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[GMCnet] Soft Brake issue??? [message #155108] Mon, 02 January 2012 13:03 Go to next message
JP Winger is currently offline  JP Winger   United States
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Registered: September 2011
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Member
Happy New Year!

My brakes have gone soft. I push them in hard and they hardly stop the bus. I can pump them hard again but it's a momentary fix.

The brake fluid is really dirty / dark and overflowing in the front 'well' and about an inch from the top at the back one.

It happened a couple of weeks ago around the time our alt belt broke and the battery died but it came right, perhaps after I mopped out the fluid from the 2 wells and refilled it?!

It also seems to be overflowing / leaking a little from the front well, and when I started to open it while hot yesterday (guessing now your not supposed to do that?) it started to overflow as I was prying the top off so I quickly closed it.

So, is it usually so dark and any suggestions on what I should do??
Is synthetic Dot 3 ok to use?? that's what I put in it last time.

Thanks!

JP


John-Paul Winger & Miriam Clancy | US+1 310 9231126 | NZ+64 21 997919 | Skype:lavidalocations | facebook.com/ilovemiriamclancy

1973 26' Canyon Lands

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Re: [GMCnet] Soft Brake issue??? [message #155111 is a reply to message #155108] Mon, 02 January 2012 13:27 Go to previous messageGo to next message
JohnL455 is currently offline  JohnL455   United States
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Location: Woodstock, IL
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JP just guessing but I'm guessing the master cyl. If you filled both evenly and it's pumping from rear and overflowing front??? internal seal issue? Should be easy swap and since the lines are up high you can bleed the master with the lines ajar and then snug them down. If the lines are up high and still full there should be very little air that gets in. You can do the 2 person pressure on pedal, loosen, tighten sequence to be sure the master is air free. Then you can flush and bleed the entire system later when you are in a better location. I use good old store brand DOT 3 as you aren't on the race track. Buy a flair nut wrench before you start so you don't round off the lines.

John Lebetski
Woodstock, IL
77 Eleganza II
Re: [GMCnet] Soft Brake issue??? [message #155115 is a reply to message #155111] Mon, 02 January 2012 13:53 Go to previous messageGo to next message
JP Winger is currently offline  JP Winger   United States
Messages: 86
Registered: September 2011
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Ah thanks John,

Although it's mostly gobblydegook to me, as don't know where/what the master cylinder is etc. But I'll try and muddle my way through the manual.

So do I potentially need to buy a seal?? Are they hard to come by parts-wize?

So open the lines somewhere, not sure what you mean by snug them down but I guess I need to familiarize myself with the parts to hold a decent conversation.

I'm in a kind of ok location at the moment - parked on the road outside our temp apartment in Brooklyn... and there's an autozone 300 yards up the road which is a plus. SO maybe it's better I learn how to bleed the system to start with.

I take it if I get someone to pump the pedal I do something at the same time??
> You can do the 2 person pressure on pedal, loosen, tighten sequence to be sure the master is air free.



Thanks!
JP

310 9231126


On 2/01/2012, at 2:27 PM, John R. Lebetski wrote:

>
>
> JP just guessing but I'm guessing the master cyl. If you filled both evenly and it's pumping from rear and overflowing front??? internal seal issue?
> Should be easy swap and since the lines are up high you can bleed the master with the lines ajar and then snug them down. If the lines are up high and still full there should be very little air that gets in. You can do the 2 person pressure on pedal, loosen, tighten sequence to be sure the master is air free. Then you can flush and bleed the entire system later when you are in a better location. I use good old store brand DOT 3 as you aren't on the race track. Buy a flair nut wrench before you start so you don't round off the lines.
> --
> John Lebetski
> Chicago, IL
> 77 Eleganza II
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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Re: [GMCnet] Soft Brake issue??? [message #155120 is a reply to message #155115] Mon, 02 January 2012 15:31 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
Senior Member
Lets make this easy on you. Go to AutoZone and get a Master cylinder for a 75 Toronado. The part numbers you need are listed in the GMCMI parts interchange book which I do not have in front of me right now.

Also get a quart of DOT 4 Brake fluid. DOT 4 and DOT 3 are Compatible and DOT 4 has a higher wet boiling point that you will appreciate later. DO NOT USE SYNTHETIC DOT 5.

