Brakes 101
August 24th, 2011, 10:28 PM
#1
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Brakes 101
I worked as a technical consultant for Bendix training technicians for a few years and hopefully this thread will help with some basic and a few more advanced diagnostics and repair procedures for those who want to work on their brakes. This is mostly for disc/drum systems but drum/drum systems use the same information.
Let's start with the basics...
First and most importantly - USE THE HIGHEST QUALITY PARTS YOU CAN AFFORD!!! These are your brakes, the number one safety feature of your car. If the car doesn't run, you won't die. If your brakes don't work, you can get killed or injured! Don't skimp on the brakes!
Brake fluid - You must replace it every 12K mile or once a year. Brake fluid is similar to motor oil in that it is designed to encapsulate the moisture and sediment in brake systems but it only has so much capacity to do so. As it ages the boiling point drops, deposits collect, and problems start becoming more expensive to correct. Flush and bleed the brakes after every other oil change and you'll avoid 70% of common brake issues. I recommend DOT 4 fluid or Castrol LMA fluid (low moisture absorbtion) as it has a higher temperature rating and is less suceptible to breakdown in high-performance use.
Wheel cylinders - If you have drum brakes on your car and over 15K miles on them I will bet the wheel cylinders are either leaking or sticking. I'll also bet alot of folks here think they are supposed to leak and operate just fine like that. THEY ARE NOT SUPPOSED TOO!! Wheel cylinders operate at far higher pressures than calipers just to open the return springs, much less stop the car. Peel back the dust boots on the ends and if you find any brake fluid at all (assembly grease is OK) go ahead and replace them. Often, wheel cylinders will blow their seal during a hard stop, squirt tiny amounts of fluid, then draw air into the lines when you release the pedal. This essentially renders rear drum brakes useless on a disc/drum car, overworking the fronts causing excessive heat, wear, and dramatically increased braking distances. It will also cause spongy brake pedals, more so on drum/drum cars. If you have the hardware off check to see if the cylinders move freely back and forth, about 1/4" of travel. If they stick, replace them, it's cheap insurance!
Hardware - Anytime you replace pads or shoes replace the caliper hardware and/or return springs as well. These items are cheap and allow the system components to slide and return properly. Worn caliper hardware will cause uneven pad wear from the leading-to-trailing ends. Worn return springs will cause heel-toe shoe wear (different wear in leading and trailing shoes).
Calipers - 70% of your braking power is right here and most of you will have the standard 78mm single piston GM standard mid-size caliper. These are a stout piece for around town driving and the large bore is fairly resistant to sediment binding when maintained properly. For high-performance use they are marginal at best but this is a maintenance and repair thread so lets fix what you have. The most common problem afflicting calipers is sediment bind due to poor maintenance. The heat cycling calipers go through is staggering and the large-bore calipers tend to "cook" the fluid under heavy use and flushing the fluid yearly is essential to keep these working well. Binding is diagnosed through the pads, look for uneven wear, pitting (numerous small holes on the pad face), and scoring (the pads look like the surface of an old LP record). I would recommend rebuilding the ones on your car before getting remans, no matter how cheap they are. Why? Your's have been in service recently, you know their history, and they haven't been sitting in a junkyard for who knows how long awaiting rebuild while exposed to the elements. It's also very inexpensive, about $5 per corner! You would probably be stunned if you opened a reman caliper for an older car. Many will have heavy corrosion pitting on the piston, scored bores, corrosion scarring, and heli-coiled line and bleeder threads. None of these conditions are acceptable your brakes shouldn't have these issues.
Let's start with the basics...
First and most importantly - USE THE HIGHEST QUALITY PARTS YOU CAN AFFORD!!! These are your brakes, the number one safety feature of your car. If the car doesn't run, you won't die. If your brakes don't work, you can get killed or injured! Don't skimp on the brakes!
Brake fluid - You must replace it every 12K mile or once a year. Brake fluid is similar to motor oil in that it is designed to encapsulate the moisture and sediment in brake systems but it only has so much capacity to do so. As it ages the boiling point drops, deposits collect, and problems start becoming more expensive to correct. Flush and bleed the brakes after every other oil change and you'll avoid 70% of common brake issues. I recommend DOT 4 fluid or Castrol LMA fluid (low moisture absorbtion) as it has a higher temperature rating and is less suceptible to breakdown in high-performance use.
Wheel cylinders - If you have drum brakes on your car and over 15K miles on them I will bet the wheel cylinders are either leaking or sticking. I'll also bet alot of folks here think they are supposed to leak and operate just fine like that. THEY ARE NOT SUPPOSED TOO!! Wheel cylinders operate at far higher pressures than calipers just to open the return springs, much less stop the car. Peel back the dust boots on the ends and if you find any brake fluid at all (assembly grease is OK) go ahead and replace them. Often, wheel cylinders will blow their seal during a hard stop, squirt tiny amounts of fluid, then draw air into the lines when you release the pedal. This essentially renders rear drum brakes useless on a disc/drum car, overworking the fronts causing excessive heat, wear, and dramatically increased braking distances. It will also cause spongy brake pedals, more so on drum/drum cars. If you have the hardware off check to see if the cylinders move freely back and forth, about 1/4" of travel. If they stick, replace them, it's cheap insurance!
