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SGKent 
Samba Member
Joined: October 30, 2007
Posts: 42917
Location: at the beach in Northern Wokistan
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 Posted: Thu Apr 30, 2020 8:31 am Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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We approach life differently Ray. I simply bought a new one from VW, installed it, and it works fine.
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 23432
Location: Oklahoma City
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| Posted: Thu Apr 30, 2020 7:45 am Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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| SGKent wrote: |
| Ray, get help. You've gone over the edge. These are 40 to 50 year old antiques where people point to something in a photo and say, what's this? Then someone says that is what is left of an old beach sandal that melted. |
So...I see. Even though people in this very forum....are content to take a burned out wreck and spend 20 years painstakingly reshaping back to original with hammer and dollies.....you/they cant handle a little testing with a pair of cones on flat piece of parking lot?
You have people here spending $$$$$ and years to have NEW rubber made for brake calipers, new bolts that are not available......new upholstery that is sewn from scratch.....trying new wheels with adapters from other vehicles.....new engines WITH watercooling.....from Japanese vehicles....and spending $$$$.....people using hammers and a torch to drive out and replace ball joints....working with pressurized gasoline and sparks.....building their own millivolt sensitive wiring harness from scratch with,$65 worth of Chinese tools ....................and more importantly.....most importantly....people using totally different aftermarket calipers and master cyljnders .....and STAINLESS BRAIDED lines.....and making and bending their own brake lines.......and...making seat belt extensions and swapping in seat belt parts....and using freaking drop spindles (those out of all of these should scare the shit out of you)......for DECADES.....without a huge rash of deaths and accidents......
And.....the brake companies have sold MILLIONS of adjustable regulators in thousands of designs....for the better part of 75 years.....
......And you somehow have this hilarious belief that the thousands of above owners can't handle a fairly simple afternoon of testing.....that comprises:
1. Drive bus 100 yards on stone cold brakes in straight line on flat level ground...reach 35-40 mph....punch/stomp brakes as hard as possible and instantly release...
2.ask assistant if the rears locked
3. Turn knob....wait till brakes cool ....repeat.
4. Drive bus 100 yards in 2nd gear at 20 mph with foot lightly on brakes until temp gun says they are hot
5. Repeat 1 through 3
6. Try higher speeds
7. Advanced test with bus loaded and unloaded
You are saying that bus owners are ok to do all of that meticulous, time consuming and dangerous work listed above.....but are too retarded or slow witted to do a little testing and turn a knob with no more equipment outlay than a $20 temp gun.????????
So....I guess you are saying that bus owners should ONLY be content to drive these vehicles until the FACTORY ONLY spares.....all run dry....and they have no brakes.....so they cannot be driven.....and then well.....thats all she wrote.....time to scrap the bus.......no more parts....and we are all too stupid/timid/retarded....to do anything else.....and its just far to dangerous to attempt. Is this what you are saying??????.
Ray |
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Abscate
Samba Member
Joined: October 05, 2014
Posts: 24357
Location: NYC/Upstate/ROW
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| Posted: Thu Apr 30, 2020 5:17 am Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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If I load the back of my Bus with beach Sandles, will that stop,the back brakes from locking up?
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mlesniak
Samba Member
Joined: April 08, 2015
Posts: 350
Location: Wisconsin
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| Posted: Thu Apr 30, 2020 5:02 am Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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| SGKent wrote: |
| Ray, get help. You've gone over the edge. These are 40 to 50 year old antiques where people point to something in a photo and say, what's this? Then someone says that is what is left of an old beach sandal that melted. |
Let's stick to the subject. I asked if the VW brake pressure regulator is replaceable with an aftermarket one and Kreemoweet and RayGreenwood did a great job answering my question. Thanks! I'll be rebuilding my original one for now, but one of these days I'd like to try an aftermarket one. Thanks again!
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 42917
Location: at the beach in Northern Wokistan
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| Posted: Wed Apr 29, 2020 10:08 pm Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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Ray, get help. You've gone over the edge. These are 40 to 50 year old antiques where people point to something in a photo and say, what's this? Then someone says that is what is left of an old beach sandal that melted.
_________________
Canned Water - the new California approved parts cleaner (except in a drought in which case rub it with sand).
George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."
Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice" |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 23432
Location: Oklahoma City
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| Posted: Wed Apr 29, 2020 10:04 pm Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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| SGKent wrote: |
| many of the folks here ask basic questions like how to adjust timing, find a fuel leak or find a fuse. Does anyone really think folks are going to find a reliable skid pad, and know how to tune an "adjustable" proportioning valve? Whats next, multiple masters with biasing rods? Give me a break. Someone has been sitting at home too long munching on wheaties. |
Why not?
I have done it many times.
People do it all the time.
Thats why they sell THOUSANDS of aftermarket adjustable brake regulators.
Its just not that hard. You don't need some "scientific".......... reliable ........skid pad. Its not like you need a perfect surface . You are not going to get to drive on one.
Relatively smooth.....about 1/4 mile...max....flat...and no one around except a buddy to help. Typically large parking lots work just fine. Or find a local track and work there. Its just not that hard.
Try it hot...try it cold. You do not have to be any particular speed. It just requires hard braking and good adjustment of your parts.
You don't need to get this up to highway speed....at all. About 35-45 mph....and jam on the brakes. You are simulating panic stop. Just jab hard and let them off.
You are not waiting around for the rear end to swing around....you want to see if they lock. It takes 1 second. Then adjust up or down.
It just not that hard. Ray |
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kreemoweet
Samba Member
Joined: March 13, 2008
Posts: 4141
Location: Seattle, WA
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| Posted: Wed Apr 29, 2020 8:56 pm Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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| SGKent wrote: |
| many of the folks here ask basic questions like how to adjust timing, find a fuel leak or find a fuse. Does anyone really think folks are going to find a reliable skid pad, and know how to tune an "adjustable" proportioning valve? Whats next, multiple masters with biasing rods? Give me a break. Someone has been sitting at home too long munching on wheaties. |
If NASkeet hasn't done it yet, it's only a matter of time ...
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mlesniak
Samba Member
Joined: April 08, 2015
Posts: 350
Location: Wisconsin
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| Posted: Wed Apr 29, 2020 8:00 pm Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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Thanks I'll definitely send a PM. Ive also messaged some other samba members that have rebuilt theirs.
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 42917
Location: at the beach in Northern Wokistan
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| Posted: Wed Apr 29, 2020 6:44 pm Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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many of the folks here ask basic questions like how to adjust timing, find a fuel leak or find a fuse. Does anyone really think folks are going to find a reliable skid pad, and know how to tune an "adjustable" proportioning valve? Whats next, multiple masters with biasing rods? Give me a break. Someone has been sitting at home too long munching on wheaties.
_________________
Canned Water - the new California approved parts cleaner (except in a drought in which case rub it with sand).
George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."
Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice" |
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kreemoweet
Samba Member
Joined: March 13, 2008
Posts: 4141
Location: Seattle, WA
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mlesniak
Samba Member
Joined: April 08, 2015
Posts: 350
Location: Wisconsin
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| Posted: Wed Apr 29, 2020 5:42 pm Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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| raygreenwood wrote: |
| kreemoweet wrote: |
It was engineered specifically for the characteristics of the VW bus braking system, so I doubt you would find
anything remotely similar in a generic item. The gasket that usually leaks is "paper". There's an o-ring internal
to that with a rectangular cross-section. Someone posted within the last week or so on this forum their measurements
of all the seals in the pressure regulator. |
Really finding an adjustable one that works for regulating the pressure...is not a problem. Summit alone has at least 400 part numbers and variations.
The difference....is that the bus unit ....uses the inertial forward shift of the bus to tell it WHEN to start regulating. What it regulates to....is not variable. Virtually none of them are.
There are two different kinds of rear brake pressure regulating that are important....not just on a bus but on any car:
1. Long moderate to hard braking (think like downhill at 60 mph) where pressure is increasing...shoes/pads are getting hotter...and therefore brake efficiency will keep increasing (to the point where they get too hot and fade).
The inertial shift is not a big issue with this one but you CAN get rear skidding. At some point when pressure gets high enough....most rear brake pressure regulators....LOCK....the pressure at that point....but sustain it. This prevents wheel skid.
2. Panic braking....sharp, hard jab at the brakes....which causes the rear of th vehicle to lift and the nose to dive. You may not have yet even reached peak "regulating" brake pressure at the rear....but when the weight lifts off the wheels....it takes less force to cause them to lock up.
This is where the inertial (the rolling incline ball) feature comes in handy. It should lock or sustain pressure so it cannot rise any further.