Before installing the new master cylinder compare the size of the brake line fittings on the one you bought with the one you currently have installed. The reason for this is the 1978 GMC used a different master cylinder and the fitting sizes are reversed.

Once you have determined that you have the correct master cylinder, remove the two lines from the old master cylinder and the 2 mounting bolts. There is a vertical mounting bracket that may also need to come off which is 2 more vertical bolts. The cylinder will then come off in your hands. Do not loose the push rod between the master cylinder and the brake booster.

Again compare your new one to the old one to be sure they are the same.

Install the new one. It should come with two short lines. Install the supplied two short lines so the ends put the fluid back into the reservoir. Fill the reservoir with DOT 4 fluid and have someone slowly step on and release the brake pedal. Watch the fluid while they are slowly pumping the pedal. What you are doing is running fluid through the master cylinder and back to the reservoir to remove the air in the master cylinder. This is called bench bleeding and there should be instructions to do this included with the Master cylinder.

When you no longer see any bubbles in the fluid the remove the short bleeding tubes and attach the coach brake lines. Your installation is done.

Now you get to bleed the system. Your brakes might work right now but there is still air in the system. Also with all of the dirt you said you have observed in the old master cylinder they definitely need to be bled.

There are 5 different methods to accomplish bleeding
1. Pressure
2. Pump the pedal
3. Vacuum
4. Gravity
5. Reverse pressure (DO NOT DO THIS ONE as it will force dirt and dirty fluid back into the master cylinder.)

I have done all of them at different times and all will work. Which method you choose is probably dependent on the equipment / tools you have available.

How about we hold this as a different discussion after we determine if you are going to replace the master cylinder yourself.


Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
Re: [GMCnet] Soft Brake issue??? [message #155125 is a reply to message #155115] Mon, 02 January 2012 16:27 Go to previous messageGo to next message
emerystora is currently offline  emerystora   United States
Messages: 4442
Registered: January 2004
Karma: 13
Senior Member
NO, you don't buy a seal. You bur a replacement master cylinder.

Reread Johns email to you he said the internal sealight be bad but he
didnt say to replace the seal that would mean that you would have to
rebuild the master cylinder yourself including honing out the bote,
replacing pistons and other parts

John said you should replace the master cylinder Llet a professional
rebuild it. Many of the rebuilt ones at the auto parts store are
rebuilt fine but once in a while you get a bad one.

You might consider buying it from Applied GMC as you should get a good
one from them


Emery Stora

O
On Jan 2, 2012, at 12:53 PM, JP Winger <lavidalocations@gmail.com>
wrote:

> Ah thanks John,
>
> Although it's mostly gobblydegook to me, as don't know where/what
> the master cylinder is etc. But I'll try and muddle my way through
> the manual.
>
> So do I potentially need to buy a seal?? Are they hard to come by
> parts-wize?
>
> So open the lines somewhere, not sure what you mean by snug them
> down but I guess I need to familiarize myself with the parts to hold
> a decent conversation.
>
> I'm in a kind of ok location at the moment - parked on the road
> outside our temp apartment in Brooklyn... and there's an autozone
> 300 yards up the road which is a plus. SO maybe it's better I learn
> how to bleed the system to start with.
>
> I take it if I get someone to pump the pedal I do something at the
> same time??
>> You can do the 2 person pressure on pedal, loosen, tighten sequence
>> to be sure the master is air free.
>
>
>
> Thanks!
> JP
>
> 310 9231126
>
>
> On 2/01/2012, at 2:27 PM, John R. Lebetski wrote:
>
>>
>>
>> JP just guessing but I'm guessing the master cyl. If you filled
>> both evenly and it's pumping from rear and overflowing front???
>> internal seal issue?
>> Should be easy swap and since the lines are up high you can bleed
>> the master with the lines ajar and then snug them down. If the
>> lines are up high and still full there should be very little air
>> that gets in. You can do the 2 person pressure on pedal, loosen,
>> tighten sequence to be sure the master is air free. Then you can
>> flush and bleed the entire system later when you are in a better
>> location. I use good old store brand DOT 3 as you aren't on the
>> race track. Buy a flair nut wrench before you start so you don't
>> round off the lines.
>> --
>> John Lebetski
>> Chicago, IL
>> 77 Eleganza II
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
> _______________________________________________
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> Unsubscribe or Change List Options:
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Re: [GMCnet] Soft Brake issue??? [message #155127 is a reply to message #155125] Mon, 02 January 2012 16:55 Go to previous messageGo to next message
JP Winger is currently offline  JP Winger   United States
Messages: 86
Registered: September 2011
Karma: 0
Member
Ok, thanks all - can I do this with a standard socket set, etc and perhaps a flair nut wrench and my limited investigative approach?