Hardware - Anytime you replace pads or shoes replace the caliper hardware and/or return springs as well. These items are cheap and allow the system components to slide and return properly. Worn caliper hardware will cause uneven pad wear from the leading-to-trailing ends. Worn return springs will cause heel-toe shoe wear (different wear in leading and trailing shoes).
Calipers - 70% of your braking power is right here and most of you will have the standard 78mm single piston GM standard mid-size caliper. These are a stout piece for around town driving and the large bore is fairly resistant to sediment binding when maintained properly. For high-performance use they are marginal at best but this is a maintenance and repair thread so lets fix what you have. The most common problem afflicting calipers is sediment bind due to poor maintenance. The heat cycling calipers go through is staggering and the large-bore calipers tend to "cook" the fluid under heavy use and flushing the fluid yearly is essential to keep these working well. Binding is diagnosed through the pads, look for uneven wear, pitting (numerous small holes on the pad face), and scoring (the pads look like the surface of an old LP record). I would recommend rebuilding the ones on your car before getting remans, no matter how cheap they are. Why? Your's have been in service recently, you know their history, and they haven't been sitting in a junkyard for who knows how long awaiting rebuild while exposed to the elements. It's also very inexpensive, about $5 per corner! You would probably be stunned if you opened a reman caliper for an older car. Many will have heavy corrosion pitting on the piston, scored bores, corrosion scarring, and heli-coiled line and bleeder threads. None of these conditions are acceptable your brakes shouldn't have these issues.
August 24th, 2011, 10:39 PM
#2
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We have covered the basics for maintenance and pad/shoe problems, lets get deeper...
The newest cars I've seen on this board are typically late 80's cars. A minimum of 25 years of wear, tear, some neglect, and just normal use can cause more difficult to diagnose problems in the hydraulics.
MASTER CYLINDER - The master cylinder is the most important part of your car!!! Think about it, it's true!
Look inside your master cylinder reservoir for a moment and look at the fluid. Does it look like apple cider, tea, or coffee? It should be a golden clear color. If it's slightly darker (like tea) it's time for a change. If it's really dark (like coffee) and there is sediment at the bottom (wet black film) you have extensive seal deterioration and need a new master cylinder, PERIOD!
How about green fluid? Never seen it? Ask a neighbor who owns a 3 year-old ford if you can see his master cylinder. If he's like 90% of people, it's the OEM fluid and I'm willing to bet it's green! Green fluid indicates the copper in the brake fluid has started turning acidic from excessive moisture and is eating the brake-line inner coating and corroding them from the inside out. Fords do it quickly but after a dozen years or so I'll bet some of our board member's cars have this too.
Getting back to the blackened fluid - That film is particulates from the seals coming apart. Our master cylinders are made up of;
2 pistons (primary & secondary)
2 chambers (primary & secondary)
2 primary seals (named for pressure sealing, not location)
2-3 secondary seals (used for separation and sealing)
2 springs (primary & secondary piston return)
and a housing and reservior
If one of the secondary seals goes bad you will still have a decent pedal but your brakes will wear one or the other end much faster than the other. You can usually identify this problem when opening a master cylinder cap and finding one chamber lower than normal and the other near overflowing. Replace the master cylinder.
If one of the primary seals is dead you will still have brakes but with a low pedal and little stopping power. Replace the master cylinder.
If one or both of the springs are losing tension the pedal will return slowly and drag the brakes after you release pressure. Replace the master cylinder.
Also, consider replacement if you have headers and more than 30K miles on your master cylinder. The extra heat will damage the springs (heat-stress) and seals (hardening) inside the master.
Proportioning/Combo valve - Disc/drum cars and those built after 1967 use a 3-function combination valve (proportioning valve, metering valve, and brakelight warning switch) and are prone to many of the same problems as the master.
The prop valve is an umbrella-shaped seal that ONLY REACTS AT PEAK SYSTEM PRESSUREs! It is designed to keep the rear-end from locking-up and is designed to close off the rear brakes at a specific pressure, allowing no additional pressure. The excess pressure is fed to the fronts.
The metering valve is designed to pressurize the rear brakes FIRST, under light pedal application, to promote more even braking. On drum brake cars it can hold up to 125 psi before allowing any fluid to the fronts, simply to overcome the force of the return springs and engage both front and rear brakes simultaniously. Disc/disc metering valves operate at lower pressures as it only takes about 3-5 psi to move a piston.
If EITHER of these valve fail or the springs are weakened, you will have excessive brake wear on one end of the car. Drum to disc rear conversion? CHANGE THE COMBINATION VALVE DURING THE CONVERSION or you will tear up your new rear brakes!
Headers + 30K miles? Notice how close the combo valve is too the headers? Remember how springs and seals deteriorate when exposed to high heat? Replace your combo valve ASAP!
