Home » Public Forums » GMCnet » [GMCnet] master cylinder support bracket
| [GMCnet] master cylinder support bracket [message #100233] |
Sat, 18 September 2010 11:43  |
Dave Motorhome
Messages: 175
Registered: July 2007
Karma: 2
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Senior Member |
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I am replacing the Master cylinder. In removing the MC you have to
unbolt the bracket that supports the MC. this bracket is bolted in at
the top, the runs between the MC and the brake booster. I had bad luck
on the 2 bolts supporting the bracket, the first bolt broke.. the
second is just spinning.
how do i remove the spinning bolt?
once it has been removed and i am ready for reinstalation, can i use
self tapping screws to support the bracket? or a different way?
thanks,
David Paliotta
75 Glenbrook
Tulsa, OK
http://75glenbrook.googlepages.com/
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| Re: [GMCnet] master cylinder support bracket [message #100282 is a reply to message #100233] |
Sat, 18 September 2010 17:14  |
Gil Slaw
Messages: 69
Registered: May 2006
Location: Hampshire, IL
Karma: 0
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Member |
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| Dave Motorhome wrote on Sat, 18 September 2010 11:43 |
I am replacing the Master cylinder. In removing the MC you have to
unbolt the bracket that supports the MC. this bracket is bolted in at
the top, the runs between the MC and the brake booster. I had bad luck
on the 2 bolts supporting the bracket, the first bolt broke.. the
second is just spinning.
how do i remove the spinning bolt?
once it has been removed and i am ready for reinstalation, can i use
self tapping screws to support the bracket? or a different way?
thanks,
David Paliotta
75 Glenbrook
Tulsa, OK
http://75glenbrook.googlepages.com/
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That is bad luck Dave, I removed the dash on mine a few years ago so my recollection now is a bit dim: however I don't recall any wiring or plumbing in that area, only the heater/defroster plenum and drilling into that should not cause any issues. Those captive nuts are spot welded in place so not easily repairable. A couple of big sheet metal screw or short 1/4" lag screws should work.
Good luck
Gil
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| Re: [GMCnet] master cylinder support bracket [message #100286 is a reply to message #100233] |
Sat, 18 September 2010 17:48 |
fred v
Messages: 999
Registered: April 2006
Location: pensacola, fl.
Karma: 0
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Senior Member |
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i don't remember for sure but i believe my bracket was between the MC and the booster. it is supposed to be forward of the MC. i hope someone else will confirm this. with it on the wrong side your pedal won't work right.
Fred V
'77 Royale RB 455
P'cola, Fl
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| Re: [GMCnet] master cylinder support bracket [message #100336 is a reply to message #100233] |
Sun, 19 September 2010 15:39 |
kingd
Messages: 592
Registered: June 2004
Karma: 2
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Dave Motorhome, if you damaged a REAR bearing you may have done something very wrong or something was very wrong before you started. The "rear" wheel bearings on a GMCMH are configured like the front wheel bearings used to be on rear wheel drive cars. Once the spindle nut is off "assuuming" the brake drum is not hung up on the brake shoes, the drum should come off with little effort. The inner bearing is held in by the inner grease seal, and for the outer bearing, the part with the rollersmay fall out during drum removal as nothing holds it in once the nut is off. Make sure everything is OK before re-assembly. The part of each bearing that is in the hub(the race) is supposed to be a "press"(but not too much)fit. The bearing part(the part with the rollers) should be cleaned with solvent and inspected for pitting, discoloration, etc. If the bearing is to be replaced, the race should/must be replaced also. There are further details on repacking a bearing to be re-used or packing a new bearing and what kind of grease is suggested, etc, but this is getting long. You really don't want a seized bearing as the wheel assembly may/will come off. NOT GOOD
DAVE KING
been doing bearing for 45 years.
DAVE KING
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
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| Re: [GMCnet] master cylinder support bracket [message #100397 is a reply to message #100389] |
Sun, 19 September 2010 21:22 |
captjack
Messages: 271
Registered: February 2010
Location: Sebastopol, California
Karma: 1
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Senior Member |
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As Fred pointed out the master cylinder connects directly to the booster, and the support bracket is on the outside of the Master Cylinder between the hold down nuts and the master cylinder. I just put mine back in today.
