Home » Public Forums » GMCnet » Re: [GMCnet] vacuum booster MC seal (Tom Whitton)
| Re: [GMCnet] vacuum booster MC seal (Tom Whitton) [message #270857] |
Fri, 30 January 2015 22:48  |
Tom Whitton
Messages: 235
Registered: February 2004
Location: Paducah, KY
Karma: 0
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Senior Member |
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Rob,
Thanks for the information. I don't know if I have that seal (Key 9 - Seal / PN 5460935) or not. I'll have to take a look over the weekend. If not, do you think installing the seal will decrease the cycling of the vacuum pump or are Dave's components necessary for the decrease? I haven't looked yet to see if the seal is available these days. If memory serves, Emery wrote that the seal that Dave furnished reduced cycling of his vacuum pump. Emery did not mention Dave's manifold, etc.
Tom Whitton
26 foot updated GMC
Paducah, KY
Message: 15
Date: Sat, 31 Jan 2015 13:36:59 +1100
From: "Robert Mueller"
To:
Subject: Re: [GMCnet] vacuum booster MC seal
Message-ID:
Content-Type: text/plain; charset="us-ascii"
Tom,
Dave makes a "plastic" sleeve that goes over the "tail" of the master cylinder to center it in the booster. They come with
sensitized boosters purchased from him.
I spoke to him just now and he advised that has made some for GMC owners but there are a number of variables concerning the booster
and master cylinder installed that he has to know before he can make one. Basically he needs to know the ID of the booster and the
OD of the master cylinder because they are not all the same.
He noted that at a later date he would be willing to make them available; however, at the moment making these is a low priority due
to his health issues.
My personal request to everybody out there, PLEASE don't start calling him for this item!
Even if the booster was vacuum tight your vacuum pump would still cycle because the pressure switch that senses pressure is between
the booster check valve and the vacuum pump. There are check valves in the vacuum pump that leak allowing air into that line and
when the pressure goes above the setting the pump starts. Dave also makes a manifold that plugs into the booster and the check valve
plugs into it, The pressure switch goes into that manifold and senses the pressure in the booster upstream of the check valve.
See Parts Book 78Z / Section 4 - Brakes / Page 4-8 & / Key 9 - Seal / PN 5460935. Note how it is cup shaped to fit over the M/C
Tail.
Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
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| Re: [GMCnet] vacuum booster MC seal (Tom Whitton) [message #270859 is a reply to message #270857] |
Fri, 30 January 2015 23:09  |
Emery Stora
Messages: 959
Registered: January 2011
Karma: 4
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Senior Member |
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Yes, Tom. I bought the vacuum pump, the manifold, the gauge and the pressure switch from Dave Lenzi. It all works great with no leakage or cycling.
Rob has said that there are check valves in the vacuum pump that leak however I haven’t seen that. Mine don’t leak.
Emery Stora
On Jan 30, 2015, at 9:48 PM, Tom Whitton wrote:
>
> Rob,
>
> Thanks for the information. I don't know if I have that seal (Key 9 - Seal / PN 5460935) or not. I'll have to take a look over the weekend. If not, do you think installing the seal will decrease the cycling of the vacuum pump or are Dave's components necessary for the decrease? I haven't looked yet to see if the seal is available these days. If memory serves, Emery wrote that the seal that Dave furnished reduced cycling of his vacuum pump. Emery did not mention Dave's manifold, etc.
>
> Tom Whitton
> 26 foot updated GMC
> Paducah, KY
>
>
> Message: 15
> Date: Sat, 31 Jan 2015 13:36:59 +1100
> From: "Robert Mueller"
> To:
> Subject: Re: [GMCnet] vacuum booster MC seal
> Message-ID:
> Content-Type: text/plain; charset="us-ascii"
>
> Tom,
>
> Dave makes a "plastic" sleeve that goes over the "tail" of the master cylinder to center it in the booster. They come with
> sensitized boosters purchased from him.
