4 wheel manual disc brakes - The 1947 - Present Chevrolet & GMC Truck Message Board Network

1malo68 · 09-02-2011, 05:13 AM

Has anybody done this upgrade with 3/4 ton axles? I know it is done all of the time with power brakes but I'm looking for brakes without the engine running. I know the master cylinder has to be smaller than a 1" bore but I've been told that I can't get enough volume for the big single piston calipers and I like the reliability of single pistons

. Any info or vendors would be appreciated.

msgross · 09-02-2011, 09:37 PM

why brakes without the engine running?

1malo68 · 09-04-2011, 02:37 PM

If I'm coming down the side of a Mountain and the engine floods out or dies for whatever reason, I'd still like to have brakes.

1malo68 · 09-08-2011, 06:24 AM

So nobody has done this?

thirdstreettito · 09-08-2011, 10:32 AM

Ask the guy on Pro-touring.com. They have lots of manual 4-wheel discs brakes. Many times running dual, triple, or even quadruple master cylinders. They are definitely the guys to talk to.

BurnoutNova · 09-09-2011, 05:01 PM

I did this mod to my 86 K10, but still have the power booster.

I'm confused about why the volume would change, or should I say I believe it will not change. You still have the same volume of fluid being displaced weather you have the booster or no booster. I used stock front K20 calipers. I think the Cadillac ones with the ratcheting e brake pistons use less fluid. They appear smaller anyway. The original Master cylinder seems to have enough volume to make it work.

Mine works fine, I just used a cheap adjustable prop valve to get the bias correct so I don't slide the rear tires. Haven't used it on the trail, just cruised around the block so far.

OrrieG · 09-09-2011, 06:05 PM

Not exactly the same application but my experience. 59 truck with 74 K10 axles, disc/drum and 74 stock MC and proportioning valve. I ran them as manual for 15 years. Builds up leg strength, especially on long down hill runs, but does stop, I could lock the tires up. This time I added a booster and can't wait to see the difference. I think a lot would have to do with the leverage from the pedal and push rod arm lengths.

thirdstreettito · 09-09-2011, 06:42 PM

Quote:

Originally Posted by OrrieG

I think a lot would have to do with the leverage from the pedal and push rod arm lengths.

Altec · 09-09-2011, 09:07 PM

Biggest thing about changing the leverage on the pedal is the throw. Moving the actuator arm up 1" on my truck was enough to make the pedal hit the firewall well before bottoming out. There just isn't much room to get more power there.

Something to keep in mind is that vacuum boosters will still work for a period of time after the engine shuts off, and Hydro boosters have a accumulator for this very purpose.

If I was really concerned about loosing the use of power brakes, I'd consider running vacuum booster, in conjunction with a electric vacuum pump as a backup. Just a thought...

1malo68 · 09-12-2011, 04:38 AM

Thanks for all of the input. I talked to a guy I know that builds race cars and he suggested dual master cylinders and a balance bar. Wilwood and Tilton both make them. That seems to make a lot of sense to me. I would have 2 completely separate systems, 1 for the front and 1 for the back. Pedal ratio should be about 7 to 1. The balance bar lets me set up brake bias. 400PSI is enough for drum brakes but it takes about 1000PSI for discs. From what I understand, and please correct me if I'm wrong, @ 7 to 1, I would need 142lbs of pressure on the pedal to get 1000PSI @ the MC. Smaller brake lines and a smaller MC bore should also increase the pressure, Right? I'm thinking about 3/16" hard lines and a 7/8" bore MCs. Factory PDB MCs are 1-1/8" bore. Do you think I've lost my mind yet?

thirdstreettito · 09-12-2011, 06:57 AM

I'm not sure on the pressure but I do have a question, what formula's did you use to come up with the numbers? I'm always looking for formulas to make things easier.