And so pretty certain the diagnosis would be replace the master cylinder - sure I don't just need to bleed and replace the oil?

Thanks!
JP

On 2/01/2012, at 5:27 PM, Emery Stora wrote:
> it from Applied GMC as you should get a good
> one from them
>
>
> Emery Stora
>
>
NO, you don't buy a seal. You bur a replacement master cylinder.

Reread Johns email to you he said the internal sealight be bad but he
didnt say to replace the seal that would mean that you would have to
rebuild the master cylinder yourself including honing out the bote,
replacing pistons and other parts

John said you should replace the master cylinder Llet a professional
rebuild it. Many of the rebuilt ones at the auto parts store are
rebuilt fine but once in a while you get a bad one.

You might consider buying
>
> O
> On Jan 2, 2012, at 12:53 PM, JP Winger <lavidalocations@gmail.com>
> wrote:
>
>> Ah thanks John,
>>
>> Although it's mostly gobblydegook to me, as don't know where/what
>> the master cylinder is etc. But I'll try and muddle my way through
>> the manual.
>>
>> So do I potentially need to buy a seal?? Are they hard to come by
>> parts-wize?
>>
>> So open the lines somewhere, not sure what you mean by snug them
>> down but I guess I need to familiarize myself with the parts to hold
>> a decent conversation.
>>
>> I'm in a kind of ok location at the moment - parked on the road
>> outside our temp apartment in Brooklyn... and there's an autozone
>> 300 yards up the road which is a plus. SO maybe it's better I learn
>> how to bleed the system to start with.
>>
>> I take it if I get someone to pump the pedal I do something at the
>> same time??
>>> You can do the 2 person pressure on pedal, loosen, tighten sequence
>>> to be sure the master is air free.
>>
>>
>>
>> Thanks!
>> JP
>>
>> 310 9231126
>>
>>
>> On 2/01/2012, at 2:27 PM, John R. Lebetski wrote:
>>
>>>
>>>
>>> JP just guessing but I'm guessing the master cyl. If you filled
>>> both evenly and it's pumping from rear and overflowing front???
>>> internal seal issue?
>>> Should be easy swap and since the lines are up high you can bleed
>>> the master with the lines ajar and then snug them down. If the
>>> lines are up high and still full there should be very little air
>>> that gets in. You can do the 2 person pressure on pedal, loosen,
>>> tighten sequence to be sure the master is air free. Then you can
>>> flush and bleed the entire system later when you are in a better
>>> location. I use good old store brand DOT 3 as you aren't on the
>>> race track. Buy a flair nut wrench before you start so you don't
>>> round off the lines.
>>> --
>>> John Lebetski
>>> Chicago, IL
>>> 77 Eleganza II
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> _______________________________________________
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Re: [GMCnet] Soft Brake issue??? [message #155133 is a reply to message #155120] Mon, 02 January 2012 18:04 Go to previous messageGo to next message
Bob de Kruyff   United States
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
Senior Member
""Before installing the new master cylinder compare the size of the brake line fittings on the one you bought with the one you currently have installed. The reason for this is the 1978 GMC used a different master cylinder and the fitting sizes are reversed.

""

Ken, I'm sort of baffled by that.I have a 78 and had to install a 76 MC since I was on the road and at the time only Cinnabar had a true 78 MC. All the lines fit just fine. The tube nuts have a different size hex, but the actual threaded portions are the same front and rear.


