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Home » Public Forums » GMCnet » Re: [GMCnet] My First Vapor Lock- loss of brakes
Re: [GMCnet] My First Vapor Lock- loss of brakes [message #175570] Thu, 05 July 2012 01:48 Go to next message
mickeysss is currently offline  mickeysss   United States
Messages: 1476
Registered: January 2012
Karma: 0
Senior Member


On Jul 04, 2012, at 11:37 PM, Mickey Space Ship Shuttle <mickeysss@me.com> wrote:

On Jul 4, 2012, at 8:28 PM, Mickey Space Ship Shuttle wrote:
The emergency brake is another alternative i forgot that might stop you. But this seems to not work very well with anyone it seems? mine does not seem to hold very well.  jamming it in park at 10 miles per hour is out off list. I had a vacuum hose pulled off under the trans that is why it stayed in 2nd gear at one time. I did not know anything about the vacuum to the trans. That was later discovered in time with lots of questions. This vacuum deal with the gmc is a big deal. This was the computer of the early 70's. ???  or not. Any help on the dymaxion idea to make this design work would be a great help. How to stop the gmc when the motor stops? how to always have gas on any road level? How to have the vacuum working the longest time possible? 

I will keep searching the archives. thank you.

stopping is more important than going. If you drive these hills, you would know why it is a big deal. they are so steep and deep canyons a fire truck went off of them last year and the two in the cab  died. It is like a paved mule  path down the grand canyon. I just ordered new back springs from JimK, for all four back brakes. They tend to fall off sometimes. I am leaning to the vacuum tank now.It seems at high rpm or heavy lifting with the motor these vacuum hoses blow off, like it did for my trans and robs up hill event. How do you get them to stay on with high rpm.

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Re: [GMCnet] My First Vapor Lock- loss of brakes [message #175584 is a reply to message #175570] Thu, 05 July 2012 06:39 Go to previous messageGo to next message
Mr ERFisher is currently offline  Mr ERFisher   United States
Messages: 7117
Registered: August 2005
Karma: 2
Senior Member
> How to stop the gmc when the motor stops?



> How to have the vacuum working the longest time possible?
>

I do not understand, have you been reading the posts?

A pump is the only answer for continuous vacuum when the engine is not
running.
the the JC4, is a great pump with all the controls built-in

http://gmcmotorhome.info/list.html#Brakes

- lives have been lost with out a pump.
- this is not optional add-on ( in my mind)
- read the horror stories
- JimK sells the pump ( insist on the OEM type cable)
- this pump is -new - built for this function, being used on new trucks,
(sigh)
- stopping is not the problem, driving without the engine is the problem
- the pump is a redundant, back-up, system, that does not fail.(good thing)
- install it this way
http://www.gmcmhphotos.com/photos/vacuum-booster-pump-auxiliary-gmc-jc4/p27712-yeager.html

- when you hear the pump running , you know you have a problem (diagnostic)
- ask a person with an accumulator tank, to back down from an on/off ramp
when the engine dies, it cannot be done, with a tank.

read the horror stories

arrrgggggg
gene
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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Re: [GMCnet] My First Vapor Lock- loss of brakes [message #175587 is a reply to message #175584] Thu, 05 July 2012 07:13 Go to previous messageGo to next message
Jim Bounds is currently offline  Jim Bounds   United States
Messages: 842
Registered: January 2004
Karma: 0
Senior Member
Like a few other issues, I think we can agree that folks need to address this issue, no matter how they do it.  If we were in Syria it would be different.  I have definite ideas about electrical components and wiring being dead nuts reliable but hey, I can feel that way.  These "countermeasures" may never be needed but when they do, I want them to work.  Work to stop the coach, guaranteed.  To me, electrical circuits, components and power is not as reliable as I would like them to be for a job such as this.  Backing off a ramp will not cause death unless a red neck in a big truck wants to get around you.  I just want to know I can stop the coach, from there let Mr. Hook figure out how to move it.  Maybe we are saying we need both, now we're crossing into that paranoia side of it!
 
I would like to leave it at I will not install a vacuum pump and put myself into that liability loop.  I will take a chance on the tanks, less liability and no matter what else happens to the coach (loss of power, an accident, fire, etc.) the tanks are passive-- stand alone and automatic based on the vacuum on the input side of the check valve and that forces the tanks to work and that works for me.  Do it how you like just remember, along with decisions on modifications to your coach come responsibility.  Do ANY of these things at your own risk...
 
