The Complete Brake Job

[nthach]

I remember when I was in a friend's Jetta VR6 and he was charging hard through the canyon near my house and his brakes began to fade - he was able to shift into 2nd for engine braking. Upon closeer inspection, his brake fluid was dirty and full of moisture.

The Germans call for a brake fluid flush every 2 years, and I make it a point to do so regardless of car.

 

[labman]

Old, dirty, or wet fluid has nothing to do with fade. It can lead to complete loss of pedal from boiling, but never a firm, but ineffective pedal. That is what fade means.

 

[benjamming]

I bet you pad/rotor caused that fade, nthach.

 

[Lorenzo]

A rebuild kit with seals and boots is maybe $50 and a few hours work for all 4 corners. If you do the work yourself that's pretty cheap. Although if you go to a shop and pay for labor it would probably be cheaper to pay for new or remanufactured calipers.

If I worked at a brake shop and got paid to sell new components, I would never recommend a fluid flush either. On my car I flush the fluid every 2 or 3 years.

 

[benjamming]

Why would you never recommend a fluid flush - that's extra revenue!

 

[nthach]

Originally Posted By: benjamming
I bet you pad/rotor caused that fade, nthach.

He was running Zimmermann rotors and British-made Mintex street/track pads. I take that back, he almost lost his service brakes, not fade.

I believe fluid flushes are necessary braking system maintenance, especially because some cars have brake-by-wire(Mercedes E Class, Toyota Prius) and most cars have ABS or traction control - and to replace the ABS/TRAC modulator or the main brake-by-wire control unit is obscenely expensive...

 

[Gary Allan]

Originally Posted By: Shannow
I can't understand why brakes have grown into a field where you now need to completely redo the entire system, where before, pads, a runout check, and a bleed would leave you good to go for another long time.

Why have the manufacturers made such a simple system (in it's pure form) so hideously planned obsolescent ?


Devolving through complexity. Now it's become brain surgery. Decades of simple and reliable caliper/pad/rotor combos on millions of units that produced ZERO need for "advancing" to this level of vulnerability to dysfunction.

 

[sciphi]

I replaced the slider pins on my 99 LeSabre, which uses what is about the most inane caliper design ever. Even though the original slider pins still slid, they didn't slide far enough out to let the outer pad work. We'll see if the current ceramic pads last longer than 30k miles.

 

[mechtech2]

Modern cars have smaller brakes. They run much hotter than before.
Not only is this harder on pads and rotors, but the calipers and mounts, as well.
Put fresh fluid in the system every year or two - a good flush.
This is important, but there's much else we can do for the hydraulic end of the system.

 

[labman]

My 81 Phoenix had 9.72'' discs and my 02 Cavalier has 10.12. If anything, I would guess it is lighter. Now what I do know the rotor is thinner and so are pads and the recommended minimum thickness you let them wear. That will indeed result in more heat to the calipers.

 

[Familyguy]

Originally Posted By: labman
My 81 Phoenix had 9.72'' discs and my 02 Cavalier has 10.12. If anything, I would guess it is lighter. Now what I do know the rotor is thinner and so are pads and the recommended minimum thickness you let them wear. That will indeed result in more heat to the calipers.


I suspect a lot of things have changed with car brake systems since 1981.....

The amount of heat transferred to the calipers during and after braking is likely influenced by a number of factors. The "size" of the rotor merely being one of them. There's also the amount of airflow around/through the system, the ability/inability of the pad material to transfer heat through the pad meterial to the pad backing plate and then through the relatively tiny contact area between the piston and the pad backing plate (the piston is hollow so there is actually very little surface area in contact with the pad).

The article referenced above is designed to sell calipers. I suspect if you read a white paper from Gates about timing belt changes, they'll recommend changes more often than most auto manufacturers do...so they can sell more belts. Imagine that.

I wouldn't change or rebuild a caliper unless there was a demonstrable problem with it (torn piston boot or hanging piston). Of much bigger concern to me would be the premature failures of expensive ABS components when owners follow misguided advice about never needing to change their brake fluid.

 

[KrisZ]

Quote:
I wouldn't change or rebuild a caliper unless there was a demonstrable problem with it (torn piston boot or hanging piston). Of much bigger concern to me would be the premature failures of expensive ABS components when owners follow misguided advice about never needing to change their brake fluid.


I am also not a fan of changing parts that are in good working condition just because they're old. The only reason this is promoted and people see this as preventative maintenance, is beacuse those rebuild calipers are comming from China, Mexico and other cheap labour places and are dirt cheap.

Why people don't advocate changing ABS modules? They are more likely to fail than the caliper. The reason, PRICE.

I bet, that if in 10 to 15 years manufacturers can lower the price of ABS and brake force distribution modules, we will have the exact same question asked; "Why not change that ABS module at every brake job, it's only 60 bucks".

 

[labman]

I don't believe in letting things go until they fail, especially not brakes and other things that could kill me when they fail.

 

[KrisZ]

Originally Posted By: labman
I don't believe in letting things go until they fail, especially not brakes and other things that could kill me when they fail.


