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Need help identifying this part? [message #326774] Tue, 05 December 2017 21:01 Go to next message
GMC Jimmy is currently offline  GMC Jimmy   Canada
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Registered: September 2016
Location: Niagara, Ontario
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Senior Member
Hello All, getting ready to install my Fitech and need to plumb a return line into the fuel filler neck and noticed this part... can you tell me what it is?

http://www.gmcmhphotos.com/photos/my-75-royale/p64083-image348.html

Also, I will need to wire the fuel injection system, where did - would you tap into for an ignition source?

Thanks for your help,
Regards,
Mike
Re: Need help identifying this part? [message #326776 is a reply to message #326774] Tue, 05 December 2017 21:19 Go to previous messageGo to next message
Dennis S is currently offline  Dennis S   United States
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Registered: November 2005
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Mike
Looks like someone cobbled together a brake proportioning valve replacement.
Here's what the original looks like.

http://appliedgmc.com/prod.itml/icOid/770

Dennis

GMC Jimmy wrote on Tue, 05 December 2017 21:01
Hello All, getting ready to install my Fitech and need to plumb a return line into the fuel filler neck and noticed this part... can you tell me what it is?

http://www.gmcmhphotos.com/photos/my-75-royale/p64083-image348.html

Also, I will need to wire the fuel injection system, where did - would you tap into for an ignition source?

Thanks for your help,
Regards,
Mike


Dennis S
73 Painted Desert 230
Memphis TN Metro
Re: Need help identifying this part? [message #326777 is a reply to message #326774] Tue, 05 December 2017 21:28 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
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Senior Member
GMC Jimmy wrote on Tue, 05 December 2017 22:01
Hello All, getting ready to install my Fitech and need to plumb a return line into the fuel filler neck and noticed this part... can you tell me what it is?

http://www.gmcmhphotos.com/photos/my-75-royale/p64083-image348.html

Also, I will need to wire the fuel injection system, where did - would you tap into for an ignition source?

Thanks for your help,
Regards,
Mike


Mike,

I actually recognize the part, but what it is doing there, I have no idea.

I believe it is a proportioning regulator (c.1980). It was used before the burden (weight on the suspension) version became available in pickups and other light trucks. The top switch was actually a pressure sensing brake light switch and the lower one is part of a fault sensing circuit that I am having a hard time recalling the function of.

Is it in the rear brake line?? Maybe I should have asked that first.

I hate to admit that the LED recently installed over my head just came on......
There is a decent bet that it was put in to try to stop the rear brake lock up.
If it did work, in the case of a GMC all it would do is reduce total brake effectiveness.

Matt


Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
Re: [GMCnet] Need help identifying this part? [message #326779 is a reply to message #326777] Tue, 05 December 2017 21:40 Go to previous messageGo to next message
Billy Massey is currently offline  Billy Massey   United States
Messages: 662
Registered: January 2004
Location: Central Texas
Karma: 4
Senior Member

It's not a line lock is it?


On Dec 5, 2017 9:29 PM, "Matt Colie" wrote:

GMC Jimmy wrote on Tue, 05 December 2017 22:01
> Hello All, getting ready to install my Fitech and need to plumb a return
line into the fuel filler neck and noticed this part... can you tell me
> what it is?
>
> http://www.gmcmhphotos.com/photos/my-75-royale/p64083-image348.html
>
> Also, I will need to wire the fuel injection system, where did - would
you tap into for an ignition source?
>
> Thanks for your help,
> Regards,
> Mike


Mike,

I actually recognize the part, but what it is doing there, I have no idea.

I believe it is a proportioning regulator (c.1980). It was used before the
burden (weight on the suspension) version became available in pickups and
other light trucks. The top switch was actually a pressure sensing brake
light switch and the lower one is part of a fault sensing circuit that I am
having a hard time recalling the function of.

Is it in the rear brake line?? Maybe I should have asked that first.