Jack Christensen - K6ROW,
'76 Glenbrook/Clasco - "The Silver Bullet",
Sebastopol, CA
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| Re: [GMCnet] master cylinder support bracket [message #100402 is a reply to message #100397] |
Sun, 19 September 2010 21:38 |
Dave Motorhome
Messages: 175
Registered: July 2007
Karma: 2
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Senior Member |
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the bearing was damaged when i tried to remove the seal. I got
overzealous.... It was a silly mistake, I rushed. everything else went
very well.
i will take the drums this week to get turned..
As for rear brake pads., I am going to talk to applied in the AM, but
i need the brakes by Friday. to install this weekend, so i might have
to buy local. I am a member of the internationals: the parts book
separates the 73- 75 models and the 76- 78. the brake pads listed for
my 75 did not seem to be very common. does anyone have a relevant part
number.
thanks for all the input!!!
David Paliotta
75 Glenbrook
Tulsa, OK
http://75glenbrook.googlepages.com/
On Sun, Sep 19, 2010 at 9:22 PM, Jack Christensen <captjack@sonic.net> wrote:
>
>
> As Fred pointed out the master cylinder connects directly to the booster, and the support bracket is on the outside of the Master Cylinder between the hold down nuts and the master cylinder. I just put mine back in today.
> --
> Jack Christensen - K6ROW
> '76 Glenbrook/Clasco
> Sebastopol, CA
> _______________________________________________
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| Re: [GMCnet] master cylinder support bracket [message #100403 is a reply to message #100397] |
Sun, 19 September 2010 21:45 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Careful now. With all the PO work, we've got to be sure what we're starting
with. The OEM arrangement was indeed to have the master cylinder adjacent
to the booster, with the support bracket installed last.
But when installing different master cylinders, such as the 34mm P-30, it's
better to install the support bracket between the booster and the MC. That
requires installing a longer push rod (by ABOUT 0.10") between the booster
and MC to maintain the proper 0.015" clearance. If that's not done, the
pedal will be very low and won't provide full MC operation.
Now, if someone reverts to the OEM, or other, MC which fits better with the
support bracket again being installed last, that push rod had better be
changed back to the shorter length. Otherwise, the pressure relief ports in
the MC will not be exposed and the brakes will never release.
The safest course of action is probably to always do a modeling clay
clearance check on the push rod to be sure its length is correct. No use
throwing away pedal travel by using too short a rod, but one too long can
burn up the brakes.
Just want to be sure newbies don't fall in a PO-left hole. :-)
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com
On Sun, Sep 19, 2010 at 10:22 PM, Jack Christensen <captjack@sonic.net>wrote:
>
>
> As Fred pointed out the master cylinder connects directly to the booster,
> and the support bracket is on the outside of the Master Cylinder between the
> hold down nuts and the master cylinder. I just put mine back in today.
> --
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] master cylinder support bracket [message #100404 is a reply to message #100403] |
Sun, 19 September 2010 21:55 |
Dave Motorhome
Messages: 175
Registered: July 2007
Karma: 2
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Senior Member |
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no, the master cylinder is exactly like it was before. everything is
done to spec. (bill bramlett used to be my crutch, till he moved away)
the MC bracket that mounts to the firewall has predrilled holes in it
that allow side to side movement, I just set new bolts 1/4 in from the
original spot. the MC was purchased from Applied GMC along with all 4
new cylinders and hose.
I am 35, i have a wife and a 5, 3 , and 1 year old.. they are my
world.. no shortcuts with the GMC
David Paliotta
75 Glenbrook
Tulsa, OK
http://75glenbrook.googlepages.com/
On Sun, Sep 19, 2010 at 9:45 PM, Ken Henderson <hend4800@bellsouth.net> wrote:
> Careful now. With all the PO work, we've got to be sure what we're starting
> with. The OEM arrangement was indeed to have the master cylinder adjacent
> to the booster, with the support bracket installed last.
>
fall in a PO-left hole. :-)
>
> Ken H.
> Americus, GA
> '76 X-Birchaven w/Cad500/Howell EFI+ & EBL
> www.gmcwipersetc.com
>
>
>
> On Sun, Sep 19, 2010 at 10:22 PM, Jack Christensen <captjack@sonic.net>wrote:
>
>>
>>
>> As Fred pointed out the master cylinder connects directly to the booster,
>> and the support bracket is on the outside of the Master Cylinder between the
>> hold down nuts and the master cylinder. I just put mine back in today.
>> --
--
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| Re: [GMCnet] master cylinder support bracket [message #100455 is a reply to message #100404] |
Mon, 20 September 2010 19:03 |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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G'day,
Two years ago I noticed there was brake fluid running down the front of the
brake booster.