>
> I spoke to him just now and he advised that has made some for GMC owners but there are a number of variables concerning the booster
> and master cylinder installed that he has to know before he can make one. Basically he needs to know the ID of the booster and the
> OD of the master cylinder because they are not all the same.
>
> He noted that at a later date he would be willing to make them available; however, at the moment making these is a low priority due
> to his health issues.
>
> My personal request to everybody out there, PLEASE don't start calling him for this item!
>
> Even if the booster was vacuum tight your vacuum pump would still cycle because the pressure switch that senses pressure is between
> the booster check valve and the vacuum pump. There are check valves in the vacuum pump that leak allowing air into that line and
> when the pressure goes above the setting the pump starts. Dave also makes a manifold that plugs into the booster and the check valve
> plugs into it, The pressure switch goes into that manifold and senses the pressure in the booster upstream of the check valve.
>
> See Parts Book 78Z / Section 4 - Brakes / Page 4-8 & / Key 9 - Seal / PN 5460935. Note how it is cup shaped to fit over the M/C
> Tail.
>
> Regards,
> Rob M.
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| Re: [GMCnet] vacuum booster MC seal (Tom Whitton) [message #270860 is a reply to message #270859] |
Fri, 30 January 2015 23:38 |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Dave / Emery,
If you take the heads off the Ford vacuum pump (as I have) you will find flapper (check) valves that control the flow through the
pump, they are not a perfect seal and will leak. They are under the lumps in the heads:
http://www.gmcmhphotos.com/photos/vacuum-pump-for-brakes-lenzi/p55346-pump-mount.html
The reason Emery's pump does not cycle is because his switch is mounted in the manifold Dave makes. It plugs directly into the
booster and the check valve plugs into that manifold.
http://www.gmcmhphotos.com/photos/vacuum-pump-for-brakes-lenzi/p55345-pump-mount.html
A hose connects the outlet of the booster check valve to the inlet on the pump. The switch senses pressure in the booster and only
comes on when the pressure in the booster goes above the set point of the switch. The pressure in the line that connects the pump to
the switch can go to atmospheric pressure and as long as the pressure in the booster is lower than the switch set point the pump
will not run.
However, if one does not have the manifold that Dave makes and the switch is installed between the booster check valve and the Ford
vacuum pump the flapper valves in the pump will leak and allow the pressure in the line to increase and the pump will come on. It
will run until the pressure in the line is below the switch set point and it will switch off. This cycling will occur whether or not
you actuate the brakes.
The reason Dave made the manifold is because people complained that their pump was cycling.
Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Emery Stora
Sent: Saturday, January 31, 2015 4:09 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] vacuum booster MC seal (Tom Whitton)
Yes, Tom. I bought the vacuum pump, the manifold, the gauge and the pressure switch from Dave Lenzi. It all works great with no
leakage or cycling.
Rob has said that there are check valves in the vacuum pump that leak however I haven't seen that. Mine don't leak.
Emery Stora
On Jan 30, 2015, at 9:48 PM, Tom Whitton wrote:
>
> Rob,
>
> Thanks for the information. I don't know if I have that seal (Key 9 - Seal / PN 5460935) or not. I'll have to take a look over
the weekend. If not, do you think installing the seal will decrease the cycling of the vacuum pump or are Dave's components
necessary for the decrease? I haven't looked yet to see if the seal is available these days. If memory serves, Emery wrote that
the seal that Dave furnished reduced cycling of his vacuum pump. Emery did not mention Dave's manifold, etc.
>
> Tom Whitton
> 26 foot updated GMC
> Paducah, KY
>
>
> Message: 15
> Date: Sat, 31 Jan 2015 13:36:59 +1100
> From: "Robert Mueller"
> To:
> Subject: Re: [GMCnet] vacuum booster MC seal
> Message-ID:
> Content-Type: text/plain; charset="us-ascii"
>
> Tom,
>
> Dave makes a "plastic" sleeve that goes over the "tail" of the master cylinder to center it in the booster. They come with
> sensitized boosters purchased from him.
