Problem with brass body proportioning valve

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
78 Royale w/500 Caddy
Menomonie, WI.
 
> 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
 
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
 
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

>
> 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:
 
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 <

> 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
>
>
>
> > On Oct 11, 2021, at 12:14 PM, Russell Keith

> >
> > 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:
>
 
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 <

>
> > 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
> >
> >
> >
> > > On Oct 11, 2021, at 12:14 PM, Russell Keith

> > >
> > > 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
http://www.gmcrvparts.com
1-800-752-7502
 
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
 
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
 
I see that the valves are on the Applied GMC site, I just ordered one along with some other bits.
Thanks Jim

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

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

> > 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
> > 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
http://www.gmcrvparts.com
1-800-752-7502
 
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