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| GMC didn't make the deadline for my trip! [message #130506] |
Thu, 16 June 2011 23:10  |
thorndike
Messages: 406
Registered: January 2011
Location: Conifer, Colorado
Karma: 0
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Well, I WAS planning on taking the GMC to visit my brother in Colorado this week. My plan was to leave on Saturday morning. To get ready, I started replacing the isolation pads on Memorial Day to be followed by the disc brake upgrade.
As usual things took longer than expected. I did get the pads replaced after a few days and then started on the brakes. Well, JimK's brake it is fairly simple to install. It is everything else involved that takes time! I found myself dealing with broken and stuck cotter pins, discovering that the dealer I bought it from neglected to connect a shock absorber, rounded brake line connectors, bad master cylinder, etc. I could not have done it without JimK's help over the phone. He kept in touch to make sure that everything was going well, and when it wasn't offered advice that was always on the mark. Thanks Jim.
Well, tonight I had to make the call and cancel the GMC trip. I have been unable to get the brake lines bled completely. I have a power bleeder but have been unable to get a complete seal around the master cylinder, so even when I pressurize the pump to 1-2 psi, I blow fluid out between the seal. When that hasn't worked, I have had my son, and some friends pressing the pedal while I open and close the valve at each wheel. I started bleeding the wheels on Tuesday after work and have continued each evening until dark. That is now about 10 hours of brake bleeding with no success. I have run over a gallon of brake fluid through the lines and still the pedal goes to the floor.
I am getting fluid moving through the lines and I am not seeing any air bubbles coming out as I bleed them. I have also kept an eye open for leaks elsewhere in the system but haven't seen any spots on the ground to indicate another leak.
Any thoughts?
Robert Peesel
1976 Royale 26'
Side Dry Bath
Conifer, Colorado
[Updated on: Thu, 16 June 2011 23:11] Report message to a moderator |
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| Re: [GMCnet] GMC didn't make the deadline [message #130507 is a reply to message #130506] |
Thu, 16 June 2011 23:31  |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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On Jun 16, 2011, at 10:10 PM, Robert Peesel wrote:
>
>
> Well, I WAS planning on taking the GMC to visit my brother in Colorado this week. My plan was to leave on Saturday morning. To get ready, I started replacing the isolation pads on Memorial Day to be followed by the disc brake upgrade.
>
> As usual things took longer than expected. I did get the pads replaced after a few days and then started on the brakes. Well, JimK's brake it is fairly simple to install. It is everything else involved that takes time! I found myself dealing with broken and stuck cotter pins, discovering that the dealer I bought it from neglected to connect a shock absorber, rounded brake line connectors, bad master cylinder, etc. I could not have done it without JimK's help over the phone. He kept in touch to make sure that everything was going well, and when it wasn't offered advice that was always on the mark. Thanks Jim.
>
> Well, tonight I had to make the call and cancel the GMC trip. I have been unable to get the brake lines bled completely. I have a power bleeder but have been unable to get a complete seal around the master cylinder, so even when I pressurize the pump to 1-2 psi, I blow fluid out between the seal. When that hasn't worked, I have had my son, and some friends pressing the pedal while I open and close the valve at each wheel. I started bleeding the wheels on Tuesday after work and have continued each evening until dark. That is now about 10 hours of brake bleeding with no success. I have run over a gallon of brake fluid through the lines and still the pedal goes to the floor.
>
> I am getting fluid moving through the lines and I am not seeing any air bubbles coming out as I bleed them. I have also kept an eye open for leaks elsewhere in the system but haven't seen any spots on the ground to indicate another leak.
>
> Any thoughts?
> --
> R
You didn't say whether you also put in a new master cylinder. When I did the six wheel disk brake conversion back in 1999 I had the same problems that you are describing. It was only after installing a higher capacity master cylinder that I was able to bleed the brakes. It sounds to me that you might not be getting enough fluid back to the rear calipers. They take a lot more fluid than the wheel cylinders that you have replaced.
I am now running a 34 mm master cylinder. If you need any information on which one to get or how to install it, including adjusting the length of the push rod, let me know.
