Bigger Brake Booster? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

LSUMurse · 01-24-2013, 10:08 PM

I am about to add power brakes to my manual brake '68 C10. I will eventually be towing and/or carrying a slide in camper, so I am thinking of going ahead and putting in a bigger brake booster (keeping it drum/drum for now). I believe the booster and brackets I have are from a '71 (I should have the definitive answer on that shortly).

I have read quite a few threads and have some questions.

Some threads say that the master cylinders are different on the trucks equipped with bigger boosters. The reseviors for the front and back brakes are reversed. Is this true?

Also, are there any upgrades or changes that need to be done to the rest of the braking system once it is under a higher load?

Thanks,
Stephen

hugger6933 · 01-24-2013, 10:30 PM

It is me again your neihbor to the north. I'll take another swing at trying to get your truck to stop real well as it is your daily and if I recall your better half drives it some as well. The res. is swapped and bigger but not because of the bigger booster but the 71 is disc brake. All disc brake M/C are swapped from the position you normally find in the M/C in a drum drum set up. The other reson for the larger one side of the res being larger is the difference in fluid it takes to operate the wheels cyl or calipers [whatever the case may be] also I think it is front on back side of the M/c and the back on the front side of the m/c on a disc brake m/c but since the drum drum take the same amount of fluid the sizes of the res is the same if that makes sense.

68gmsee · 01-24-2013, 10:51 PM

The booster is strictly to aid in stopping. Has nothing to do with the master cylinder type. I installed a booster on my 68 drum/drum and used the original master cylinder that came with the truck. I just moved it forward enough to install the booster and bracket and made sure the push rod matched the master cylinder and was adjusted properly.

Just recently, my original master cylinder started leaking and I installed a disc/drum master cylinder I had from another vehicle. After bleeding everything works just like before.

LSUMurse · 01-25-2013, 12:25 AM

So, if I am thinking this through correctly, I should be able to buy a booster for 3/4 ton (I have a 1/2 ton), move the master cylinder forward, slap the booster, brackets, and push rod in place, make adjustments, and go town.

This way I won't have to bleed the brakes.

Sound about right?

PanelDeland · 01-25-2013, 12:36 AM

A buddy had a one ton furd old school wrecker with a Holmes Boom.It ran good but was a bit iffy in the brake dept with a car on.He was walking thru the JY one day and spotted a Bus of the same make/model.He grabbed the booster/MC and installed that.It worked pretty well,if you didn't mind having a car up on the boom when you stopped.It actually worked very well except that the brakes were pretty touchy.After a few drives it got to where you could use it without slamming someone thru the windshield.Not an answer to your question but an example of what you can have happen if you dont match the brake components.

capev86 · 01-25-2013, 09:04 PM

i like the big brake booster on my 72 Burb C20 and would recommend it to anyone in your position!

Mike C · 01-26-2013, 11:17 AM

Disc and drum brake boosters were different. Sometimes a manual master cylinder will have a different depth hole in the back compared to a power cylinder, you'll just have to try and see if it works.

The disc brake boosters are a different design than the drum boosters, but work the same way.

I did a disc conversion on my '70 big block GMC and used the original drum booster with no problems. Getting ready to do a disc swap on a '69 shortie I have and will use a drum booster I have from a parts truck.

THE BOSS · 01-26-2013, 11:50 AM

if you go with the dual diaphragm booster you have to use the matching master cylinder, the single diaphragm master cylinder will not work with the duel diaphragm booster.

if you go with the duel diaphragm set up you have to get the lines to swap fluid flow to the porpoising valve.

Livrat · 01-26-2013, 01:19 PM

Any drum or disc brake (67-72) 1/2 ton booster and brackets are a "bolt on".. You can also use a 67-70 3/4 ton booster (dual diaphram) and brackets, All with your current stock master cylinder, just unbolt it from the firewall and pull it forward, bolt on the booster and brackets, plumb in the vacuum and bolt the master cylinder back on..

01-24-2013, 10:08 PM	#1
LSUMurse Registered User Join Date: Mar 2012 Location: New Orleans, La Posts: 406	Bigger Brake Booster? I am about to add power brakes to my manual brake '68 C10. I will eventually be towing and/or carrying a slide in camper, so I am thinking of going ahead and putting in a bigger brake booster (keeping it drum/drum for now). I believe the booster and brackets I have are from a '71 (I should have the definitive answer on that shortly). I have read quite a few threads and have some questions. Some threads say that the master cylinders are different on the trucks equipped with bigger boosters. The reseviors for the front and back brakes are reversed. Is this true? Also, are there any upgrades or changes that need to be done to the rest of the braking system once it is under a higher load? Thanks, Stephen __________________ It's not that I am apathetic, I just don't care. If your life is a joke, it appears death will be your punchline.

