| What new Master Cylinder to use [message #259046] |
Sat, 16 August 2014 12:42  |
Ray E
Messages: 13
Registered: January 2006
Location: Wauwatosa, Wisconsin
Karma: 0
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Junior Member |
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I plan to install a new brake master cylinder. I have disk brakes on the front and center axles and drum brakes on the rear axle. What would be the best master cylinder to use???
I know I've seen this info before but I can't seem to locate it.
Thanks for the help.
Ray Erspamer - 78 Royale
Wauwatosa, Wisconsin 53226
78gmc-roayale@att.net
414-484-9431
Our Web Page: http://ray-lisa.page.tl
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| Re: What new Master Cylinder to use [message #259057 is a reply to message #259046] |
Sat, 16 August 2014 16:12  |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Senior Member |
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Ray E wrote on Sat, 16 August 2014 12:42I plan to install a new brake master cylinder. I have disk brakes on the front and center axles and drum brakes on the rear axle. What would be the best master cylinder to use???
I know I've seen this info before but I can't seem to locate it.
Thanks for the help.
Ray
I have the same setup as you do, 80mm disc's front and mid axle with drums in the rear and the 15/16 wc, and am using the MC originally designed for the GMC. My pedal is not up as high as it would be with the 34mm MC, but with the original MC and a sensitized booster from Dave L., I have great brakes.
Before you make any kind of purchase like this, attend Dave Lenzi's Brake session at the fall GMCMI rally. He did this at the spring rally inMontgomery TX and will be repeating it at Chippewa Falls. He has some pretty strong evidence regarding the best MC to use. I could tell you what he found, but it is best to see and experience it for yourself, I cannot do the presentation justice in a few paragraphs. A really eye opening presentation.
I left a message on your phone, call me when you get a chance.
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: What new Master Cylinder to use [message #259112 is a reply to message #259057] |
Sun, 17 August 2014 10:58 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Larry wrote on Sat, 16 August 2014 17:12Before you make any kind of purchase like this, attend Dave Lenzi's Brake session at the fall GMCMI rally. He did this at the spring rally in Montgomery TX and will be repeating it at Chippewa Falls. He has some pretty strong evidence regarding the best MC to use. I could tell you what he found, but it is best to see and experience it for yourself, I cannot do the presentation justice in a few paragraphs. A really eye opening presentation.
I left a message on your phone, call me when you get a chance.
Boy, you got that right...
Every time I can listen to Dave, I learn something.
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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| Re: What new Master Cylinder to use [message #259157 is a reply to message #259112] |
Sun, 17 August 2014 18:09 |
Ray E
Messages: 13
Registered: January 2006
Location: Wauwatosa, Wisconsin
Karma: 0
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Junior Member |
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I currently have the 34mm master cylinder. I have brand new ones on hand of both, the standard OEM MC and a 34mm MC. I recently had some brake problems and I don't want to wait until the rally. So which would be the best to put in??? Larry, I'll give you a call soon.
Ray
Ray Erspamer - 78 Royale
Wauwatosa, Wisconsin 53226
78gmc-roayale@att.net
414-484-9431
Our Web Page: http://ray-lisa.page.tl
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| Re: What new Master Cylinder to use [message #259160 is a reply to message #259157] |
Sun, 17 August 2014 18:49 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Senior Member |
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Ray E wrote on Sun, 17 August 2014 18:09I currently have the 34mm master cylinder. I have brand new ones on hand of both, the standard OEM MC and a 34mm MC. I recently had some brake problems and I don't want to wait until the rally. So which would be the best to put in??? Larry, I'll give you a call soon.
Ray
If your OEM MC is in good condition, that would be my choice. That piston is smaller than the 34mm. The smaller the psiton, the more pressure you can exert on the system. Also, If your 34mm is new, it may have some issues. Even if it isn't new, it could have issues. If you use the OEM MC, make sure your shoes on the 3rd axle are adjusted up. That will help keep the pedal up. JMHO
Larry
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: What new Master Cylinder to use [message #259207 is a reply to message #259160] |
Mon, 18 August 2014 02:42 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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I have had the 34 mm. master cylinder on mine for about 8 years. I have 80 mm. front calipers 1-1/16" middle wheel cylinders, and 15/16" rear wheels cylinders. What can I say? It works.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] What new Master Cylinder to use [message #259213 is a reply to message #259207] |
Mon, 18 August 2014 07:18 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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I've used OEM and 34mm MC's for years each. At the moment, with 1-ton
front calipers and 63mm (?) at the other 4 wheels, I'm using OEM. The
pedal travel is longer than I like, but the braking force is much more
satisfactory than with the 34mm.
One problem with the 34mm is that it's a "later, improved" design, with
O-ring seals. When one of those begins to leak, it's gonna LEAK; pumping
the pedal has little effect. With the older designs, such as OEM, the cup
seals retain pressure better as more pedal force is applied, so that even a
leaking MC can still be quite effective. This is a point that Dave Lenzi
has emphasized repeatedly. He and I discussed finding an earlier design
large-bore, cup-sealed, MC, and I know that he bought one to try; I don't
know his results so am anxious to talk to him at Chippewa Falls (I'm always
reluctant to call and interrupt his BUSY schedule).
Ken H.
On Mon, Aug 18, 2014 at 3:42 AM, Ken Burton wrote:
> I have had the 34 mm. master cylinder on mine for about 8 years. I have 80
> mm. front calipers 1-1/16" middle wheel cylinders, and 15/16" rear wheels
> cylinders. What can I say? It works.
> --
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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