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Topic: brake booster replacement

in Forum: C3 Engines

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brake booster replacement (1/10)
9/10/12 7:49am

VikingVette
Former Member
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Greer, SC - USA

Vette(s):
1978 Black with Viking mural painted under hood AM/FM/CB radio, T-top and a 2013 Cyber Gray Grand Sport Coupe, 2LT for my daily driver

Joined: 3/13/2012
Posts: 264

About 4 years ago, had a chrome master cylinder on my '78, but had the original black brake vacuum booster. I found a chrome booster so I had the mechanic install that along with the (I am soo dumb sometimes...wadda you mean SOMETIMES) the fitting that brings the vacuum from the base the carb to booster, with a chrome fitting. After that replacement, I did not have much brake pedal, it went a loooong ways before the brakes would engage. The mechanic claimed it was the booster. The 2nd mechanic said the pistons in the master cylinder was 'bypassing". I had a new (and really cool looking) master cylinder installed last week with this new mechanic. It did not solve the bake issue totally. It is better, but not as good as it used to be.

Two questions:

1. the fitting that attaches to the booster where the vacuum line attaches, is there a moving part in there (like a check valve) that could be malfunctioning).

2. Can a mechanically challenged dumbbell replace a booster? I would not need to bleed any brake lines, right? Isn't this a purely mechanical disconnect and re-connect? I know that there is a rod that runs into the master cylinder that needs to be connected. Would there be enough flex to detatch the master cylinder from the booster without disconnecting the brake line?

One question on the new valve seals. I drove the car home (less than 3 miles) from this new mechanic on Wednesday night. Friday afternoon I fired it up, to back it out, to hose the dust off of the engine. A cloud of blue smoke emerged from my tail pipes. I know he had both valve covers off and replaced all the spark plugs. Will the new valve seals take a few miles to limber up to seal properly? Also, I have found out the GM put out a service bulletin on this exact issue...valve seals on a ZZ4. If I can get a copy of that, does that mean that GM will cover the cost to replacing the valve seals? Or do ANYTHING?

I bet you guys are getting to dislike this newbie! I wished so much that ANY of you that are smarter than me (which is 99.9%) would live closer to me, since Dr. Joel won't make house calls.

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Warning: The surgeon general has declared that it is NOT unhealthy to smoke your competition AND I just discovered that my corvette is a hybred. It burns gas and rubber!

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Re: brake booster replacement (2/10)
9/10/12 10:12am

Adams' Apple

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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 20206

Changing a brake booster on these cars is a study in patience....and the use of foul language. Getting to the four nuts that hold the booster on is a major pain, even with the correct tools. If you enjoy hanging upside down under the dash of your Shark for a few hours, then you might have a blast. Removing and re-installing the small clip that holds the linkage rod to the pedal can also turn your day into a nightmare, unless you have really tiny hands, and eyeballs that can see around corners.....

You can take the master cylinder loose, and gently move it out of the way, and not have to break loose any brake lines.

In other words, yes, it can be done by those not mechanically inclined, but it can be a real test of your determination, the amount of skin on your hands, and how large your swear jar is.....

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Joel Adams
C3VR Lifetime Member #56
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Re: brake booster replacement (3/10)
9/10/12 10:28am

Thank you Dr. Adams. I am a 6'-1" and not tiny, so I do not fit under a dash...right-side-up, up-side down sideways or any ways. Clint could fit. Clint is so fit and trim, that I could fold him up and have him work on it from inside the dash! I naively thought that it was four bolts, a linkage and presto!

I am developing a new artifical joint. It can be implanted halfway between the elbow and wrist for situations just like this.

Is there anything in the vacuum check valve that could cause the excessive pedal travel? I just KNOW you are going to say NO Pinch

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Warning: The surgeon general has declared that it is NOT unhealthy to smoke your competition AND I just discovered that my corvette is a hybred. It burns gas and rubber!