01-24-2013, 10:30 PM	#2
hugger6933 Registered User Join Date: Oct 2008 Location: Marianna Arkansas Posts: 7,280	Re: Bigger Brake Booster? It is me again your neihbor to the north. I'll take another swing at trying to get your truck to stop real well as it is your daily and if I recall your better half drives it some as well. The res. is swapped and bigger but not because of the bigger booster but the 71 is disc brake. All disc brake M/C are swapped from the position you normally find in the M/C in a drum drum set up. The other reson for the larger one side of the res being larger is the difference in fluid it takes to operate the wheels cyl or calipers [whatever the case may be] also I think it is front on back side of the M/c and the back on the front side of the m/c on a disc brake m/c but since the drum drum take the same amount of fluid the sizes of the res is the same if that makes sense.

01-24-2013, 10:51 PM	#3
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: Bigger Brake Booster? The booster is strictly to aid in stopping. Has nothing to do with the master cylinder type. I installed a booster on my 68 drum/drum and used the original master cylinder that came with the truck. I just moved it forward enough to install the booster and bracket and made sure the push rod matched the master cylinder and was adjusted properly. Just recently, my original master cylinder started leaking and I installed a disc/drum master cylinder I had from another vehicle. After bleeding everything works just like before. __________________ 68 GMC 250/3 speed Saginaw p/b p/s 69 Chevy 350/350 currently in pieces still lookin for a cab 06 Trailblazer I just want a vehicle that I can work on, that won't talk to me, leave error msgs or keep track of how I drive...

01-25-2013, 12:25 AM	#4
LSUMurse Registered User Join Date: Mar 2012 Location: New Orleans, La Posts: 406	Re: Bigger Brake Booster? So, if I am thinking this through correctly, I should be able to buy a booster for 3/4 ton (I have a 1/2 ton), move the master cylinder forward, slap the booster, brackets, and push rod in place, make adjustments, and go town. This way I won't have to bleed the brakes. Sound about right? __________________ It's not that I am apathetic, I just don't care. If your life is a joke, it appears death will be your punchline.

01-25-2013, 12:36 AM	#5
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,992	Re: Bigger Brake Booster? A buddy had a one ton furd old school wrecker with a Holmes Boom.It ran good but was a bit iffy in the brake dept with a car on.He was walking thru the JY one day and spotted a Bus of the same make/model.He grabbed the booster/MC and installed that.It worked pretty well,if you didn't mind having a car up on the boom when you stopped.It actually worked very well except that the brakes were pretty touchy.After a few drives it got to where you could use it without slamming someone thru the windshield.Not an answer to your question but an example of what you can have happen if you dont match the brake components. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

01-25-2013, 09:04 PM	#6
capev86 Registered User Join Date: May 2009 Location: Eliot, Maine Posts: 1,314	Re: Bigger Brake Booster? i like the big brake booster on my 72 Burb C20 and would recommend it to anyone in your position!

01-26-2013, 11:17 AM	#7
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,728	Re: Bigger Brake Booster? Disc and drum brake boosters were different. Sometimes a manual master cylinder will have a different depth hole in the back compared to a power cylinder, you'll just have to try and see if it works. The disc brake boosters are a different design than the drum boosters, but work the same way. I did a disc conversion on my '70 big block GMC and used the original drum booster with no problems. Getting ready to do a disc swap on a '69 shortie I have and will use a drum booster I have from a parts truck. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

01-26-2013, 11:50 AM	#8
THE BOSS Registered User Join Date: Jun 2012 Location: Kalamazoo MI Posts: 104	Re: Bigger Brake Booster? if you go with the dual diaphragm booster you have to use the matching master cylinder, the single diaphragm master cylinder will not work with the duel diaphragm booster. if you go with the duel diaphragm set up you have to get the lines to swap fluid flow to the porpoising valve.

01-26-2013, 01:19 PM	#9
Livrat Member #1049 Join Date: Jun 2000 Location: Troy Montana Posts: 3,940	Re: Bigger Brake Booster? Any drum or disc brake (67-72) 1/2 ton booster and brackets are a "bolt on".. You can also use a 67-70 3/4 ton booster (dual diaphram) and brackets, All with your current stock master cylinder, just unbolt it from the firewall and pull it forward, bolt on the booster and brackets, plumb in the vacuum and bolt the master cylinder back on..



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