Got nasty fluid in the master? Guess what else needs replacement?!
Remember, gravity does it's thing with particulates too so when you find it in the master cylinder/prop valve you'll certainly find it in the calipers/wheel cylinders.
The newest cars I've seen on this board are typically late 80's cars. A minimum of 25 years of wear, tear, some neglect, and just normal use can cause more difficult to diagnose problems in the hydraulics.
MASTER CYLINDER - The master cylinder is the most important part of your car!!! Think about it, it's true!
Look inside your master cylinder reservoir for a moment and look at the fluid. Does it look like apple cider, tea, or coffee? It should be a golden clear color. If it's slightly darker (like tea) it's time for a change. If it's really dark (like coffee) and there is sediment at the bottom (wet black film) you have extensive seal deterioration and need a new master cylinder, PERIOD!
How about green fluid? Never seen it? Ask a neighbor who owns a 3 year-old ford if you can see his master cylinder. If he's like 90% of people, it's the OEM fluid and I'm willing to bet it's green! Green fluid indicates the copper in the brake fluid has started turning acidic from excessive moisture and is eating the brake-line inner coating and corroding them from the inside out. Fords do it quickly but after a dozen years or so I'll bet some of our board member's cars have this too.
Getting back to the blackened fluid - That film is particulates from the seals coming apart. Our master cylinders are made up of;
2 pistons (primary & secondary)
2 chambers (primary & secondary)
2 primary seals (named for pressure sealing, not location)
2-3 secondary seals (used for separation and sealing)
2 springs (primary & secondary piston return)
and a housing and reservior
If one of the secondary seals goes bad you will still have a decent pedal but your brakes will wear one or the other end much faster than the other. You can usually identify this problem when opening a master cylinder cap and finding one chamber lower than normal and the other near overflowing. Replace the master cylinder.
If one of the primary seals is dead you will still have brakes but with a low pedal and little stopping power. Replace the master cylinder.
If one or both of the springs are losing tension the pedal will return slowly and drag the brakes after you release pressure. Replace the master cylinder.
Also, consider replacement if you have headers and more than 30K miles on your master cylinder. The extra heat will damage the springs (heat-stress) and seals (hardening) inside the master.
Proportioning/Combo valve - Disc/drum cars and those built after 1967 use a 3-function combination valve (proportioning valve, metering valve, and brakelight warning switch) and are prone to many of the same problems as the master.
The prop valve is an umbrella-shaped seal that ONLY REACTS AT PEAK SYSTEM PRESSUREs! It is designed to keep the rear-end from locking-up and is designed to close off the rear brakes at a specific pressure, allowing no additional pressure. The excess pressure is fed to the fronts.
The metering valve is designed to pressurize the rear brakes FIRST, under light pedal application, to promote more even braking. On drum brake cars it can hold up to 125 psi before allowing any fluid to the fronts, simply to overcome the force of the return springs and engage both front and rear brakes simultaniously. Disc/disc metering valves operate at lower pressures as it only takes about 3-5 psi to move a piston.
If EITHER of these valve fail or the springs are weakened, you will have excessive brake wear on one end of the car. Drum to disc rear conversion? CHANGE THE COMBINATION VALVE DURING THE CONVERSION or you will tear up your new rear brakes!
Headers + 30K miles? Notice how close the combo valve is too the headers? Remember how springs and seals deteriorate when exposed to high heat? Replace your combo valve ASAP!
Got nasty fluid in the master? Guess what else needs replacement?!
Remember, gravity does it's thing with particulates too so when you find it in the master cylinder/prop valve you'll certainly find it in the calipers/wheel cylinders.
August 24th, 2011, 10:47 PM
#3
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I want to address another issue, specifically regarding adjustable prop valves. I've been blasted on tech boards and even in classrooms 1000 times for this but I'll stick to my guns... If your car is driven on the street, use an OEM prop valve.
I draw very distinct lines between street cars and race cars and build each according to the primary conditions they will be used. Varying loads, road conditions, tires, weather, and suspension wear are all realities the OEM valves will cover, even though it is heavily biased to the front. If you are having other problems with your brakes, particularly the rears, do not just slap on an APV to solve the issue! This is a band aid at best and flat out dangerous at worst! If you don't have the technical skill to diagnose and repair a problem, don't work on it until you've learned about it! Also, please don't jump to the next level and modify a brake system you know little to nothing about! If your rear calipers aren't working properly, fix them! I'm sure someone on this forum knows someone who has done the APV, set it up in perfect conditions to balance his pressures, then did some trail braking going into a corner in the rain and flown off the road a$$-end first. Problem is, they may not have lived to back me on this. I'm not trying to enflame anyone, I'm just saying go to a library and learn about the brakes before messing with them. Their are a lot of knowledgable folks on here, there are also those who should be banned from posting any advise on the brake board, and their are 1000's of professional mechanics who don't know squat about proper brake repair. Think I'm full of it? The first post in this thread contains more info than is covered in an ASE MASTER CERTIFICATION exam for brakes, all 25 questions of it. Think about that!!!! Good luck!!!