You got me all wrong. I never said to wait until the caliper fails. Not working properly is different from completley failed and if you inspect brake components regularly you will find problems long before the failure, and IMO that's when I would start replacing parts. I just don't agree with a blanket statement that calipers should be changed with brake pads.

 

[Familyguy]

Originally Posted By: labman
I don't believe in letting things go until they fail, especially not brakes and other things that could kill me when they fail.


I see...so a caliper that's dragging and prematurely wearing out the inboard pad is "going to kill you." Um....

Not only do you get PLENTY of warning when a piston is hanging, but the brakes still work just fine...until months or perhaps years later when you finally wear out the pad material on the affected caliper. I'm all for preventative maintenance, but this is just silly and unecessary.

Again, this is bogus advice designed to sell parts. That money would be better spent on flushing your brake fluid (which labman says he knows nothing about in his brake shop) which actually is necessary as brake fluid absorbs water over a strikingly short period of time, reducing its effectiveness and promoting corrosion throughout the brake system.

 

[labman]

Go back and read my one long post and learn a little about brakes.

 

[froggy81500]

Originally Posted By: Familyguy
Originally Posted By: labman
My 81 Phoenix had 9.72'' discs and my 02 Cavalier has 10.12. If anything, I would guess it is lighter. Now what I do know the rotor is thinner and so are pads and the recommended minimum thickness you let them wear. That will indeed result in more heat to the calipers.


I suspect a lot of things have changed with car brake systems since 1981.....

The amount of heat transferred to the calipers during and after braking is likely influenced by a number of factors. The "size" of the rotor merely being one of them. There's also the amount of airflow around/through the system, the ability/inability of the pad material to transfer heat through the pad meterial to the pad backing plate and then through the relatively tiny contact area between the piston and the pad backing plate (the piston is hollow so there is actually very little surface area in contact with the pad).

The article referenced above is designed to sell calipers. I suspect if you read a white paper from Gates about timing belt changes, they'll recommend changes more often than most auto manufacturers do...so they can sell more belts. Imagine that.

I wouldn't change or rebuild a caliper unless there was a demonstrable problem with it (torn piston boot or hanging piston). Of much bigger concern to me would be the premature failures of expensive ABS components when owners follow misguided advice about never needing to change their brake fluid.



In its most basic of function and design, brake systems haven't changed a whole lot. There are more modern items incorporated into the braking system, like ABS and traction control, but the rest is still pretty much the same.

replacing calipers if they aren't showing signs of needing to be replaced is just foolish. Familyguy has very good points in this post. If a wheel cylinder isn't showing signs of leaking, you wouldn't replace it, so why would you replace a perfectly working caliper?

Preventative maintenance is about checking certain items to see if they need to be replaced/addressed BEFORE they fail. That's the point. of course you don't want to wait until your brakes fail to replace them, that's why pads have wear indicators on them to squawk at you when they are getting thin.

 

[The Critic]

Originally Posted By: froggy81500

replacing calipers if they aren't showing signs of needing to be replaced is just foolish. Familyguy has very good points in this post. If a wheel cylinder isn't showing signs of leaking, you wouldn't replace it, so why would you replace a perfectly working caliper?

Preventative maintenance is about checking certain items to see if they need to be replaced/addressed BEFORE they fail. That's the point. of course you don't want to wait until your brakes fail to replace them, that's why pads have wear indicators on them to squawk at you when they are getting thin.


Did you read the second link? What do you have to say about the seal in the picture? The seal is obviously stretched.

My rear calipers will pass a visual inspection just fine. The pads wear relatively evenly as well. However, I'm starting to go through pads about every 25-30k. The first set of pads lasted 100k. Are you suggesting that my calipers are still OK?

 

[benjamming]

They might be just fine or not. How do the pads & rotors compare to original? How is your brake usage habits?

 

[KrisZ]

Originally Posted By: The Critic
Originally Posted By: froggy81500

replacing calipers if they aren't showing signs of needing to be replaced is just foolish. Familyguy has very good points in this post. If a wheel cylinder isn't showing signs of leaking, you wouldn't replace it, so why would you replace a perfectly working caliper?

Preventative maintenance is about checking certain items to see if they need to be replaced/addressed BEFORE they fail. That's the point. of course you don't want to wait until your brakes fail to replace them, that's why pads have wear indicators on them to squawk at you when they are getting thin.


Did you read the second link? What do you have to say about the seal in the picture? The seal is obviously stretched.

My rear calipers will pass a visual inspection just fine. The pads wear relatively evenly as well. However, I'm starting to go through pads about every 25-30k. The first set of pads lasted 100k. Are you suggesting that my calipers are still OK?



Did you check if the wear is the same on both sides? Did you try spinning the wheel while in the air to see how much drag there is, compare that to the other side or rear, check if the wheels get significantly hotter after normal driving (they should be warm and you should be able to keep your hand on the wheel without burning yourself).

25k to 30k while not steller is not too bad either and alone should not be taken as a fault in the system, if anything it should prompt you to check the system more carefully than a visual inspection.