Brake booster quick question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Row · 03-04-2009, 11:25 PM

Is the booster the same for drums and discs? My booster has a vacuum leak and needs to be replaced. Problem is, I wanna switch to front discs soon. So can I replace the booster and then switch to disc and be ok?

Sammy · 03-04-2009, 11:29 PM

Yes same. Difference is valve on the side of the master cylinder.

Row · 03-05-2009, 12:10 AM

tyvm

**SactoJim** · 03-05-2009, 12:42 AM

I concur.....I'm running 4 WDB with stock vacuum booster and Corvette style master cylinder.

spinning wheels · 03-05-2009, 01:12 AM

Quote:

Originally Posted by Row

Is the booster the same for drums and discs? My booster has a vacuum leak and needs to be replaced. Problem is, I wanna switch to front discs soon. So can I replace the booster and then switch to disc and be ok?

Where is it leaking from? Do you hear a leak? Or are you loosing pedal pressure? There is a small seal between the master cylinder and the booster, it may just be leaking from there.

Row · 03-05-2009, 09:27 AM

Spinning wheels: to be honest, I really don't know where it's leaking! I think it's the booster diaphram because my engine dies when I'm coming to a stop. Also, when I mash the brake pedal, it makes a swooshing sound.

spinning wheels · 03-05-2009, 10:49 PM

Quote:

Originally Posted by Row

Spinning wheels: to be honest, I really don't know where it's leaking! I think it's the booster diaphram because my engine dies when I'm coming to a stop. Also, when I mash the brake pedal, it makes a swooshing sound.

When you remove the booster. A knowledgeable brake shop can bench test it for you. I thought I was given, (well I bought it), a bad booster. But when they bench tested it, it worked fine.

It was missing the seal, about a $1 part. The hard part was chasing down what part was bad, as I changed booster, master cylinder, proportioning valve and added speed bleeders.
Next time, I'll change one thing at a time

Also, check your valve going into the booster. That little white plastic thingy, (my technical term), were you hookup the vacuum line from the engine. On yeah, you are getting around 15 inches of vacuum to the booster, right? Big cams will kill your vacuum.

ED67C20 · 03-05-2009, 01:18 AM

I've been told on this forum that they were different. Something that has to do with the push rod going into the back of the master cyl. Huh, I guess I can just try it. ED67C20

Scottshotrods · 03-05-2009, 02:02 AM

the bore size on the master
are diffrent
disc and disc 1 1/8 bore
disc and drum 1 inch bore
justin
www.scottshotrods.com

Row · 03-06-2009, 12:56 AM

Soon as I remove it I'll have it tested. Thanx for all the input!!!

ED67C20 · 03-07-2009, 05:59 PM

Row, I have tested them before with one of those mityvac vacuum pumps. As long as it will pump vacuum and hold it you should be O.K. I have another car with a bad booster. It will be idling perfect until I press on the brake pedal. It makes a hissing sound then it causes a vacuum leak to the motor making a rough idle. ED67C20

03-04-2009, 11:25 PM	#1
Row Registered User Join Date: Feb 2009 Location: )(&)(&&&^%$ Posts: 51	Brake booster quick question Is the booster the same for drums and discs? My booster has a vacuum leak and needs to be replaced. Problem is, I wanna switch to front discs soon. So can I replace the booster and then switch to disc and be ok?

03-04-2009, 11:29 PM	#2
Sammy Registered User Join Date: Apr 2000 Location: Bonne Terre, Mo Posts: 3,005	Re: Brake booster quick question Yes same. Difference is valve on the side of the master cylinder. __________________ '69 Chevy Long Fleet & '71 GMC Short Step & Project "ODD BALL" "You can wash a pig, soak it in most expensive perfume. In the end it is still just a pig." ODD BALL build thread http://67-72chevytrucks.com/vboard/s...d.php?t=478629"

03-05-2009, 12:10 AM	#3
Row Registered User Join Date: Feb 2009 Location: )(&)(&&&^%$ Posts: 51	Re: Brake booster quick question tyvm

03-05-2009, 12:42 AM	#4
SactoJim Registered User Join Date: Oct 2005 Location: Sacramento, CA Posts: 1,970	Re: Brake booster quick question I concur.....I'm running 4 WDB with stock vacuum booster and Corvette style master cylinder. __________________ 72 Cheyenne SWB Fleet Nut & bolt frame off in progress...99.9999% - supercharged 383 - 4 wheel discs - relocated fuel tank - My Build Thread

03-05-2009, 09:27 AM	#6
Row Registered User Join Date: Feb 2009 Location: )(&)(&&&^%$ Posts: 51	Re: Brake booster quick question Spinning wheels: to be honest, I really don't know where it's leaking! I think it's the booster diaphram because my engine dies when I'm coming to a stop. Also, when I mash the brake pedal, it makes a swooshing sound.

03-05-2009, 01:18 AM	#8
ED67C20 Registered User Join Date: Aug 2006 Location: spokane, washington Posts: 37	Re: Brake booster quick question I've been told on this forum that they were different. Something that has to do with the push rod going into the back of the master cyl. Huh, I guess I can just try it. ED67C20

03-05-2009, 02:02 AM	#9
Scottshotrods Registered User Join Date: Oct 2008 Location: oxnard ca Posts: 2,201	Re: Brake booster quick question the bore size on the master are diffrent disc and disc 1 1/8 bore disc and drum 1 inch bore justin www.scottshotrods.com

03-06-2009, 12:56 AM	#10
Row Registered User Join Date: Feb 2009 Location: )(&)(&&&^%$ Posts: 51	Re: Brake booster quick question Soon as I remove it I'll have it tested. Thanx for all the input!!!

03-07-2009, 05:59 PM	#11
ED67C20 Registered User Join Date: Aug 2006 Location: spokane, washington Posts: 37	Re: Brake booster quick question Row, I have tested them before with one of those mityvac vacuum pumps. As long as it will pump vacuum and hold it you should be O.K. I have another car with a bad booster. It will be idling perfect until I press on the brake pedal. It makes a hissing sound then it causes a vacuum leak to the motor making a rough idle. ED67C20



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