GMCforum: GMCnet » Re: [GMCnet] update on master cylinder replace

Home » Public Forums » GMCnet » Re: [GMCnet] update on master cylinder replace

Show: Today's Messages :: Polls :: Message Navigator

Re: [GMCnet] update on master cylinder replace [message #198212]

Tue, 12 February 2013 10:19

Messages: 1262
Registered: September 2009

Karma: 0

Senior Member

> The simple short answer is - NO.

Thanks Matt.

So what is the difference between a master cylinder for
disc-disc and one for disc-drum? There's a huge variety
of master cylinders listed for things like P30 vehicles.
Sometimes the units even look identical on the outside,
but are listed for different applications.

thanks
Karen
1973 23'
1975 26'

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

Karen 1975 26' San Jose, CA

Report message to a moderator

Re: [GMCnet] update on master cylinder replace [message #198217 is a reply to message #198212]

Tue, 12 February 2013 11:37

WD0AFQ

Messages: 7111
Registered: November 2004
Location: Dexter, Mo.

Karma: 207

Senior Member

I can't answer your question. When I needed one I called Jim K. and had it in two days. I am sure all of the suppliers have them. When I got the larger M/c I also ordered a bracket so it fit properly. Some things I will buy at a local supplier and have bought a M/C locally. It lasted not quite a year. So, from now on, with this kind of part I deal with the GMC motorhome suppliers.
Dan

3 In Stainless Exhaust Headers One Ton All Discs/Reaction Arm 355 FD/Quad Bag/Alum Radiator Manny Tran/New eng. Holley EFI/10 Tire Air Monitoring System Solarized Coach/Upgraded Windows Satelite TV/On Demand Hot Water/3Way Refer

Report message to a moderator

Re: [GMCnet] update on master cylinder replace [message #198220 is a reply to message #198212]

Tue, 12 February 2013 12:03

emerystora

Messages: 4442
Registered: January 2004

Karma: 13

Senior Member

On Feb 12, 2013, at 9:19 AM, KB wrote:

>> The simple short answer is - NO.
>
>
> Thanks Matt.
>
> So what is the difference between a master cylinder for
> disc-disc and one for disc-drum? There's a huge variety
> of master cylinders listed for things like P30 vehicles.
> Sometimes the units even look identical on the outside,
> but are listed for different applications.
>

The main differences in the master cylinders is the volume of the fluid delivered with the piston stroke. The calipers have a larger surface area on their pistons so they take more fluid to move them a certain distance. On the other hand the caliper pistons do not have to move as far as the smaller diameter drum brake pistons but it does take more volume for the calipers.

There is also a trade off between the volume delivered by the master cylinder and the travel distance of the pedal.

In my case, using the 34 mm master cylinder, I feel that I have adequate pedal for my six wheel disk brakes. The original master cylinder just did not have enough volume to operate 6 wheel disk brakes.

Emery Stora
77 Kingsley
Frederick, CO
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

Report message to a moderator

Re: [GMCnet] update on master cylinder replace [message #198221 is a reply to message #198220]

Tue, 12 February 2013 12:08

tphipps

Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL

Karma: 9

Senior Member

Since we are on brakes, has anyone installed the 110 mm calipers that are available? Clearance problems, or just plain old pronlems with this.
Tom, MS II

2012 Phoenix Cruiser model 2552 KA4CSG

Report message to a moderator

Re: [GMCnet] update on master cylinder replace [message #198222 is a reply to message #198220]

Tue, 12 February 2013 12:18

WD0AFQ

Messages: 7111
Registered: November 2004
Location: Dexter, Mo.

Karma: 207

Senior Member

The main differences in the master cylinders is the volume of the fluid delivered with the piston stroke. The calipers have a larger surface area on their pistons so they take more fluid to move them a certain distance. On the other hand the caliper pistons do not have to move as far as the smaller diameter drum brake pistons but it does take more volume for the calipers.

There is also a trade off between the volume delivered by the master cylinder and the travel distance of the pedal.