1malo68 · 09-13-2011, 03:32 AM

Here's some links to a few of the places that I got that info
http://www.mpbrakes.com/uploads/docu...alratiopdf.pdf
http://www.mpbrakes.com/technical-su...-cylinders.cfm
http://www.mpbrakes.com/technical-su...isc-brakes.cfm
http://wilwood.com/TechTip/TechFaqs.aspx
http://www.deanoshiro.com/brakes/brakearticle.html

lindajamison76 · 09-13-2011, 10:08 PM

Well, great work! You have helped me to improve my knowledge about this field. Thank you so much for sharing.

mcmlxix · 10-05-2011, 05:39 AM

The size of the hard line has nothing to do with pressure. The size of the MC determines pressure and volume. After it leaves the MC, a 3/16 line or a 2" line would still move the same amount of fluid at the same PSI exerted by the MC... this is a common debate on the Pro-Touring site...

This is not to be confused with a fuel system that needs a larger line to move more fluid

09-02-2011, 05:13 AM	#1
1malo68 Registered User Join Date: Aug 2010 Location: Lost Wages, NV Posts: 201	4 wheel manual disc brakes Has anybody done this upgrade with 3/4 ton axles? I know it is done all of the time with power brakes but I'm looking for brakes without the engine running. I know the master cylinder has to be smaller than a 1" bore but I've been told that I can't get enough volume for the big single piston calipers and I like the reliability of single pistons. Any info or vendors would be appreciated.

09-02-2011, 09:37 PM	#2
msgross Registered User Join Date: Jul 2006 Location: Central PA Posts: 12,201	Re: 4 wheel manual disc brakes why brakes without the engine running? __________________ The Garage: 1968 K-10 SWB - "Project Money Pit" 1996 Z-71 - "huntin rig" 1969 C-10 LWB (SOLD) "Project flip that truck or else" 1993 Passport, F@rd 1-ton (SOLD)"Project Cousin Eddie" My Garage Build "The 1,000 footer"

09-04-2011, 02:37 PM	#3
1malo68 Registered User Join Date: Aug 2010 Location: Lost Wages, NV Posts: 201	Re: 4 wheel manual disc brakes If I'm coming down the side of a Mountain and the engine floods out or dies for whatever reason, I'd still like to have brakes.

09-08-2011, 06:24 AM	#4
1malo68 Registered User Join Date: Aug 2010 Location: Lost Wages, NV Posts: 201	Re: 4 wheel manual disc brakes So nobody has done this?

09-08-2011, 10:32 AM	#5
thirdstreettito Resident of Here Join Date: May 2008 Location: Wesley Chapel, FL, USA Posts: 7,716	Re: 4 wheel manual disc brakes Ask the guy on Pro-touring.com. They have lots of manual 4-wheel discs brakes. Many times running dual, triple, or even quadruple master cylinders. They are definitely the guys to talk to. __________________ ~Bradley~ 2004 Black GTO LS2/T56 too much to list Miss having a truck

09-09-2011, 05:01 PM	#6
BurnoutNova Registered User Join Date: Mar 2004 Location: CA Posts: 2,057	Re: 4 wheel manual disc brakes I did this mod to my 86 K10, but still have the power booster. I'm confused about why the volume would change, or should I say I believe it will not change. You still have the same volume of fluid being displaced weather you have the booster or no booster. I used stock front K20 calipers. I think the Cadillac ones with the ratcheting e brake pistons use less fluid. They appear smaller anyway. The original Master cylinder seems to have enough volume to make it work. Mine works fine, I just used a cheap adjustable prop valve to get the bias correct so I don't slide the rear tires. Haven't used it on the trail, just cruised around the block so far.