Jim Bounds
----------------------


________________________________
From: gene Fisher <mr.erfisher@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Thursday, July 5, 2012 7:39 AM
Subject: Re: [GMCnet] My First Vapor Lock- loss of brakes

> How to stop the gmc when the motor stops?



>  How to have the vacuum working the longest time possible?
>

I do not understand, have you been reading the posts?

A  pump is the only answer for continuous vacuum when the engine is not
running.
the the JC4, is a great pump with all the controls built-in

http://gmcmotorhome.info/list.html#Brakes

- lives have been lost with out a pump.
- this is not optional add-on ( in my mind)
- read the horror stories
- JimK sells the pump ( insist on the OEM type cable)
- this pump is -new - built for this function, being used on new trucks,
(sigh)
- stopping is not the problem, driving without the engine is the problem
- the pump is a redundant, back-up, system, that does not fail.(good thing)
- install it this way
http://www.gmcmhphotos.com/photos/vacuum-booster-pump-auxiliary-gmc-jc4/p27712-yeager.html

- when you hear the pump running , you know you have a problem (diagnostic)
- ask a person with an accumulator tank, to back down from an on/off ramp
when the engine dies,  it cannot be done, with a tank.

read the horror stories

arrrgggggg
gene
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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Re: [GMCnet] My First Vapor Lock- loss of brakes [message #175591 is a reply to message #175570] Thu, 05 July 2012 08:03 Go to previous messageGo to next message
shawnee is currently offline  shawnee   United States
Messages: 422
Registered: February 2004
Location: NC
Karma: 0
Senior Member
mickeysss wrote on Thu, 05 July 2012 02:48



On Jul 04, 2012, at 11:37 PM, Mickey Space Ship Shuttle <mickeysss@me.com> wrote:

On Jul 4, 2012, at 8:28 PM, Mickey Space Ship Shuttle wrote:
The emergency brake is another alternative i forgot that might stop you. But this seems to not work very well with anyone it seems? mine does not seem to hold very well.  jamming it in park at 10 miles per hour is out off list. I had a vacuum hose pulled off under the trans that is why it stayed in 2nd gear at one time. I did not know anything about the vacuum to the trans. That was later discovered in time with lots of questions. This vacuum deal with the gmc is a big deal. This was the computer of the early 70's. ???  or not. Any help on the dymaxion idea to make this design work would be a great help. How to stop the gmc when the motor stops? how to always have gas on any road level? How to have the vacuum working the longest time possible? 

I will keep searching the archives. thank you.

stopping is more important than going. If you drive these hills, you would know why it is a big deal. they are so steep and deep canyons a fire truck went off of them last year and the two in the cab  died. It is like a paved mule  path down the grand canyon. I just ordered new back springs from JimK, for all four back brakes. They tend to fall off sometimes. I am leaning to the vacuum tank now.It seems at high rpm or heavy lifting with the motor these vacuum hoses blow off, like it did for my trans and robs up hill event. How do you get them to stay on with high rpm.



Mickey,

If you want a true parking brake, contact Albert Branscombe. He sells an outstanding brake.


Gene Dotson
74 Canyonlands
www.bdub.net/Motorhome_Enhancements New Windows and Aluminum Radiators
Re: [GMCnet] My First Vapor Lock- loss of brakes [message #175592 is a reply to message #175584] Thu, 05 July 2012 08:26 Go to previous messageGo to next message
USAussie is currently offline  USAussie   United States
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
Senior Member
Gene,

I would ask the naysayers the following questions:

How many vehicles were produced with a vacuum assist pump?

How many vehicles were produced with a vacuum tank?

Regards,
Rob M.

-----Original Message-----
From: gene Fisher

I do not understand, have you been reading the posts?

