Should I do this or just change the pads?

[abimanyu]

I found this else where in the net. Basically it says that if you don't have the time, then just do the pads and general check up of the brake system. but, if you have the time(and the money I guess) you should do a complete brake job. Should I do it everytime I change the pads or is there's a certain time as the car ages? My corolla is 3 years old and still have not change the pads yet ,should I do the complete brake job as outlined below?


Disc Brake Service
Disc brakes are a tremendous improvement over drums. They dissipate heat much better, they don't lose their stopping power when wet, their linings last a long, long time, they stay in adjustment automatically, and replacing pads is normally a simple job with no return or hold-down springs or self-adjuster mechanisms to contend with. Good as they are, however, servicing them is still a critical operation -- after all, the only thing more dangerous than a car that won't stop is one that won't steer. So, the following review of proper disc brake work procedures is important to everybody who works on cars.
The complete job
To begin with, I believe that caliper hydraulic service should accompany relining much more often than it actually does in the real world. Why? Because when the caliper pistons are forced back into their bores to accommodate the thick, new pads, the fluid seals have to work against a surface that's probably corroded and contaminated, which very often causes a leak.
There are cases in which it's most cost-efficient to just install new linings, such as when pads are found to be contaminated or defective after being in use for too short a time for there to be much hydraulic system deterioration, or when they are replaced frequently as regular preventative maintenance. But these will be the exceptions.
Getting thin?
When to reline is another point. Although minimum thickness specifications for the layer of friction material are published by most car makers, there's a good rule of thumb: replace when the lining approaches the thickness of the pad's steel backing plate. Of course, with riveted linings, you can see when the rivets are getting uncomfortably close to the level of the friction surface.
I suggest that whenever you're doing any service that requires the removal of the wheels, you check the condition of the brakes. Most calipers have an inspection hole through which you can view the outer edge of the pads in order to judge how much life they have left in them. Also, examine the area around piston dust boots for evidence of fluid leaks, and always remember to give those flexible rubber brake hoses a careful inspection to determine if they're splitting, cracking, swelling, or otherwise deteriorating. Nothing else can cause as sudden a loss of stopping power as a ruptured hose, yet these parts are frequently overlooked -- it's fortunate that they're so well made.





Procedure
When it comes to the actual job of replacing linings, the procedure for a typical single-piston front caliper is as follows:
1. Siphon some fluid out of the master cylinder reservoir to prevent messy overflow.
2. Raise and safely support the vehicle, then remove the front wheels.
3. Open the caliper bleeder screw so dirty old fluid doesn't get forced up into the works, then, using a C-clamp of sufficient size to span the distance between the back of the outboard pad and the back of the caliper cylinder, compress the piston into its bore all the way. Alternately, you can pull or pry the caliper outward to compress the piston.
4. Do what's necessary to expose the pads. This may involve removing one or more bolts, pins, or keys in order to separate the part of the caliper that contains the hydraulic cylinder from its mounting. On some units, you simply remove the lower bolt, then lift the caliper so that it rotates on the upper bolt. In any case, be certain that the hydraulic hose isn't stretched or twisted -- support the weight of the caliper by means of a wire or rope connected to the suspension.
5. Remove the old pads and any shims or anti-rattle springs that are present, carefully noting their position. By the way, it's always best when working on an unfamiliar design to service one side at a time so you can use the other side as a model for reassembly.
6. Check for evidence of fluid leakage around the piston dust boot. As I said, it's good practice to overhaul the caliper even if no leaks are yet present.
7. Carefully examine the surface of the rotor. If it looks okay and there was no braking shudder or pulsation, you can probably just install the new pads. If, however, there was braking roughness, check the discs for excessive runout, sufficient thickness, and proper parallelism (I'll get to the specifics of these shortly). Machine or replace the rotor if necessary.
8. Install the new pads along with any shims or springs.
9. Place the caliper back over the rotor and fasten it as the design requires. If bolts are used, torque them to specifications.
10. Refill the master cylinder reservoir, then REMEMBER TO PUMP THE BRAKE PEDAL SEVERAL TIMES to bring the pads against the rotors before your test drive. Otherwise, you could have an accident before you even get out of your yard.
11. Break in new linings gently -- no panic stops or heavy downhill braking.
On rigidly-mounted calipers having two or four pistons, pad extraction is usually a matter of prying the pistons away from the rotor, removing guide pins, then pulling the pads out through the open area of the caliper. Otherwise, most of the above steps apply.


