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Original Master Cylinder - How to identify? [message #308978] Tue, 18 October 2016 08:54 Go to next message
jcurran is currently offline  jcurran   United States
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Registered: May 2009
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Member
Hi Folks,
Does anyone know how to determine if a master cylinder is original?

Also, when putting brake lines together should there be any kind of thread sealant or just metal to metal?

Thanks,
Jim


Jim Curran 1976 Palm Beach Alexandria, OH
Re: [GMCnet] Original Master Cylinder - How to identify? [message #308987 is a reply to message #308978] Tue, 18 October 2016 09:54 Go to previous messageGo to next message
powerjon is currently offline  powerjon   United States
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Registered: January 2004
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Senior Member
Jim,

The look of the stock brake master cylinder should be similar to this.

http://www.gmcmhphotos.com/photos/general-pictures/p59294-dl-brake-layout.html
and


If you have a P30 brake master cylinder then it will look like this.



Look at the 3 pictures under the main picture.

JR Wright
78 Buskirk Stretch
75 Avion
Michigan


> On Oct 18, 2016, at 9:54 AM, Jim Curran wrote:
>
> Hi Folks,
> Does anyone know how to determine if a master cylinder is original?
>
> Also, when putting brake lines together should there be any kind of thread sealant or just metal to metal?
>
> Thanks,
> Jim
>
> --
> Jim Curran
> 1976 Palm Beach
> Alexandria, OH

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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
Re: [GMCnet] Original Master Cylinder - How to identify? [message #308988 is a reply to message #308978] Tue, 18 October 2016 09:51 Go to previous messageGo to next message
Dolph Santorine is currently offline  Dolph Santorine   United States
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Registered: April 2011
Location: Wheeling, WV
Karma: -41
Senior Member
I don’t know if there are markings on the master cylinder, and if you would be able to tell.

You can see if it’s an original type part.

Also, flared fitting create their own seal.

I have a power bleeding kit. Let me know if you want me to bring it by.

Dolph

DE N8JPC

Wheeling, West Virginia

1977 26’ ex-PalmBeach
1-Ton, Sullybilt Bags, Reaction Arms, 3.70 LSD, Manny Transmission, EV-6010

“The Aluminum and Fiberglass Mistress"





> On Oct 18, 2016, at 9:54 AM, Jim Curran wrote:
>
> Hi Folks,
> Does anyone know how to determine if a master cylinder is original?
>
> Also, when putting brake lines together should there be any kind of thread sealant or just metal to metal?
>
> Thanks,
> Jim
>
> --
> Jim Curran
> 1976 Palm Beach
> Alexandria, OH
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

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Re: Original Master Cylinder - How to identify? [message #308996 is a reply to message #308978] Tue, 18 October 2016 11:23 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
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Registered: March 2007
Location: S.E. Michigan
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Senior Member
jcurran wrote on Tue, 18 October 2016 09:54
Hi Folks,
Does anyone know how to determine if a master cylinder is original?

Also, when putting brake lines together should there be any kind of thread sealant or just metal to metal?

Thanks,
Jim

Jim,

As a resident of a rust-belt state. Do yourself and the next owner a favor.
As you will be doing a flush and bleed with the master cylinder change, take the time to get new rubber caps for all the bleed screws (6). And while you are messing with it, take each bleed screw out and clean it and wrap it with teflon tape. This is not for system sealing. It is to keep:
A - The road water from getting in to the threads of the bleed screw and corroding them, and
B - The brake fluid leaked during bleeding from getting in to the threads of the bleed screw and corroding them.
I started doing this about 30 years ago and have not broken a bleed screw that was so treated yet. (I was using pipe dope, but Chuck Boyd suggested the teflon tape and it works even better.)

While the system sealing is all done by the flare, a coat of anti-seize or pipe dope on the line nut threads will simply make life easier for someone else done the road.

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
Re: [GMCnet] Original Master Cylinder - How to identify? [message #309029 is a reply to message #308978] Tue, 18 October 2016 23:58 Go to previous messageGo to next message
jimk is currently offline  jimk   United States
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Location: Belmont, CA
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Senior Member
Most brake fittings fit in a way to where you do not use sealants.
Should you have problems, you can use a flared copper washer to create a
better seal.

On Tue, Oct 18, 2016 at 6:54 AM, Jim Curran wrote:

> Hi Folks,
> Does anyone know how to determine if a master cylinder is original?
>
> Also, when putting brake lines together should there be any kind of thread
> sealant or just metal to metal?
>
> Thanks,
> Jim
>
> --
> Jim Curran
> 1976 Palm Beach
> Alexandria, OH
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>



--
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
Re: Original Master Cylinder - How to identify? [message #309036 is a reply to message #308978] Wed, 19 October 2016 06:47 Go to previous messageGo to next message
jcurran is currently offline  jcurran   United States
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Registered: May 2009
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Member
Thanks for the pointers, guys.

Dolph your generosity never seems to end. Looking forward to showing you my paint job.


FWIW the only marks I can see now are on the left side, as the cylinder is mounted:

614003 or 614009.
LOTS of surface rust which is what has me wondering if it is original. In any case it is getting replaced.

Jim


Jim Curran 1976 Palm Beach Alexandria, OH
Re: Original Master Cylinder - How to identify? [message #309038 is a reply to message #308978] Wed, 19 October 2016 10:09 Go to previous message
77Royale   United States
Messages: 461
Registered: June 2014
Location: Mid Michigan
Karma: 6
Senior Member
If you haven't already you may look to Dave Lenzi for a new Master, He machines the mounting ears so the nuts have enough threads to provide a proper bite.

I got mine from him along with a sensitized booster and push rod and am very very happy with the results.

http://www.bdub.net/lenzi/


77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy. Mid Michigan
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