Home » Public Forums » GMCnet » Problem with brass body proportioning valve (Read about it in Winter 2021 Vintage RVing)
Re: Problem with brass body proportioning valve [message #365809 is a reply to message #365805] |
Sun, 01 August 2021 14:37 |
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Matt Colie
Messages: 8547 Registered: March 2007 Location: S.E. Michigan
Karma: 7
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Larry wrote on Sun, 01 August 2021 14:03I 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
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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
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Senior Member |
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Matt Colie wrote on Sun, 01 August 2021 14:37Larry wrote on Sun, 01 August 2021 14:03I 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? 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
78 Royale w/500 Caddy
Menomonie, WI.
[Updated on: Sun, 01 August 2021 15:06] Report message to a moderator
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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
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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
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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
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Senior Member |
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Thomas Pryor wrote on Fri, 17 September 2021 12:38Be 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
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[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
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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:
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[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
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Senior Member |
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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:
>
_______________________________________________
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[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
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Senior Member |
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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
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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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
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Senior Member |
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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 20:17The 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
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[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
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Senior Member |
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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
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