put new rubber cable boots on each end. You cables will not rust or stick in your lifetime.
2. The rear pad windage adjustment on disc brake calipers can be a little off with new seals.
But before you adjust pad windage.....just like the front pads need to be bedded in by specific braking patterns....the same must be done with the rears ...to wear the pads to fit the rotors. You do this by getting on a large parking lot....get up to about 30 mph...and apply the rear parking brake ONLY...to do a long slow stop. Do this several times.
If you have drums (for other people who may be reading this with other cars)....same thing and then readjust.
3. This can happen rarely if you have not gotten all of the air out.
4. What kind of fluid do you have? If you have gone to DOT 5 and somehow have not gotten every last micro-drop of dot-3/4 out...it can cause locking like this due to forming and emulsion between teh two fluids. Been there,,,,,done that and it was ugly.
Ray |
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Cptn. Calzone
Samba Member
Joined: June 27, 2007
Posts: 1855
Location: S>E>Alabama
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| Posted: Sun Mar 26, 2017 10:32 am Post subject: Re: emergency brake shoes sticking |
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Fluid is ATE blue and was ATE blue.I suspect the cables as the problem was non existant prior to the stop and application of the hand brake.
_________________
71 westfalia
67 912 Porsche Quintilla
67 Single Cab aka my work horse |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21513
Location: Oklahoma City
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| Posted: Sun Mar 26, 2017 3:47 pm Post subject: Re: emergency brake shoes sticking |
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| Cptn. Calzone wrote: |
| Fluid is ATE blue and was ATE blue.I suspect the cables as the problem was non existant prior to the stop and application of the hand brake. |
Does yours have the e-brake built into the caliper or is in an inhoard brake shoe assembly? Rwy |
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Cptn. Calzone
Samba Member
Joined: June 27, 2007
Posts: 1855
Location: S>E>Alabama
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| Posted: Sun Mar 26, 2017 5:27 pm Post subject: Re: emergency brake shoes sticking |
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Inboard brake shoe assembly.Looks to be a PITA to get to the shoes
_________________
71 westfalia
67 912 Porsche Quintilla
67 Single Cab aka my work horse |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21513
Location: Oklahoma City
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| Posted: Sun Mar 26, 2017 8:45 pm Post subject: Re: emergency brake shoes sticking |
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| Yep...sounds like cable sticking....or it could be general crustiness of hardware or of the shoe hold down points. Ray |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21513
Location: Oklahoma City
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| Posted: Mon Mar 27, 2017 8:12 pm Post subject: Re: emergency brake shoes sticking |
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I almost forgot.....be sure its the E-brakes sticking and not the calipers.
Have you replaced the rear soft brake hydraulic hoses? With age they swell up and can delaminate in the inside. This causes either no fluid flow or sometimes lack of fluid release. Ray |
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