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darindeb Samba Member
Joined: February 21, 2016 Posts: 5 Location: United States
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Posted: Mon Dec 25, 2017 11:25 pm Post subject: Re: 411-412 rear brake pressure regulator |
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We have a 72 auto 411. Been sitting for some time. Guy put alot of money into it but never got to really enjoy it. Brake system was rebuilt but believe not the pressure regulator. That being stated, will the PMB psi regulator rebuild kit for the 914 work to rebuild the one in the 411?
Your posts are very informative on many issues. Thank you so much for sharing your knowledge.
Dub on,
Darindeb |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21520 Location: Oklahoma City
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Posted: Tue Dec 26, 2017 9:19 am Post subject: Re: 411-412 rear brake pressure regulator |
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Hello Darindeb!.....yes....the PMB regulator kit will fit.....however...and I think you can see from what I showed in this thread......on one hand actual assembly wise this is an easy rebuild.....IF you have the kit with thr assembly mandrel.
But.....about 3 out of 4 of these cylinders at this age are rough inside. They could REALLY use/stand a replating to be sure they work well enough to operate without changing adjustment due to leakage internally.
For the cost of the kit...which is fair.....its almost worth first opening your cylinder up and inspecting it to make sure that its not absolutely shot or rusted to pieces.....and then send it to PMB to rebuild. Yes....it costs an extra $100.....but.....they will zink plate it and paint it....and....they test and adjust it.....and bear this in mind....I have experience with these and even with a mandrel, putting the small cup seal on is difficult. There is a risk....about as high as 20%.....that you can damage the seal even when using the mandrel they provide.
Also its common that the brass valve is frozen to the aluminum valve body. It can happen that you damage the nylon pintle inside. With all of the parts they rework for 914 and BMW.....I can bet you that they have boxes of good used spare parts around.
Having worked on quite a few of these....Its a good bet that they have some small breakage issues in at least 20-30% of these.....and since they are on the hook for it when they rebuild it.....they will fix anything they break .....so unless you have a few parts laying around.....there is a bit of risk and work that makes paying to have this part rebuilt....worthwhile. Something to think about. Ray |
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darindeb Samba Member
Joined: February 21, 2016 Posts: 5 Location: United States
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Posted: Tue Dec 26, 2017 8:11 pm Post subject: Re: 411-412 rear brake pressure regulator |
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Ray,
Thank you for the quick reply. We are taking your infinite advice.
We will remove it and send to have rebuilt. No sense in more frustration than needed. Besides gives us time to do something we know we can do. Working to get this one on road before Ricks 71 Fastback comes back from body and paint. And he still needs to go thru that motor.
Love our classic Volkswagens.
Happing dubbing,
Rick and Darindeb |
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titan3c Samba Member
Joined: February 16, 2012 Posts: 568 Location: Coweta, Oklahoma
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Posted: Sat Mar 16, 2019 7:59 am Post subject: Re: 411-412 rear brake pressure regulator |
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I still have my pressure regulator, and haven't done anything with it yet. I installed a T connection way back. Just wondering if there is a way to bench test the regulator to see if it's functioning properly. Bob |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21520 Location: Oklahoma City
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Posted: Sat Mar 16, 2019 12:58 pm Post subject: Re: 411-412 rear brake pressure regulator |
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titan3c wrote: |
I still have my pressure regulator, and haven't done anything with it yet. I installed a T connection way back. Just wondering if there is a way to bench test the regulator to see if it's functioning properly. Bob |
Well...you would need a master cylinder or hydraulic cylinder hooked up to it....and a gauge on the input and output that goes to 600 psi.
You "could" do it with one gauge on the inlet side and look for fluid pressure to still rising while inlet still goes up...while listening for the click.
Gauges from 0-600 in 10 psi increments can be had from McmMaster carr for about $25 each.
If yours has not been rebuilt. There is no point in messing with it. In fact its best to open it up asap and stop any rust thats in there while you decide to either send it out to PMB and have it rebuilt...or order their kit. Ray |
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