| Brake Issue [message #222330] |
Fri, 13 September 2013 19:56  |
Nicholls
Messages: 36
Registered: January 2008
Location: Pensacola, FL
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1) In a static condition, my pedal is high and firm but with engine running and vacumn booster engaged it bottoms out more than half way down. Is this normal? Why? Can it be improved?
2) The manual is very specific about using a master cylinder with the same two letter code. What is the proper code? Where can it be found? I used a NAPA M2085. There is a stamped 29895-C on the body and what looks like a GL 5 near the made in USA stamp The L is located slightly below the G. I measured the indent for the booster rod at approximately 17mm or 42/64ths. Is this close enough? If not, what should it be?
John Nicholls,
78 Royale w/455
Pensacola, FL
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| Re: Brake Issue [message #222336 is a reply to message #222330] |
Fri, 13 September 2013 20:21  |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
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| Nicholls wrote on Fri, 13 September 2013 19:56 |
1) In a static condition, my pedal is high and firm but with engine running and vacumn booster engaged it bottoms out more than half way down. Is this normal? Why? Can it be improved?
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What do you mean by 'bottoms out' John? If you mean that the pedal goes down about 1/2 way to the floor and gets hard, that is pretty normal. The booster provides enough extra boost that you'll get more pedal travel with the same foot pressure.
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
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| Re: Brake Issue [message #222400 is a reply to message #222336] |
Sat, 14 September 2013 10:19 |
Nicholls
Messages: 36
Registered: January 2008
Location: Pensacola, FL
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Kerry, that is what I meant. It just seems that the travel is overlong. I get that queasy feeling when it takes what my brain says is too long to reach the point where you know it is fully applied.
John Nicholls,
78 Royale w/455
Pensacola, FL
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| Re: Brake Issue [message #222419 is a reply to message #222400] |
Sat, 14 September 2013 13:13 |
xplorid
Messages: 213
Registered: February 2012
Location: Boise
Karma: 0
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Replace your MC. Do a search for the thread with the part numbers, or bounce back I'll look up what I did in July.
1974/94 GMCII by Explorer
Manny 6.5 TD Al radiator
1 ton front 4 bags back
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| Re: Brake Issue [message #222517 is a reply to message #222419] |
Sun, 15 September 2013 13:03 |
Nicholls
Messages: 36
Registered: January 2008
Location: Pensacola, FL
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Please bounce back. I don't know how to look up the thread.
Thanks
John Nicholls,
78 Royale w/455
Pensacola, FL
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| Re: Brake Issue [message #222598 is a reply to message #222330] |
Sun, 15 September 2013 21:00 |
Craig Lechowicz
Messages: 541
Registered: October 2006
Location: Waterford, MI
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Often, excessive brake pedal travel is due to the rear brakes (if you still have drums) being out of adjustment. Theoretically, they self adjust on repeated hard stops when backing up, but that works better on cars then it does on hard to see behind you GMC's. It might be worth manually adjusting the rear and intermediate brakes.
Craig Lechowicz
'77 Kingsley, Waterford, MI
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| Re: Brake Issue [message #222609 is a reply to message #222517] |
Sun, 15 September 2013 22:29 |
xplorid
Messages: 213
Registered: February 2012
Location: Boise
Karma: 0
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Which Brake Master Cylinder Replacement [message #217668]
look that up, the thread just came back up today and is now on pg 2. At the top of this page is a search bar if you cannot find it search the site (not google).
The MC cost under $20 and was actually an easy job. Got all my pedal back and more.
Jeff
1974/94 GMCII by Explorer
Manny 6.5 TD Al radiator
1 ton front 4 bags back
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| Re: Brake Issue [message #222615 is a reply to message #222330] |
Sun, 15 September 2013 22:46 |
bhayes
Messages: 263
Registered: March 2010
Karma: 1
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I'm curious about brake pedal travel as well. I replaced my MC a while back, bled the brakes (twice), recently adjusted the rear drums, but my pedal travels quite a bit before the brakes bite. The coach still stops well, but the amount of pedal travel required to get to that point is a little unnerving.
A little off topic, but one thing I did notice while inspecting and adjusting the drums is that the parking brake cable is only connected to the rear drums. The mid wheel cable is disconnected and tucked up between the frame and body. And I wondered why the parking brake didn't seem to work.
Bryan Hayes
'76 Eleganza II
Salt Lake City, Utah
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| Re: Brake Issue [message #222616 is a reply to message #222609] |
Sun, 15 September 2013 22:47 |
Nicholls
Messages: 36
Registered: January 2008
Location: Pensacola, FL
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Thanks to all that responded. Somehow I missed the listings in the GMCMI parts list. I see the NAPA P2085 listed so now just need to ask them how that corresponds to the M2085 I used.
I have been told as stated that the rear brake shoe (drums) adjustment controls the pedal travel but I can't seem to make it make a difference.
Most of the thread furnished seems to address the P30 unit.
John Nicholls,
78 Royale w/455
Pensacola, FL
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| Re: Brake Issue [message #222617 is a reply to message #222616] |
Sun, 15 September 2013 23:12 |
bhayes
Messages: 263
Registered: March 2010
Karma: 1
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John, I recently adjusted my drums. What I found is that the rear drums were adjusted too tight, but the middle drums were a little too loose. I evened them out, but unfortunately it didn't make any difference in pedal travel.
Bryan Hayes
'76 Eleganza II
Salt Lake City, Utah
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| Re: [GMCnet] Brake Issue [message #222634 is a reply to message #222615] |
Mon, 16 September 2013 07:17 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Even with the rears pulled up correctly there's a bit more travel on mine than on my truck or car. I think it's due to the pressure required to activate the proportioning valve, which wants a bit of fluid and thus a bitr of pedal travel.
--johnny
--------------------------------------------
On Mon, 9/16/13, Bryan Hayes <hayesnet1@gmail.com> wrote:
Subject: Re: [GMCnet] Brake Issue
To: gmclist@temp.gmcnet.org
Date: Monday, September 16, 2013, 3:46 AM
I'm curious about brake pedal travel as well. I replaced my
MC a while back, bled the brakes (twice), recently adjusted
the rear drums, but my pedal travels quite a bit before the
brakes bite. The coach still stops well, but the amount of
pedal travel required to get to that point is a little
unnerving.
A little off topic, but one thing I did notice while
inspecting and adjusting the drums is that the parking brake
cable is only connected to the rear drums. The mid wheel
cable is disconnected and tucked up between the frame and
body. And I wondered why the parking brake didn't seem to
work.
--
Bryan Hayes
'76 Eleganza II
Salt Lake City, Utah
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Brake Issue [message #222648 is a reply to message #222647] |
Mon, 16 September 2013 09:05 |
Don A
Messages: 895
Registered: October 2008
Location: Dallas, TX
Karma: 0
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Also remember you have six cylinders, not just four. So it takes a little more pedal travel than your car.
Don Adams Dallas, TX
'76 26' Glenbrook, '90 Sidekick
rebuilt by R Archer, powered by J Bounds, Koba
[IMG]http://www.gmcmhphotos.com/photos/data/6109/G2.jpg[/IMG]
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