Home » Public Forums » GMCnet » Brakes - disk all around, been sitting, where do i start ?
| Brakes - disk all around, been sitting, where do i start ? [message #358468] |
Thu, 10 September 2020 10:07  |
hertfordnc
Messages: 1164
Registered: September 2009
Location: East NC
Karma: 0
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Senior Member |
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The coach has a disk brakes all around with very few miles on them. It sat for a while and there is rust on the rotors.
The pedal feels consistent, it does not stiffen with pumping so i don't think there is a leak or a need to bleed.
On a low speed stop they feel like they grab pretty well.
At higher speed it feels like when you tow something way over your limit without trailer brakes (don't say you never did that)
It just ignores your foot and slows down in its own time.
Where do i start ?
Dave & Ellen Silva
Hertford, NC
76 Birchaven, 1-ton and other stuff
Currently planning the Great american Road Trip Summer 2021
It's gonna take a lot of Adderall to get this thing right.
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| Re: [GMCnet] Brakes - disk all around, been sitting, where do i start ? [message #358469 is a reply to message #358468] |
Thu, 10 September 2020 10:10  |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Run it and the rust will work off
On Thu, Sep 10, 2020 at 8:08 AM dave silva via Gmclist <
gmclist@list.gmcnet.org> wrote:
> The coach has a disk brakes all around with very few miles on them. It
> sat for a while and there is rust on the rotors.
>
> The pedal feels consistent, it does not stiffen with pumping so i don't
> think there is a leak or a need to bleed.
>
> On a low speed stop they feel like they grab pretty well.
>
> At higher speed it feels like when you tow something way over your limit
> without trailer brakes (don't say you never did that)
>
>
> It just ignores your foot and slows down in its own time.
>
> Where do i start ?
>
>
>
>
> --
> Dave & Ellen Silva
>
> 1972 Revcon Olds 455, toro drive train. All Stock
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.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: [GMCnet] Brakes - disk all around, been sitting, where do i start ? [message #358472 is a reply to message #358470] |
Thu, 10 September 2020 11:50 |
6cuda6
Messages: 975
Registered: June 2019
Karma: -6
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Senior Member |
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If you decide to sand the pads do not sand them length wise...sand them across the width or you rotors will look like a record because the pads will work make grooves in them....some 40, 80 grit or what ever you have on hand placed, on a board etc [something flat], pads in hand not paper in hand and just simply clean off the pads surface....if they are grooved dont worry about sanding to remove the grooves.
stu@97381.com, Emery wrote on Thu, 10 September 2020 11:13First try some hard stopping to get the brake pads broken in to the rotors. If that doesn’t work take out the pads and sand the surfaces a little bit or replace them. I would suggest Performance Friction pads.
Emery Stora
77 Kingsley
Frederick CO
> On Sep 10, 2020, at 9:09 AM, dave silva via Gmclist wrote:
>
> The coach has a disk brakes all around with very few miles on them. It sat for a while and there is rust on the rotors.
>
> The pedal feels consistent, it does not stiffen with pumping so i don't think there is a leak or a need to bleed.
>
> On a low speed stop they feel like they grab pretty well.
>
> At higher speed it feels like when you tow something way over your limit without trailer brakes (don't say you never did that)
>
>
> It just ignores your foot and slows down in its own time.
>
> Where do i start ?
>
>
>
>
> --
> Dave & Ellen Silva
>
> 1972 Revcon Olds 455, toro drive train. All Stock
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
_______________________________________________
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Unsubscribe or Change List Options:
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Rich Mondor,
Brockville, ON
77 Hughes 2600
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| Re: [GMCnet] Brakes - disk all around, been sitting, where do i start ? [message #358473 is a reply to message #358472] |
Thu, 10 September 2020 12:19 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Dave, sounds to me like perhaps you have some hard rotors, combine those
with soft lining materials, and you can very quickly form a polished glassy
surface on the linings. My advice? Inspect the linings. If they are glazed,
two solutions. Replacement with semi-metallic pads (best) or deglazing the
pads with 60 grit open coat abrasive on a pad, not your hand and fingers.