Bob de Kruyff
78 Eleganza
Chandler, AZ
Re: [GMCnet] Soft Brake issue??? [message #155135 is a reply to message #155127] Mon, 02 January 2012 18:10 Go to previous messageGo to next message
Bob de Kruyff   United States
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
Senior Member
""Ok, thanks all - can I do this with a standard socket set, etc and perhaps a flair nut wrench and my limited investigative approach?

And so pretty certain the diagnosis would be replace the master cylinder - sure I don't just need to bleed and replace the oil?

""

Those tube fittings can be a real bugger some times. Also, make sure the master cylinder gets bled otherwise it will hold that air forever. If you get the air out of the cylinder, the rest of the system won;t need bleeding. It does sound like your brake fluid should be totally purged when you get a chance,


Bob de Kruyff
78 Eleganza
Chandler, AZ
Re: [GMCnet] Soft Brake issue??? [message #155136 is a reply to message #155133] Mon, 02 January 2012 18:11 Go to previous messageGo to next message
emerystora is currently offline  emerystora   United States
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Registered: January 2004
Karma: 13
Senior Member
Bob
You have me baffled by your statement that the threaded portions are the same, front and rear.
The original GMC master cyclinders have a 9/16" in the front and a 1/2" in the rear.

When I installed my 34 mm master cylinder I had to reverse the lines as the front was 1/2" and the rear was 9/16".

Are you absolutely certain that they are the same? That would be highly unusual and if so, I wonder what master cylinder you have?
If your nuts have different size wrench hexes then I would suspect that they are two different size openings.

Emery Stora

On Jan 2, 2012, at 5:04 PM, Bob de Kruyff wrote:

>
>
> ""Before installing the new master cylinder compare the size of the brake line fittings on the one you bought with the one you currently have installed. The reason for this is the 1978 GMC used a different master cylinder and the fitting sizes are reversed.
>
> ""
>
> Ken, I'm sort of baffled by that.I have a 78 and had to install a 76 MC since I was on the road and at the time only Cinnabar had a true 78 MC. All the lines fit just fine. The tube nuts have a different size hex, but the actual threaded portions are the same front and rear.
> --
> Bob de Kruyff
> 78 Eleganza
> Chandler, AZ
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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Re: [GMCnet] Soft Brake issue??? [message #155154 is a reply to message #155136] Mon, 02 January 2012 20:40 Go to previous messageGo to next message
Bob de Kruyff   United States
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
Senior Member

Bob
You have me baffled by your statement that the threaded portions are the same, front and rear.
The original GMC master cyclinders have a 9/16" in the front and a 1/2" in the rear.

When I installed my 34 mm master cylinder I had to reverse the lines as the front was 1/2" and the rear was 9/16".

Are you absolutely certain that they are the same? That would be highly unusual and if so, I wonder what master cylinder you have?
If your nuts have different size wrench hexes then I would suspect that they are two different size openings.

""

I'll double check that Emery but I distinctly remember that when I replaced the MC in Dayton, when the gal gave me the replacement I first told her it was the wrong one because both ports were the same size thread. She assured me it was correct and since I was only parked across the street, I thought it was worth a try. I was amazed when I got the tube fittings out that the thread size was the same!! I may have a pic somewhere, if not, I'll take one.


Bob de Kruyff
78 Eleganza
Chandler, AZ
Re: [GMCnet] Soft Brake issue??? [message #155160 is a reply to message #155136] Mon, 02 January 2012 21:01 Go to previous messageGo to next message
Bob de Kruyff   United States
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
Senior Member
emerystora wrote on Mon, 02 January 2012 17:11

Bob
You have me baffled by your statement that the threaded portions are the same, front and rear.
The original GMC master cyclinders have a 9/16" in the front and a 1/2" in the rear.

When I installed my 34 mm master cylinder I had to reverse the lines as the front was 1/2" and the rear was 9/16".

Are you absolutely certain that they are the same? That would be highly unusual and if so, I wonder what master cylinder you have?
If your nuts have different size wrench hexes then I would suspect that they are two different size openings.

