Home » Public Forums » GMCnet » [GMCnet] Disc brake project still in failure mode
| Re: [GMCnet] Disc brake project still in failure mode [message #281980 is a reply to message #281958] |
Mon, 13 July 2015 06:59   |
Neil Fonville
Messages: 68
Registered: May 2014
Karma:
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Member |
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Jim,
I will inspect for the gaps. With one set of the wheels off on one side
at a time, I don¹t see any gap but will look much more closely.
How important is the parking brake being setup correctly initially. I
have not done that yet. I was planning on that being the last step?
Thanks,
Neil
On 7/12/15, 8:19 PM, "Gmclist on behalf of James Hupy"
wrote:
> Neil, Jack up your coach and remove the wheels and tires. I surmise here
> that you have the rear/rear calipers with parking brakes. I have found
> that
> if the short lug protruding from the inside brake pad is not indexed with
> the caliper piston that the pad will not sit squarely onto the piston, and
> there will be way too much space between the components. That pad material
> should ride in slight contact with the rotor when they are broken in, and
> there should also be no visible space between the caliper piston and the
> backing plate on the pad. Same on all disc/rotors. If you broke the
> retaining clip off the back of the pad and left anything sticking up in
> the
> middle of the pad where the rivet is, the pad should be removed and the
> rivet head ground down. Also you need to pre adjust the parking brake
> ratcheting mechanism to eliminate all the space. If you have clearance
> where I have just described, you will use up available pedal travel taking
> up that clearance before any pressure can build up in the system. Low
> pedal, and poor stopping is the result.
> Jim Hupy
> Salem, Oregon
> 78 GMC ROYALE 403
> On Jul 12, 2015 5:20 PM, "Neil Fonville" wrote:
>
>> I'm back to working on my brake project and just not getting it done.
>> Still have soft pedal and it's takes way too much distance to stop.
>> It's
>> far worse from where is started with 2 Disc and 4 Drums that were not
>> working good.
>>
>> Here is rehash of what steps I have taken and maybe someone can help get
>> me back on track. I'm still amazed I can't find a mechanic/shop in the
>> Dallas area that could help me with my projects.
>>
>> First I installed the Manny rear disc brake kit. Install was straight
>> forward.
>> Bleed the system with the standard 2 man pump and release fluid method.
>> Never felt right and the vehicle was not even remotely drivable.
>> Replaced proportion valve with Disc/Disc model.
>> Removed OEM MC and replaced MC with new one from O'rilly. Used the P30
>> (PN
>> NMC1668).
>> Did not bench bleed. Bleed with 2 man pump and release fluid. Still
>> pedal too soft and not drivable. Removed MC and put on bench and found
>> front chamber not pushing fluid.
>> Replaced with another new MC from O'rilly same part number. Pedal
>> pumped
>> up tighter but it leaked between the fluid reservoir and cast metal
>> piston. Still not drivable.
>> Replaced MC with new one from Autozone (PN NM1641 ). Purchased the Hupy
>> bleeder. Bleed according to his directions which is RR moving to LF.
>> Removed lots of air and pumped about 1/2 gallon of fluid through the
>> system. Still not drivable, pedal too soft and vehicle does not stop.
>> From 30 to zero takes about 1/4 mile.
>>
>> So how do I go about troubleshooting the individual components? How do
>> I
>> test hydraulic pressure?
>>
>> I'm hoping for someone to give me a systematic approach to resolve this
>> and get this working.
>>
>> Yes, I have spoke with Manny and I really don't think any of the
>> calipers
>> are defective.
>>
>> Thanks Neil Fonville
>> 1975 GMC II
>>
>>
>>
>>
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1975 GMC II
Allen, TX
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