Emery Stora
77 Kingsley
Santa Fe, NM
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| Re: [GMCnet] GMC didn't make the deadline [message #130508 is a reply to message #130507] |
Thu, 16 June 2011 23:43 |
thorndike
Messages: 406
Registered: January 2011
Location: Conifer, Colorado
Karma: 0
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Senior Member |
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Emory,
Yes, I did install the bigger master cylinder. I bench bled it before putting it on as well.
Everything seems to be working..except for the fact that the brake pedal goes all the way to the floor.
I even replaced the proportion valve.
Bob
Robert Peesel
1976 Royale 26'
Side Dry Bath
Conifer, Colorado
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| Re: GMC didn't make the deadline for my trip! [message #130509 is a reply to message #130506] |
Thu, 16 June 2011 23:44 |
Adrien G.
Messages: 474
Registered: May 2008
Location: Burns Flat, OK 73624
Karma: 1
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Robert,
1. Did you remove the residual check valve? You don't want it for disc. It's inside the piston bore.
2. Did you bleed the MC before you put on line (installed)?
I read that you pushed a gal of fluid, but the pedal bleed system is too slow and small of fluid volume movement to push air that's trapped in cylinders and line bends.
I used a flat 1/4" plate for the MC cover with a hose fitting and clamped with 2 C clamps, with a gasket of coarse. For the pressure tank I use a 1/2 gal garden sprayer.
Been there and done that.
Hope this helps you.
Adrien & Jenny Genesoto
75 Glenbrook (26-3) Mods LS3.70 FD / Reaction Sys / 80mm Front&Intermidiate / Hydroboost / 16" Tires / Frame Rebuild / Interior Rebuild
Yuba City,Ca. Text 530-nine-3-three-3-nine-nine-6
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| Re: GMC didn't make the deadline for my trip! [message #130510 is a reply to message #130506] |
Thu, 16 June 2011 23:45 |
GMC Cruse
Messages: 606
Registered: June 2009
Location: SE Michigan
Karma: 3
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| thorndike wrote on Fri, 17 June 2011 00:10 |
Well, I WAS planning on taking the GMC to visit my brother in Colorado this week. My plan was to leave on Saturday morning. To get ready, I started replacing the isolation pads on Memorial Day to be followed by the disc brake upgrade.
As usual things took longer than expected. I did get the pads replaced after a few days and then started on the brakes. Well, JimK's brake it is fairly simple to install. It is everything else involved that takes time! I found myself dealing with broken and stuck cotter pins, discovering that the dealer I bought it from neglected to connect a shock absorber, rounded brake line connectors, bad master cylinder, etc. I could not have done it without JimK's help over the phone. He kept in touch to make sure that everything was going well, and when it wasn't offered advice that was always on the mark. Thanks Jim.
Well, tonight I had to make the call and cancel the GMC trip. I have been unable to get the brake lines bled completely. I have a power bleeder but have been unable to get a complete seal around the master cylinder, so even when I pressurize the pump to 1-2 psi, I blow fluid out between the seal. When that hasn't worked, I have had my son, and some friends pressing the pedal while I open and close the valve at each wheel. I started bleeding the wheels on Tuesday after work and have continued each evening until dark. That is now about 10 hours of brake bleeding with no success. I have run over a gallon of brake fluid through the lines and still the pedal goes to the floor.
I am getting fluid moving through the lines and I am not seeing any air bubbles coming out as I bleed them. I have also kept an eye open for leaks elsewhere in the system but haven't seen any spots on the ground to indicate another leak.
Any thoughts?
|
I recently did a brake job on my brother's non-GMC RV and had same problem. Turned out the booster was bad and fluid was getting past a seal and filling up booster. Must have drained a quart out of it. Do you hear a swoosh of air when pushing on master cylinder when motor is running?
Mike K.
'75 PB
Southeast Michigan
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| Re: [GMCnet] GMC didn't make the deadline [message #130511 is a reply to message #130508] |
Thu, 16 June 2011 23:47 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Bob, did you cock the rear calipers at 12 O clock, when you bled the rear.