>
> I spoke to him just now and he advised that has made some for GMC owners but there are a number of variables concerning the
booster
> and master cylinder installed that he has to know before he can make one. Basically he needs to know the ID of the booster and the
> OD of the master cylinder because they are not all the same.
>
> He noted that at a later date he would be willing to make them available; however, at the moment making these is a low priority
due
> to his health issues.
>
> My personal request to everybody out there, PLEASE don't start calling him for this item!
>
> Even if the booster was vacuum tight your vacuum pump would still cycle because the pressure switch that senses pressure is
between
> the booster check valve and the vacuum pump. There are check valves in the vacuum pump that leak allowing air into that line and
> when the pressure goes above the setting the pump starts. Dave also makes a manifold that plugs into the booster and the check
valve
> plugs into it, The pressure switch goes into that manifold and senses the pressure in the booster upstream of the check valve.
>
> See Parts Book 78Z / Section 4 - Brakes / Page 4-8 & / Key 9 - Seal / PN 5460935. Note how it is cup shaped to fit over the M/C
> Tail.
>
> Regards,
> Rob M.
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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
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| Re: [GMCnet] vacuum booster MC seal (Tom Whitton) [message #270955 is a reply to message #270857] |
Sun, 01 February 2015 13:12 |
Emery Stora
Messages: 959
Registered: January 2011
Karma: 4
|
Senior Member |
|
|
Tom
If you order from the Corvette internet parts site you want number 4901113 which is GM part number 5460935. It is for a 1963 Corvette and will not fit a 64-67.
this is a flat seal which is different from the original GMC seal that had a cup that fit over the end of the master cylinder. That is why I needed the adapter made by Dave Lenzi that fit over the end of the master cylinder and pressed against the new flat seal.
Emery Stora
> On Jan 30, 2015, at 9:48 PM, Tom Whitton wrote:
>
> Rob,
>
> Thanks for the information. I don't know if I have that seal (Key 9 - Seal / PN 5460935) or not. I'll have to take a look over the weekend. If not, do you think installing the seal will decrease the cycling of the vacuum pump or are Dave's components necessary for the decrease? I haven't looked yet to see if the seal is available these days. If memory serves, Emery wrote that the seal that Dave furnished reduced cycling of his vacuum pump. Emery did not mention Dave's manifold, etc.
>
> Tom Whitton
> 26 foot updated GMC
> Paducah, KY
>
>
> Message: 15
> Date: Sat, 31 Jan 2015 13:36:59 +1100
> From: "Robert Mueller"
> To:
> Subject: Re: [GMCnet] vacuum booster MC seal
> Message-ID:
> Content-Type: text/plain; charset="us-ascii"
>
> Tom,
>
> Dave makes a "plastic" sleeve that goes over the "tail" of the master cylinder to center it in the booster. They come with
> sensitized boosters purchased from him.
>
> I spoke to him just now and he advised that has made some for GMC owners but there are a number of variables concerning the booster
> and master cylinder installed that he has to know before he can make one. Basically he needs to know the ID of the booster and the
> OD of the master cylinder because they are not all the same.
>
> He noted that at a later date he would be willing to make them available; however, at the moment making these is a low priority due
> to his health issues.
>
> My personal request to everybody out there, PLEASE don't start calling him for this item!
>
> Even if the booster was vacuum tight your vacuum pump would still cycle because the pressure switch that senses pressure is between
> the booster check valve and the vacuum pump. There are check valves in the vacuum pump that leak allowing air into that line and
> when the pressure goes above the setting the pump starts. Dave also makes a manifold that plugs into the booster and the check valve
> plugs into it, The pressure switch goes into that manifold and senses the pressure in the booster upstream of the check valve.
>
> See Parts Book 78Z / Section 4 - Brakes / Page 4-8 & / Key 9 - Seal / PN 5460935. Note how it is cup shaped to fit over the M/C
> Tail.