A pump is the only answer for continuous vacuum when the engine is not
running.
the the JC4, is a great pump with all the controls built-in

http://gmcmotorhome.info/list.html#Brakes

- lives have been lost with out a pump.
- this is not optional add-on ( in my mind)
- read the horror stories
- JimK sells the pump ( insist on the OEM type cable)
- this pump is -new - built for this function, being used on new trucks,
(sigh)
- stopping is not the problem, driving without the engine is the problem
- the pump is a redundant, back-up, system, that does not fail.(good thing)
- install it this way
http://www.gmcmhphotos.com/photos/vacuum-booster-pump-auxiliary-gmc-jc4/p277
12-yeager.html

- when you hear the pump running , you know you have a problem (diagnostic)
- ask a person with an accumulator tank, to back down from an on/off ramp
when the engine dies, it cannot be done, with a tank.

read the horror stories

arrrgggggg
gene


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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] My First Vapor Lock- loss of brakes [message #175593 is a reply to message #175587] Thu, 05 July 2012 08:33 Go to previous messageGo to next message
Richard Denney is currently offline  Richard Denney   United States
Messages: 920
Registered: April 2010
Karma: 9
Senior Member
On Thu, Jul 5, 2012 at 8:13 AM, Jim Bounds <gmccoop@yahoo.com> wrote:
> I would like to leave it at I will not install a vacuum pump and put myself into that liability loop.  I will take a chance on the tanks, less liability and no matter what else happens to the coach (loss of power, an accident, fire, etc.) the tanks are passive--

Jim, the tanks are not passive devices just because there's no wire
going to them. They still require that check valves are functioning
properly in order to hold that vacuum when needed, and those check
valves have moving parts and are subject to failure. If they fail, the
tank's vacuum will be filled up by the engine's intake air if the
engine dies and the intake is no longer pulling a vacuum.

And if the requirement you are trying to fulfill is being able to
brake down the length of a downhill, then those tanks just don't hold
enough vacuum. The highest spot in Florida is 300 feet above sea
level, and that's not in the part of the state where you have your
shop. I've had my engine die from vapor lock on a steep uphill Forest
Service road, and were I unable to restart the engine, I'd have needed
to back that coach down the hill to a wide-enough spot to work the
situation. It would take a pretty big tank to store that much
vacuum--too big to fit in the available space.

I had my coach engine die from a clogged fuel filter while climbing a
hill, and was unable to stop the coach where I wanted to without the
power brakes. When that happened (I was driving the coach home from
where I bought it), I was able to leg-press 750 pounds, which I
suspect is out on the tail of the GMC owner distribution. Fortunately,
I ran out of hill before I ran out of blood in my leg muscles. Of
course, those uphills are where clogged fuel filters will first make
themselves known.

But there's another aspect to safety systems, too. I know my vacuum
pump works--I can hear it and test it by turning on the key but not
starting the engine and repeatedly pressing the brake pedal. It's not
so easy to test the check valve that makes that tank work.

Be careful of extrapolating your requirements to others too broadly
(including your completely understandable desire not to get sued,
which is quite different from safety-related requirements).

Rick "who now has both a supplemental vacuum tank and a pump" Denney

--
'73 230 "Jaws"
Northern Virginia
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Re: [GMCnet] My First Vapor Lock- loss of brakes [message #175599 is a reply to message #175593] Thu, 05 July 2012 09:20 Go to previous messageGo to next message
mickeysss is currently offline  mickeysss   United States
Messages: 1476
Registered: January 2012
Karma: 0
Senior Member

sherlock says to Dr. watson look up what do you see, he says millions of light years of stars sherlock says no someone stole our tent.

the game is a foot. this is one of the biggest problems with the best dam rv in the world. I think having both is the way to go like you state below.

I live in the avatar floating mountians, really, this place is scary to go too in a porsche.

So -

i would like to order one of the plans and also join the co-op to help out as well, i have already bought the pump from jimK, and did not ask for the

right wiring i suppose. Is the wiring someone stated a plug or something on it. mine just has the red and black wire - does this go to the

yellow blower wire, or where should this be wired into, and is it before or after the JimB tank if you do both.

Is there any pictures of the both rig. any where.