I hate to admit that the LED recently installed over my head just came
on......
There is a decent bet that it was put in to try to stop the rear brake lock
up.
If it did work, in the case of a GMC all it would do is reduce total brake
effectiveness.
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bdub
bdub.net
Re: [GMCnet] Need help identifying this part? [message #326782 is a reply to message #326779] Tue, 05 December 2017 22:33 Go to previous messageGo to next message
jimk is currently offline  jimk   United States
Messages: 4498
Registered: July 2006
Location: Belmont, CA
Karma: 5
Senior Member
It is the Line Lock for rear parking brake, electrical switch.

On Tue, Dec 5, 2017 at 7:40 PM, Billy Massey wrote:

> It's not a line lock is it?
>
>
> On Dec 5, 2017 9:29 PM, "Matt Colie" wrote:
>
> GMC Jimmy wrote on Tue, 05 December 2017 22:01
>> Hello All, getting ready to install my Fitech and need to plumb a return
> line into the fuel filler neck and noticed this part... can you tell me
>> what it is?
>>
>> http://www.gmcmhphotos.com/photos/my-75-royale/p64083-image348.html
>>
>> Also, I will need to wire the fuel injection system, where did - would
> you tap into for an ignition source?
>>
>> Thanks for your help,
>> Regards,
>> Mike
>
>
> Mike,
>
> I actually recognize the part, but what it is doing there, I have no idea.
>
> I believe it is a proportioning regulator (c.1980). It was used before the
> burden (weight on the suspension) version became available in pickups and
> other light trucks. The top switch was actually a pressure sensing brake
> light switch and the lower one is part of a fault sensing circuit that I am
> having a hard time recalling the function of.
>
> Is it in the rear brake line?? Maybe I should have asked that first.
>
> I hate to admit that the LED recently installed over my head just came
> on......
> There is a decent bet that it was put in to try to stop the rear brake lock
> up.
> If it did work, in the case of a GMC all it would do is reduce total brake
> effectiveness.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>



--
Jim Kanomata
Applied/GMC, Newark,CA
jimk-AT-appliedairfilters-DOT-com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk-AT-appliedairfilters-DOT-com
www.appliedgmc.com
1-800-752-7502
Re: Need help identifying this part? [message #326788 is a reply to message #326774] Wed, 06 December 2017 06:00 Go to previous messageGo to next message
Russell K. is currently offline  Russell K.   United States
Messages: 44
Registered: October 2016
Location: Dunedin, Florida
Karma: 0
Member
Mike,
Its a Mico Electric Activated Brake Lock, there should be a switch to activate it.

http://www.gmcmhphotos.com/photos/data/7009/medium/20170414_143413.jpg

http://www.gmcmhphotos.com/photos/data/7009/medium/Found_this_switch_cover_in_a_box_in_the_GMC.jpg

mine is currently deactivated, so I am no help to its use. Here is some info I found for it.

http://www.gmcmhphotos.com/photos/data/7009/Electric_Activated_Brake_Lock.pdf

Let me know if it works well for you.





Russell Keith, 1978 Eleganza II "Harry" 403, Danny Dunn Tranny (w/shift kit, 3.50 sprockets, Allison), Thorley, Stock Brakes w/Remote Vacuum Brake Booster, Mico Electric Actuated brake lock, Dakota Digital Dash, 6.5kW Onan, Dunedin, Florida
Re: Need help identifying this part? [message #326789 is a reply to message #326774] Wed, 06 December 2017 06:15 Go to previous messageGo to next message
Russell K. is currently offline  Russell K.   United States
Messages: 44
Registered: October 2016
Location: Dunedin, Florida
Karma: 0
Member
Mike,
I don't see the proportioning valve in your photo. Do you have disc brakes on all six?


