81 brake question

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Mar 11, 2009 | 12:50 AM

Brian74n81

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From: Mississippi

81 brake question

Brake pedal goes all the way to the floor and can barely get the car to stop. Master is full and no noticeable leaks. Can has been sitting up for about 10 months or so.......

I can take the vac line off booster and plug, and get full brake pedal. Plug back up, and soft pedal.

?? Any suggestions?

Mar 11, 2009 | 07:55 AM

guitarcrazy02

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From: North Royaton Ohio

Silly question, but have you tried bleeding the brakes?

Mar 11, 2009 | 09:23 AM

Brian74n81

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From: Mississippi

Quote:

Originally Posted by guitarcrazy02

Silly question, but have you tried bleeding the brakes?

Actually, NO. Just trying to figure out what to do at this point.

Mar 11, 2009 | 10:26 AM

CA-Legal-Vette

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From: Scottsdale Arizona

I wouldn't worry about the change with removing the booster vacuum hose. I suspect that if you tried to drive it without the booster, it still wouldn't stop but you'd have to push harder.

I'd start by inspection all four calipers for leaks and closely look at all of the brake lines for rust/signs of leaks. If you don't find anything, I'd suggest bleeding the system next. If that doesn't do it, the master cylinder would be next on my list. Replace it and rebleed.

Last edited by CA-Legal-Vette; Mar 11, 2009 at 02:12 PM.

Mar 12, 2009 | 10:45 PM

dburgjohn

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From: Dyersburg TN

you said it had been sitting, was it working before the long rest? Did you check the master cylinder? Low fluid there would indicate it is coming out somewhere. If it is not low and no fluid is leaking the master cylinder seals have gone bad. When you press the brake the fluid by-passes the seals and does not leave the master cylinder. If this is the case you can usually get some brake by pumping the pedal to get more fluid out while a single push and hold will drop down.

Mar 12, 2009 | 11:22 PM

larryg3

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From: Antioch IL

I would have to agree sounds like you have faulty master cylinder seals.
change the seals and bleed the system.

Mar 13, 2009 | 11:02 AM

dburgjohn

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From: Dyersburg TN

Quote:

Originally Posted by larryg3

I would have to agree sounds like you have faulty master cylinder seals.
change the seals and bleed the system.

Don't forget to bench bleed the MC off the car and level. Doing on the car will trap a air bubble. Trust me on this one.

Mar 13, 2009 | 03:10 PM

RaymondD

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From: Bronx New York

I had a problem with my brakes for the last couple of years. I would bleed them and everything was fine for about a half hour and then I'd loose almost all pedal travel. Thinking it was the master cylinder I changed that and the same thing happened. I even changed it again thinking I got a bad one. I looked for leaks but didn't find any. I unbolted the calipers and each one started to leak when I took them off the rotor. I guess the pressure was keeping it from leaking but would suck in air after a few stops. I rebuilt the calipers with the O-ring seals and haven't had a problem with them yet.