On Jul 5, 2012, at 6:33 AM, Richard Denney wrote:

> On Thu, Jul 5, 2012 at 8:13 AM, Jim Bounds <gmccoop@yahoo.com> wrote:
>> I would like to leave it at I will not install a vacuum pump and put myself into that liability loop. I will take a chance on the tanks, less liability and no matter what else happens to the coach (loss of power, an accident, fire, etc.) the tanks are passive--
>
> Jim, the tanks are not passive devices just because there's no wire
> going to them. They still require that check valves are functioning
> properly in order to hold that vacuum when needed, and those check
> valves have moving parts and are subject to failure. If they fail, the
> tank's vacuum will be filled up by the engine's intake air if the
> engine dies and the intake is no longer pulling a vacuum.
>
> And if the requirement you are trying to fulfill is being able to
> brake down the length of a downhill, then those tanks just don't hold
> enough vacuum. The highest spot in Florida is 300 feet above sea
> level, and that's not in the part of the state where you have your
> shop. I've had my engine die from vapor lock on a steep uphill Forest
> Service road, and were I unable to restart the engine, I'd have needed
> to back that coach down the hill to a wide-enough spot to work the
> situation. It would take a pretty big tank to store that much
> vacuum--too big to fit in the available space.
>
> I had my coach engine die from a clogged fuel filter while climbing a
> hill, and was unable to stop the coach where I wanted to without the
> power brakes. When that happened (I was driving the coach home from
> where I bought it), I was able to leg-press 750 pounds, which I
> suspect is out on the tail of the GMC owner distribution. Fortunately,
> I ran out of hill before I ran out of blood in my leg muscles. Of
> course, those uphills are where clogged fuel filters will first make
> themselves known.
>
> But there's another aspect to safety systems, too. I know my vacuum
> pump works--I can hear it and test it by turning on the key but not
> starting the engine and repeatedly pressing the brake pedal. It's not
> so easy to test the check valve that makes that tank work.
>
> Be careful of extrapolating your requirements to others too broadly
> (including your completely understandable desire not to get sued,
> which is quite different from safety-related requirements).
>
> Rick "who now has both a supplemental vacuum tank and a pump" Denney
>
> --
> '73 230 "Jaws"
> Northern Virginia
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

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Re: [GMCnet] My First Vapor Lock- loss of brakes [message #175603 is a reply to message #175593] Thu, 05 July 2012 09:46 Go to previous messageGo to next message
Jim Bounds is currently offline  Jim Bounds   United States
Messages: 842
Registered: January 2004
Karma: 0
Senior Member
See that, you went the belt AND suspenders way!  At least you did something and if you are trying to protect yourself from every possible event then I hear ya and certainly do not want to press my ideas ontoyou because there will always be some sort of hole in any safety device.  Yea, there is a check valve which must work, they seem to be pretty reliable though. 
 
Checking the system is easier to listen for the motor to fire up but you can just push the pedal until it goes hard and you know the tanks are working.  As far as backing down the hil yes, 5 or 6 presses on the brakes with vacuum may not get you down the hill and this is where the preparing for every eventuality kicks in.  I just wanna stop the coach.  Yea, it may be a *&&^^%$# to do something from there but at least you would not be at the bottom of the ravine!  Life is good as long as you are still in it. 
 
When I got my coach "JayGee" it had one of the older styled GM vacuum pumps, it did not work.  Don't really know why because I pulled it out but something made it fail.  I have had the tanks in Larry since the first ES rally in Bowling Green, is still in there and still works.  I forget it's there and that to me is the mark of a reliable safety device.
 
All this I guess has to go under personal decisions though they are very important safety devices.  Think about this though, the GM attorneys did not feel this level of backup was necessary, neither does any other car have this or truck, motorhome or anything.  Most have the E brake as the "backup".  Unfortunately, I feel if you do anythng less than putting in the entire system Albert Branscomb offers that that E brake system is pretty much useless.  I have 2 rules when you step onto this property---1. never lock the entry door without using the key-- for obvious reasons  2. never touch the emergency brake handle unless it's something we are going to work on-- if it jams and burns off the rear shoes , we didn;t do it!
 
If you do something to your coach in your backyard then you and whoever held your beer willbe responsible, if I do it to your coach--- brother that's another thing alltogether!  It's not just the getting sued thing, it's I do not want to take a chance because I am not a braking engineer that I missed something that caused harm.  Hey, we are not the ones to actually make hard recommendations-- go talk to an engineer before you make decisions if you wanna really have a good bet all is good-- who has the time or $ for that?  I have to make decisions that could cause harm so I take that responsibility very seriously.
 