Russell Keith, 1978 Eleganza II "Harry" 403, Danny Dunn Tranny (w/shift kit, 3.50 sprockets, Allison), Thorley, Stock Brakes w/Remote Vacuum Brake Booster, Mico Electric Actuated brake lock, Dakota Digital Dash, 6.5kW Onan, Dunedin, Florida
Re: Need help identifying this part? [message #326791 is a reply to message #326774] Wed, 06 December 2017 07:59 Go to previous messageGo to next message
RF_Burns is currently offline  RF_Burns   Mexico
Messages: 1438
Registered: June 2008
Location: S. Ontario, Canada
Karma: 6
Senior Member
Mike,

It definitely is a line line. Usually plumbed into the rear brake line. Put your foot on the brake and flip its switch ON then let you foot off the brakes. It will hold the rear brakes ON. Its not DOT approved for a parking brake because it could eventually release due to cooling drums or disks, fluid leaks etc.
To release it, flip the switch to OFF then press and release the brake pedal. Opps, now I see someone has posted the switch plate with the instructions.

It looks like a PO has replaced the proportioning valve with just a "T" to the front brakes and the backs are plumbed on their own. Two issues I can think of there... the brake pressures won't be balanced front to back and you wont have the Brake Light come ON if you have a brake problem. They are not expensive, but there is a different valve depending on whether you have original drums on the back, or disk brakes on the rear.


Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
Hubler 1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
Re: Need help identifying this part? [message #326798 is a reply to message #326774] Wed, 06 December 2017 10:08 Go to previous messageGo to next message
GMC Jimmy is currently offline  GMC Jimmy   Canada
Messages: 148
Registered: September 2016
Location: Niagara, Ontario
Karma: 1
Senior Member
Thanks Dennis, Matt, Billy & Jim, I appreciate your input on this.

Russell, I do have the same brake-lock switch/plate, the system works as I tried it previously but didn't know this is the control unit, thanks for that... and yes, I do have disc brakes on all 6 wheels, should I have the proportioning valve with this set-up?

Bruce, thanks for your explanation. Earlier this past spring I had a new in-dash stereo system wired in, on the drive home I had an issue with the dash AC switch working intermittently, assuming it had something to do with the stereo install I went back to the installer and he removed the front dash fascia to check wiring.

Got the AC switch working again, however, during this time I noticed the brake system warning light on (IIRC there was a wire which was not connected, once the installer connected the wire the brake system warning light in the dash illuminated... co-incidence? probably not). I assumed the wire hadn't been connected due to the modification from drum brakes to disc all around. I did not experience any braking issues while driving.

Should I investigate further?

"Two issues I can think of there... the brake pressures won't be balanced front to back and you wont have the Brake Light come ON if you have a brake problem. They are not expensive, but there is a different valve depending on whether you have original drums on the back, or disk brakes on the rear."
... Which valve should I look for due to having disc brakes?

Thanks again for the help guys,

Stay Well,
Mike
Re: Need help identifying this part? [message #326804 is a reply to message #326798] Wed, 06 December 2017 13:44 Go to previous messageGo to next message
Russell K. is currently offline  Russell K.   United States
Messages: 44
Registered: October 2016
Location: Dunedin, Florida
Karma: 0
Member
Mike,

Regarding the need for a proportioning valve with 6 wheel disc brakes, I am not qualified to provide that answer. However I suspect that some pressure regulation front-to-back would be helpful for optimized braking. Call Jim Kanomata at 800-752-7502, or Jim Bounds at 407-857-5777, or Jeff Sirum at 863-763-1121. The good news is that we have very knowledgeable people just a phone call away. I have talked to each of them and they are always willing to help me. They are great guys!

