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08-14-2022
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#1 |
 
Join Date: Dec 2005
Location: Delanson, NY
Posts: 923
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Brake petal goes low intermittently
Took my 1990 out today, was running great. After about a half hour of driving when coming to a light to stop, petal went way down before the brakes engaged. Brake light on for a short time. Petal felt strange. Brakes seemed to work after that but then it happened again after about 6 or so more stops. Fluid in the two reservoirs are where they should be.
Any thoughts on what may be causing this? Thanks in advance.
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1968 convertible Lemans Blue, 1986 coupe Medium Blue NCRS Top Flight (sold), 1990 ZR1 #2529 Red NCRS Regional and National Top Flight (sold), 1990 ZR1 #2124 Charcoal Metallic NCRS Top Flight 2010 & 2018, 2003 Anniversary Red Convertible (sold) |
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08-15-2022
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#2 | |
  
Join Date: May 2007
Location: Peoria, AZ
Posts: 9,160
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Re: Brake petal goes low intermittently
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__________________
GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director  91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V |
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08-15-2022
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#3 | |
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Join Date: Dec 2005
Location: Delanson, NY
Posts: 923
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Re: Brake petal goes low intermittently
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Thanks.
__________________
1968 convertible Lemans Blue, 1986 coupe Medium Blue NCRS Top Flight (sold), 1990 ZR1 #2529 Red NCRS Regional and National Top Flight (sold), 1990 ZR1 #2124 Charcoal Metallic NCRS Top Flight 2010 & 2018, 2003 Anniversary Red Convertible (sold) |
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08-16-2022
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#4 | |
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Join Date: May 2007
Location: Peoria, AZ
Posts: 9,160
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Re: Brake petal goes low intermittently
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I hope it's the master cylinder as those are easier to find and the 4 bolt vacuum boosters are a bear to find.
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GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V |
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08-15-2022
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#5 |
 
Join Date: Sep 2016
Location: Ocala, FL
Posts: 902
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Re: Brake petal goes low intermittently
Install a new master cylinder immediately. Do not drive it anymore.
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Steve Young 1991 ZR-1 Quasar Blue Metallic/Black #729 Second Owner 1991 ZR-1 Dark Red Metallic/Black #2040 SOLD 1990 ZR-1 Dark Red Metallic/Saddle #1670 SOLD Double your happiness.....complain half as much. |
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08-15-2022
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#6 | |
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Join Date: Dec 2005
Location: Delanson, NY
Posts: 923
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Re: Brake petal goes low intermittently
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__________________
1968 convertible Lemans Blue, 1986 coupe Medium Blue NCRS Top Flight (sold), 1990 ZR1 #2529 Red NCRS Regional and National Top Flight (sold), 1990 ZR1 #2124 Charcoal Metallic NCRS Top Flight 2010 & 2018, 2003 Anniversary Red Convertible (sold) |
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08-17-2022
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#7 |
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Join Date: Sep 2016
Location: Ocala, FL
Posts: 902
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Re: Brake petal goes low intermittently
Booster is an assist and has nothing to do with the height of the pedal. The pedal went down because fluid escaped past the pistons in the master cylinder. That causes the light to come on. It happened to me once, right before my favorite twisties. O Reillys has a master cylinder for you for under $150.00. Brakes are life and death and thus my abruptness brother.
__________________
Steve Young 1991 ZR-1 Quasar Blue Metallic/Black #729 Second Owner 1991 ZR-1 Dark Red Metallic/Black #2040 SOLD 1990 ZR-1 Dark Red Metallic/Saddle #1670 SOLD Double your happiness.....complain half as much. |
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08-18-2022
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#8 | |
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Join Date: Dec 2005
Location: Delanson, NY
Posts: 923
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Re: Brake petal goes low intermittently
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__________________
1968 convertible Lemans Blue, 1986 coupe Medium Blue NCRS Top Flight (sold), 1990 ZR1 #2529 Red NCRS Regional and National Top Flight (sold), 1990 ZR1 #2124 Charcoal Metallic NCRS Top Flight 2010 & 2018, 2003 Anniversary Red Convertible (sold) |
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08-18-2022
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#9 |
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Join Date: Jul 2016
Location: Greater St. Louis
Posts: 490
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Re: Brake petal goes low intermittently
Tricky part of the MC replacement is the C-clip from the pedal to the rod. You?re upside down with your head in the footwell and it?s dark even with a good light. Be patient, it will work.
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08-18-2022
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#10 |
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Join Date: May 2007
Location: Peoria, AZ
Posts: 9,160
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Re: Brake petal goes low intermittently
If the booster is good to go then the master cylinder is the culprit. Looks like you are in good hands advise wise. GC
__________________
GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V |
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