Jim Bounds
-----------------


________________________________
From: Richard Denney <rwdenney@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Thursday, July 5, 2012 9:33 AM
Subject: Re: [GMCnet] My First Vapor Lock- loss of brakes

On Thu, Jul 5, 2012 at 8:13 AM, Jim Bounds <gmccoop@yahoo.com> wrote:
> I would like to leave it at I will not install a vacuum pump and put myself into that liability loop.  I will take a chance on the tanks, less liability and no matter what else happens to the coach (loss of power, an accident, fire, etc.) the tanks are passive--

Jim, the tanks are not passive devices just because there's no wire
going to them. They still require that check valves are functioning
properly in order to hold that vacuum when needed, and those check
valves have moving parts and are subject to failure. If they fail, the
tank's vacuum will be filled up by the engine's intake air if the
engine dies and the intake is no longer pulling a vacuum.

And if the requirement you are trying to fulfill is being able to
brake down the length of a downhill, then those tanks just don't hold
enough vacuum. The highest spot in Florida is 300 feet above sea
level, and that's not in the part of the state where you have your
shop. I've had my engine die from vapor lock on a steep uphill Forest
Service road, and were I unable to restart the engine, I'd have needed
to back that coach down the hill to a wide-enough spot to work the
situation. It would take a pretty big tank to store that much
vacuum--too big to fit in the available space.

I had my coach engine die from a clogged fuel filter while climbing a
hill, and was unable to stop the coach where I wanted to without the
power brakes. When that happened (I was driving the coach home from
where I bought it), I was able to leg-press 750 pounds, which I
suspect is out on the tail of the GMC owner distribution. Fortunately,
I ran out of hill before I ran out of blood in my leg muscles. Of
course, those uphills are where clogged fuel filters will first make
themselves known.

But there's another aspect to safety systems, too. I know my vacuum
pump works--I can hear it and test it by turning on the key but not
starting the engine and repeatedly pressing the brake pedal. It's not
so easy to test the check valve that makes that tank work.

Be careful of extrapolating your requirements to others too broadly
(including your completely understandable desire not to get sued,
which is quite different from safety-related requirements).

Rick "who now has both a supplemental vacuum tank and a pump" Denney

--
'73 230 "Jaws"
Northern Virginia
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Re: [GMCnet] My First Vapor Lock- loss of brakes [message #175604 is a reply to message #175587] Thu, 05 July 2012 09:51 Go to previous messageGo to next message
Mr ERFisher is currently offline  Mr ERFisher   United States
Messages: 7117
Registered: August 2005
Karma: 2
Senior Member
>
> I would like to leave it at I will not install a vacuum pump and put
> myself into that liability loop

yes, I understand your position about liability

this is why you do not do rear disk brakes
and vacuum pumps,

you cannot stand the liability risks. It has nothing to do with
reliability.

but
you know the pumps are very , very good. ( show me a bad JC4)
they are used every day in diesel rigs .
YOU- know if you tow or push a GMC, a pump is the only thing that will give
you brakes getting home.

as always, folks must do what is best for them.

so folks- to make your decision
------DO THE TEST------
go to the top of a hill and turn off the engine.
drive down a winding road for a couple of miles,
see if you could do that backwards, with a toad
see how long your tank lasts
could you stop for the guy in front of you


but I will answer all new posts on this subject, because lives are at risk,
There used to be a Cascader in Washington, that rebuilt pumps, because some
of his friends were killed because the engine quit and he felt (like I do)
that there is no other option.

JWID -DO THE TEST

I hate diodes in safety circuits
gene


Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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Re: [GMCnet] My First Vapor Lock- loss of brakes [message #175614 is a reply to message #175604] Thu, 05 July 2012 10:25 Go to previous messageGo to next message
emerystora is currently offline  emerystora   United States
Messages: 4442
Registered: January 2004
Karma: 13
Senior Member

On Jul 5, 2012, at 8:51 AM, gene Fisher wrote:

>>
> There used to be a Cascader in Washington, that rebuilt pumps, because some
> of his friends were killed because the engine quit and he felt (like I do)
> that there is no other option.
>

Pete Papas
hawk_ii_mail@yahoo.com

rebuilds the pumps. I had sent him mine a couple of years ago and he installed a new vacuum switch into in. I am not sure if he replaces diaphrams but he might.

