GMCforum: GMCnet » Problem with brass body proportioning valve

Home » Public Forums » GMCnet » Problem with brass body proportioning valve (Read about it in Winter 2021 Vintage RVing)

Show: Today's Messages :: Polls :: Message Navigator

Re: Problem with brass body proportioning valve [message #365809 is a reply to message #365805]

Sun, 01 August 2021 14:37

Matt Colie

Messages: 8547
Registered: March 2007
Location: S.E. Michigan

Karma: 7

Senior Member

Larry wrote on Sun, 01 August 2021 14:03

I changed my Combination/Proportioning valve back in 2005 when I did the whole braking system. At that time that "valve" was the old steel one and was quite rusty, so got one from, IIRC, Applied GMC. It was Brass, so I felt I had to check it for the proportioning rubber plug. I did it while installed on the coach. First thing I did was make sure the master cylinder was full and then put the proportioning valve bleed tool for holding to the differential spool valve in place. Then remove the brake line going to the rear wheels, and capped the line off with a inverted flare cap. With fluid trickling out of the combination valve, using a mirror and a flashlight, looked up the valve for the rubber plug and spring. NOT THERE!! So I put it back together and bled the line. Apparently some of the brass ones sold back in the early 2000's did not have that proportioning spring and plug in them. So it is possible that some of you may have the correct brass "combination valve". IMO it is best to check it anyway.

Tom Pryor found out that the design for the PVMH has existed a long time and they believe some were made. You may have gotten one.

Look underneath and see if it is stamped PVMH or PV2/4.

Matt

Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

Report message to a moderator

Re: Problem with brass body proportioning valve [message #365811 is a reply to message #365809]

Sun, 01 August 2021 15:06

Larry

Messages: 2875
Registered: January 2004
Location: Menomonie, WI

Karma: 10

Senior Member

Matt Colie wrote on Sun, 01 August 2021 14:37

Larry wrote on Sun, 01 August 2021 14:03
I changed my Combination/Proportioning valve back in 2005 when I did the whole braking system. At that time that "valve" was the old steel one and was quite rusty, so got one from, IIRC, Applied GMC. It was Brass, so I felt I had to check it for the proportioning rubber plug. I did it while installed on the coach. First thing I did was make sure the master cylinder was full and then put the proportioning valve bleed tool for holding to the differential spool valve in place. Then remove the brake line going to the rear wheels, and capped the line off with a inverted flare cap. With fluid trickling out of the combination valve, using a mirror and a flashlight, looked up the valve for the rubber plug and spring. NOT THERE!! So I put it back together and bled the line. Apparently some of the brass ones sold back in the early 2000's did not have that proportioning spring and plug in them. So it is possible that some of you may have the correct brass "combination valve". IMO it is best to check it anyway.
Tom Pryor found out that the design for the PVMH has existed a long time and they believe some were made. You may have gotten one.

Look underneath and see if it is stamped PVMH or PV2/4.

Matt

Awwww Geese...do I have to? Sad

Sad

Maybe next time I have the front end up and the drivers side wheel and wheel well off.....

I was actually surprised that the plug and spring were not there. I was under the impression from all of the talk about it, that ALL brass combo valves had it....but...noooooo!!

Larry

Smile

78 Royale w/500 Caddy
Menomonie, WI.

[Updated on: Sun, 01 August 2021 15:06]

Report message to a moderator

Re: Problem with brass body proportioning valve [message #365814 is a reply to message #365293]

Sun, 01 August 2021 16:00

blur911

Messages: 166
Registered: December 2020
Location: Kingston, Ontario

Karma: 4

Senior Member

I just stuck my phone in and took a photo of the underside of the valve, looks like I have a shiny new PV2 courtesy of the previous owner's brother. He did tell me he never got the rear brakes bled right either.
With the wheel and well liner out it doesn't look horrible to work on in place, I might try that first and see if there is indeed a rubber piston in it, as I suspect there is.

Burl Vibert
Kingston, Ontario
1976 GMC 26 foot, Sheridan reno, don't know original model but we call her Roxie

Report message to a moderator

Re: Problem with brass body proportioning valve [message #365818 is a reply to message #365807]

Sun, 01 August 2021 17:24

Jp Benson

Messages: 649
Registered: October 2011
Location: Fla

Karma: 2

Senior Member

Bill Van Vlack wrote on Sun, 01 August 2021 13:10

Jp Benson wrote on Sat, 31 July 2021 21:19
Should I check mine that was purchased from a vendor several years ago? I'm not inclined to open up the hydraulic brake lines.

