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06-03-2015, 11:14 AM | #1 |
Registered User
Join Date: Jun 2013
Location: Hillsville va
Posts: 35
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Brake issues on 72 burb
Hey guys, any suggestions will be appreciated. I am about at my wits end chasing my brake issue. I was driving and headed down an old mountain road on the Blue Ridge Parkway and I felt my pedal get spongy, so I pressed it to the floor and it didn;t stop. I was able to gear down and get it stopped. When I got out the front rotors were so hot they were smoking, anyway, I got it home by a tow. I put it on a lift and couldn't find any leaks or broken lines. I double checked that the rear brakes were adjusted, bled the brakes several times. The pedal still seems weak to me, it stops but I don't think its as good as it was. The only other thing I can think of is the plunger for the proportioning valve is worn out. I can move it with my finger and I thought it should have pressure on it so it would be moved so easily? And I think it would be rare that it would fail? Im having trouble finding a replacement that is AC Delco, so if I have to replace it any suggestions on quality aftermarket. Thanks...Also right as I got it stopped the brake light came on in the dash and hasn't went out since.
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06-03-2015, 01:17 PM | #2 |
Registered User
Join Date: May 2014
Location: Melbourne, FL
Posts: 297
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Re: Brake issues on 72 burb
I had to replace my master cylinder when my pedal would slowly go to the floor. I had to pump the brakes even at a stop light to stay stopped. A new master cylinder fixed though.
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06-03-2015, 01:29 PM | #3 |
Ephesians 2:8
Join Date: Mar 2008
Location: Delavan, IL
Posts: 677
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Re: Brake issues on 72 burb
It does sound like a master cylinder. I upgraded mine to a 72 C30 booster/Master Cylinder combo from Oriellys. Stops really well now!
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06-03-2015, 01:32 PM | #4 |
Senior Member
Join Date: Jul 2012
Location: Oblong, Illinois
Posts: 7,028
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Re: Brake issues on 72 burb
Sounds like front brakes became over heated and started experiencing brake fade. Same as doing a number of high speed stops and the brakes become less effective. The pads are likely glazed and don't work as well now. If mine, I would replace the pads, look the rotor surface over for pitting / grooves, measure for parallel, bleed to balance the warning switch and evaluate. And may be a bad master too.
Also check the front hoses for collapse. If you weren't using the brakes much and they got hot, a hose internal collapse can keep the caliper applied overheating the brakes. |
06-04-2015, 06:10 PM | #5 |
The Older Generation
Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,815
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Re: Brake issues on 72 burb
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If the light is staying on that normally means that one of the brake systems is not working, either the front or the rear. Was either of the fluid reservoirs low on fluid when you first took the master cylinder cover off? LockDoc
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Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - |
06-04-2015, 09:14 PM | #6 |
Registered User
Join Date: Apr 2011
Location: Klein Texas
Posts: 3,852
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Re: Brake issues on 72 burb
I've seen one, in my lifetime working on cars, proportioning valve fail like the OP said.
Very similar symptoms to a failed master cylinder.
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My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe |
06-05-2015, 03:13 PM | #7 |
Registered User
Join Date: Jun 2013
Location: Hillsville va
Posts: 35
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Re: Brake issues on 72 burb
Thanks guys, I replaced the master cylinder and as I was bleeding the brakes, the front passengers side had a small flow and the pedal didn't go to the floor. So I went ahead and cracked the drivers side (after closing passenger) and on the second try and bunch of junk came out and then really good flow, went back to passengers side and got good flow. So is it possible that the trash in the lines caused the problems? Thanks again
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06-05-2015, 03:55 PM | #8 |
Registered User
Join Date: Apr 2011
Location: Klein Texas
Posts: 3,852
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Re: Brake issues on 72 burb
It might be time for new brake hoses. They don't last forever.
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My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe |
07-18-2015, 11:30 AM | #9 | |
Registered User
Join Date: Sep 2010
Location: anywhere, Texas
Posts: 66
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Re: Brake issues on 72 burb
Quote:
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Rich |
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07-18-2015, 03:10 PM | #10 |
Registered User
Join Date: Jun 2013
Location: Hillsville va
Posts: 35
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Re: Brake issues on 72 burb
Everything is getting ready to be new
..thanks guys |
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