>
> Regards,
> Rob M.
> The Pedantic Mechanic
> Sydney, Australia
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] vacuum booster MC seal (Tom Whitton) [message #270958 is a reply to message #270955] |
Sun, 01 February 2015 13:31 |
Tom Whitton
Messages: 235
Registered: February 2004
Location: Paducah, KY
Karma: 0
|
Senior Member |
|
|
Emery,
Thanks very much for the information. If I understand what you are saying, using 491113, I will not need Dave Lenzi's adapter. Is this correct?
All the best,
Tom
----- Original Message -----
From: Emery Stora
To: gmclist@temp.gmcnet.org
Cc: Tom Whitton ; Robert Mueller
Sent: Sunday, February 01, 2015 1:12 PM
Subject: Re: [GMCnet] vacuum booster MC seal (Tom Whitton)
Tom
If you order from the Corvette internet parts site you want number 4901113 which is GM part number 5460935. It is for a 1963 Corvette and will not fit a 64-67.
this is a flat seal which is different from the original GMC seal that had a cup that fit over the end of the master cylinder. That is why I needed the adapter made by Dave Lenzi that fit over the end of the master cylinder and pressed against the new flat seal.
Emery Stora
On Jan 30, 2015, at 9:48 PM, Tom Whitton wrote:
Rob,
Thanks for the information. I don't know if I have that seal (Key 9 - Seal / PN 5460935) or not. I'll have to take a look over the weekend. If not, do you think installing the seal will decrease the cycling of the vacuum pump or are Dave's components necessary for the decrease? I haven't looked yet to see if the seal is available these days. If memory serves, Emery wrote that the seal that Dave furnished reduced cycling of his vacuum pump. Emery did not mention Dave's manifold, etc.
Tom Whitton
26 foot updated GMC
Paducah, KY
Message: 15
Date: Sat, 31 Jan 2015 13:36:59 +1100
From: "Robert Mueller"
To:
Subject: Re: [GMCnet] vacuum booster MC seal
Message-ID:
Content-Type: text/plain; charset="us-ascii"
Tom,
Dave makes a "plastic" sleeve that goes over the "tail" of the master cylinder to center it in the booster. They come with
sensitized boosters purchased from him.
I spoke to him just now and he advised that has made some for GMC owners but there are a number of variables concerning the booster
and master cylinder installed that he has to know before he can make one. Basically he needs to know the ID of the booster and the
OD of the master cylinder because they are not all the same.
He noted that at a later date he would be willing to make them available; however, at the moment making these is a low priority due
to his health issues.
My personal request to everybody out there, PLEASE don't start calling him for this item!
Even if the booster was vacuum tight your vacuum pump would still cycle because the pressure switch that senses pressure is between
the booster check valve and the vacuum pump. There are check valves in the vacuum pump that leak allowing air into that line and
when the pressure goes above the setting the pump starts. Dave also makes a manifold that plugs into the booster and the check valve
plugs into it, The pressure switch goes into that manifold and senses the pressure in the booster upstream of the check valve.
See Parts Book 78Z / Section 4 - Brakes / Page 4-8 & / Key 9 - Seal / PN 5460935. Note how it is cup shaped to fit over the M/C
Tail.
Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
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| Re: [GMCnet] vacuum booster MC seal (Tom Whitton) [message #270987 is a reply to message #270978] |
Sun, 01 February 2015 18:53 |
|
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Wally,
Dave would be proud of you as you fixed the issue!
I'd say that your original booster was an "inch" booster and your replacement was a "metric" booster.
Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: Wally Anderson
I'm not nearly Dave Lenzi but had read of the possible centering issue and use of a spacer shim with a new style booster. Made a pvc
spacer to fit on the nose of the master that fit in the new booster. Don't know if it would have been a problem as I did it on
installation. New booster doesn't use a cup seal like the original. Pics here
http://www.gmcmhphotos.com/photos/g6732-booster-seal-and-shim.html
just what i did
--
Wally
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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
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