JP
I did and it did; I don't think anyone's found a brass valve on the market that didn't have the proportioning section. I'm hoping Tom Pryor's efforts change that. I put the steel valve back in.

Bill, thanks for the feedback. I didn't see any marking on the underside of the valve. The marks (cast on the side of the valve) are HJ 04 84 9419. These are preceded by an irregular rectangular symbol that I do not recognize.

Guess I'll get a couple quarts of fluid, do a flush, install the speed bleeders (with teflon tape) and open up the proportion/combo valve when the rainy season ends here in FL. If I have to modify the valve and there's a dramatic improvement in braking I'll report back,

JP

Report message to a moderator

Re: Problem with brass body proportioning valve [message #366850 is a reply to message #365293]

Fri, 17 September 2021 12:38

Thomas Pryor

Messages: 143
Registered: January 2011

Karma: 1

Senior Member

Be Advised that Applied is receiving a MOQ (minimum order quantity) of the tested and confirmed combination brake BRASS replacement valve for our fleet!

Look for this image in the Brake section of the Applied website, http://www.gmcmhphotos.com/photos/combination-valves/p68350-appled-pvmh.html

With the availability of these tested valves there should be no need to modify or take responsibility for modifying a PV2 Valve. Just Say'n.

Report message to a moderator

Re: Problem with brass body proportioning valve [message #366853 is a reply to message #366850]

Fri, 17 September 2021 17:49

Larry

Messages: 2875
Registered: January 2004
Location: Menomonie, WI

Karma: 10

Senior Member

Before you go and replace the BRASS proportioning valve, check the one you have first. I got mine back in 2005 from one of the vendors, and not knowing if it was correct or not, I pulled the line going to the rear brakes off and using a mirror, looked inside ready to pull the proportioning portion out only to find that my brass valve did not have the proportioning portion in it. Check first. JWID

Larry

Smile

78 Royale w/500 Caddy
Menomonie, WI.

Report message to a moderator

Re: Problem with brass body proportioning valve [message #367137 is a reply to message #366850]

Sun, 10 October 2021 13:23

blur911

Messages: 166
Registered: December 2020
Location: Kingston, Ontario

Karma: 4

Senior Member

Thomas Pryor wrote on Fri, 17 September 2021 12:38

Be Advised that Applied is receiving a MOQ (minimum order quantity) of the tested and confirmed combination brake BRASS replacement valve for our fleet!

Look for this image in the Brake section of the Applied website, http://www.gmcmhphotos.com/photos/combination-valves/p68350-appled-pvmh.html

With the availability of these tested valves there should be no need to modify or take responsibility for modifying a PV2 Valve. Just Say'n.

I'm looking at the Applied GMC site and can only find the old valves, not the PVMH??
Gotta put in an order soon.

Burl Vibert
Kingston, Ontario
1976 GMC 26 foot, Sheridan reno, don't know original model but we call her Roxie

Report message to a moderator

Re: Problem with brass body proportioning valve [message #367161 is a reply to message #365293]

Mon, 11 October 2021 13:14

Russell K.

Messages: 178
Registered: October 2016
Location: Dunedin, Florida

Karma: 4

Senior Member

So, is this the wrong combination valve?, Which I installed a few years ago. I see the PV2 / 12M86 part number. If I do the modification, am I more likely to flat-spot the rears before the fronts lock up? The brakes "appear" to be fine now, but perhaps I don't know any better. Rolling Eyes

Rolling Eyes

http://www.gmcmhphotos.com/photos/data/7010/medium/Combination_Valve2.jpg

1978 Eleganza II, Dunedin, Florida

Report message to a moderator

[GMCnet] Re: Problem with brass body proportioning valve [message #367162 is a reply to message #367161]

Mon, 11 October 2021 14:43

stu@97381.com, Emery

Messages: 232
Registered: June 2020

Karma: 2

Senior Member

That looks like the valve that I put on years back. I checked mine out some time back and it didn’t need a modification.
I don’t think that you could lock up the fronts before the rears if you had the modification or not.
If I were you I would not do anything to it. If your brakes are working now I would not mess with the valve.

