7" vs. 9" vacuum booster for brakes...which is better? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

67Dad · 06-22-2010, 05:36 PM

67-c10...we are adding power brakes. Apparently the conversion can be either 7" or 9". Do any of you have experience with which is best? 7" presumably leaves more engine access room, but we have a straight 6 292. Does 9" give much more "boost"? Thanks in advance!

Mark

umwtnt · 06-22-2010, 05:50 PM

A 9inch booster is better. Its simple physics, the 9 inch has more sq in for the vacuum to act upon the the 7 inch. This helps apply more force with less pedal pressure. You have the room you can go to a bigger booster if their available.

mbgmike · 06-22-2010, 07:22 PM

Quote:

Originally Posted by 67Dad

67-c10...we are adding power brakes. Apparently the conversion can be either 7" or 9". Do any of you have experience with which is best? 7" presumably leaves more engine access room, but we have a straight 6 292. Does 9" give much more "boost"? Thanks in advance!

Mark

Actually the unit that came on it was 11" in dia.
You have more boost. Sometimes they use a dual diaphragm booster in the smaller sizes to gain more room. If you have any questions feel free to call or drop buy we have done a lot of conversions.

Mike

Musclerodz · 06-22-2010, 11:27 PM

Either run a factory 11" or dual 9". Don't bother with single diaphragm boosters less than 11".

67Dad · 06-30-2011, 12:23 PM

OK...we are back on the brake project after many diversions. Any opinions out there as to the best all around solution to adding power brakes (w/ new master cylinder in the process) to what was a manual brake 67 C10?

Thanks.

ChevLoRay · 06-30-2011, 02:48 PM

Ummm, just do it.

68gmsee · 06-30-2011, 09:36 PM

Quote:

Originally Posted by 67Dad

OK.... Any opinions out there as to the best all around solution to adding power brakes (w/ new master cylinder in the process) to what was a manual brake 67 C10? Thanks.

Go to Webster and talk to mbgmike. He'll set you up or give you good advice on what you need.

Otherwise if you have a salvage yard that has some 67-72 trucks find one with the power brakes and take everything off that pertains to the p.brakes: mounting bracket, master cylinder, prop valve and include the brake pushrod inside the cab. The rubber hose and check valve you can get at local parts stores and if the booster is defective you'll have the core.

1969stepside · 07-01-2011, 09:46 PM

what i would do is to take a power booster off a 3/4 ton and put it on a half ton because the 3/4 ton booster is desgined to stop a heavier truck and the half ton is lighter and then u can have alot of brakes lol that is what i would do just go to autozone and order u a 3/4 power booster and use ur 1/2 ton booster as a core

sick69 · 07-02-2011, 05:41 AM

Or to throw another twist,,,,convert to hydroboost and skip the vac booster

mcmlxix · 07-02-2011, 06:19 AM

Either way get a booster bracket from CaptainFab... it allows you to use the late model 1988-1998 full size truck/Tahoe/Burb booster (smaller, less expensive, can be found at any parts store) unless your going for stock resto... The only thing to check is column shift clearance. Click HERE

You can also use this for hydroboost if you want to upgrade (now or later)...

1969stepside · 07-02-2011, 10:43 PM

i like how that bracket is smaller and does not stick out as much as the stock one

usmcchevy · 07-03-2011, 08:48 AM

Quote:

Originally Posted by sick69

Or to throw another twist,,,,convert to hydroboost and skip the vac booster

X2, I love my hydroboost!

**1970 CST Short Wide** · 07-03-2011, 10:28 AM

Quote:

Originally Posted by usmcchevy

X2, I love my hydroboost!

I like to see how the hydroboost looks and works on your truck. Could you post or send me some pics

usmcchevy · 07-03-2011, 04:42 PM

Quote:

Originally Posted by 1970 CST Short Wide

I like to see how the hydroboost looks and works on your truck. Could you post or send me some pics

PM replied, Pics and some info are on pages 9, 10 and 13 of my build thread. Link in sig

06-22-2010, 05:36 PM	#1
67Dad Registered User Join Date: Mar 2010 Location: houston texas Posts: 84	7" vs. 9" vacuum booster for brakes...which is better? 67-c10...we are adding power brakes. Apparently the conversion can be either 7" or 9". Do any of you have experience with which is best? 7" presumably leaves more engine access room, but we have a straight 6 292. Does 9" give much more "boost"? Thanks in advance! Mark __________________ Mark 57 Austin Healey 3000 (sold many moons ago, unfortunately) 67 C10 (in progress, son's) w/ 1993 350 SBC, '96 Vortec heads (custom polished ports), EPS Performer intake, Holley carb, cam, MSD ignition 93 C4 Corvette (mostly done, son's)

