Brake Fade
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 2,235
Likes: 65
From: Herndon VA
Brake Fade
Can someone explain why brakes fade? What can you do to prevent it? I changed my pads/rotors and noticed a bit of an improvement. I notice all this talk about fluids. Is that my next step? I don't really road race, but like the spirited drive now and then 
Pro
Joined: Aug 1999
Posts: 532
Likes: 0
From: Lone Oak Texas
Re: Brake Fade (shizon'00)
Brake fade is caused by your brake fluid boiling. As soon as it boils you get bubbles in the fluid, which since they are a gas are compressible, so when you press on the pedal you don't get a direct reaction at the caliper pistons. This is why there is such a big deal made about brake fluid boiling point temperatures. This will occur after repeated high speed braking such as on a road course track. It is unlikely that you would create brake fade in a C5 on the street unless you were driving extremely agressively.
There are several ways to prevent (defer?) brake fade in order of expense;
1. Make sure the brake fluid is freshly bled and use a high boiling point fluid.
2. Improve the cooling to the brakes for example by improving the air ducting to the front brakes.
3. Install bigger brakes with better heat dissipating capability.
Brake fade is a transient condition, once the fluid cools below the boiling point the brakes aren't fading anymore. Or in other words brake fade isn't improved by changing pads/rotors. Hope this helps.
There are several ways to prevent (defer?) brake fade in order of expense;
1. Make sure the brake fluid is freshly bled and use a high boiling point fluid.
2. Improve the cooling to the brakes for example by improving the air ducting to the front brakes.
3. Install bigger brakes with better heat dissipating capability.
Brake fade is a transient condition, once the fluid cools below the boiling point the brakes aren't fading anymore. Or in other words brake fade isn't improved by changing pads/rotors. Hope this helps.
Racer
Joined: Dec 2000
Posts: 339
Likes: 2
From: West Hartford, CT, USA
Re: Brake Fade (shizon'00)
Bassfisher's explanation is dead nuts on for solving the problem of a soft/mushy pedal, if that's what you meant by 'fade'.
If, on the other hand, you meant that the pedal is firm , but increased pedal pressure doesn't seem to produce faster stopping, then something other than fluid may be at work.
This kind of fade occurs because the friction surface of the pad gets less grippy as the pad & rotor heat up. One cause of this is that a thin film of gas from the pad is built up between the pad and rotor and causes a condition similar to when your tire hydroplanes on water. Solutions include changing pads, or having your rotors slotted or cross-drilled. The slots and holes are to aid in this 'outgassing' problem.
Frankly, I think I'd just change the pads, since the other stuff tends to reduce rotor life. I'd also change to the higher boiling temp fluid. It's cheap and if this isn't your problem yet, it's quite likely it will be at some point. Think of it as cheap insurance.
If, on the other hand, you meant that the pedal is firm , but increased pedal pressure doesn't seem to produce faster stopping, then something other than fluid may be at work.
This kind of fade occurs because the friction surface of the pad gets less grippy as the pad & rotor heat up. One cause of this is that a thin film of gas from the pad is built up between the pad and rotor and causes a condition similar to when your tire hydroplanes on water. Solutions include changing pads, or having your rotors slotted or cross-drilled. The slots and holes are to aid in this 'outgassing' problem.
Frankly, I think I'd just change the pads, since the other stuff tends to reduce rotor life. I'd also change to the higher boiling temp fluid. It's cheap and if this isn't your problem yet, it's quite likely it will be at some point. Think of it as cheap insurance.
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 2,235
Likes: 65
From: Herndon VA
Re: Brake Fade (SweetSavannah)
I already changed my pads and rotors to slotted rotors and metalux pads. They are great, but when on a forum cruise, we were driving rather aggressively and was braking hard from 130mph or so. After that I had almost no pedal. That's what I meant from fade as I understand the definition.
So what kind of fluid should I go with? I don't road race or anything, I just like the occasional spirited trip on the back roads (where I experience some fading when I think I should have some more brake left).
So what kind of fluid should I go with? I don't road race or anything, I just like the occasional spirited trip on the back roads (where I experience some fading when I think I should have some more brake left).
Melting Slicks
Joined: Jul 2000
Posts: 2,651
Likes: 6
From: redlands,ca.-usa
Re: Brake Fade (shizon'00)
A good fluid which is much etter than GM is Ford H/D-4 bucks a can at your
Ford dealer--there are better fluids for a lot more bucks but for the street its hard to beat Ford fluid.Has a very high boiling point compared to GM
Ford dealer--there are better fluids for a lot more bucks but for the street its hard to beat Ford fluid.Has a very high boiling point compared to GM
Tech Contributor
Joined: Oct 1999
Posts: 41,037
Likes: 9,798
From: Charlotte, NC (formerly Endicott, NY)
Re: Brake Fade (shizon'00)
It depends on how many times you stopped from 130. With the stock pads there probably is little chance of boiling the fluid since the stock pads do not operate at a high enough temperature. However, you can get pad taper that will cause increased pedal travel due to increased caliper piston movement. The symptom is a low but not mush pedal, when the pads finally fully engage you have a hard pedal. In some cases of hard usage like a two day track event you may have to stroke the pedal twice to move the pistons out far enough to get a hard pedal before it hits bottom. The only solution to the pad taper problem is to get new pads. You can bleed the fluid for hours but it will not help.
Bill
Bill
Pro
Joined: Aug 1999
Posts: 532
Likes: 0
From: Lone Oak Texas
Re: Brake Fade (Bill Dearborn)
The amount of heat generated in the brakes is proportional to the square of the speed so repeated stops from 130 could generate very high brake fluid temps. The Ford brake fluid has a high dry boiling point but a normal wet boiling point. If you are bleeding your brakes before every hard use, as in a race car, the wet boiling point isn't important. However for a street car with longer fluid change intervals both boiling points are important.
Dot 3,4 and 5.1 are all compatible (according to DOT rules) you just have to shop around to see what is the best tradeoff for you with relation to price, availability, and wet/dry boiling points. Do not use DOT 5.0 fluid as it is incompatible with the others and is slightly compressible so doesn't perform as well in a performance application. I use AP Lockheed Dot 5.1 but there are many other good fluids available.
Dot 3,4 and 5.1 are all compatible (according to DOT rules) you just have to shop around to see what is the best tradeoff for you with relation to price, availability, and wet/dry boiling points. Do not use DOT 5.0 fluid as it is incompatible with the others and is slightly compressible so doesn't perform as well in a performance application. I use AP Lockheed Dot 5.1 but there are many other good fluids available.
Racer
Joined: Dec 2000
Posts: 339
Likes: 2
From: West Hartford, CT, USA
Re: Brake Fade (shizon'00)
I use MOTUL 600.
This should help you not boil the fluid.
Nonetheless, if you are stopping the car from 100+ w/ any frequency, you're going to discover that the stock system is probably not up to the task. When you get there, please post again.
This should help you not boil the fluid.
Nonetheless, if you are stopping the car from 100+ w/ any frequency, you're going to discover that the stock system is probably not up to the task. When you get there, please post again.
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