In my case, using the 34 mm master cylinder, I feel that I have adequate pedal for my six wheel disk brakes. The original master cylinder just did not have enough volume to operate 6 wheel disk brakes.

Emery Stora
77 Kingsley
Frederick, CO
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

[/quote]

Exactly what I was thinking Emery. Very Happy

Report message to a moderator

Re: [GMCnet] update on master cylinder replace [message #198243 is a reply to message #198221]

Tue, 12 February 2013 16:32

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

Tom,

Are you talking about the dual piston calipers that go on a 1 ton Chevy front end like the one Jim Rountree has on his GMC?

There's a picture of the setup somewhere on the Photosite but I can't find it for the life of me!

Regards,
Rob M.

-----Original Message-----
From: Thomas Phipps

Since we are on brakes, has anyone installed the 110 mm calipers that are available? Clearance problems, or just plain old pronlems
with this.
Tom,

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426

Report message to a moderator

Re: [GMCnet] update on master cylinder replace [message #198252 is a reply to message #198243]

Tue, 12 February 2013 18:03

tphipps

Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL

Karma: 9

Senior Member

Yes, I seem to remember that it has 2 pucks with less volume than the 80mm calipers. Might solve the MC volume capacity problem.
Just filing in back of mind.
Tom, MS II

2012 Phoenix Cruiser model 2552 KA4CSG

Report message to a moderator

Re: [GMCnet] update on master cylinder replace [message #198255 is a reply to message #198252]

Tue, 12 February 2013 18:15

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

Tom,

I found the picture of the two piston caliper:

http://www.gmcmhphotos.com/photos/showfull.php?photo=43537

As you can see it's a monster!

Regards,
Rob M.

-----Original Message-----
From: Thomas Phipps

Yes, I seem to remember that it has 2 pucks with less volume than the 80mm calipers. Might solve the MC volume capacity problem.
Just filing in back of mind.
Tom

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426

Report message to a moderator

Re: [GMCnet] update on master cylinder replace [message #198257 is a reply to message #198220]

Tue, 12 February 2013 18:28

Matt Colie

Messages: 8547
Registered: March 2007
Location: S.E. Michigan

Karma: 7

Senior Member

emerystora wrote on Tue, 12 February 2013 13:03

Emery is correct about that, and it works out OK because disk brakes actually run slightly lower pressures than most drums.

But the real difference that only matters to manufactures is that an all disk vehicle has to have a large reservoir to fit the maintenance rules as set down first by California and then later NHTSI. As disk brakes wear, that wear is accommodated by additional fluid in the caliper, but a modern self adjusting drum brake does not have this volume change.

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

Report message to a moderator

Re: [GMCnet] update on master cylinder replace [message #198308 is a reply to message #198217]

Wed, 13 February 2013 08:22

jhbridges

Messages: 8412
Registered: May 2011
Location: Braselton ga

Karma: -74

Senior Member

I took the old rusty one to O'Reilly and they matched it with a rebuild that had the same number cast in it... on sale, 19.95.
�
--johnny
'76 23' transmode norris
'76 palm beach

From: Dan Gregg <gregg_dan@hotmail.com>
To: gmclist@temp.gmcnet.org
Sent: Tuesday, February 12, 2013 12:37 PM
Subject: Re: [GMCnet] update on master cylinder replace

I can't answer your question. When I needed one I called Jim K. and had it in two days. I am sure all of the suppliers have them. When I got the larger M/c I also ordered a bracket so it fit properly. Some things I will buy at a local supplier and have bought a M/C locally. It lasted not quite a year. So, from now on, with this kind of part I deal with the GMC motorhome suppliers.
Dan
--
Dan & Teri Gregg
Dexter, Mo.

http://danandteri.blogspot.com/

_______________________________________________
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

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

Report message to a moderator

Previous Topic:	Allentown coach SOLD!
Next Topic:	Two in CA that should be checked out

Goto Forum:

-=] Back to Top [=-

Current Time: Thu Oct 03 08:28:42 CDT 2024

Total time taken to generate the page: 0.04800 seconds