06-22-2010, 05:50 PM	#2
umwtnt Registered User Join Date: Feb 2008 Location: Williamsburg, Va Posts: 226	Re: 7" vs. 9" vacuum booster for brakes...which is better? A 9inch booster is better. Its simple physics, the 9 inch has more sq in for the vacuum to act upon the the 7 inch. This helps apply more force with less pedal pressure. You have the room you can go to a bigger booster if their available. __________________ The more I learn, the more I find out I don't know. 69 Chevy SWB w/67 front end 4 wheel discs 468 BB 700R4 Bagged Coming around slowly

06-22-2010, 11:27 PM	#4
Musclerodz Senior Member Join Date: Aug 2005 Location: OKC, OK Posts: 2,364	Re: 7" vs. 9" vacuum booster for brakes...which is better? Either run a factory 11" or dual 9". Don't bother with single diaphragm boosters less than 11". __________________ Mike Redpath

06-30-2011, 12:23 PM	#5
67Dad Registered User Join Date: Mar 2010 Location: houston texas Posts: 84	Re: 7" vs. 9" vacuum booster for brakes...which is better? OK...we are back on the brake project after many diversions. Any opinions out there as to the best all around solution to adding power brakes (w/ new master cylinder in the process) to what was a manual brake 67 C10? Thanks. __________________ Mark 57 Austin Healey 3000 (sold many moons ago, unfortunately) 67 C10 (in progress, son's) w/ 1993 350 SBC, '96 Vortec heads (custom polished ports), EPS Performer intake, Holley carb, cam, MSD ignition 93 C4 Corvette (mostly done, son's)

06-30-2011, 02:48 PM	#6
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: 7" vs. 9" vacuum booster for brakes...which is better? Ummm, just do it. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.

07-01-2011, 09:46 PM	#8
1969stepside Registered User Join Date: Feb 2008 Location: Johnson City Tennessee Posts: 1,208	Re: 7" vs. 9" vacuum booster for brakes...which is better? what i would do is to take a power booster off a 3/4 ton and put it on a half ton because the 3/4 ton booster is desgined to stop a heavier truck and the half ton is lighter and then u can have alot of brakes lol that is what i would do just go to autozone and order u a 3/4 power booster and use ur 1/2 ton booster as a core __________________ Greater love hath no man than to lay down his life for a friend. Members i Have met Earl Slick68 1969 Stepside Build thread http://67-72chevytrucks.com/vboard/s...=1#post4253546 Chevy Trucks the longest lasting most dependable trucks on the road

07-02-2011, 05:41 AM	#9
sick69 Registered User Join Date: Sep 2006 Location: colorado springs colorado Posts: 737	Re: 7" vs. 9" vacuum booster for brakes...which is better? Or to throw another twist,,,,convert to hydroboost and skip the vac booster __________________ 70 chevy lwb c10 454/th400 and a 9" rearend suicide doors, marker light fuel fill, 4" cowl , mini tub

07-02-2011, 06:19 AM	#10
mcmlxix Collector of Projects Join Date: Apr 2003 Location: Las Vegas Posts: 3,106	Re: 7" vs. 9" vacuum booster for brakes...which is better? Either way get a booster bracket from CaptainFab... it allows you to use the late model 1988-1998 full size truck/Tahoe/Burb booster (smaller, less expensive, can be found at any parts store) unless your going for stock resto... The only thing to check is column shift clearance. Click HERE You can also use this for hydroboost if you want to upgrade (now or later)... __________________ Rich 1972 K5 Blazer CST Click HERE D60 BIG BRAKE UPGRADE Click HERE

07-02-2011, 10:43 PM	#11
1969stepside Registered User Join Date: Feb 2008 Location: Johnson City Tennessee Posts: 1,208	Re: 7" vs. 9" vacuum booster for brakes...which is better? i like how that bracket is smaller and does not stick out as much as the stock one __________________ Greater love hath no man than to lay down his life for a friend. Members i Have met Earl Slick68 1969 Stepside Build thread http://67-72chevytrucks.com/vboard/s...=1#post4253546 Chevy Trucks the longest lasting most dependable trucks on the road

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