Russell


Russell Keith, 1978 Eleganza II "Harry" 403, Danny Dunn Tranny (w/shift kit, 3.50 sprockets, Allison), Thorley, Stock Brakes w/Remote Vacuum Brake Booster, Mico Electric Actuated brake lock, Dakota Digital Dash, 6.5kW Onan, Dunedin, Florida
Re: Need help identifying this part? [message #326805 is a reply to message #326774] Wed, 06 December 2017 13:53 Go to previous messageGo to next message
GMC Jimmy is currently offline  GMC Jimmy   Canada
Messages: 148
Registered: September 2016
Location: Niagara, Ontario
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Senior Member
Thanks again Russell,
Mike
Re: [GMCnet] Need help identifying this part? [message #326806 is a reply to message #326779] Wed, 06 December 2017 13:58 Go to previous messageGo to next message
James Hupy is currently offline  James Hupy   United States
Messages: 4551
Registered: May 2010
Karma: 33
Senior Member
That valve of many names, when used with a combination disc/drum system
serves to separate the front system from the rear system, and it provides a
redundant capability should either of the systems fail. It also provides a
warning light on the dash that indicates that some attention should be paid
to the brake system. With an all disc system, there is less of a need for
the "hold off" feature that the valving inside it provides. That is the
major difference between the two different valves. You still need the
redundancy feature, as well as the warning light and separate reservoirs
for front and rear brakes.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

On Dec 6, 2017 11:45 AM, "Russell Keith" wrote:

Mike,

Regarding the need for a proportioning valve with 6 wheel disc brakes, I am
not qualified to provide that answer. However I suspect that some pressure
regulation front-to-back would be helpful for optimized braking. Call Jim
Kanomata at 800-752-7502, or Jim Bounds at 407-857-5777, or Jeff Sirum at
863-763-1121. The good news is that we have very knowledgeable people just
a phone call away. I have talked to each of them and they are always
willing to help me. They are great guys!

Russell
--
Russell Keith,
1978 Eleganza II "Harry" 403, Danny Dunn Tranny (w/shift kit, 3.50
sprockets, Allison), Thorley, Stock Brakes w/Remote Vacuum Brake Booster,
Mico
Electric Actuated brake lock, Dakota Digital Dash, 6.5kW Onan,
Dunedin, Florida

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Re: Need help identifying this part? [message #326835 is a reply to message #326774] Thu, 07 December 2017 09:22 Go to previous messageGo to next message
Ray Erspamer is currently offline  Ray Erspamer   United States
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Location: Milwaukee Wisconsin
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Senior Member
In the brochure it says it should be "released and reactivated every hour".......that means it would not be a very good parking brake. Not sure why anyone would need this.

Ray Erspamer 78 GMC Royale 414-484-9431
Re: [GMCnet] Need help identifying this part? [message #326838 is a reply to message #326806] Thu, 07 December 2017 10:22 Go to previous messageGo to next message
dshafer is currently offline  dshafer   United States
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Registered: June 2016
Location: SW Ohio
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Junior Member
Jim.
When I read up on this valve some time ago I concluded that there are only two uses of it instead of the three often stated. Note this quote from a link off Manny's site (spelling errors are theirs):

"The original brake combinaton valve installed in our coaches peforms two functions: it activates a warning light in the dash if there is unequal pressure between the front and rear brakes such as if there's a fluid leak on one side, and it includes a metering valve to delay the front disc brakes so they don't engage before the slow rear drum brakes"

Those who have all disks are also warned that the old valve needs mods to the metering part for that application. That leaves only one uses of the valve... a warning light.

I do highly regard your posts... maybe I am about to learn something.

Dave


1977 26 foot 403
Re: [GMCnet] Need help identifying this part? [message #326840 is a reply to message #326838] Thu, 07 December 2017 10:44 Go to previous messageGo to next message
USAussie is currently offline  USAussie   United States
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Registered: July 2007
Location: Sydney, Australia
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Senior Member
David,

See the text under this photo for what's in the Maintenance Manual X-7525:

http://www.gmcmhphotos.com/photos/combination-valve/p59582-combination-valve.html

Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808


-----Original Message-----
From: Gmclist [mailto:gmclist-bounces-AT-list-DOT-gmcnet-DOT-org] On Behalf Of David Shafer
Sent: Thursday, December 7, 2017 10:23 AM
To: gmclist-AT-list-DOT-gmcnet-DOT-org
Subject: Re: [GMCnet] Need help identifying this part?

