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| Re: [GMCnet] vacuum house routing [message #175566 is a reply to message #175534] |
Wed, 04 July 2012 23:00   |
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ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
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The transducer connects to manifold vacuum from the big port, and then to the vacuum motor from the little port. I may be using the term vacuum motor incorrectly - what I mean is that big diaphragm that controls the throttle with a chain.
The vacuum hose from the vacuum motor is T'd and continues on to some place beyond my curiosity.
Larry Davick
A Mystery Machine
Sent from my iPad
On Jul 4, 2012, at 3:03 PM, "Len Novak" <B52Rule@RoadRunner.Com> wrote:
>
> For the stock cruise control...........
>
> I see two connectors next to each other on the transducer, but I only have
> one hose available
>
> Thanks,
> Len and Pat
> 1978 GMC Kingsley
> The Beast II with dash lights that work and labels you can see!
> Fallbrook, CA new email: B52Rule@Roadrunner.Com
> http://www.gmcmhphotos.com/photos/showgallery.php?cat=4375
>
> www.bdub.net/novak/
>
> _______________________________________________
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Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
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| Re: [GMCnet] vacuum house routing [message #175642 is a reply to message #175566] |
Thu, 05 July 2012 14:41 |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
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| ljdavick wrote on Wed, 04 July 2012 23:00 |
The vacuum hose from the vacuum motor is T'd and continues on to some place beyond my curiosity.
Larry Davick
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It goes to a vacuum dump valve on the brake pedal. This valve is mounted next to the brake light switch.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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| Re: [GMCnet] vacuum house routing [message #175656 is a reply to message #175652] |
Thu, 05 July 2012 16:48 |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
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| emerystora wrote on Thu, 05 July 2012 16:15 |
Dave
Are you certain that is a vacuum dump switch? My 1977 had an electrical switch there but no vacuum switch.
We're these on earlier models? Or did you just assume it is a vacuum switch?
Emery Stora
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Nope - it was a vacuum dump valve. There is also a CC electrical cutoff switch (that I saved for my Rostra installation).
Here is the quote from the 73/74 MM:
"BRAKE RELEASE SWITCHES
Two brake release switches are employed in the
Cruise Control System. When the brake pedal is depressed;
an electric release switch cuts off the voltage
supplied to the engagement switch, hence cuts off
power to the regulator unit. The regulator is then
disengaged and requires engagement switch operation
to return it to operation. A vacuum release
switch operates simultaneously with the electric release
switch whenever the brake pedal is depressed.
This switch opens a port to atmospheric pressure
which rapidly bleeds down the vacuum in the servo
unit thereby returning the throttle to the idle position."
The 75/76 manual has the same comments. Not sure about anything later. This is in the chassis electrical section of the MM.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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| Re: [GMCnet] vacuum house routing [message #175657 is a reply to message #175652] |
Thu, 05 July 2012 16:48 |
Ray Erspamer
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
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Senior Member |
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Our 78 had the vacuum dump switch under the instrument panel.
Ray
Ray & Lisa
78 Royale "Great Lakes Eagle"
Center Kitchen TZE368V101144
Wauwatosa, Wisconsin 53226
Email: 78GMC-Royale@att.net
414-745-3188
Web Site: http://ray-lisa.page.tl/
________________________________
From: Emery Stora <emerystora@mac.com>
To: "gmclist@temp.gmcnet.org" <gmclist@temp.gmcnet.org>
Sent: Thu, July 5, 2012 4:15:47 PM
Subject: Re: [GMCnet] vacuum house routing
Dave
Are you certain that is a vacuum dump switch? My 1977 had an electrical switch
there but no vacuum switch.
We're these on earlier models? Or did you just assume it is a vacuum switch?
Emery Stora
Emery
On Jul 5, 2012, at 1:41 PM, Steve Southworth <midlf@centurytel.net> wrote:
>
>
> ljdavick wrote on Wed, 04 July 2012 23:00
>> The vacuum hose from the vacuum motor is T'd and continues on to some place
>>beyond my curiosity.
>>
>>
>> Larry Davick
>
>
> It goes to a vacuum dump valve on the brake pedal. This valve is mounted next
>to the brake light switch.
> --
> Steve Southworth
> 1974 Glacier TZE064V100150 (for workin on)
> 1975 Transmode TZE365V100394 (parts & spares)
> Palmyra WI
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Ray Erspamer
78 GMC Royale Center Kitchen
403, 3.70 Final Drive
Holley Sniper Quadrajet EFI System,
Holley Hyperspark Ignition System
414-484-9431
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| Re: [GMCnet] vacuum house routing [message #175685 is a reply to message #175667] |
Thu, 05 July 2012 19:27 |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
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Senior Member |
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| emerystora wrote on Thu, 05 July 2012 17:16 |
Is the vacuum switch mounted higher up? I know that the two side by side switches are electrical.
It has been so many years since I replaced my OEM cruise control that I don't remember what I unhooked.
Emery Stora
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Hmmm - not sure. I just remember laying on the floor and cursing at it as I tried to get it and the vacuum hose out of there.
Looking at the 73 MM (section 12 figure 47) it shows the electrical as being two switches on one plunger. The second plunger is the vacuum dump valve. The two are located next to each other. However who knows what was done by a PO on any one coach.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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| Re: [GMCnet] vacuum house routing [message #175696 is a reply to message #175652] |
Thu, 05 July 2012 20:11 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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All the early 70s GM stuff using the same servo had the vacuum dump. Matterofact, my 91 VW Jetta has one also. It is a safety feature in case the servo does not disengage - the vacuum line has a slight restriction to the manifold while the dump valve has none. Thus if the dump is open, the back of the diaphragm which pulls the chain will stay at ambient instead of at MAP, and the throttle will not be pulled.