Emery Stora

On Jan 2, 2012, at 5:04 PM, Bob de Kruyff wrote:

>
>
> ""Before installing the new master cylinder compare the size of the brake line fittings on the one you bought with the one you currently have installed. The reason for this is the 1978 GMC used a different master cylinder and the fitting sizes are reversed.
>
> ""
>
> Ken, I'm sort of baffled by that.I have a 78 and had to install a 76 MC since I was on the road and at the time only Cinnabar had a true 78 MC. All the lines fit just fine. The tube nuts have a different size hex, but the actual threaded portions are the same front and rear.
> --
> Bob de Kruyff
> 78 Eleganza
> Chandler, AZ
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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Here's a pic of the M/C from autozone--although it's not for certain, but the openings look the same here. I'll just have to check the coach since my curiosity is up now
: http://www.autozone.com/autozone/parts/Fenco-Reman-Master-Cylinder-Brake-System/1978-Oldsmobile-Toronado/_/N-in5hxZ8kn47?counter=1&filterByKeyWord =master+cylinder&fromString=search&itemIdentifier=227967_56045_0_


Bob de Kruyff
78 Eleganza
Chandler, AZ
Re: [GMCnet] Soft Brake issue??? [message #155174 is a reply to message #155160] Mon, 02 January 2012 23:03 Go to previous messageGo to next message
JP Winger is currently offline  JP Winger   United States
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Thanks for the link, I now know what I'm looking at.

John-Paul Winger / US+1 310 9231126 / NZ+64 21 997919 / lavidalocations@gmail.com / Skype: lavidalocations

On Jan 2, 2012, at 10:01 PM, Bob de Kruyff <NEXT2POOL@AOL.COM> wrote:

>
>
> emerystora wrote on Mon, 02 January 2012 17:11
>> Bob
>> You have me baffled by your statement that the threaded portions are the same, front and rear.
>> The original GMC master cyclinders have a 9/16" in the front and a 1/2" in the rear.
>>
>> When I installed my 34 mm master cylinder I had to reverse the lines as the front was 1/2" and the rear was 9/16".
>>
>> Are you absolutely certain that they are the same? That would be highly unusual and if so, I wonder what master cylinder you have?
>> If your nuts have different size wrench hexes then I would suspect that they are two different size openings.
>>
>> Emery Stora
>>
>> On Jan 2, 2012, at 5:04 PM, Bob de Kruyff wrote:
>>
>>>
>>>
>>> ""Before installing the new master cylinder compare the size of the brake line fittings on the one you bought with the one you currently have installed. The reason for this is the 1978 GMC used a different master cylinder and the fitting sizes are reversed.
>>>
>>> ""
>>>
>>> Ken, I'm sort of baffled by that.I have a 78 and had to install a 76 MC since I was on the road and at the time only Cinnabar had a true 78 MC. All the lines fit just fine. The tube nuts have a different size hex, but the actual threaded portions are the same front and rear.
>>> --
>>> Bob de Kruyff
>>> 78 Eleganza
>>> Chandler, AZ
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>> _______________________________________________
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>
> Here's a pic of the M/C from autozone--although it's not for certain, but the openings look the same here. I'll just have to check the coach since my curiosity is up now
> :http://www.autozone.com/autozone/parts/Fenco-Reman-Master-Cylinder-Brake-System/1978-Oldsmobile-Toronado/_/N-in5hxZ8kn47?counter=1&filterByKeyWor d=master+cylinder&fromString=search&itemIdentifier=227967_56045_0_
> --
> Bob de Kruyff
> 78 Eleganza
> Chandler, AZ
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Re: [GMCnet] Soft Brake issue??? [message #155180 is a reply to message #155154] Tue, 03 January 2012 01:30 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
Messages: 10030
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Location: Hebron, Indiana
Karma: 10
Senior Member
Bob,

I was transporting a 1978 GMC to the west coast for someone a few years back and the master cylinder developed leak. I stopped at AZ somewhere is the midwest and bought a Master cylinder for a GMC based on the GMCMI parts listing. I also bought 2 quarts of Fluid. I intended to change out the master cylinder but got lazy and simply filled up the old one. The brakes worked fine but I needed to top off the MC at least once a day. I drove it that way all the way to California.

I gave the new AZ supplied MC to the owner. Later when he went to install it he discovered that the MC on his coach had the size of the lines reversed. The owner of the 78 GMC returned the MC to AZ. He had to look around for a while before he found one froma different supplier that fit his coach.