On Thu, Jun 16, 2011 at 9:43 PM, Robert Peesel <thorndike@pldsllc.com> wrote:
>
>
> Emory,
>
> Yes, I did install the bigger master cylinder. Â I bench bled it before putting it on as well.
>
> Everything seems to be working..except for the fact that the  brake pedal goes all the way to the floor.
>
> I even replaced the proportion valve.
>
> Bob
> --
> Robert Peesel
>
> 1976 Royale 26'
>
> Side Dry Bath
>
> Sterling, Va
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: GMC didn't make the deadline for my trip! [message #130521 is a reply to message #130510] |
Fri, 17 June 2011 01:37 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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| GMC Cruse wrote on Thu, 16 June 2011 21:45 |
I recently did a brake job on my brother's non-GMC RV and had same problem. Turned out the booster was bad and fluid was getting past a seal and filling up booster. Must have drained a quart out of it. Do you hear a swoosh of air when pushing on master cylinder when motor is running?
|
Something about this sounds odd...
In order for fluid to be in the booster, something besides the booster needs to be bad. If it gets full of brake fluid, the master cylinder would be the main suspect.
Not saying the booster wasn't bad....
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: [GMCnet] GMC didn't make the deadline for my trip! [message #130523 is a reply to message #130521] |
Fri, 17 June 2011 02:21 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Mike,
I agree - BIG deal!
I reckon whoever sent the message in meant to write; "Turned out the MASTER
CYLINDER was bad and fluid was getting past a seal and filling up booster.
that the
Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Mike Miller
Sent: Friday, June 17, 2011 4:37 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] GMC didn't make the deadline for my trip!
Something about this sounds odd...
In order for fluid to be in the booster, something besides the booster needs
to be bad. If it gets full of brake fluid, the master cylinder would be the
main suspect.
Not saying the booster wasn't bad....
--
Mike
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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] GMC didn't make the deadline [message #130524 is a reply to message #130506] |
Fri, 17 June 2011 03:22 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Robert, exactly which MC do you presently have installed, and did you check
the length of the operating rod and determine the correct amount of free
space when the brake pedal is released? Two things come to mind. First and
most likely, you have a new master cylinder that is bad. New is only new,
not necessarily good, based on the state of the after market supply of
offshore parts. I have run into that issue. Second, the pushrod is too long,
and does not allow the piston in the MC to retract all the way. This will
not allow the fluid to enter the piston area from the resevoir and you will
not be able to get any pedal pressure. Do you now have a total disc brake
system, or are you still running some drum brakes as well? Diagnosing by
long distance requires that you be very specific about the changes that you
have made, in order that we might be more helpful.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Thu, Jun 16, 2011 at 9:10 PM, Robert Peesel <thorndike@pldsllc.com>wrote:
>
>
> Well, I WAS planning on taking the GMC to visit my brother in Colorado this
> week. My plan was to leave on Saturday morning. To get ready, I started
> replacing the isolation pads on Memorial Day to be followed by the disc
> brake upgrade.
>
> As usual things took longer than expected. I did get the pads replaced
> after a few days and then started on the brakes. Well, JimK's brake it is
> fairly simple to install. It is everything else involved that takes time!
> I found myself dealing with broken and stuck cotter pins, discovering that
> the dealer I bought it from neglected to connect a shock absorber, rounded
> brake line connectors, bad master cylinder, etc. I could not have done it
> without JimK's help over the phone. He kept in touch to make sure that
> everything was going well, and when it wasn't offered advice that was always
> on the mark. Thanks Jim.
>
> Well, tonight I had to make the call and cancel the GMC trip. I have been
> unable to get the brake lines bled completely. I have a power bleeder but
> have been unable to get a complete seal around the master cylinder, so even
> when I pressurize the pump to 1-2 psi, I blow fluid out between the seal.
> When that hasn't worked, I have had my son, and some friends pressing the
> pedal while I open and close the valve at each wheel. I started bleeding
> the wheels on Tuesday after work and have continued each evening until dark.