09-09-2011, 06:05 PM	#7
OrrieG Registered User Join Date: Jun 2006 Location: Idaho Posts: 8,800	Re: 4 wheel manual disc brakes Not exactly the same application but my experience. 59 truck with 74 K10 axles, disc/drum and 74 stock MC and proportioning valve. I ran them as manual for 15 years. Builds up leg strength, especially on long down hill runs, but does stop, I could lock the tires up. This time I added a booster and can't wait to see the difference. I think a lot would have to do with the leverage from the pedal and push rod arm lengths. __________________ 1959 Chevy Short Fleetside w/ 74 4WD drive train (current project) OrrieG Build Thread 1964 Chevelle Malibu w/ 355-350TH (daily driver) Helpful AD and TF Manual Site Old Car Manual Project

09-09-2011, 09:07 PM	#9
Altec Getcha Pull Join Date: Nov 2010 Location: MD Posts: 691	Re: 4 wheel manual disc brakes Biggest thing about changing the leverage on the pedal is the throw. Moving the actuator arm up 1" on my truck was enough to make the pedal hit the firewall well before bottoming out. There just isn't much room to get more power there. Something to keep in mind is that vacuum boosters will still work for a period of time after the engine shuts off, and Hydro boosters have a accumulator for this very purpose. If I was really concerned about loosing the use of power brakes, I'd consider running vacuum booster, in conjunction with a electric vacuum pump as a backup. Just a thought... __________________ '81 K10 454/SM465 '86 S10 Blazer '95 H-D Softail '96 Integra

09-12-2011, 04:38 AM	#10
1malo68 Registered User Join Date: Aug 2010 Location: Lost Wages, NV Posts: 201	Re: 4 wheel manual disc brakes Thanks for all of the input. I talked to a guy I know that builds race cars and he suggested dual master cylinders and a balance bar. Wilwood and Tilton both make them. That seems to make a lot of sense to me. I would have 2 completely separate systems, 1 for the front and 1 for the back. Pedal ratio should be about 7 to 1. The balance bar lets me set up brake bias. 400PSI is enough for drum brakes but it takes about 1000PSI for discs. From what I understand, and please correct me if I'm wrong, @ 7 to 1, I would need 142lbs of pressure on the pedal to get 1000PSI @ the MC. Smaller brake lines and a smaller MC bore should also increase the pressure, Right? I'm thinking about 3/16" hard lines and a 7/8" bore MCs. Factory PDB MCs are 1-1/8" bore. Do you think I've lost my mind yet?

09-12-2011, 06:57 AM	#11
thirdstreettito Resident of Here Join Date: May 2008 Location: Wesley Chapel, FL, USA Posts: 7,716	Re: 4 wheel manual disc brakes I'm not sure on the pressure but I do have a question, what formula's did you use to come up with the numbers? I'm always looking for formulas to make things easier. __________________ ~Bradley~ 2004 Black GTO LS2/T56 too much to list Miss having a truck

09-13-2011, 03:32 AM	#12
1malo68 Registered User Join Date: Aug 2010 Location: Lost Wages, NV Posts: 201	Re: 4 wheel manual disc brakes Here's some links to a few of the places that I got that info http://www.mpbrakes.com/uploads/docu...alratiopdf.pdf http://www.mpbrakes.com/technical-su...-cylinders.cfm http://www.mpbrakes.com/technical-su...isc-brakes.cfm http://wilwood.com/TechTip/TechFaqs.aspx http://www.deanoshiro.com/brakes/brakearticle.html

09-13-2011, 10:08 PM	#13
lindajamison76 Registered User Join Date: Sep 2011 Location: USA Posts: 1	Re: 4 wheel manual disc brakes Well, great work! You have helped me to improve my knowledge about this field. Thank you so much for sharing. __________________ Watch Horrible Bosses Online Free

10-05-2011, 05:39 AM	#14
mcmlxix Collector of Projects Join Date: Apr 2003 Location: Las Vegas Posts: 3,106	Re: 4 wheel manual disc brakes The size of the hard line has nothing to do with pressure. The size of the MC determines pressure and volume. After it leaves the MC, a 3/16 line or a 2" line would still move the same amount of fluid at the same PSI exerted by the MC... this is a common debate on the Pro-Touring site... This is not to be confused with a fuel system that needs a larger line to move more fluid __________________ Rich 1972 K5 Blazer CST Click HERE D60 BIG BRAKE UPGRADE Click HERE



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