Question about brakes
Thread Starter
Racer
Joined: Dec 2001
Posts: 333
Likes: 1
From: Laughlin NV.
Question about brakes
I went on a little fun run with a group today. After a little mountian road driving, car drove great, brakes worked great, got to the bottom of the hill at a stop light. After the light finely turned green I moved about a car length, hit the brakes because of a dip, brakes went to the floor. I pumped the brake one time and had a good pedal again, pulled in to a parking lot every time I hit the brakes same thing, had to pump the pedal to stop. Went in had lunch. After lunch brakes worked fine, after cooling. Question What would cause this? Brakes are new just put on new rotors and pads on the front. About two hundred miles on them. Could it be the fluid is bad, old. If that is the trouble, could anybody tell me how do you exchange it out with new. By the way it is an 87 convertible. Thanks Jack
Burning Brakes
Joined: Dec 2004
Posts: 825
Likes: 0
From: Hanging out back with the dark horses. Wa.
Sounds like you got the fluid hot. When you do that it pumps the hot fluid into you stock rubber brake lines. When that happens the rubber gets soft and expands more. Thats why most of us use SS braided lines, no flexing.
Try shifting to a lower rear when coming down long hills. let the motor and trans do the work.
Try shifting to a lower rear when coming down long hills. let the motor and trans do the work.
Melting Slicks
Joined: May 2003
Posts: 3,490
Likes: 68
From: Hewitt NJ
Agree, sounds like you were suffering from brake fade. Make sure you flush out the system and use some high quality fluid that has a higher boiling point. Another solution is to upgrade to the C5 brakes. 
Thread Starter
Racer
Joined: Dec 2001
Posts: 333
Likes: 1
From: Laughlin NV.
To flush out the system, do you do the same as when bleeding for air? Just keep going till the fluid looks new.
Where is a good place to get the SS brake lines and about how much should it cost?
Where is a good place to get the SS brake lines and about how much should it cost?
Last edited by convertible lover; Apr 10, 2005 at 07:57 PM.
Melting Slicks
Joined: Dec 1999
Posts: 2,816
Likes: 2
From: Austin, TX
Originally Posted by convertible lover
To flush out the system, do you do the same as when bleeding for air? Just keep going till the fluid looks new.
should it cost?
should it cost?
I bought my SS lines from doug Rippie ( www.dougrippie.com ) but there are a lot of places that sell them. Can't remember the price.
Burning Brakes
Joined: Dec 2004
Posts: 825
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From: Hanging out back with the dark horses. Wa.
Got my russels SS lines from summit racing. around $100.
To flush the fluid , yes just like bleeding brakes, keep bleeding until it's clean. You can buy a kits to do this at your auto parts store. Do some reading and talk to folks about the best fluid. Some say synthetic, some just OEM fluid. Thats your choice.
To flush the fluid , yes just like bleeding brakes, keep bleeding until it's clean. You can buy a kits to do this at your auto parts store. Do some reading and talk to folks about the best fluid. Some say synthetic, some just OEM fluid. Thats your choice.
Race Director
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From: Almost all Skyline Cruises Vettes at Waterside 1-5
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I really like Valvoline "synpower" brake fluid
I run it hard and brake hard aand no sign of overheating the fluid
Jack
I run it hard and brake hard aand no sign of overheating the fluid
Jack
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Melting Slicks
Joined: May 2003
Posts: 3,490
Likes: 68
From: Hewitt NJ
Originally Posted by rws.1
Valvoline Synpower is Dot 3+ DOT 4...
I swtiched ot it a year ago. glad I did.
I swtiched ot it a year ago. glad I did.
Team Owner
Joined: May 2002
Posts: 24,337
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
If you lost pedal pressure, it's leaking past the m/c, or the fluid is boiling.
Check the fluid level. If that's ok, it maybe water in the fluid vaporizing, which reduces line pressure. (and corrodes everything too).
If the pedal was firm, but it just didn't stop, then it's brake fade. That has nothing to do with the fluid or brake lines. It's when the rotors and pads overheat and lose their friction coefficient. Only way to fix that is upgrade to heavier rotors or change your driving habits.
Check the fluid level. If that's ok, it maybe water in the fluid vaporizing, which reduces line pressure. (and corrodes everything too).