(second best) If your disc brake conversion involved a P-30 master
cylinder, consider returning to an OEM master cylinder. You need all the
hydraulic pressure that you can get with all disc systems. Another option
might be a hydro-boost hydraulic master cylinder.
Jim Hupy
Salem, Oregon
On Thu, Sep 10, 2020, 9:50 AM 6cuda6--- via Gmclist
wrote:
> If you decide to sand the pads do not sand them length wise...sand them
> across the width or you rotors will look like a record because the pads will
> work make grooves in them....some 40, 80 grit or what ever you have on
> hand placed, on a board etc [something flat], pads in hand not paper in hand
> and just simply clean off the pads surface....if they are grooved dont
> worry about sanding to remove the grooves.
>
> stu@97381.com, Emery wrote on Thu, 10 September 2020 11:13
>> First try some hard stopping to get the brake pads broken in to the
> rotors. If that doesn’t work take out the pads and sand the surfaces a
>> little bit or replace them. I would suggest Performance Friction pads.
>>
>> Emery Stora
>> 77 Kingsley
>> Frederick CO
>>
>>> On Sep 10, 2020, at 9:09 AM, dave silva via Gmclist wrote:
>>>
>>> The coach has a disk brakes all around with very few miles on them.
> It sat for a while and there is rust on the rotors.
>>>
>>> The pedal feels consistent, it does not stiffen with pumping so i
> don't think there is a leak or a need to bleed.
>>>
>>> On a low speed stop they feel like they grab pretty well.
>>>
>>> At higher speed it feels like when you tow something way over your
> limit without trailer brakes (don't say you never did that)
>>>
>>>
>>> It just ignores your foot and slows down in its own time.
>>>
>>> Where do i start ?
>>>
>>>
>>>
>>>
>>> --
>>> Dave & Ellen Silva
>>>
>>> 1972 Revcon Olds 455, toro drive train. All Stock
>>>
>>>
>>>
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> --
> Rich Mondor,
>
> Brockville, ON
>
> 77 Hughes 2600
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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| Re: [GMCnet] Brakes - disk all around, been sitting, where do i start ? [message #358475 is a reply to message #358473] |
Thu, 10 September 2020 16:46 |
hertfordnc
Messages: 1164
Registered: September 2009
Location: East NC
Karma: 0
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Senior Member |
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I'm told the brakes worked really well when installed. It's whatever system Jim bounds was offering in 2013. I'm not going to do any re-engineering until i make it like it was.
Dave & Ellen Silva
Hertford, NC
76 Birchaven, 1-ton and other stuff
Currently planning the Great american Road Trip Summer 2021
It's gonna take a lot of Adderall to get this thing right.
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| Re: [GMCnet] Brakes - disk all around, been sitting, where do i start ? [message #358476 is a reply to message #358475] |
Thu, 10 September 2020 16:54 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Good thinking. But, the no braking when towing would surely prompt me into
doing something pretty wiki-wiki. (That means sooner, rather than later) At
least, don't tow anything till you sort it out.
Jim Hupy
Salem, Oregon
On Thu, Sep 10, 2020, 2:47 PM dave silva via Gmclist <
gmclist@list.gmcnet.org> wrote:
> I'm told the brakes worked really well when installed. It's whatever
> system Jim bounds was offering in 2013. I'm not going to do any
> re-engineering
> until i make it like it was.
>
>
> --
> Dave & Ellen Silva
>
> 1972 Revcon Olds 455, toro drive train. All Stock
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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| Re: Brakes - disk all around, been sitting, where do i start ? [message #358488 is a reply to message #358468] |
Fri, 11 September 2020 08:06 |
 |
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Dave,
The rusty brakes going bad with speed is something that was identified in our brake laps because mostly because of warranty issues. At lower surface speeds, the rust-dust doesn't move much, but at higher speeds it can fluidize and literally lubricate the friction surfaces. We looked for a cheap and quick fix for the report, and never found one.
The rust on the pad surface does not do much because it will inbed in the pad material unless it is a good metallic pad and then it won't matter.
The disk face is a different story. Clean that with a hard powered wire brush or open coat sandpaper just enough to make the surface look clean. If there is pitting remaining, that won't be real bad because the iron oxide will be coming out of that pitting with thermal cycles and at a relatively small rate.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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