Re: brake booster replacement (4/10)
9/10/12 11:10am

ebo

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Holland Patent, NY - USA

Vette(s):
#1 *1980 White, Red interior 14,000 mile #2 *1980 Red, Oyster interior 93,000 miles Resto project car, rebuilt to 383 stroker

Joined: 6/3/2008
Posts: 4421

I do not think easy is a reconized word when it comes to the C3. I saw a booster replaced at the MAMO gathering....it was not pretty! (and Joel was there)

ebo

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ebo

Re: brake booster replacement (5/10)
9/10/12 12:30pm

Mr. Ebo,

Are you saying Joel was not pretty, or the booster replacement was not pretty hehehe

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Warning: The surgeon general has declared that it is NOT unhealthy to smoke your competition AND I just discovered that my corvette is a hybred. It burns gas and rubber!

Re: brake booster replacement (6/10)
9/10/12 4:39pm

ebo

I SEE NUTTINNNGGGG!

ebo

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ebo

Re: brake booster replacement (7/10)
9/10/12 7:08pm

danascar
Standard Member
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Germansville, PA - USA

Vette(s):
1974 Coupe 358ci 4 speed Black w/Medium Saddle interior w/79 custom leather seats. . 1999 C5 Convertible, 6 speed, Atomic orange, Oak interior.

Joined: 1/28/2010
Posts: 859

You need the best tool for going under the dash to do a booster......Barb Shimer!! Big smile

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DanT

Re: brake booster replacement (8/10)
9/10/12 7:16pm

JPD1stVette

Gold Member
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Scotch Plains, NJ - USA

Vette(s):
1981 Corvette Coupe, Stock, Black on Black, 4 Spd

Joined: 1/11/2006
Posts: 241

I replaced my Booster & M.C. at the same time in my driveway.

The Speedo/Tach, drivers seat, steering column & Brake/clutch bracket were removed and still wasn't easy! Each of those needed work too.

I won't tell ya how long it took, but it was worth it.

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Re: brake booster replacement (9/10)
9/10/12 7:22pm

Sarge81

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WEST SENECA, NY - USA

Vette(s):
1981 Blue Ice Met. w/pearl ghost flames TKO500 5speed. LS1 Swap 3.45 Dana 44.

Joined: 12/3/2001
Posts: 2379

I took the seat, steering column and clutch and brake pedal assembly out to give me room to get to those PITA booster nuts. That was not a fun evening.

The check valve on the brake booster is basically a one way check valve.
Pull the hose off the engine side and try to blow into the end of it. You shouldn't be able to blow through what so ever.
Then try to suck air through the hose. You should be able to draw so air through. If not, gently wiggle the check valve out of the grommet on the booster and try it again. There may be stored vacuum in the booster already. If you do have to wiggle the valve out and you hear a hissing noise that will tell you the booster and valve are working to hold vacuum.

|UPDATED|9/10/2012 7:22:15 PM (AZT)|/UPDATED|

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GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.

3.54 Dana 44

'69 "N11" Sidepipes
Borgeson Steering Box
Born 8/1981
Sequence #3975

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Re: brake booster replacement (10/10)
9/11/12 11:37am

I did drive the '78 to work yesterday to experiment with the brakes. I do have more brakes then before the master cylinder replacment. When I press on the pedal, I cna tell it is an immediate reaction. I get to the place where I figure I should be sliding the tires and the pedal just travels more. I am kind of wondering about the rubber brake line. I have heard that they can become soft over the years, and then expand when having pressure put on them. I know a lot of autocrosser's that change out the rubber to stainless just for that reason. As far as I know, the rubber brake lines have never been replaced. Might that be where some of the "sponginess" feeling is coming from?

Norsky and Sundew, if you read this, think about taking the 'Tail of the Dragon' with iffy brakes! The epitomy of DUMB, huh? Of course I took it slower than I did with my C5!!!!!! Although my wife almost wore a hole in her side of the floorboards hitting that imaginary brake she has over there.

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Warning: The surgeon general has declared that it is NOT unhealthy to smoke your competition AND I just discovered that my corvette is a hybred. It burns gas and rubber!

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