From the cross section diagram posted earlier....I 'think"....the bus regulator does both jobs.
While the layout is different than the 914/411/412 unit.....the parts shape, size and function based on their fluid ducting are the same. That type of unit has a pre-set pressure (based on the spring between the primary and secondary piston).
So even with non-panic braking....when you increase pressure to the pre-set point....it cuts off the feed but maintains the braking pressure on the line. You let off...it instantly bleeds down just like the front brakes at the same time.
The ball keeps the poppit valve closed...until inertia pulls it away...and that just bleeds pressure off....but then when that back chamber floods with this pressure it should equalize across the primary piston...and "may" also modulate the pressure and not just bleed it off. But that last part is speculation.
That inertia effect is pretty important on the bus....for panic braking.
However....if you just needed the normal brake pressure modulation I described earlier....yes....you can find a whole rage of adjustable rear pressure regulators....but you need to choose carefully. It has to have the right range of adjustment and should maintain pressure at the stop point...not just bleed it off.
The 914 model does this. It has no inertia feature like the bus. It has a sensitive set up that is designed to stop increasing brake pressure at 530 lbs.
I have a little bit about aftermarket pressure regulators in this thread
https://www.thesamba.com/vw/forum/viewtopic.php?t=664753
But...with the height and weight of the bus...you really need teh inertia feature....unless you do something that prevents a good portion of it (i.e...less weight in the back, some lowering and suspension stroke limiters).
Ray |
I actually started reading your thread! Thats where I got the idea for the Wilwood regulator. I'll have to look more into it. Thanks! Sounds like I should stick with rebuilding the original for now. I'll do more research on the aftermarket ones.
I edited in a question about Karropak gasket material on my other post. Any idea if this would be a suitable replacement for the paper gasket in the original VW brake pressure regulator?
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 23432
Location: Oklahoma City
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| Posted: Wed Apr 29, 2020 5:28 pm Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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| kreemoweet wrote: |
It was engineered specifically for the characteristics of the VW bus braking system, so I doubt you would find
anything remotely similar in a generic item. The gasket that usually leaks is "paper". There's an o-ring internal
to that with a rectangular cross-section. Someone posted within the last week or so on this forum their measurements
of all the seals in the pressure regulator. |
Really finding an adjustable one that works for regulating the pressure...is not a problem. Summit alone has at least 400 part numbers and variations.
The difference....is that the bus unit ....uses the inertial forward shift of the bus to tell it WHEN to start regulating. What it regulates to....is not variable. Virtually none of them are.
There are two different kinds of rear brake pressure regulating that are important....not just on a bus but on any car:
1. Long moderate to hard braking (think like downhill at 60 mph) where pressure is increasing...shoes/pads are getting hotter...and therefore brake efficiency will keep increasing (to the point where they get too hot and fade).
The inertial shift is not a big issue with this one but you CAN get rear skidding. At some point when pressure gets high enough....most rear brake pressure regulators....LOCK....the pressure at that point....but sustain it. This prevents wheel skid.
2. Panic braking....sharp, hard jab at the brakes....which causes the rear of th vehicle to lift and the nose to dive. You may not have yet even reached peak "regulating" brake pressure at the rear....but when the weight lifts off the wheels....it takes less force to cause them to lock up.
This is where the inertial (the rolling incline ball) feature comes in handy. It should lock or sustain pressure so it cannot rise any further.
From the cross section diagram posted earlier....I 'think"....the bus regulator does both jobs.
While the layout is different than the 914/411/412 unit.....the parts shape, size and function based on their fluid ducting are the same. That type of unit has a pre-set pressure (based on the spring between the primary and secondary piston).
So even with non-panic braking....when you increase pressure to the pre-set point....it cuts off the feed but maintains the braking pressure on the line. You let off...it instantly bleeds down just like the front brakes at the same time.
The ball keeps the poppit valve closed...until inertia pulls it away...and that just bleeds pressure off....but then when that back chamber floods with this pressure it should equalize across the primary piston...and "may" also modulate the pressure and not just bleed it off. But that last part is speculation.
That inertia effect is pretty important on the bus....for panic braking.
However....if you just needed the normal brake pressure modulation I described earlier....yes....you can find a whole rage of adjustable rear pressure regulators....but you need to choose carefully. It has to have the right range of adjustment and should maintain pressure at the stop point...not just bleed it off.