> That is now about 10 hours of brake bleeding with no success. I have run
> over a gallon of brake fluid through the lines and still the pedal goes to
> the floor.
>
> I am getting fluid moving through the lines and I am not seeing any air
> bubbles coming out as I bleed them. I have also kept an eye open for leaks
> elsewhere in the system but haven't seen any spots on the ground to indicate
> another leak.
>
> Any thoughts?
> --
> Robert Peesel
>
> 1976 Royale 26'
>
> Side Dry Bath
>
> Sterling, Va
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] GMC didn't make the deadline [message #130545 is a reply to message #130533] |
Fri, 17 June 2011 08:46 |
thorndike
Messages: 406
Registered: January 2011
Location: Conifer, Colorado
Karma: 0
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Senior Member |
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Thanks for all the responses.
Here is a bit more information for you all.
I installed Jim K's four wheel disc upgrade. For those that aren't aware, the four wheel upgrade utilizes the original front discs in addition to the four new discs and calipers.
I also installed a new proportion valve and master cylinder. I purchased the new booster, but did not install it due to time constraints. Jim K. approved and said that the original booster would work fine with the new brakes and master cylinder.
I have a new pin for the booster/master cylinder, I did not install it as I thought Jim said it was to be installed with the new BOOSTER not the master cylinder. If I misunderstood, then that could be my problem.
Jim, if you see this before I call you, can you clarify?
As to my power bleeder, yes I purchased the Motiv bleeder as my brother-in-law the car builder swears by it. I was never able to get a seal as others have mentioned as the plate seems to bend when tightened. I will have to find a metal plate instead.
I will keep everyone posted.
Bob
Robert Peesel
1976 Royale 26'
Side Dry Bath
Conifer, Colorado
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| Re: [GMCnet] GMC didn't make the deadline [message #130551 is a reply to message #130545] |
Fri, 17 June 2011 09:02 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Bob,
The pin for the MC is equally applicable to the old booster. The
primary reason for needing it is that the new vertical brace mounts
differently than the old one, changing the distance of the MC from the
booster. IIRC, the difference is about 0.060" longer. Multiply that
by the mechanical advantage of the brake pedal and it's more like 1/2"
at the MC piston. That's undoubtedly your problem.
In every MC replacement, it's a good idea to check the pin clearance.
A bit of modelling clay on one end will be compressed during a
temporary assembly, then measure the pin length with & without the
clay; adjust as necessary to achive the 0.015" (IIRC) clearance.
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com
On Fri, Jun 17, 2011 at 9:46 AM, Robert Peesel wrote:
>...
> I have a new pin for the booster/master cylinder, I did not install it as I thought Jim said it was to be installed with the new BOOSTER not the master cylinder. If I misunderstood, then that could be my problem.
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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] GMC didn't make the deadline for my trip! [message #130553 is a reply to message #130523] |
Fri, 17 June 2011 09:13 |
GMC Cruse
Messages: 606
Registered: June 2009
Location: SE Michigan
Karma: 3
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Senior Member |
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| Robert Mueller wrote on Fri, 17 June 2011 03:21 |
Mike,
I agree - BIG deal!
I reckon whoever sent the message in meant to write; "Turned out the MASTER
CYLINDER was bad and fluid was getting past a seal and filling up booster.
that the
Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Mike Miller
Sent: Friday, June 17, 2011 4:37 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] GMC didn't make the deadline for my trip!
Something about this sounds odd...
In order for fluid to be in the booster, something besides the booster needs
to be bad. If it gets full of brake fluid, the master cylinder would be the
main suspect.
Not saying the booster wasn't bad....
--
Mike
|
You guys are correct. In an effort to keep the post short it, did not come out right. Prior to doing brake work on his RV which is almost as old as our GMC's. He noticed the air swoosh from the booster with the engine running when depressing the brake pedal. After replacing the brake lines and installing pads/shoes, pedal kept going to floor even after bleeding. Also, rear resevoir would loose fluid even when sitting. What happens is when bleeding brakes and pushing pedal to floor, piston in master cylinder goes deeper into the bore than it normally does. This area of the bore may have rougher walls and messes up the seals and seals then starts leaking. While not as likely, this can also happen with a new/rebuilt master cylinder when pedal goes to floor. So he had two problems, the master cylinder seal was allowing fluid to get past it and the booster was leaking air. The should have posted we installed a new "loaded" booster ( i.e. one with a new master cylinder attached) which solved both problems. Brakes are fine now.