I asked Helen to push on the pedal so I could see where it was coming from.
To my great surprise the master cylinder and booster assembly moved towards
the front of the GMC when she pressed on the pedal.
When I removed the master cylinder I found the two OEM bolts where missing
and the bracket was held in with 1/4" lag bolts. Two of which had fallen out
completely the other one was loose. The OEM rivet nuts spun in their holes
which explained the sheet metal screws. I replaced the missing lag bolts
when I replaced the P-30 Master Cylinder.
I did this in Pennsylvania at the start of our tour that year. By the time I
got to Orlando I had a hit list a mile long and decided to spend some time
at Jim B's COOP and fix as many as I could.
I found rivet nuts at McMaster Carr that work like Molly bolts and got some
to replace the lag bolts.
http://www.gmcmhphotos.com/photos/showphoto.php?photo=27933
http://www.gmcmhphotos.com/photos/showphoto.php?photo=27934
When I installed them I applied two part epoxy to the rivet nuts, expanded
them, and then let them cure overnight. The next day I installed machine
bolts.
http://www.gmcmhphotos.com/photos/showphoto.php?photo=28379
http://www.gmcmhphotos.com/photos/showphoto.php?photo=28378
To date the bracket does not move.
Regards,
Rob M.
USAussie
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of David
Sent: Sunday, September 19, 2010 10:55 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] master cylinder support bracket
no, the master cylinder is exactly like it was before. everything is
done to spec. (bill bramlett used to be my crutch, till he moved away)
the MC bracket that mounts to the firewall has predrilled holes in it
that allow side to side movement, I just set new bolts 1/4 in from the
original spot. the MC was purchased from Applied GMC along with all 4
new cylinders and hose.
I am 35, i have a wife and a 5, 3 , and 1 year old.. they are my
world.. no shortcuts with the GMC
David Paliotta
75 Glenbrook
Tulsa, OK
http://75glenbrook.googlepages.com/
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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] master cylinder support bracket [message #100467 is a reply to message #100455] |
Mon, 20 September 2010 19:47 |
jw mills
Messages: 199
Registered: September 2006
Karma: -30
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Senior Member |
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Personally I would scrap the coach before I would use sheet metal or lag
screws on something like the brake system.
--
Jim Mills
Greeley, CO
1973 CanyonLands 260 TZE-063V100731(under renovation)
1973 Glacier 230 TZE-033V101993
On Mon, 2010-09-20 at 20:03 -0400, Rob Mueller wrote:
> G'day,
>
> Two years ago I noticed there was brake fluid running down the front of the
> brake booster.
>
> I asked Helen to push on the pedal so I could see where it was coming from.
>
> To my great surprise the master cylinder and booster assembly moved towards
> the front of the GMC when she pressed on the pedal.
>
> When I removed the master cylinder I found the two OEM bolts where missing
> and the bracket was held in with 1/4" lag bolts. Two of which had fallen out
> completely the other one was loose. The OEM rivet nuts spun in their holes
> which explained the sheet metal screws. I replaced the missing lag bolts
> when I replaced the P-30 Master Cylinder.
>
> I did this in Pennsylvania at the start of our tour that year. By the time I
> got to Orlando I had a hit list a mile long and decided to spend some time
> at Jim B's COOP and fix as many as I could.
>
> I found rivet nuts at McMaster Carr that work like Molly bolts and got some
> to replace the lag bolts.
>
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=27933
>
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=27934
>
> When I installed them I applied two part epoxy to the rivet nuts, expanded
> them, and then let them cure overnight. The next day I installed machine
> bolts.
>
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=28379
>
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=28378
>
> To date the bracket does not move.
>
> Regards,
> Rob M.
> USAussie
>
>
> -----Original Message-----
> From: gmclist-bounces@temp.gmcnet.org
> [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of David
> Sent: Sunday, September 19, 2010 10:55 PM
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] master cylinder support bracket
>
> no, the master cylinder is exactly like it was before. everything is
> done to spec. (bill bramlett used to be my crutch, till he moved away)
> the MC bracket that mounts to the firewall has predrilled holes in it
> that allow side to side movement, I just set new bolts 1/4 in from the
> original spot. the MC was purchased from Applied GMC along with all 4
> new cylinders and hose.
> I am 35, i have a wife and a 5, 3 , and 1 year old.. they are my
> world.. no shortcuts with the GMC
>
> David Paliotta
> 75 Glenbrook
> Tulsa, OK
> http://75glenbrook.googlepages.com/
>
>
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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