I draw very distinct lines between street cars and race cars and build each according to the primary conditions they will be used. Varying loads, road conditions, tires, weather, and suspension wear are all realities the OEM valves will cover, even though it is heavily biased to the front. If you are having other problems with your brakes, particularly the rears, do not just slap on an APV to solve the issue! This is a band aid at best and flat out dangerous at worst! If you don't have the technical skill to diagnose and repair a problem, don't work on it until you've learned about it! Also, please don't jump to the next level and modify a brake system you know little to nothing about! If your rear calipers aren't working properly, fix them! I'm sure someone on this forum knows someone who has done the APV, set it up in perfect conditions to balance his pressures, then did some trail braking going into a corner in the rain and flown off the road a$$-end first. Problem is, they may not have lived to back me on this. I'm not trying to enflame anyone, I'm just saying go to a library and learn about the brakes before messing with them. Their are a lot of knowledgable folks on here, there are also those who should be banned from posting any advise on the brake board, and their are 1000's of professional mechanics who don't know squat about proper brake repair. Think I'm full of it? The first post in this thread contains more info than is covered in an ASE MASTER CERTIFICATION exam for brakes, all 25 questions of it. Think about that!!!! Good luck!!!
Last edited by Murco; August 24th, 2011 at 10:49 PM.
August 25th, 2011, 04:46 AM
#5
welcome Murco what kind of olds do you have and how did you find CO ? If the single piston caliper is not the top choice than what would you pick for a 15" wheel. Would you recomend a 11" drum in the rear like the ones master power sells? This would be for a A body.
August 25th, 2011, 05:02 AM
#6
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This is very nice-sounding, and we do appreciate your input, but this particular recommendation is followed by no one. In all my years of driving and buying cars, I've never seen a recommendation in ANY owner's or service manual for any car that you should change your brake fluid, period, let alone every 12 months or 12,000 miles. If this was really so serious an issue, it would most certainly be mentioned.
There's probably two people on the planet who do this. You, and someone in Tibet!
There's probably two people on the planet who do this. You, and someone in Tibet!
Last edited by jaunty75; August 25th, 2011 at 05:12 AM.
August 25th, 2011, 05:10 AM
#7
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Brake fluid - You must replace it every 12K mile or once a year. Brake fluid is similar to motor oil in that it is designed...... you'll avoid 70% of common brake issues.
August 25th, 2011, 06:52 AM
#9
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Murco, this is the the technical BS you hear from car dealerships and mechanics trying to justify goofey preventative maint schedules presented to the mechanically illiterate and gouging their customers. Every 12k miles for a brake fluid change, PLEASE!!!!! With all do respect, brake cylinders generally don't leak @ 15k miles, you don't have to replace your hardware at every shoe change, and beyond poular belief you don't have to cut your drums and rotors unless they are warped or seriously scored, shoes and pads will conform to the surfaces!! I do agree that discolored fluid is a sign of contamination and issues!!!
I also believe in annual checkups and cleanings for brake systems! I also believe that wheel bearings should be repacked and inspected during this process!
I also believe in annual checkups and cleanings for brake systems! I also believe that wheel bearings should be repacked and inspected during this process!
August 25th, 2011, 08:54 AM
#10
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Location: Ramsey, MN
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Ok, on the brake fluid... This was taken from my notes when I trained technicians in Florida who worked on daily driven, late model cars. ABS systems have huge failure rates in humid climates and big replacement costs so yearly fluid changes are cheap insurance.
The biggest reason for changing brake fluid regularly, and what makes brake fluid unique, is that it is hygroscopic - it agressively absorbs moisture. If you work with brakes regularly youl'll find that 90% of all hydraulic system damage is caused by moisture in the system. Yes, your system is sealed, but moisture gets in through the master cylinder gasket and even gets absorbed through the hoses. Humidity plays a huge part in that but even regular rainfall can add to this.
If you get some brake fluid on your hand you'll notice it burns a little and afterward your cuticles will dry out. Brake fluid sucks the moisture out of your skin and this is also how it strips paint, it sucks the binders out. Once you open a bottle of brake fluid dispose of what you don't use within a week, it absorbs moisture from humidity from just being opened. This is much more prevalent in Florida than it would be in Iowa, but it still a problem.
Unless your car is strickly a trailer/show queen that is only driven in parades you can use DOT 5, but never on a street car and you must flush the system entirely with alcohol before doing the change.
Beyond fluid my comments on wheel cylinders, calipers, and master cylinder/prop valves are due to one thing - heat. They all have rubber in them and rubber degrades with heat cycling. In the old days when all our aftermarket components where made in the USA the quality was far higher and this wasn't as big an issue. These days so many replacement parts are made in China with such variation in quality (even from the same manufacturer) it's worth watching for leaking wheel cylinders in particular. This is also why I said "Use the highest quality products you can afford."
I just looked at the owners manual for my 2006 Jetta GLI, it says the brake fluid should be replaced every 24 months/24,000 miles with an asterisk for higher heat/humidity conditions or regions. I'll check the owners manual on the wife's 2011 Malibu when she gets home.
