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Brake problem

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Brake problem

Posted: 7/13/07 10:30amMessage 1 of 29
n
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Carson City, NV - USA
Joined: 4/20/2007
Posts: 33
Vette(s): Powder Blue 1981 Corvette-350 cubic inch fuel injected 400 horsepower

I am having a brake problem and have taken it in to mechanic a couple of times but still the problem remains.  After driving for 250-300 miles the brakes become sluggish, slow response time.  I had to hit the brakes hard coming back from Santa Cruz, Ca. and now the brake light remains on, has happened before.  As we are leaving for Florida in two weeks (in the Corvette, of course) I really need some help with this.  Any suggestions???????????? It seems to me that brakes heat up and just don't work right.  Not sure but seems that is what is happening

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Brake problem

Posted: 7/13/07 10:36amMessage 2 of 29
O
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Eastern Oklahoma County, OK - USA
Joined: 1/3/2006
Posts: 1560
Vette(s): 1980 Black L48 T-Tops
2 questions:
 
1: have you changed the fluid, rubber lines to calipers or calipers?
 
2: are there any visible signs of trace leakage around the ends of the calipers where the two sides connect?
 
I had that problem and it turned out to be the left rear caliper drawing air back into the system.  I would completely lose brakes over time and have to re-bleed.  I solved it by replacing the calipers, changing to braded steel lines,  and replacing the master cylinder/changing the fluid.
 
It took all of these to eventually eliminate the problem of soft brakes completely. 
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Brake problem

Posted: 7/13/07 10:57amMessage 3 of 29
n
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Carson City, NV - USA
Joined: 4/20/2007
Posts: 33
Vette(s): Powder Blue 1981 Corvette-350 cubic inch fuel injected 400 horsepower
Have replaced the master cylinder, completely drain and replaced brake fluid, replaced the rotars on the front, back rotors were fine.  Brake pads been inspected and said they couldn't find anything wrong.  Will try that with the calipers.  Thanks alot.  Bo
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Brake problem

Posted: 7/13/07 4:00pmMessage 4 of 29
R
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BINGHAMTON, NY - USA
Joined: 7/19/2003
Posts: 3825
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Try replacing the rubber brake hoses,they may look good on the outside ,but they turn into mush on the inside,sometimes the fluid wont back flow or just get trapped in the hose

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Brake problem

Posted: 7/13/07 5:31pmMessage 5 of 29
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Victor, NY - USA
Joined: 7/12/2004
Posts: 6842
Vette(s): 2004 Commemorative Edition Coupe, Auto w/HUD. 13K miles in 2015. Sold 1982 Red Coupe

If they didn't do it already, have them check the runout on all 4 rotors.

The specs allow .005" TIR, but if you have more than .003" the brake pistons will pump air into the lines.
 
Have him bleed the lines again, starting with rear pass. side, then rear drive side then front pass side and finally front drive side.
 
Also have the proportional valve checked to see if it is sticking.
 
 
 
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Brake problem

Posted: 7/13/07 8:05pmMessage 6 of 29
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 22720
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
Bo, is your pedal going down too far, or, farther than "normal" when this happens?
If you had to "hit the brakes hard", and the light came on, that's telling you the proportioning valve has tripped, and there is a problem on one end or the other. You either have air in the system, or...when you got on the binders hard, the hoses swelled enough to trip the p-valve.

With the car running, you should be able to pop the pedal hard & quick, and the p-valve should reset, unless there is still air in the system, or the master is leaking internally.

Joel Adams
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Brake problem

Posted: 7/13/07 8:45pmMessage 7 of 29
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baytown, TX - USA
Joined: 4/21/2004
Posts: 160
Vette(s): 1979 maui blue/doe skin, fuel injected 383, 6-speed manual, hooker sidepipes, 3.90 gear
I installed a set of extreme brake calipers with stainless linings and new master cylinder with silicone fluid and for years now I've never had those problems againThumbs%20Up
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Brake problem

Posted: 7/20/07 8:30pmMessage 8 of 29
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Naples, FL - USA
Joined: 2/26/2005
Posts: 133
Vette(s): 1976 coupe with a custom body and a 396 big block with nitrous installed. Runs great!!
Stainless braided lines are the way to go. You will feel the difference in pedal firmness. The rubber lines will expand ever so slightly and therefore reduce the pressure to the calipers. I did mine and will never put rubber on anything. Unless you want NCRS compliance do yourself a favor. A few bucks more but well worth it.
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Brake problem

Posted: 7/24/07 3:25pmMessage 9 of 29
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Albuquerque, NM - USA
Joined: 3/11/2006
Posts: 47
Vette(s): 1971 454 BB , matching numbers, 4spd,a/c,pb,ps, Blue
I also have a brake problem and have done the following: Bought new master cylinder, s/s calipers, pads, rubber hoses, power booster and bled the system 3-4 times with no air coming out. I am getting a good flow when bleeding but still have little peddle and stopping power is very weak. If I didn't bleed the master cylinder enough would I still have a good flow?Cry  
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Brake problem

Posted: 7/24/07 8:04pmMessage 10 of 29
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 22720
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
Vette calipers can be a pain to fully bleed, due to the two sided design, and the dual bleeders on them in the rear. A pressure bleeder works best, but I know not everyone has one. Sometimes, a rubber mallet tapping on the caliper while bleeding will help dislodge air bubbles. It's best to fill the calipers with fluid before installing them, also.
Always start by bleeding the master cyl first. Most parts houses sell a kit("Help") with plastic fittings, and hose for doing this, if your master did not come with them.
Bleed 'em to death!

Joel Adams
C3VR Lifetime Member #56    

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             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

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