I used that same MC part number on my 76 so I know by part number at least that it works on a 76 GMC. This was my basis for warning the GMCer to check the line sizes before removing the old MC.

I guess it is possible that the MC in the box did not match the part number on the outside. I never tried to install it myself so my knowledge is second hand. I believe that the owner knew what he was doing. He is a trusted member of GMCnet and the GMC community. So I'm 95% sure my information is correct.


Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
Re: [GMCnet] Soft Brake issue??? [message #155181 is a reply to message #155135] Tue, 03 January 2012 01:34 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
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I'm not sure but I think you might need a box end wrenche to get to the mounting nuts. Take a look and see if you can get to them with a socket.

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
Re: [GMCnet] Soft Brake issue??? [message #155193 is a reply to message #155160] Tue, 03 January 2012 07:38 Go to previous messageGo to next message
USAussie is currently offline  USAussie   United States
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Bob,

Take a look at this photo - it appears to me that the front line has a larger OD.

http://www.gmcmhphotos.com/photos/showphoto.php?photo=26032

Regards,
Rob M.

-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Bob de Kruyff

Here's a pic of the M/C from autozone--although it's not for certain, but the openings look the same here. I'll just have to check
the coach since my curiosity is up now

:http://www.autozone.com/autozone/parts/Fenco-Reman-Master-Cylinder-Brake-System/1978-Oldsmobile-Toronado/_/N-in5hxZ8kn47?counter=1&
filterByKeyWord=master+cylinder&fromString=search&itemIdentifier=227967_56045_0_

Bob

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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
Re: [GMCnet] Soft Brake issue??? [message #155206 is a reply to message #155108] Tue, 03 January 2012 09:39 Go to previous messageGo to next message
Hardie Johnson is currently offline  Hardie Johnson   United States
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Senior Member
JP Winger wrote on Mon, 02 January 2012 14:03

My brakes have gone soft. I push them in hard and they hardly stop the bus. I can pump them hard again but it's a momentary fix.
The brake fluid is really dirty / dark and overflowing in the front 'well' and about an inch from the top at the back one.
<>
Is synthetic Dot 3 ok to use?? that's what I put in it last time.
<>

John, DOT3 is fine, DOT4 may be better, DOT5 is _not_ good for us.
I am concerned that you are thinking to do a master cylinder change with the current weather and your apparent skill level. Can you get help; is there a Black list GMCer nearby?
Unless you plan a long trip soon, I'd suggest you just flush the system and refill as needed.
The best bleed method is a power bleeder with a big reservoir of fluid. You fill it, attach to master cylinder, pump it up, then just go around and open the bleeders one at a time, checking for the fresh fluid and making sure you do not empty the tank.
Bleeders tend to be rusty; be sure you soak in Kroil or another rust breaker SEVERAL DAYS BEFORE YOU START.(brake fluid mixed with transmission oil has been suggested) A box wrench is important for this part as they are easy to round off.
If you break one it is no big deal, just buy a new _pair_ of calipers or wheel cylinders. They are easy to change and not horribly expensive. There are detailed directions on bleeding brakes all over the network. There was a discussion of the balancing valve here just this week.
Good luck.
sings:"what are you doing New Year's Eve^W week?"


Hardie Johnson "Crashj"
1973 26 foot Glacier, White Thing
Raleigh NC
Re: [GMCnet] Soft Brake issue??? [message #155237 is a reply to message #155193] Tue, 03 January 2012 12:36 Go to previous messageGo to next message
Bob de Kruyff   United States
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
Senior Member
Robert Mueller wrote on Tue, 03 January 2012 06:38

Bob,

Take a look at this photo - it appears to me that the front line has a larger OD.

http://www.gmcmhphotos.com/photos/showphoto.php?photo=26032

Regards,
Rob M.

-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Bob de Kruyff

Here's a pic of the M/C from autozone--although it's not for certain, but the openings look the same here. I'll just have to check
the coach since my curiosity is up now

:http://www.autozone.com/autozone/parts/Fenco-Reman-Master-Cylinder-Brake-System/1978-Oldsmobile-Toronado/_/N-in5hxZ8kn47?counter=1&
filterByKeyWord=master+cylinder&fromString=search&itemIdentifier=227967_56045_0_

Bob

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Yes--that is definitley the case and mine is like that as well. The rear brakes flow more fluid. My curiosity is definitely up but I can't check my coach till Saturday. Logic would tll you that the enire front fitting is larger but I distinctly remember being surprised by the fact that it wasn't--only the hex. I was sober when I installed the MC so maybe that's the proble.