As for turning drums and rotors - if they have a smooth finish, no scoring, no heat discoloration, no pad/shoe material deposits, aren't warped and you are using the exact same pad/shoe compounds you don't need to turn them. If you have any of these conditions - turn them. Before turning them make sure there is at least .010" of material to work with before discard size, a good technician should be able to get a good finish with .005-.008" of material removal with no warping issues. NEVER exceed min/max sizing, ever!
As an aside, in 1998 GM stopped recommending turning rotors for dealership technicians. This wasn't because of the lack of need, it was because the techs were so poorly trained in proper machining they were causing more issues and costing GM warranty expenses. As I said, ASE "Master Certification" tests only have 25 basic brake questions, disturbing for the primary safety feature of every car out there!
I'm not Moses coming down from the mountain with brake commandments, just sharing what my experiences have taught me going into shops every day for 8 years. Do what you wish, it's your car. Regular maintainence for brakes is soooo cheap and easy, why not ensure your prized car is able to stop it's very best when the ABS-equipped Kia being driven in front of you by a teenager talking on a cell phone slams on the stop pedal! An new mid-sixties drum/drum GM car in perfect condition would stop from 60 mph in about 180-200 feet, a late model car with ABS will do the same stop in 115-140 feet - do the math, protect yourself, and protect others!
*** NOTE - Don't pour any fluids/chemicals on your hands to test my example, chemicals that get on your skin end up in your liver within 30 minutes. Liver damage is a huge problem for technicians!
The biggest reason for changing brake fluid regularly, and what makes brake fluid unique, is that it is hygroscopic - it agressively absorbs moisture. If you work with brakes regularly youl'll find that 90% of all hydraulic system damage is caused by moisture in the system. Yes, your system is sealed, but moisture gets in through the master cylinder gasket and even gets absorbed through the hoses. Humidity plays a huge part in that but even regular rainfall can add to this.
If you get some brake fluid on your hand you'll notice it burns a little and afterward your cuticles will dry out. Brake fluid sucks the moisture out of your skin and this is also how it strips paint, it sucks the binders out. Once you open a bottle of brake fluid dispose of what you don't use within a week, it absorbs moisture from humidity from just being opened. This is much more prevalent in Florida than it would be in Iowa, but it still a problem.
Unless your car is strickly a trailer/show queen that is only driven in parades you can use DOT 5, but never on a street car and you must flush the system entirely with alcohol before doing the change.
Beyond fluid my comments on wheel cylinders, calipers, and master cylinder/prop valves are due to one thing - heat. They all have rubber in them and rubber degrades with heat cycling. In the old days when all our aftermarket components where made in the USA the quality was far higher and this wasn't as big an issue. These days so many replacement parts are made in China with such variation in quality (even from the same manufacturer) it's worth watching for leaking wheel cylinders in particular. This is also why I said "Use the highest quality products you can afford."
I just looked at the owners manual for my 2006 Jetta GLI, it says the brake fluid should be replaced every 24 months/24,000 miles with an asterisk for higher heat/humidity conditions or regions. I'll check the owners manual on the wife's 2011 Malibu when she gets home.
As for turning drums and rotors - if they have a smooth finish, no scoring, no heat discoloration, no pad/shoe material deposits, aren't warped and you are using the exact same pad/shoe compounds you don't need to turn them. If you have any of these conditions - turn them. Before turning them make sure there is at least .010" of material to work with before discard size, a good technician should be able to get a good finish with .005-.008" of material removal with no warping issues. NEVER exceed min/max sizing, ever!
As an aside, in 1998 GM stopped recommending turning rotors for dealership technicians. This wasn't because of the lack of need, it was because the techs were so poorly trained in proper machining they were causing more issues and costing GM warranty expenses. As I said, ASE "Master Certification" tests only have 25 basic brake questions, disturbing for the primary safety feature of every car out there!
I'm not Moses coming down from the mountain with brake commandments, just sharing what my experiences have taught me going into shops every day for 8 years. Do what you wish, it's your car. Regular maintainence for brakes is soooo cheap and easy, why not ensure your prized car is able to stop it's very best when the ABS-equipped Kia being driven in front of you by a teenager talking on a cell phone slams on the stop pedal! An new mid-sixties drum/drum GM car in perfect condition would stop from 60 mph in about 180-200 feet, a late model car with ABS will do the same stop in 115-140 feet - do the math, protect yourself, and protect others!
*** NOTE - Don't pour any fluids/chemicals on your hands to test my example, chemicals that get on your skin end up in your liver within 30 minutes. Liver damage is a huge problem for technicians!
Last edited by Murco; August 25th, 2011 at 09:08 AM.
August 25th, 2011, 09:06 AM
#11
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Location: southeastern Michigan
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I once had an '05 Ford Freestyle, and I still have a pdf version of the owner's manual and maintenance schedule on my computer. There is not a single mention of changing brake fluid, or even checking it, through 150,000 miles of scheduled maintenance, which is as high in mileage as the chart goes.
