Home » Public Forums » GMCnet » Disc Brake Pedal Travel Dilemma (Pedal travels half way to the floor)
| Disc Brake Pedal Travel Dilemma [message #200205] |
Thu, 28 February 2013 17:41  |
Who_dun_it
Messages: 176
Registered: April 2007
Location: Thousand Oaks, CA
Karma: 1
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Hi - new setup, all-wheel disc. I have installed the required parts and pieces fot this setup. The pedal travels half way to the floor before I get any 'resistance'. What have I missed??
Les
T.O. CA
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| Re: Disc Brake Pedal Travel Dilemma [message #200210 is a reply to message #200205] |
Thu, 28 February 2013 17:57  |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
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Still have an air bubble in the lines somewhere?. It's normal for the first pump after a brake job to go way down because the pads are a long way off the rotors and it takes a good bit of fluid to get them to their actually run position (just off the rotor).
If you're using the stock MC, you might have used up all the fluid in the MC reservoir and sucked in a bit of air. Have you verified the MC still has fluid?
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
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| Re: [GMCnet] Disc Brake Pedal Travel Dilemma [message #200212 is a reply to message #200205] |
Thu, 28 February 2013 18:23 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Les, Did you replace the Master cylinder? If you installed the P-30 master
cylinder with the bracket between the booster and the cylinder, it is
likely that your operating pushrod is too short, allowing pedal travel
before moving the pistons in the cylinder. That has been a problem with
other installs including some that I have done. Carefully measure the
pushrod length and the space it installs into. The pushrod should be no
shorter than about 1/16" less than that space. Someone just devised a
measuring rod to verify the space. As I recall, it was two tubes that slid
fairly tightly, one inside the other. The rod was pulled out longer than
the space, then the m/c was mounted, compressing the rod. The assembly was
then taken apart and the rod removed and measured. That length was how long
the new pushrod should be. Simple and ALMOST idiot proof.
Jim Hupy
Salem, Or
78 Gmc Royale 403
On Feb 28, 2013 3:41 PM, "Les Leach" <les.leach@yahoo.com> wrote:
>
>
> Hi - new setup, all-wheel disc. I have installed the required parts and
> pieces fot this setup. The pedal travels half way to the floor before I get
> any 'resistance'. What have I missed??
>
> Les
> T.O. CA
> _______________________________________________
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| Re: [GMCnet] Disc Brake Pedal Travel Dilemma [message #200219 is a reply to message #200212] |
Thu, 28 February 2013 19:22 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Les,
On top of what Kerry and Jim have said, when I did the disc brake conversion, I found that the pedal feel was different. It wasn't quite as you described it, but the pedal does have a softer feel than it did with the rear drum brakes. If you still feel a difference, after you get all the air out of the lines and make sure the brake rod is the right length, you will get used to the new pedal feel after a while.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Disc Brake Pedal Travel Dilemma [message #200221 is a reply to message #200212] |
Thu, 28 February 2013 19:43 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Here's the pushrod gauge:
http://www.gmcmhphotos.com/photos/g6289-master-cylinder-pushrod-gauge.html
or
http://goo.gl/Of6S8
(I'd CRS'd I'd already posted it!)
Ken H.
On Thu, Feb 28, 2013 at 7:23 PM, James Hupy wrote:
> .... Carefully measure the
> pushrod length and the space it installs into. The pushrod should be no
> shorter than about 1/16" less than that space. Someone just devised a
> measuring rod to verify the space. As I recall, it was two tubes that slid
> fairly tightly, one inside the other. The rod was pulled out longer than
> the space, then the m/c was mounted, compressing the rod. The assembly
> was then taken apart and the rod removed and measured. That length was how
> long the new pushrod should be. Simple and ALMOST idiot proof.
>
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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] Disc Brake Pedal Travel Dilemma [message #200228 is a reply to message #200225] |
Thu, 28 February 2013 20:59 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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| Who_dun_it wrote on Thu, 28 February 2013 19:18 |
What I think I am hearing here is that the pushrod supplied with the P30 MC, is not necessarily the correct length. Is that correct?
Les
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Mine was long enough. In fact, I had to grind a little off of it (very little).
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Disc Brake Pedal Travel Dilemma [message #200233 is a reply to message #200205] |
Thu, 28 February 2013 22:23 |
jim kanomata
Messages: 257
Registered: March 2007
Location: fremont,ca
Karma: 12
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Senior Member |
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Sometimes the calipers will be mounted differently on some kits that will require one to note at what position the bleeder valve is located.
I know that on our kits the bleeder ends at 2:00 position, so you need to undo one pin and pivot it to 12:00 then bleed.
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Disc Brake Pedal Travel Dilemma [message #200289 is a reply to message #200251] |
Fri, 01 March 2013 19:03 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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When I was the Zone service Manager for Ford Motor , I had to show several
dealer senior mechanics some ways to do things that they said was not going
to work.
Being that most of the Zone service managers did not have much experience,
the dealer personal figured most did not know much.
I made it a point to understand before I would tell them how to do
something, otherwise I told them up front that I was relaying information
from Dearborn ,MI.
Once they realized that my knowledge was limited, but could get information
from the factory, we developed a great relationship and we all learned from
each.
On Fri, Mar 1, 2013 at 8:15 AM, Les Leach <les.leach@yahoo.com> wrote:
>
>
> Thank you all for the input. Now I will get back at it and see if I can
> make it better.
>
> Les
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--
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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