Which brings an interesting point in light of the recent vacuum pump discussions - do NOT connect the cruise servo lione to a pump, connect it only to the intake. The servo is self limiting - as it pulls the throttle open, MAP rises, and at some point equals ambient. This limits the amount of throttle which the servo can apply. When run by a pump - as in my Diesel VW and other diesels - throttle limit has to come from somewhere else.
n.b. MAP = manifold absolute pressure. The idea of higher vacuum relative to higher pressure confuses me. As long as ever thing is listed in terms of positive pressure, I can keep up with it.
--johnny
'76 23' transmode norris
'76 palm beach
From: Emery Stora <emerystora@mac.com>
To: "gmclist@temp.gmcnet.org" <gmclist@temp.gmcnet.org>
Sent: Thursday, July 5, 2012 5:15 PM
Subject: Re: [GMCnet] vacuum house routing
Dave
Are you certain that is a vacuum dump switch? My 1977 had an electrical switch there but no vacuum switch.
We're these on earlier models? Or did you just assume it is a vacuum switch?
Emery Stora
Emery
On Jul 5, 2012, at 1:41 PM, Steve Southworth <midlf@centurytel.net> wrote:
>
>
> ljdavick wrote on Wed, 04 July 2012 23:00
>> The vacuum hose from the vacuum motor is T'd and continues on to some place beyond my curiosity.
>>
>> Larry Davick
>
>
> It goes to a vacuum dump valve on the brake pedal. This valve is mounted next to the brake light switch.
> --
> Steve Southworth
> 1974 Glacier TZE064V100150 (for workin on)
> 1975 Transmode TZE365V100394 (parts & spares)
> Palmyra WI
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] vacuum house routing [message #175725 is a reply to message #175534] |
Fri, 06 July 2012 05:02 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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I think you guys confused Len.
There is a vacuum hose from the manifold that goes to a "tee" that feeds both ports.
There is a second "tee" in the hose that goes to the diaphragm / bellows that pulls on the accelerator. The hose off of that "tee" goes inside the coach and connects to a vacuum dump valve / switch that operates when you press on the brake.
Ken B.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] vacuum house routing [message #175780 is a reply to message #175775] |
Fri, 06 July 2012 12:55 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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supplies vacuum to the modulator. Which varies shift points based on vacuum and induirectly load.
--johnny
From: Mickey Space Ship Shuttle <mickeysss@me.com>
To: gmclist@temp.gmcnet.org
Sent: Friday, July 6, 2012 1:42 PM
Subject: Re: [GMCnet] vacuum house routing
what does the vacuum hose do that goes to the transmission bottom? any one
mickey
anaheim ca.
77 palm beach
On Jul 6, 2012, at 3:02 AM, Ken Burton wrote:
>
>
> I think you guys confused Len.
>
> There is a vacuum hose from the manifold that goes to a "tee" that feeds both ports.
>
> There is a second "tee" in the hose that goes to the diaphragm / bellows that pulls on the accelerator. The hose off of that "tee" goes inside the coach and connects to a vacuum dump valve / switch that operates when you press on the brake.
>
> Ken B.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
> _______________________________________________
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] vacuum house routing [message #175785 is a reply to message #175778] |
Fri, 06 July 2012 13:40 |
mickeysss
Messages: 1476
Registered: January 2012
Karma: 0
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Senior Member |
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i geared down behind a truck and blew that vacuum hose off the bottome of the trans, it then stuck in second gear and i was going to walk to manny's and
get him out of bed because i though it blew up after spending $1700 but he drove 600 miles to do it. so it was fair. he did a great job.
i am glad i did not wake him up, for he would have beat the shi out of me.
The place i went too did not tell me about this hose until i had talked to manny about 4 times thinking the trans was bad. Thank god it was just the hose
off. I can't speak of this so for get it. Manny did a great job, but i wish i would have known about the hose, i could have just put that back on with
a screw driver and gone on home. I needed a new booster so i did that it was leaking and i did not know about the hose. I thought it was the little
white plastic gear stripped.
On Jul 6, 2012, at 10:46 AM, Emery Stora wrote:
>
> That goes to the rear passenger side. It connects to the transmission modulator. That controls your shifting. If the hose is detached the transmission won't up shift.
>
>
> Emery Stora
>
> On Jul 6, 2012, at 11:42 AM, Mickey Space Ship Shuttle <mickeysss@me.com> wrote:
>
>>
>> what does the vacuum hose do that goes to the transmission bottom? any one
>>
>> mickey
>>
>> anaheim ca.
>> 77 palm beach
>>
>>
>> On Jul 6, 2012, at 3:02 AM, Ken Burton wrote:
>>
>>>
>>>
>>> I think you guys confused Len.
>>>
>>> There is a vacuum hose from the manifold that goes to a "tee" that feeds both ports.
>>>
>>> There is a second "tee" in the hose that goes to the diaphragm / bellows that pulls on the accelerator. The hose off of that "tee" goes inside the coach and connects to a vacuum dump valve / switch that operates when you press on the brake.
>>>
>>> Ken B.
>>> --
>>> Ken Burton - N9KB
>>> 76 Palm Beach
>>> Hebron, Indiana
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
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| Re: [GMCnet] vacuum house routing [message #175831 is a reply to message #175685] |
Fri, 06 July 2012 22:58 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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""Hmmm - not sure. I just remember laying on the floor and cursing at it as I tried to get it and the vacuum hose out of there.
Looking at the 73 MM (section 12 figure 47) it shows the electrical as being two switches on one plunger. The second plunger is the vacuum dump valve. The two are located next to each other. However who knows what was done by a PO on any one coach. ""
Every GM vehicle with that type of cruise (the GMC included) all had a vacuum dump valve.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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