I have often taken my new cars to the dealers I bought them from for regular maintenance over the last couple of decades, and I've never once had a service writer or service department head or anyone at all ever mention changing brake fluid.
I'll check the manuals in my current vehicles when I get home tonight.
August 25th, 2011, 09:14 AM
#12
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Location: Ramsey, MN
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Well, here is why my Jetta recommends brake fluid changes!
From this article... "in many European countries, regular brake fluid checks are required, and half of all cars routinely fail such tests"
http://www.aa1car.com/library/bfluid.htm
From this article... "in many European countries, regular brake fluid checks are required, and half of all cars routinely fail such tests"
http://www.aa1car.com/library/bfluid.htm
August 25th, 2011, 09:41 AM
#13
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Turning drums and rotors - You need to watch what your tech is doing when they turn drums and rotors. First, make sure they (or you) mark the index position of the drum (mark the hole and stud that went through it - or rotor if you happen to be working with a late model that has separate rotor/hub). When the machine work is done put them back on at that same marked position as this will compensate for any run-out of the hub.
Watch when the tech puts the drum or rotor on the machine. If he just chucks it on there and starts setting up the cutter - STOP HIM, get your piece, and LEAVE! He doesn't know wtf he's doing and should be fired. A properly trained tech will test the run-out of the disc/drum and adjust the holding cups of the lathe many times, swapping the positions in quadrants each time. This also applies to integrated discs with integrated hubs like on most of the classic GM cars from the 60's through the 90's, make sure the tech adjusts the inserts that ride on the bearing cups. If you see him doing this for a few minutes and checking each adjustment go relax and have some coffee - you've got a well trained tech working with your parts! I have had brake techs with 20 years of experience fired for incompetence on the lathe. Just because someone has done something for 20+ years does not mean they've done it correctly!
Watch when the tech puts the drum or rotor on the machine. If he just chucks it on there and starts setting up the cutter - STOP HIM, get your piece, and LEAVE! He doesn't know wtf he's doing and should be fired. A properly trained tech will test the run-out of the disc/drum and adjust the holding cups of the lathe many times, swapping the positions in quadrants each time. This also applies to integrated discs with integrated hubs like on most of the classic GM cars from the 60's through the 90's, make sure the tech adjusts the inserts that ride on the bearing cups. If you see him doing this for a few minutes and checking each adjustment go relax and have some coffee - you've got a well trained tech working with your parts! I have had brake techs with 20 years of experience fired for incompetence on the lathe. Just because someone has done something for 20+ years does not mean they've done it correctly!
August 25th, 2011, 10:08 AM
#14
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Join Date: Jun 2011
Posts: 6,657
every year or 12k may be an aggressive schedule for brake fluid changes, but I will add anytime I have changed my fluid, from 90k/6yo on my truck to 20k 4yo on my bike the result has been an impressive improvement in pedal feel....so much so that I changed the fluid in my sleds which really dont use the brake all that much (at least mine dont LOL) with similar impressive results in lever feel
I cant/didnt quantify the actual braking distance improvement but seat of the pants they all feel like they stop better/quicker
I cant/didnt quantify the actual braking distance improvement but seat of the pants they all feel like they stop better/quicker
August 25th, 2011, 10:09 AM
#15
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The other thing about drums and discs is that you only need to remove enough metal to make it true and smooth. Smaller cut passes are better than 1 big cut. they should be somewhat smooth when finished, not really rough with metal shards sticking out all over!!
August 25th, 2011, 10:19 AM
#16
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Well- I'm one of those freaks of nature who used to flush my brake hydraulics every year and I didn't have near the brake issues when I did that. Unfortunately do not have the time to do such things any more, and me old cars have suffered for it.
Murco, are you the guy who posted some excellent brake info on AACA.org a few weeks back? Somebody in admin poofed that thread for whatever unknown reason (and no one will fess up to doing it
) and several people have been wanting it back, including the editor of the AACA magazine.
Murco, are you the guy who posted some excellent brake info on AACA.org a few weeks back? Somebody in admin poofed that thread for whatever unknown reason (and no one will fess up to doing it
) and several people have been wanting it back, including the editor of the AACA magazine.
August 25th, 2011, 10:34 AM
#17
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August 25th, 2011, 10:52 AM
#18
NOVICE car nut
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, ive never changed my brake fluid , but then again its always looked clean when I checked it ( dont get brake fluid on any painted surface
, I found that out the hard way ) I always have done the brakes on my car myself , and would buy decent brake pads and replace the rotors ( newer cars ) when needed , and ive always had great brakes ..... never any problems , unless a line blew out or something.... which reminds me , I have to check my brake fluid.... thanks
August 25th, 2011, 10:57 AM
#19
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Murco, are you the guy who posted some excellent brake info on AACA.org a few weeks back? Somebody in admin poofed that thread for whatever unknown reason (and no one will fess up to doing it ) and several people have been wanting it back, including the editor of the AACA magazine.
) and several people have been wanting it back, including the editor of the AACA magazine.