By the way it really isn’t a proportioning valve. It should be properly called a combination valve. It puts a small amount of pressure on the front brakes before it puts the full pressure to both the front and read. It does not proportion any pressure to either the front or rears.
It also has a shuttle inside it which will turn on a light on the dash telling you if there is no pressure on either the front or rear. This is to tell you that you might have a leak in the system or low fluid on the front or rear.

Emery Stora
emerystora@mac.com

> On Oct 11, 2021, at 12:14 PM, Russell Keith wrote:
>
> So, is this the wrong combination valve?, Which I installed a few years ago. I see the PV2 / 12M86 part number. If I do the modification, am I more
> likely to flat-spot the rears before the fronts lock up? The brakes "appear" to be fine now, but perhaps I don't know any better. :roll:
>
> http://www.gmcmhphotos.com/photos/data/7010/medium/Combination_Valve2.jpg
>
>
> --
> Russell Keith,
> 1978 E2 "Harry" 403 (still carbureted), Danny Dunn Tranny, Thorley, Stock Brakes w/Remote Vacuum Brake Booster, Quad Bags, Dakota Digital Dash, 6.5 kW
> Onan, Dunedin, Florida
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:

Report message to a moderator

[GMCnet] Re: Problem with brass body proportioning valve [message #367164 is a reply to message #367162]

Mon, 11 October 2021 15:55

stu@97381.com, Emery

Messages: 232
Registered: June 2020

Karma: 2

Senior Member

Emory,

Either your age is showing, or mine's about to!: IIRC, the combination
valve PREVENTS pressure from reaching the front brakes until the rears
receive about 135 psi. The purpose being to take up the free play in the
rear drums before the fronts engage. After reaching that point, the front
and rear brakes soon receive the same pressure. With all disc brakes, that
delay function is not required and should not be in the "proportioning"
valve -- which really keeps only the distribution and system monitor
functions. This may help some to understand how it works:
http://www.gmcmhphotos.com/photos/g3510-deciphering-the-combination-valve.html

Ken H.

On Mon, Oct 11, 2021 at 3:44 PM Emery Stora via Gmclist <
gmclist@list.gmcnet.org> wrote:

> That looks like the valve that I put on years back. I checked mine out
> some time back and it didn’t need a modification.
> I don’t think that you could lock up the fronts before the rears if you
> had the modification or not.
> If I were you I would not do anything to it. If your brakes are working
> now I would not mess with the valve.
>
> By the way it really isn’t a proportioning valve. It should be properly
> called a combination valve. It puts a small amount of pressure on the
> front brakes before it puts the full pressure to both the front and read.
> It does not proportion any pressure to either the front or rears.
> It also has a shuttle inside it which will turn on a light on the dash
> telling you if there is no pressure on either the front or rear. This is
> to tell you that you might have a leak in the system or low fluid on the
> front or rear.
>
> Emery Stora
> emerystora@mac.com
>
>
>
>> On Oct 11, 2021, at 12:14 PM, Russell Keith
> wrote:
>>
>> So, is this the wrong combination valve?, Which I installed a few years
> ago. I see the PV2 / 12M86 part number. If I do the modification, am I
> more
>> likely to flat-spot the rears before the fronts lock up? The brakes
> "appear" to be fine now, but perhaps I don't know any better. :roll:
>>
>>
> http://www.gmcmhphotos.com/photos/data/7010/medium/Combination_Valve2.jpg
>>
>>
>> --
>> Russell Keith,
>> 1978 E2 "Harry" 403 (still carbureted), Danny Dunn Tranny, Thorley,
> Stock Brakes w/Remote Vacuum Brake Booster, Quad Bags, Dakota Digital Dash,
> 6.5 kW
>> Onan, Dunedin, Florida
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:

Report message to a moderator

[GMCnet] Re: Problem with brass body proportioning valve [message #367168 is a reply to message #367164]

Mon, 11 October 2021 20:17

jimk

Messages: 6734
Registered: July 2006
Location: Belmont, CA

Karma: 9

Senior Member

The shipment from China that Tom P. has tested should arrive this week and
will be available and will have an Identifying mark.
I am as leary as anyone on a product made there, but who else will do few
hundred at affordable price?
I will soon find out.