Bob de Kruyff
78 Eleganza
Chandler, AZ
Re: [GMCnet] Soft Brake issue??? [message #155276 is a reply to message #155206] Tue, 03 January 2012 17:06 Go to previous messageGo to next message
Nelson Wright is currently offline  Nelson Wright   United States
Messages: 147
Registered: May 2004
Karma: 0
Senior Member

On Jan 3, 2012, at 10:39 AM, Hardie Johnson wrote:

>
>
> Bleeders tend to be rusty; be sure you soak in Kroil or another rust
> breaker SEVERAL DAYS BEFORE YOU START.(brake fluid mixed with
> transmission oil has been suggested) A box wrench is important for
> this part as they are easy to round off.

Hardie,
I don't know if "brake fluid mixed with transmission oil" works for a
penetrating oil, but Acetone/ATF mixture does. And I would recommend
a FLARE NUT wrench for those bleed fittings

Nelson Wright
Orlando FL
78 Royale rear bath



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Re: [GMCnet] Soft Brake issue??? [message #155281 is a reply to message #155108] Tue, 03 January 2012 17:55 Go to previous messageGo to next message
JohnL455 is currently offline  JohnL455   United States
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
Senior Member
Right JP, No "seal" to buy. I meant internal MC seal issue, an internal leak as if you had a hole in your heart chamber to chamber. Of course if you can have JimK overnight or 2 day the MC to you for a 73 then all the guesswork is eliminated. The OE MC is good to hang on to for the core per Emery. I was only suggesting NOT to bleed the entire system (only bench bleed the MC as suggested) as doing the full bleed is not a NYC curbside friendly winter project. And dangerous without proper saftey equipment for jacking. AND I can bet you will have a rusted bleeder or 4 and you need the bleeder wrench. If you break one off, you are in for major cold curb work. NG. Agree DOT 4 is better but since you are not running Laguna Seca this winter 3 will work fine. No DOT 5 silicone racing fluid as it does not absorb water in a sacrificial manner. Just like ringing off the bleeders, be carefull when you rotate the flair nuts to be sure the tubing is not twisting. I'd WD40 or Kroil at the tube to flair nut junction before trying. Don't mean to be the doom sayer here, just putting it in the perspective of working on a cold NY street and not wanting you to get in deeper than necessary. I know I wouldn't want to try to work in those conditions. That's a young man's sport.

John Lebetski
Woodstock, IL
77 Eleganza II
Re: [GMCnet] Soft Brake issue??? [message #155294 is a reply to message #155276] Tue, 03 January 2012 19:15 Go to previous messageGo to previous message
jhbridges is currently offline  jhbridges   United States
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
Senior Member
Second the flare nut wrench idea.  And on really old/cruddy ones, after some PB Blaster or Kroil for a few days, apply the red wrench gently, enough to warm the housing the fitting is in, then take a pair of ViceGrips <tm> and glom onto the flare wrench so that it can't expand any at all.   Then get down on it.  You may wring off the fitting, but you won't round the corners.
 
--johnny
 
'76 23' Transmode norris
'76 palm beach


________________________________
From: Nelson Wright <f25ccapt@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Tuesday, January 3, 2012 6:06 PM
Subject: Re: [GMCnet] Soft Brake issue???


On Jan 3, 2012, at 10:39 AM, Hardie Johnson wrote:

>
>
> Bleeders tend to be rusty; be sure you soak in Kroil or another rust 
> breaker SEVERAL DAYS BEFORE YOU START.(brake fluid mixed with 
> transmission oil has been suggested) A box wrench is important for 
> this part as they are easy to round off.

Hardie,
I don't know if "brake fluid mixed with transmission oil" works for a 
penetrating oil, but Acetone/ATF mixture does.  And I would recommend 
a FLARE NUT wrench for those bleed fittings

Nelson Wright
Orlando FL
78 Royale rear bath



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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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