Topic: No Brakes
in Forum: C4 Handling Components
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Huron, OH - USA
Joined: 12/5/2009
Posts: 179
Vette(s): 1989 Red Convertible - 160,000 fun-filled miles -
Over the last few weeks, I could feel the brake pedal getting a little spongy. I took it out last night and the pedal went to the floor and pumping the pedal builds up enough pressure to stop the car (never went over 35mph). Both reservoirs have maintained their fluid levels so there's no leak there. When the pedal goes soft and before pumping it, there's almost zero braking action. I think that tells me it isn't a bad caliper since the front and rear are independant of each other according to my Haynes manual.
Now I'm trying to determine a few things before digging in....
I'm fairly certain it's the master cylinder - anybody have any advice how to determine the failing component before dismantling ?
After the repairs are done, I plan on a thoroughly draining all of the brake fuid in the whole system. I'll need to decide whether to refill with the original DOT3 or go to something newer. I haven't checked into this much but have come across an article or two in Vette magazines that suggest a few newer products. Any advice or experience on the type of fluid is much appreciated.
The car has nearly 150K miles, so I am also wondering if the booster should be replaced as well while I'm at it? I had a brake job done about 25K miles ago and the pads and rotors look fine, but the condition of the calipers is unknown at this point.
Thanks folks !
Dave
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Huron, OH - USA
Joined: 12/5/2009
Posts: 179
Vette(s): 1989 Red Convertible - 160,000 fun-filled miles -
Forgot to mention the information center displays "Brake P I" when the pedal goes to the floor, and then turns off after pumping up some pressure
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Spring Hill, FL - USA
Joined: 8/9/2010
Posts: 59
Vette(s): 1992 coupe.
Custom.
Once a year, I flush the entire brake system.
Sounds like a MC, could be something else.
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lanoka harbor, NJ - USA
Joined: 3/22/2009
Posts: 1363
Vette(s): 1990 L-98 white/ red/black leather interior targa top auto
1975 L48 blue/black leather interior t tops auto
dave,
first thing i would do is to check each caliper for any signs of brake fluid. if none is found i would try bleeding the brakes as air in the lines will do the same thing as you describe. if the pedal stays hard thats great. if not then i would consider the m/c. as parts are expensive i would hate to see you replace stuff that didn't need replacing.
dave
the dynamic duo
c3vr life member #97
If you're not loosing fluid externally then--- yes IMO it sounds like a master cylinder---i'm also assuming you've done no other repairs to the brake system to allow air to get in the system---if not once again sounds like the MC.
96LT1 2010-08-12 04:58:06
I flushed my brake system about 2 years ago using a synthetic fluid made by BG products (Dot 4) and i'm pleased. Many members of some of the online Vette forums say to never ever use synthetic brake fluid in a C4 "it will destroy the ABS unit" 
---but i've had no issues with mine. They may be correct on the earlier C4s the ABS pumps vary from year to year. You can't go wrong using the factory recommended fluid (Dot 3)--- the important thing is to flush the system periodically it is usually something which gets neglected.
---but i've had no issues with mine. They may be correct on the earlier C4s the ABS pumps vary from year to year. You can't go wrong using the factory recommended fluid (Dot 3)--- the important thing is to flush the system periodically it is usually something which gets neglected. Vaughn
BTW--- as far as the booster goes since the fluid level isn't dropping I'm guessing fluid isn't leaking into the booster--- so IMO it should be ok
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Huron, OH - USA
Joined: 12/5/2009
Posts: 179
Vette(s): 1989 Red Convertible - 160,000 fun-filled miles -
Thanks for all the input guys !
I checked all over the place for a new or remanufactured MC and everybody is out of stock, Ecklers, Mid America, Corvette Central, Summit, Race Pages, Auto Parts Warehouse, and the list goes on. My local NAPA guy made tons of phone calls too. I ended up getting a rebuild kit from JC Whitney and should be here in 7-10 days (can't believe I won't be able to drive it for 2+ weeks, crud)
I have no experience with MC's - looked at a few DIY's and it looks fairly straight forward
I'm pretty sure I'm going to use DOT3 heavy duty fluid when I flush the entire system.
Still on the fence about the booster. Car has 150K miles and I have no intention of ever selling it. My approach over the last 6 years is to do each project the best I can.... since the 2 components are directly related, I'm still thinking of replacing it. The brakes have never been as good as they should since I bought it and there's no way of knowing if it was the MC, booster, or both..... hmmmm..... think think think
Wish me luck, I'll be really torqued if the rebuild kit is wrong or on back order too....
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lanoka harbor, NJ - USA
Joined: 3/22/2009
Posts: 1363
Vette(s): 1990 L-98 white/ red/black leather interior targa top auto
1975 L48 blue/black leather interior t tops auto
instead of going through ordering it from the ones you stated, did you try your local parts store. i picked mine up from advance auto and it comes with a lifetime guarantee. most times if they dont have it in stock it will be there the next day.
the dynamic duo
c3vr life member #97
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Huron, OH - USA
Joined: 12/5/2009
Posts: 179
Vette(s): 1989 Red Convertible - 160,000 fun-filled miles -
Yeap, NAPA, Auto World, and Auto Zone (the 1st two also made phone calls to confirm there was no availablilty and ask for alternatives)
How long ago did you buy yours ?
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lanoka harbor, NJ - USA
Joined: 3/22/2009
Posts: 1363
Vette(s): 1990 L-98 white/ red/black leather interior targa top auto
1975 L48 blue/black leather interior t tops auto
the first one was 2 years ago and just had it replaced in june. first time they had it in stock second time i had it the next day.
the dynamic duo
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Huron, OH - USA
Joined: 12/5/2009
Posts: 179
Vette(s): 1989 Red Convertible - 160,000 fun-filled miles -
Oh Nooooooooooooooooooooooooooooooo................ just got this email from JC Whitney
Dear Dave,
Thank you for your recent order with JC Whitney.
We regret to inform you that the item you ordered, 079358 ( Professional Grade Brake Master Cylinder )
will not work with the make and model of your vehicle. Our supplier is unable
to provide a match for your vehicle. Therefore, this item has been cancelled
from your order. We apologize for any inconvenience this may cause.
Your business is very important to us, and we appreciate your patronage.
If you have any questions regarding this cancellation notification, please contact
our Customer Service Department by using the link or phone number below.
JC Whitney
Thank you for your recent order with JC Whitney.
We regret to inform you that the item you ordered, 079358 ( Professional Grade Brake Master Cylinder )
will not work with the make and model of your vehicle. Our supplier is unable
to provide a match for your vehicle. Therefore, this item has been cancelled
from your order. We apologize for any inconvenience this may cause.
Your business is very important to us, and we appreciate your patronage.
If you have any questions regarding this cancellation notification, please contact
our Customer Service Department by using the link or phone number below.
JC Whitney
Now I gotta restart my search for a brake master cylinder GM# 130.62080 or rebuild kit
in Forum: C4 Handling Components
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