August 25th, 2011, 11:05 AM
#20
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This whole brake fluid thing is just overkill. If brake failure due to bad brake fluid were really a problem, then we would be reading about accidents by brake failures.
Think about it. When's the last time you read about an auto accident that was determined to have been caused by brake failure? I'll go out on a limb here and guess that you never have. Ever. It just doesn't happen. Failure to control, excessive speed, DUI, following too closely, and more, yes. We've all read about accidents caused for those reasons. But bad brakes? No.
Time to cross this one off the list and resume worrying about global warming, hurricanes, drug-resistant bacteria and all the other things that are going to kill us.
Think about it. When's the last time you read about an auto accident that was determined to have been caused by brake failure? I'll go out on a limb here and guess that you never have. Ever. It just doesn't happen. Failure to control, excessive speed, DUI, following too closely, and more, yes. We've all read about accidents caused for those reasons. But bad brakes? No.
Time to cross this one off the list and resume worrying about global warming, hurricanes, drug-resistant bacteria and all the other things that are going to kill us.
August 25th, 2011, 11:06 AM
#21
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Which brings up another point, check your lines and hoses once a year too! If you bend a hose and see cracks, replace it. Check your hard lines for corrosion, crimping, dents and especially where there are clips that hold them. If the clips are corroded electrolysis will corrode the lines too, often from within. Missing clips can cause chaffing or damage from lines contacting frames or bodies as you hit large bumps. I've also seen many 1994-1999 Dodge pick-ups with lines corroded right behind the cab, the gas filler tube would leak and corrode the line on the frame rail!
August 25th, 2011, 11:19 AM
#22
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This whole brake fluid thing is just overkill. If brake failure due to bad brake fluid were really a problem, then we would be reading about accidents by brake failures.
Think about it. When's the last time you read about an auto accident that was determined to have been caused by brake failure? I'll go out on a limb here and guess that you never have. Ever. It just doesn't happen. Failure to control, excessive speed, DUI, following too closely, and more, yes. We've all read about accidents caused for those reasons. But bad brakes? No.
Time to cross this one off the list and resume worrying about global warming, hurricanes, drug-resistant bacteria and all the other things that are going to kill us.
Think about it. When's the last time you read about an auto accident that was determined to have been caused by brake failure? I'll go out on a limb here and guess that you never have. Ever. It just doesn't happen. Failure to control, excessive speed, DUI, following too closely, and more, yes. We've all read about accidents caused for those reasons. But bad brakes? No.
Time to cross this one off the list and resume worrying about global warming, hurricanes, drug-resistant bacteria and all the other things that are going to kill us.
I am on retainer from several law firms and have proven conclusively 33 times that negligent brake maintenance led to accidents that have killed or maimed people. I have also testified about shoddy brake repairs and never lost a case.
If you wish to ignore your brake fluid I have no issue with that... As long as you stay in southeastern Ohio!
August 25th, 2011, 08:26 PM
#23
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I will attest that the manual for my '98 BMW says to change the brake fluid every year.
I always thought that was strange, and, of course, I never did it.
I will admit, though, that I thought about changing it a number of times, because it is obvious that most brake system problems are caused by internal corrosion, and if you remove the water, you should reduce the corrosion, this saving time and money on those annoying cylinder and caliper replacements.
Maybe I'll change my brake fluid one of these days...
- Eric
I always thought that was strange, and, of course, I never did it.
I will admit, though, that I thought about changing it a number of times, because it is obvious that most brake system problems are caused by internal corrosion, and if you remove the water, you should reduce the corrosion, this saving time and money on those annoying cylinder and caliper replacements.
Maybe I'll change my brake fluid one of these days...
- Eric
August 25th, 2011, 09:37 PM
#24
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I have my customers do a brake flush at 25-30k or a lot more often for Corvette / Camaro owners that drive thier cars hard. When I was at Lexus 30K brake fluid exchanges was required maintenance. The first time you replace a EBCM at $1100.00 you will wish you were doing it in your late model car.
August 26th, 2011, 05:11 AM
#25
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But we were talking specifically about brake FLUID changes. That, I still maintain, is just not necessary at the rate you are talking about, and I used as evidence the owner's manual for the 2005 Ford Freestyle I once owned. It makes no mention of brake fluid changes EVER, in 150,000 miles of maintenance. Not even inspecting it, let along changing it.
I just now pulled out and looked through the owner's manual's maintenance schedule for my 2002 Dodge Dakota pickup truck, and it's just like the Freestyle. Through 120,000 miles of maintenance, there are calls for regular inspection of the brake system and brake linings, but not a single mention of the brake FLUID at all, not even inspecting it, let alone changing it.
If you wish to ignore your brake fluid I have no issue with that.
Last edited by jaunty75; August 26th, 2011 at 07:03 AM.
August 26th, 2011, 06:18 AM
#26
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I have my customers do a brake flush at 25-30k or a lot more often for Corvette / Camaro owners that drive thier cars hard. When I was at Lexus 30K brake fluid exchanges was required maintenance. The first time you replace a EBCM at $1100.00 you will wish you were doing it in your late model car.