Mike K.
'75 PB
Southeast Michigan
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| Re: [GMCnet] GMC didn't make the deadline [message #130554 is a reply to message #130545] |
Fri, 17 June 2011 09:14 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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On Jun 17, 2011, at 7:46 AM, Robert Peesel wrote:
>
>
> Thanks for all the responses.
>
> Here is a bit more information for you all.
>
> I installed Jim K's four wheel disc upgrade. For those that aren't aware, the four wheel upgrade utilizes the original front discs in addition to the four new discs and calipers.
>
> I also installed a new proportion valve and master cylinder. I purchased the new booster, but did not install it due to time constraints. Jim K. approved and said that the original booster would work fine with the new brakes and master cylinder.
>
> I have a new pin for the booster/master cylinder, I did not install it as I thought Jim said it was to be installed with the new BOOSTER not the master cylinder. If I misunderstood, then that could be my problem.
>
> Jim, if you see this before I call you, can you clarify?
>
> As to my power bleeder, yes I purchased the Motiv bleeder as my brother-in-law the car builder swears by it. I was never able to get a seal as others have mentioned as the plate seems to bend when tightened. I will have to find a metal plate instead.
>
> I will keep everyone posted.
>
> Bob
> --
If you used the original pushrod with a different master cylinder then I think that is most likely your problem.
Here is how you can check your pushrod length:
Unbolt your master cylinder. You do not have to disconnect the brake lines. Pull it forward enough to remove the push rod. Put a small amount of modeling clay or plumber's putty on the end. Reinstall the rod with the clay toward the master cylinder. Bolt the master cylinder into place. Then remove it and the rod again and measure the thickness of the clay that is compressed on the end of the rod (you can measure the total length including the clay and then the length of the rod without the clay and subtract if that is easier). .015 inches of pushrod
clearance is sufficient.
If you clay is thicker then your pushrod is too short. If there is no clay left then your pushrod has no clearance.
If your rod is too long you can just grind off the end. If too short then you can either buy an adjustable pushrod or make your own.
When I made my own pushrod I used a piece of drill rod of the same diameter as my original pushrod and ground the end that goes into the master cylinder to a rounded shape and left the end that goes against the booster flat with just the edge beveled slightly.
Emery Stora
77 Kingsley
Santa Fe, NM
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| Re: GMC didn't make the deadline for my trip! [message #130564 is a reply to message #130506] |
Fri, 17 June 2011 10:26 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Senior Member |
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Two things:
I bought the motive bleeder as well. since I have alot of other cars I intend on using it on, and got all the other adaptors with it.
I had a hard time getting it to seal, but I was able to put two big c-clamps on master cylinder.(I do have a stock master). and that helped. you have to be careful not to bend the plate. the universal plate is just a little big. I will order Jim Hupy's plate before i try to pressure bleed mine again. so if you have the time, see if Jim has a plate.
I also found it to be a process of patience. you did not have to pump the pressure bleeder up much, and the brake fluid just dribbled out the calipers/wheel cylinders. I just kept the bleeders open, kept the pressure around 9-10 lbs, and let it flow for about 15-30 minutes a tire. you could definately see that I had clean fluid dripping out. and closed them up and it was excellent pedel pressure when I took off the bleeder and tested the brakes. but I thought i would see a faster rate of fluid coming out, like when you bleed pumping the pedel, but it was not the case.
second item, was a problem we found on my buddy's jeep cherokee. Same thing you described, turned out we put the calipers on the wrong sides. the bleeders ended up not on the top. and it was holding a big air pocket. not sure if you can switch side to side, but on the cherokee they bolted right up. that problem was found 2 gallons of brake fluid, and a week later.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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