Topic: 77 brakes failed
in Forum: C3 Engines, Driveline and Handling
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over a two week period ...
On the 1st occurrence I felt a brake pull; stabbed the pedal and it released. Same for the 2nd occurrence. The 3rd time I waited 20 minutes or so for the brake to release and had decided I needed to replace the rubber hoses. ...Saturday night when returning from the Somernites Cruise, (about 180 miles), when exiting the highway at the first redlight I had "no brakes". ( A scary moment)! ...luckily home was a mile or so and I crawled home, ( it was late or early depending on your definition).
So today I inspected the car expecting to find a busted hose, no such luck, the fluid level is OK, all four hoses are intact, and laying on the floor I can see no leaks, the dash brake is on and now I don't know where to start.
Suggestions, comments, ideas?
current
1977 Coupe
gone but not forgotten
1996 Grand Sport
1996 Grand Sport
1984 coupe
1974 coupe
1964 roadster
1974 coupe
1964 roadster
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Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20225
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
Appears to be a master cylinder issue.
By "no brakes", I assume you mean the pedal went to the floor? With no visible leaks at the wheels/hoses, and the fluid level is right, that really leaves only one thing that could cause all of the above symptoms...the MC..
By "no brakes", I assume you mean the pedal went to the floor? With no visible leaks at the wheels/hoses, and the fluid level is right, that really leaves only one thing that could cause all of the above symptoms...the MC..
Joel Adams
C3VR Lifetime Member #56 
My Link 
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Yes you could say the pedal went to the floor; "multiple time, rapidly in succession".
current
1977 Coupe
gone but not forgotten
1996 Grand Sport
1996 Grand Sport
1984 coupe
1974 coupe
1964 roadster
1974 coupe
1964 roadster
for the 77 if you had a leak you should only loose either front or rear brakes. If a leak happens in the front the poportioning valve will set to one side to shutoff the front brakes, this would turn on the dash brake light, and until you can get equal pressure back the poportioning valve will stay tripped. sometimes you can detect the master cylinder being bad, push on the break pedal and if it gradually goes down under the constent pressure and then can be pumped back up
Trust me when I say they cannot be pumped up...
Someone suggested stepping on the brake and if the pedal goes down when started it is the master cylinder. I tried and the pedal goes down so I guess I have my diagnosis.
current
1977 Coupe
gone but not forgotten
1996 Grand Sport
1996 Grand Sport
1984 coupe
1974 coupe
1964 roadster
1974 coupe
1964 roadster
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20225
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
Not really! If you have power brakes, the pedal will ALWAYS go down( couple of inches or less) when you start the engine...it's a function of the power booster.
I'mma thinking master, still...
I'mma thinking master, still...
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Former Member
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Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
I had a similar issue with the '78 I owned. In my case at least, it was a leaking brake caliper. It wasn't leaking fluid, it was sucking in air. Rebuilding the caliper fixed the problem.
Check all your caliper seals and see if it's the same problem I had.
Check all your caliper seals and see if it's the same problem I had.
Former Member
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Mounds View, MN - USA
Joined: 5/24/2007
Posts: 1031
Vette(s): 70 LT1 coupe, 69 350 HP coupe, 69 390HP 427 coupe, 71 LS5 convert, 85 coupe, 93 coupe
If you combine everyone's answer above, they pretty much point only to the master cylinder. If it was a leak, plugged hose, or stuck caliper, etc, you would still have brakes at the other end of the car. Unless they went bad some time ago and you didn't notice, which isn't too likely.
There are some cheap Chinese replacements on the market, but I wouldn't trust my life to one.
Larry
There are some cheap Chinese replacements on the market, but I wouldn't trust my life to one.
Larry
[QUOTE=Adams' Apple]Not really! If you have power brakes, the pedal will ALWAYS go down( couple of inches or less) when you start the engine...it's a function of the power booster.
I'mma thinking master, still...[/QUOTE]
I'mma thinking master, still...[/QUOTE]
The consences seems to be the master cylinder so I'm goin for it and new hoses... I'll ley ya' know
current
1977 Coupe
gone but not forgotten
1996 Grand Sport
1996 Grand Sport
1984 coupe
1974 coupe
1964 roadster
1974 coupe
1964 roadster
[QUOTE=Adams' Apple]Not really! If you have power brakes, the pedal will ALWAYS go down( couple of inches or less) when you start the engine...it's a function of the power booster.
I'mma thinking master, still...[/QUOTE]
I'mma thinking master, still...[/QUOTE]
...and the diagnosis was based on the booster functioning, (hence the pedal travel downward)
current
1977 Coupe
gone but not forgotten
1996 Grand Sport
1996 Grand Sport
1984 coupe
1974 coupe
1964 roadster
1974 coupe
1964 roadster
in Forum: C3 Engines, Driveline and Handling
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