On Mon, Oct 11, 2021 at 1:56 PM Ken Henderson
wrote:

> Emory,
>
> Either your age is showing, or mine's about to!: IIRC, the combination
> valve PREVENTS pressure from reaching the front brakes until the rears
> receive about 135 psi. The purpose being to take up the free play in the
> rear drums before the fronts engage. After reaching that point, the front
> and rear brakes soon receive the same pressure. With all disc brakes, that
> delay function is not required and should not be in the "proportioning"
> valve -- which really keeps only the distribution and system monitor
> functions. This may help some to understand how it works:
>
> http://www.gmcmhphotos.com/photos/g3510-deciphering-the-combination-valve.html
>
> Ken H.
>
> On Mon, Oct 11, 2021 at 3:44 PM Emery Stora via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> That looks like the valve that I put on years back. I checked mine out
>> some time back and it didn’t need a modification.
>> I don’t think that you could lock up the fronts before the rears if you
>> had the modification or not.
>> If I were you I would not do anything to it. If your brakes are working
>> now I would not mess with the valve.
>>
>> By the way it really isn’t a proportioning valve. It should be properly
>> called a combination valve. It puts a small amount of pressure on the
>> front brakes before it puts the full pressure to both the front and read.
>> It does not proportion any pressure to either the front or rears.
>> It also has a shuttle inside it which will turn on a light on the dash
>> telling you if there is no pressure on either the front or rear. This is
>> to tell you that you might have a leak in the system or low fluid on the
>> front or rear.
>>
>> Emery Stora
>> emerystora@mac.com
>>
>>
>>
>>> On Oct 11, 2021, at 12:14 PM, Russell Keith
>> wrote:
>>>
>>> So, is this the wrong combination valve?, Which I installed a few years
>> ago. I see the PV2 / 12M86 part number. If I do the modification, am I
>> more
>>> likely to flat-spot the rears before the fronts lock up? The brakes
>> "appear" to be fine now, but perhaps I don't know any better. :roll:
>>>
>>>
>>
> http://www.gmcmhphotos.com/photos/data/7010/medium/Combination_Valve2.jpg
>>>
>>>
>>> --
>>> Russell Keith,
>>> 1978 E2 "Harry" 403 (still carbureted), Danny Dunn Tranny, Thorley,
>> Stock Brakes w/Remote Vacuum Brake Booster, Quad Bags, Dakota Digital
> Dash,
>> 6.5 kW
>>> Onan, Dunedin, Florida
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:

Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502

Report message to a moderator

[GMCnet] Re: Problem with brass body proportioning valve [message #367175 is a reply to message #365293]

Tue, 12 October 2021 12:20

Thomas Pryor

Messages: 143
Registered: January 2011

Karma: 1

Senior Member

I placed an image of a Combination Valve on the Photo site that shows the
three segments of the Combination valve.
http://www.gmcmhphotos.com/photos/combination-valves/p68350-appled-pvmh.html

THE CENTER section is a SWITCH that shuttles between front and rear brake
channels. If pressure is different in either channel the switch goes to
"on" and the Safety dash light is illuminated.
All cast iron TZE coach combination valves had this feature.

THE FRONT section is a Hold Off section (called metering) valve to delay
the engagement with the front brake channel. All cast iron TZE coach
combination valves had this feature.

THE REAR section of our cast iron TZE coach combination valve had NO
FUNCTION other than a place to thread together the rear brake line
channel. "Brake design intent" for our TZE coaches was focused on all the
rear wheels receiving all the pressure that could be produced by the
vacuum assisted master cylinder.

THE REST OF THE STORY:

AFTER THE END OF TZE PRODUCTION;
All cast iron combination valves were replaced with brass combination
valves that were designed for 4 wheel pass cars/light trucks with disc/drum
designs. Those designs added a 3rd function...........limit the pressure
to the rear brake channel. WHY? Much lighter passenger and light truck
vehicles could and did suffer from rear wheel lockup, skidding and loss of
control. Brake designs of that period required not only improved stopping
distances but also improved stop control. That is the fundamental reason
for rear pressure limiting combination valves. That also meant that no
brass valve could NOT achieve the exact and necessary requirements for our
coaches. REPLACEMENT VALVES available to the Tribe were limited to the PV2
version that limits the pressure to the rear wheels, but it plumbs right in!

In my previous life as a QC guy working at Kelsey Hayes and after the
transition from Cast iron to Brass Valves, I was able to find the technical
drawing of a brass valve that had no rear pressure limiting feature. I
found that drawing in China and also discovered it was never produced,
probably because of low demand!