The 914 model does this. It has no inertia feature like the bus. It has a sensitive set up that is designed to stop increasing brake pressure at 530 lbs.
I have a little bit about aftermarket pressure regulators in this thread
https://www.thesamba.com/vw/forum/viewtopic.php?t=664753
But...with the height and weight of the bus...you really need teh inertia feature....unless you do something that prevents a good portion of it (i.e...less weight in the back, some lowering and suspension stroke limiters).
Ray |
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mlesniak
Samba Member
Joined: April 08, 2015
Posts: 350
Location: Wisconsin
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| Posted: Wed Apr 29, 2020 4:19 pm Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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I still plan on taking my original one apart and rebuilding it...
Is Fel-Pro 3046 Karropak gasket material considered "Paper"?
...I did stumble upon this Wilwood brake proportioning valve. It'd be great if something like this was useable in the bus.
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Rosita the 73' Tin-top
Last edited by mlesniak on Wed Apr 29, 2020 5:28 pm; edited 1 time in total |
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kreemoweet
Samba Member
Joined: March 13, 2008
Posts: 4141
Location: Seattle, WA
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| Posted: Wed Apr 29, 2020 3:14 pm Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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It was engineered specifically for the characteristics of the VW bus braking system, so I doubt you would find
anything remotely similar in a generic item. The gasket that usually leaks is "paper". There's an o-ring internal
to that with a rectangular cross-section. Someone posted within the last week or so on this forum their measurements
of all the seals in the pressure regulator.
_________________
'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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mlesniak
Samba Member
Joined: April 08, 2015
Posts: 350
Location: Wisconsin
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| Posted: Wed Apr 29, 2020 2:43 pm Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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My brake pressure regulator seems to be leaking. Im planning on taking it apart soon. Just curious what kind of gasket material will work with brake fluid? EPDM rubber? I've been having trouble find anything in store that's brake fluid compatible...
Also is it possible to replace the VW style brake pressure regulator with one thats more of a modern design / more readily available?
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aeromech
Samba Member
Joined: January 24, 2006
Posts: 17745
Location: San Diego, California
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| Posted: Wed Feb 21, 2018 6:02 pm Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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Sorry Ray, I couldn't find the one I thought I had
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 23432
Location: Oklahoma City
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| Posted: Wed Feb 21, 2018 4:06 pm Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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So.....the late one does have a rubber valve seal and a piston seal. Its interesting how they simplified the late unit.
The seal on the late model is also a standard cup type seal and can be machined from EPDM stock. Ray |
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 42917
Location: at the beach in Northern Wokistan
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| Posted: Wed Feb 21, 2018 3:40 pm Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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Thanks - photos below thanks to Kreemoweet & TCash
| Tcash wrote: |
To link to this post copy and paste
| Code: |
| [url=https://www.thesamba.com/vw/forum/viewtopic.php?p=8115511#8115511]Brake Pressure Regulator t2 211 612 501[/url] |
Brake Pressure Regulator t2 211 612 501
211 612 501 Brake Pressure Regulator Early t2. Note bleeder valve on top of valve.
211 612 501 A Brake Pressure Regulator Late t2. Note brake lines attach to the top. No bleeder valve.
Located on the frame rail.
GD
Tcash
| Welt wrote: |
Brake pressure regulator got the ultrasonic treatment too. Soaked the whole part in ethanol before disassembly.
Cleaned the mating surfaces with wet P800 paper.
Valve seal was fine. And all the piston bores looked ok. Piston seals were also in good condition.
Made my own gasket to replace the old crusty one.
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_________________
Canned Water - the new California approved parts cleaner (except in a drought in which case rub it with sand).
George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."
Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice" |
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kreemoweet
Samba Member
Joined: March 13, 2008
Posts: 4141
Location: Seattle, WA
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 42917
Location: at the beach in Northern Wokistan
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| Posted: Wed Feb 21, 2018 1:39 pm Post subject: Re: Brake Pressure Regulator/Proportioning Valve |
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I took my old one apart years ago and I do not recall a secondary system in it. I do recall this large ball that blocked the rear ports as it rolled. The design and shape of the early vs late regulators is somewhat different. Also the attachment point for the brake lines changes too.
early 1971 - 1972
late 1973 on
_________________
Canned Water - the new California approved parts cleaner (except in a drought in which case rub it with sand).
George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."
Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice" |
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