Emery Stora
77 Kingsley
Frederick, CO

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Re: [GMCnet] My First Vapor Lock- loss of brakes [message #175636 is a reply to message #175604] Thu, 05 July 2012 12:43 Go to previous messageGo to next message
Jim Bounds is currently offline  Jim Bounds   United States
Messages: 842
Registered: January 2004
Karma: 0
Senior Member
This was a good thread and just like other subjects we have burned to the ground before, if it drives people to do something about the subject other than saying "it will never happen to me" then it was worth it.  I put this subject and mod down as something you can do to your coach.  The closest I can come as a business to protecting someone is with using the tanks, you can do any and or all of this on your coach yourself-- I cannot.
 
You lurkers can draw from this what you will, just consider the situation and address it.  If you decide to keep working out and "armstrong" the brakes, consider how strong your steering wheel and column are to pull on.  The weakest like will limit your success...
 
Jim Bounds
------------------------------


________________________________
From: gene Fisher <mr.erfisher@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Thursday, July 5, 2012 10:51 AM
Subject: Re: [GMCnet] My First Vapor Lock- loss of brakes

>
> I would like to leave it at I will not install a vacuum pump and put
> myself into that liability loop

yes, I understand your position about liability

this is why you do not do rear disk brakes
and  vacuum  pumps,

you cannot stand the liability risks.  It has nothing to do with
reliability.

but
you know the pumps are  very , very good.  ( show me a bad JC4)
they are used every day in diesel rigs .
YOU- know if you tow or push a GMC, a pump is the only thing that will give
you brakes getting home.

as always, folks must do what is best for them.

so folks- to make your decision
------DO THE TEST------
go to the top of a hill and turn off the engine.
drive down a winding road for a couple of miles,
see if you could do that backwards, with a toad
see how long your tank lasts
could you stop for the guy in front of you


but I will answer all new posts on this subject, because lives are at risk,
There used to be a Cascader in Washington, that rebuilt pumps, because some
of his friends were killed because the engine quit and he felt (like I do)
that there is no other option.

JWID -DO THE TEST

I hate diodes in safety circuits
gene


Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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Re: [GMCnet] My First Vapor Lock- loss of brakes [message #175689 is a reply to message #175592] Thu, 05 July 2012 19:38 Go to previous message
jhbridges is currently offline  jhbridges   United States
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
Senior Member
The pump I have is off a GM automobile (Buick TheSword late 80s I think).  Good enough for the General, good enough for me - with apologies to Al Capp.

I can stay away from a single point of failure.  I can stop the dam'  thing w/o boost, I tried it.  I propose to have my airconditioner working uphill as well as down.
Actually, there is still a single point of failure - the pedal itself.  If yiou don't think it can fail, review the history of the first HMMWVs the Air Farce placed in inventory - they were sent to the FANGs.  Couple of days later we got a TWX:  red tag them till the brake pedal was replaced.  It would shear off at the pivot, as demonstrated by our Motor Pool Sergeant (who wasn't known as The BIG Raunch for nothin').  He clomped the pedal and it sheared.  On both of them.
 
johnny
'76 23' transmode norris
'76 palm beach 

From: Rob Mueller <robmueller@iinet.net.au>
To: gmclist@temp.gmcnet.org
Sent: Thursday, July 5, 2012 9:26 AM
Subject: Re: [GMCnet] My First Vapor Lock- loss of brakes

Gene,

I would ask the naysayers the following questions:

How many vehicles were produced with a vacuum assist pump?

How many vehicles were produced with a vacuum tank?

Regards,
Rob M.

-----Original Message-----
From: gene Fisher

I do not understand, have you been reading the posts?

A  pump is the only answer for continuous vacuum when the engine is not
running.
the the JC4, is a great pump with all the controls built-in

http://gmcmotorhome.info/list.html#Brakes

- lives have been lost with out a pump.
- this is not optional add-on ( in my mind)
- read the horror stories
- JimK sells the pump ( insist on the OEM type cable)
- this pump is -new - built for this function, being used on new trucks,
(sigh)
- stopping is not the problem, driving without the engine is the problem
- the pump is a redundant, back-up, system, that does not fail.(good thing)
- install it this way
http://www.gmcmhphotos.com/photos/vacuum-booster-pump-auxiliary-gmc-jc4/p277
12-yeager.html

- when you hear the pump running , you know you have a problem (diagnostic)
- ask a person with an accumulator tank, to back down from an on/off ramp
when the engine dies,  it cannot be done, with a tank.

read the horror stories

arrrgggggg
gene


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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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