If you have the OE standard TZE brake configuration on your coach use the
valve that Applied GMC offers. The PVMH is the only commercially available
brass brake combination valve that replaces the Cast Iron valve in form and
function. Jim has not yet posted the images and pricing on
his site. Patience!

--
Regards,

Tom Pryor
4188 Limerick Dr
Lake Wales, Fl 33859
Cell 248 470 9186

1977 23'B named "CASPER", HARDLY ORIGINAL, (455 EFI) (Pwr. Drive)
(tailgate) (rear bunk beds)
(Webasto petrol boiler) (MB Elect fan clutch) (Brake reaction arms) BUT
STILL A WORK IN PROGRESS!

ReplyForward
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:

Report message to a moderator

Re: Problem with brass body proportioning valve [message #367179 is a reply to message #365293]

Tue, 12 October 2021 14:59

ebyker

Messages: 37
Registered: May 2016

Karma: 1

Member

Dave Lensy in the aetical in vintage rv magazine showes 2 ways to modify the pv2 valve I removed the rear screw in part in place on the coach I thought that it was easy to remove the small diameter extention as as I had it in my hand I left the rubber valve in place as you read in my earler post I had great brakes however what I found out the hard way there was considerable pressure being held in the rear brakes In the next 12 hours of use this summer I burned off all 4 rear brakes I have since replaced the rear shoes and springs there was enough pressure in the rear brakes that when I lossened a brake line there was a big spurt of fluid way more than anyone would expect I have now removed th rubber valve as well All seems well on the last trip Now on the recomenddation ov a local brake rebuild shop I had a 10 psi line pressure valve in my rear brake line [ sinse removed] I was told that rear line pressure valve was part of the function of the combination valve but I do not see anything in the vlave or in the vareous descriptions of a line pressure fuction [ old 4 wheel drum master cylinders had that fuction in the master cyl] where is that line pressure vlave now or do we not need it and why not thanks Eelko Byker Port Colborne Ont Canada

Report message to a moderator

Re: [GMCnet] Re: Problem with brass body proportioning valve [message #367471 is a reply to message #367168]

Wed, 03 November 2021 14:39

blur911

Messages: 166
Registered: December 2020
Location: Kingston, Ontario

Karma: 4

Senior Member

I see that the PVMH valves are now on the Applied GMC site, I just ordered one, along with some other bits.
Thanks Jim

jimk wrote on Mon, 11 October 2021 20:17

The shipment from China that Tom P. has tested should arrive this week and
will be available and will have an Identifying mark.
I am as leary as anyone on a product made there, but who else will do few
hundred at affordable price?
I will soon find out.

--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:

Burl Vibert
Kingston, Ontario
1976 GMC 26 foot, Sheridan reno, don't know original model but we call her Roxie

[Updated on: Wed, 03 November 2021 14:41]

Report message to a moderator

[GMCnet] Re: Problem with brass body proportioning valve [message #367473 is a reply to message #367471]

Wed, 03 November 2021 15:26

jimk

Messages: 6734
Registered: July 2006
Location: Belmont, CA

Karma: 9

Senior Member

For those that want the correct one, we have 250each in stock.

On Wed, Nov 3, 2021 at 12:39 PM Burl Vibert wrote:

> I see that the valves are on the Applied GMC site, I just ordered one
> along with some other bits.
> Thanks Jim
>
>
>
>
> jimk wrote on Mon, 11 October 2021 20:17
>> The shipment from China that Tom P. has tested should arrive this week
> and
>> will be available and will have an Identifying mark.
>> I am as leary as anyone on a product made there, but who else will do few
>> hundred at affordable price?
>> I will soon find out.
>>
>>
>>
>> --
>> Jim Kanomata ASE
>> Applied/GMC, Newark,CA
>> jimk@appliedairfilters.com
>> http://www.gmcrvparts.com
>> 1-800-752-7502
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>
>
> --
> Burl Vibert
> Kingston, Ontario
> 1976 GMC 26 foot, Sheridan reno, don't know original model but we call her
> Roxie
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:

Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502

Report message to a moderator

Pages (3): [ « ‹ 1 2 3]

Previous Topic:	[GMCnet] sreering
Next Topic:	[GMCnet] Winterizing Options

Goto Forum:

-=] Back to Top [=-

Current Time: Sat Jun 22 05:58:42 CDT 2024

Total time taken to generate the page: 0.26861 seconds