If the pedal was firm, but it just didn't stop, then it's brake fade. That has nothing to do with the fluid or brake lines. It's when the rotors and pads overheat and lose their friction coefficient. Only way to fix that is upgrade to heavier rotors or change your driving habits.
Thread Starter
Racer
Joined: Dec 2001
Posts: 333
Likes: 1
From: Laughlin NV.
Originally Posted by CentralCoaster
If you lost pedal pressure, it's leaking past the m/c, or the fluid is boiling.
Check the fluid level. If that's ok, it maybe water in the fluid vaporizing, which reduces line pressure. (and corrodes everything too).
If the pedal was firm, but it just didn't stop, then it's brake fade. That has nothing to do with the fluid or brake lines. It's when the rotors and pads overheat and lose their friction coefficient. Only way to fix that is upgrade to heavier rotors or change your driving habits.
Check the fluid level. If that's ok, it maybe water in the fluid vaporizing, which reduces line pressure. (and corrodes everything too).
If the pedal was firm, but it just didn't stop, then it's brake fade. That has nothing to do with the fluid or brake lines. It's when the rotors and pads overheat and lose their friction coefficient. Only way to fix that is upgrade to heavier rotors or change your driving habits.
Instructor
Joined: Apr 2004
Posts: 240
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From: St. Louis MO
Originally Posted by larryfs
you need a master cylinder, plain and simple.
the stock C4 brakes work fine for what your doing.
the stock C4 brakes work fine for what your doing.
I think it's just fluid boiling. Brake fluid absorbs water, plain and simple. A sealed container of brake fluid will be about 5-20% water after one year. It absorbs moisture through containers which means a fluid change will suit you well.
As for everyone blaming the hoses, maybe, but I don't think so. I worked on brakes for a long time, as a job, and most of the time, unless the hose has split open, when a hose goes bad, it doesn't want to release. The internal lining breaks down and doesn't want to cause the fluid to return to the cylinder, causing a bad pull and definite heat.
Here's some easy steps for a hose check. Jack the car up. Have someone sit in the car. Spin one of the wheels by hand, and have the person in the car hit the brakes. The wheel should stop of course, then tell them to release. Once they release, try turning the wheel with your hands. It should spin freely, if not and it is very hard to turn or won't budge at all, bad hose.
Hope that helps and good luck!
Drifting
Joined: Dec 2002
Posts: 1,474
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From: Tracy CA
Originally Posted by larryfs
you need a master cylinder, plain and simple.
the stock C4 brakes work fine for what your doing.
the stock C4 brakes work fine for what your doing.
Change the fluid first - it's a cheap fix if that's the problem. Other than that - the pumping up of the pedal is classic master cylinder failure.
p.s. When you change pads: don't squeeze the fluid from the calipers back up to the master cylinder - always bleed the fluid off out of the bleed screw. Othewise - all the crap from the calipers end up in your master cylinder causing premature failure.
Best of luck to you!
Race Director
Joined: Dec 2002
Posts: 13,348
Likes: 233
From: SCMR Rat Pack'r Charter Member..Great Bend KS
Originally Posted by CentralCoaster
If you lost pedal pressure, it's leaking past the m/c, or the fluid is boiling.
Check the fluid level. If that's ok, it maybe water in the fluid vaporizing, which reduces line pressure. (and corrodes everything too).
If the pedal was firm, but it just didn't stop, then it's brake fade. That has nothing to do with the fluid or brake lines. It's when the rotors and pads overheat and lose their friction coefficient. Only way to fix that is upgrade to heavier rotors or change your driving habits.
Check the fluid level. If that's ok, it maybe water in the fluid vaporizing, which reduces line pressure. (and corrodes everything too).
If the pedal was firm, but it just didn't stop, then it's brake fade. That has nothing to do with the fluid or brake lines. It's when the rotors and pads overheat and lose their friction coefficient. Only way to fix that is upgrade to heavier rotors or change your driving habits.
It sounds like you boiled the fluid. Just flush/refill with Valvoline Synthetic.
The fact that the problem was gone when the system cooled tells me the master cylinder was not at fault.
Oh, yeah, there is one other thing you can do to stop fade, besides changing rotors or habits; change to a good ceramic pad. Worked for me.
...and I don't think it's a hose problem either. SS hoses will give you a better pedal feel, but they can't stop fade or fluid boiling.
Larry
code5coupe
Last edited by rocco16; Apr 12, 2005 at 05:55 PM.