Jim.
When I read up on this valve some time ago I concluded that there are only two uses of it instead of the three often stated. Note
this quote from a link off Manny's site (spelling errors are theirs):

"The original brake combinaton valve installed in our coaches peforms two functions: it activates a warning light in the dash if
there is unequal pressure between the front and rear brakes such as if there's a fluid leak on one side, and it includes a metering
valve to delay the front disc brakes so they don't engage before the slow rear drum brakes"

Those who have all disks are also warned that the old valve needs mods to the metering part for that application. That leaves only
one uses of the valve... a warning light.

I do highly regard your posts... maybe I am about to learn something.

Dave
--
1977 26 foot 403

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Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426
Re: [GMCnet] Need help identifying this part? [message #326843 is a reply to message #326840] Thu, 07 December 2017 11:07 Go to previous messageGo to next message
James Hupy is currently offline  James Hupy   United States
Messages: 4551
Registered: May 2010
Karma: 33
Senior Member
David, it serves as an inlet for the fluid from BOTH reservoirs of the
master cylinder, and an outlet point for both the front brakes, and the
rear brakes while keeping them separated hydraulically. Valving in the
original valves serves to prevent application of the front brakes until the
rear drum pressure reaches the set point of the internal spring. Then, the
fluid pressure is released to the front brakes. With an all disc system,
this feature is not necessary.
Jim Hupy

On Dec 7, 2017 8:47 AM, "Rob Mueller" wrote:

> David,
>
> See the text under this photo for what's in the Maintenance Manual X-7525:
>
> http://www.gmcmhphotos.com/photos/combination-valve/
> p59582-combination-valve.html
>
> Regards,
> Rob M.
> The Pedantic Mechanic
> Sydney, Australia
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
> USA '77 Kingsley - TZE 267V100808
>
>
> -----Original Message-----
> From: Gmclist [mailto:gmclist-bounces-AT-list-DOT-gmcnet-DOT-org] On Behalf Of David
> Shafer
> Sent: Thursday, December 7, 2017 10:23 AM
> To: gmclist-AT-list-DOT-gmcnet-DOT-org
> Subject: Re: [GMCnet] Need help identifying this part?
>
> Jim.
> When I read up on this valve some time ago I concluded that there are only
> two uses of it instead of the three often stated. Note
> this quote from a link off Manny's site (spelling errors are theirs):
>
> "The original brake combinaton valve installed in our coaches peforms two
> functions: it activates a warning light in the dash if
> there is unequal pressure between the front and rear brakes such as if
> there's a fluid leak on one side, and it includes a metering
> valve to delay the front disc brakes so they don't engage before the slow
> rear drum brakes"
>
> Those who have all disks are also warned that the old valve needs mods to
> the metering part for that application. That leaves only
> one uses of the valve... a warning light.
>
> I do highly regard your posts... maybe I am about to learn something.
>
> Dave
> --
> 1977 26 foot 403
>
> _______________________________________________
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>
>
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Re: [GMCnet] Need help identifying this part? [message #326844 is a reply to message #326843] Thu, 07 December 2017 12:22 Go to previous message
dshafer is currently offline  dshafer   United States
Messages: 28
Registered: June 2016
Location: SW Ohio
Karma: 0
Junior Member
Jim,
My point (which I forgot to state) is that there is no redundancy in the valve... though both the redundant systems flow through the valve. They are sealed from each other in the valve... see Rob's reference.

Rob,
Although the manual states there is a balance function it explains that it only checks for the balance. It does not perform any balancing between the front and rear. Therefore in my mind the valve is only two function since the balance function is only there to activate the warning switch.

I am just trying to make sure of the fine points before I decide how I modify my own brakes.

Thanks for your responses
Dave


1977 26 foot 403
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