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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:

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
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[Message index]

		Problem with brass body proportioning valve By: Matt Colie on Fri, 09 July 2021 07:59
		Re: Problem with brass body proportioning valve By: JohnL455 on Fri, 09 July 2021 09:22
		Re: Problem with brass body proportioning valve By: Matt Colie on Fri, 09 July 2021 11:07
		Re: Problem with brass body proportioning valve By: JohnL455 on Fri, 09 July 2021 14:07
		Re: Problem with brass body proportioning valve By: blur911 on Fri, 09 July 2021 15:00
		Re: Problem with brass body proportioning valve By: JohnL455 on Fri, 09 July 2021 17:40
		Re: Problem with brass body proportioning valve By: Green machine on Fri, 09 July 2021 23:35
		Re: Problem with brass body proportioning valve By: ebyker on Sat, 10 July 2021 07:43
		Re: Problem with brass body proportioning valve By: MikeB on Sat, 10 July 2021 10:01
		[GMCnet] Re: Problem with brass body proportioning valve By: Thomas Pryor on Sat, 10 July 2021 11:08
		Re: Problem with brass body proportioning valve By: Greg C. on Sat, 10 July 2021 19:05
		Re: Problem with brass body proportioning valve By: Larry on Sat, 10 July 2021 20:24
		Re: Problem with brass body proportioning valve By: Tom Katzenberger on Sat, 10 July 2021 19:38
		Re: Problem with brass body proportioning valve By: Tom Katzenberger on Sat, 10 July 2021 19:40
		Re: Problem with brass body proportioning valve By: Matt Colie on Sun, 11 July 2021 08:15
		Re: Problem with brass body proportioning valve By: Tom Katzenberger on Sun, 11 July 2021 11:16
		Re: Problem with brass body proportioning valve By: JohnL455 on Sun, 11 July 2021 13:33
		Re: Problem with brass body proportioning valve By: Greg C. on Sun, 11 July 2021 19:29
		Re: Problem with brass body proportioning valve By: Bill Van Vlack on Sun, 11 July 2021 23:24
		[GMCnet] Re: Problem with brass body proportioning valve By: James Hupy on Sun, 11 July 2021 23:33
		Re: [GMCnet] Re: Problem with brass body proportioning valve By: Bill Van Vlack on Mon, 12 July 2021 10:34
		[GMCnet] Re: Problem with brass body proportioning valve By: James Hupy on Mon, 12 July 2021 10:50
		Re: Problem with brass body proportioning valve By: wally on Mon, 12 July 2021 11:55
		Re: Problem with brass body proportioning valve By: Matt Colie on Mon, 12 July 2021 19:18
		Re: Problem with brass body proportioning valve By: TR 1 on Mon, 12 July 2021 12:44
		Re: Problem with brass body proportioning valve By: Bill Van Vlack on Mon, 12 July 2021 13:31
		Re: Problem with brass body proportioning valve By: TR 1 on Mon, 12 July 2021 14:34
		Re: Problem with brass body proportioning valve By: Bill Van Vlack on Tue, 13 July 2021 10:14
		Re: Problem with brass body proportioning valve By: Greg C. on Mon, 12 July 2021 17:02
		Re: Problem with brass body proportioning valve By: JohnL455 on Mon, 12 July 2021 17:12
		Re: Problem with brass body proportioning valve By: Greg C. on Mon, 12 July 2021 17:40
		[GMCnet] Re: Problem with brass body proportioning valve By: Thomas Pryor on Thu, 29 July 2021 14:40
		[GMCnet] Re: Problem with brass body proportioning valve By: Billy Massey on Thu, 29 July 2021 15:30
		Re: [GMCnet] Re: Problem with brass body proportioning valve By: Matt Colie on Thu, 29 July 2021 16:39
		Re: Problem with brass body proportioning valve By: JohnL455 on Thu, 29 July 2021 18:57
		Re: Problem with brass body proportioning valve By: Tom Katzenberger on Thu, 29 July 2021 20:53
		Re: Problem with brass body proportioning valve By: Matt Colie on Thu, 29 July 2021 21:55
		Re: Problem with brass body proportioning valve By: Jp Benson on Sat, 31 July 2021 21:19
		Re: Problem with brass body proportioning valve By: Bill Van Vlack on Sun, 01 August 2021 13:10
		Re: Problem with brass body proportioning valve By: Jp Benson on Sun, 01 August 2021 17:24
		Re: Problem with brass body proportioning valve By: Larry on Sun, 01 August 2021 13:03
		Re: Problem with brass body proportioning valve By: Matt Colie on Sun, 01 August 2021 14:37
		Re: Problem with brass body proportioning valve By: Larry on Sun, 01 August 2021 15:06
		Re: Problem with brass body proportioning valve By: blur911 on Sun, 01 August 2021 16:00
		Re: Problem with brass body proportioning valve By: Thomas Pryor on Fri, 17 September 2021 12:38
		Re: Problem with brass body proportioning valve By: Larry on Fri, 17 September 2021 17:49
		Re: Problem with brass body proportioning valve By: blur911 on Sun, 10 October 2021 13:23
		Re: Problem with brass body proportioning valve By: Russell K. on Mon, 11 October 2021 13:14
		[GMCnet] Re: Problem with brass body proportioning valve By: stu@97381.com, Emery on Mon, 11 October 2021 14:43
		[GMCnet] Re: Problem with brass body proportioning valve By: stu@97381.com, Emery on Mon, 11 October 2021 15:55
		[GMCnet] Re: Problem with brass body proportioning valve By: jimk on Mon, 11 October 2021 20:17
		Re: [GMCnet] Re: Problem with brass body proportioning valve By: blur911 on Wed, 03 November 2021 14:39
		[GMCnet] Re: Problem with brass body proportioning valve By: jimk on Wed, 03 November 2021 15:26
		[GMCnet] Re: Problem with brass body proportioning valve By: Thomas Pryor on Tue, 12 October 2021 12:20
		Re: Problem with brass body proportioning valve By: ebyker on Tue, 12 October 2021 14:59

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