August 26th, 2011, 06:41 AM
#27
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Don't be generalizing from the specific. I have NEVER said that you should not maintain your brakes....
But we were talking specifically about brake FLUID changes. That, I still maintain, is just not necessary at the rate you are talking about, and I used as evidence the owner's manual for the 2005 Ford Freestyle I once owned. It makes no mention of brake fluid changes EVER, in 150,000 miles of maintenance. Not even inspecting it, let along changing it.
I just now pulled out and looked through the owner's manual's maintenance schedule for my 2002 Dodge Dakota pickup truck, and it's just like the Freestyle. Through 120,000 miles of maintenance, there are calls for regular inspection of the brake system and brake linings, but not a single mention of the brake FLUID at all, not even inspecting it, let along changing it.
But we were talking specifically about brake FLUID changes. That, I still maintain, is just not necessary at the rate you are talking about, and I used as evidence the owner's manual for the 2005 Ford Freestyle I once owned. It makes no mention of brake fluid changes EVER, in 150,000 miles of maintenance. Not even inspecting it, let along changing it.
I just now pulled out and looked through the owner's manual's maintenance schedule for my 2002 Dodge Dakota pickup truck, and it's just like the Freestyle. Through 120,000 miles of maintenance, there are calls for regular inspection of the brake system and brake linings, but not a single mention of the brake FLUID at all, not even inspecting it, let along changing it.
The link I found explains why. Just as the US manufacturers don't want techs messing with rotors while under warranty I suspect that poorly trained techs have made US manufacturers leary of having them touch the fluid for fear of them costing the company more money. Notice that the European and Japanese manufacturers do recommend it!
http://www.aa1car.com/library/bfluid.htm
You have a 2005 Ford, I guarantee the fluid in the reservoir is green.
And don't mistake my sense of humor, I don't have a razor blade next to my wrist as I read replies to my posts, please don't be offended.
August 26th, 2011, 07:58 AM
#28
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Certainly the British arm of GM (Vauxhall) & Opel for the rest of Europe recommend annual changes, but based on time rather than miles travelled.
The same is true of most manufacturers in the British market.
I think it true that European cars used to have better brakes and safer handling then American cars, more because of the driving conditions than Americans being less concerned about safety but nowadays American cars are equal to the rest of the world, Japanese cars when they entered the British market in the late '60s were not great at handling & brakes either but now they also are as good as any others.
Having driven in a lot of the developed world, North America, Europe & Australia, I think it's fair to say Europeans drive harder than our transatlantic & antipodean cousins.
Brakes and tires are the first line of prmary defense in road safety, that is avoiding an accident in the first place, there have been plenty of threads regarding tires, particularly old ones on this and no doubt just about every other car forum, let's not forget that suspension and steering and chassis integrity are also vital to safety as well.
The British required annual safety inspection checks all these items as well as other safety issues such as seatbelts, visibility, lights etc. The rest of Europe have similar requirements, I believe Germany and the scandanavian countries have more rigorous standards than us.
When I first visited the USA I was surprised at some of the cars I saw being driven in Texas, in Britain they would be ordered off the road.
Roger.
The same is true of most manufacturers in the British market.
I think it true that European cars used to have better brakes and safer handling then American cars, more because of the driving conditions than Americans being less concerned about safety but nowadays American cars are equal to the rest of the world, Japanese cars when they entered the British market in the late '60s were not great at handling & brakes either but now they also are as good as any others.
Having driven in a lot of the developed world, North America, Europe & Australia, I think it's fair to say Europeans drive harder than our transatlantic & antipodean cousins.
Brakes and tires are the first line of prmary defense in road safety, that is avoiding an accident in the first place, there have been plenty of threads regarding tires, particularly old ones on this and no doubt just about every other car forum, let's not forget that suspension and steering and chassis integrity are also vital to safety as well.
The British required annual safety inspection checks all these items as well as other safety issues such as seatbelts, visibility, lights etc. The rest of Europe have similar requirements, I believe Germany and the scandanavian countries have more rigorous standards than us.
When I first visited the USA I was surprised at some of the cars I saw being driven in Texas, in Britain they would be ordered off the road.
Roger.
August 26th, 2011, 09:04 AM
#29
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i can see how brake fluid should be changed much more often than people do, including me. when racing 4 wheelers in MX full time i had to change it around every three or four races. we were very abusive on our brakes and many time in some amount of water or mud. these brake systems hold very little fluid compared to a car so on top of being in racing it also had little volume. if you didn't keep it changed, by the 5th or 6th race you would not have any brakes by the end of the race.
i have told new commers to the sport for years that if you are going to make big power with the engine you had better make good stoping power with the brakes. if you can't stop fast you can't go fast.
i have told new commers to the sport for years that if you are going to make big power with the engine you had better make good stoping power with the brakes. if you can't stop fast you can't go fast.
Last edited by jensenracing77; August 26th, 2011 at 09:10 AM.
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