Disc decisions
Rotor condition is crucial to smooth braking and long lining life. First, look and feel for scoring on the surface. If this looks dangerously deep, the disc must be replaced. Measure carefully to determine whether or not deep grooves can be eliminated without going below the minimum thickness specification, which is usually cast into the hub.
Checking for excessive runout is important in all cases, but especially so on rigidly-mounted multi-piston calipers -- they can't tolerate wobble without causing pedal pulsation because they don't have the capability of floating or sliding from side to side. Measure this movement with a dial indicator. Place its foot against the disc wear surface about one in. in from the circumference, tighten the wheel bearings enough to remove all play, zero the gauge, then rotate the disc while watching the needle. Compare the total indicator reading (in other words, both above and below zero) to specifications, which will commonly be no more than .006 in. Don't forget to readjust the wheel bearings.
Parallelism is actually thickness variation, too much of which will cause pulsation. Using a micrometer, take measurements of rotor thickness at numerous points around the wear surface. Readings that vary more than .002 in. indicate a problem.
Restoring hydraulic health
Overhauling a caliper's hydraulics is pretty much the same regardless of the design. First, detach the portion of the caliper containing the cylinder from the spindle/knuckle, then disconnect the flexible brake line. Dump the old fluid. Place a piece of wood and a folded rag in front of the piston, then apply compressed air to the brake line hole to pop the piston out of its bore. CAUTION: KEEP YOUR FINGERS OUT OF THE WAY. If you don't have an air compressor, you can expel the piston by leaving the caliper connected to the brake hose and depressing the brake pedal, but this results in a flood of spilled fluid. If the piston is frozen in place, various pullers are available to extract it, but the bore may be in such bad condition that it can't be reused anyway.
Remove the dust boot and the piston seal, wipe out the bore, and examine it for pitting, corrosion, and scoring. If the defects are shallow, it may be possible to eliminate them with a hone or fine abrasive paper, but some manufacturers recommend against this practice saying the caliper must be replaced if the bore has any defects.
Next, check the condition of the piston. If it's pitted or scored, it must be replaced because the use of any abrasive on it will simply remove what's left of the rust-preventative coating. Black stains are common, but aren't cause for replacement.
Clean the bore thoroughly with alcohol or fresh brake fluid (NEVER allow any petroleum-based solvent or lubricant to come into contact with the inside of a brake hydraulic system as it will cause the rubber parts to swell, soften, and disintegrate -- just an oily fingerprint will start the process), then coat it with fresh fluid or special brake assembly lubricant. Carefully install the piston seal, making sure it's fully seated and not twisted. Clean and lubricate the piston, then insert it squarely into the cylinder. Follow the manufacturer's instructions for the installation of the dust boot.
By the way, the bleeder screw should be checked before you even start the overhaul because if it's so frozen that it breaks off when you try to open it, either a trip to a machinist or replacement of the caliper will be necessary.
Finally, rear disc units incorporating parking brakes deserve a mention. Widely various designs are used, commonly with screw-type mechanisms. Since resetting is needed at every reline, perhaps involving rotating the piston, it's absolutely necessary that you have the proper factory service information at hand before beginning the job.
Doing it all
The following, in my opinion, comprises a complete brake job:
 Road test
 Replace pads and shoes
 Machine/grind rotors
 Inspect caliper bushings, guide pins, pad shims, etc.; replace if necessary
 Clean and lube star wheel adjusters
 Replace grease seals
 Overhaul caliper cylinders
 Overhaul or replace wheel cylinders
 Check master cylinder; overhaul or replace if necessary (includes bench bleeding)
 Inspect hydraulic hoses and lines; replace if necessary
 If there's a braking performance complaint, check the metering/proportioning/combination valve
 Flush, refill hydraulic system (includes bleeding)
 Apply anti-seize to bleeder screw threads
 Clean, repack, adjust wheel bearings on non-driving axles
 Inspect/lube or replace parking brake cables, then adjust lever travel
 Check booster operation
 Check vacuum booster hose
 Road test again
Certainly, that amounts to a great deal more effort than anybody but a third-world laborer would do for forty bucks. It's the craftsmanlike procedure, but we're talking a couple of hundred dollars. Is there some middle ground?
The answer lies in careful inspection and good judgment. Those two factors will make it possible to give the car what it really needs. In other words, what's practical, safe, and reasonably safe from future annoyances.
Although there's general agreement among technicians about the need for drum and rotor machining -- everybody does it, even on cheap jobs -- recommendations from the carmakers are changing. GM, for one, says to leave them alone unless there's a pulsation problem (see section XIV. I.).
Pinchers
Then there's caliper overhaul. In an ideal world, every specimen would be internally refurbished during a reline to insure against piston seizure and seal failure. And that's what most authorities recommend. But when was the last time you encountered a leaky caliper? The damn things last and last in most cases. So, if you're under serious time or cost pressure, you could just push those pistons back. One caveat: If you feel any roughness or binding as you force a piston home, you'd better get inside to see if overhaul or replacement is necessary (aluminum calipers are becoming popular, so expect to be buying new or remanufactured units).
What about wheel cylinders? Because they're so leak prone, most of the techs I know overhaul or replace them in every case.
Lines and hoses are critical -- I see enough total circuit failures due to corroded lines or blown hoses to be very careful in this regard. Replace lines if the rust has reached the scaly stage, and hoses if they're chafed or cracked. Some carmakers' service literature supports the idea of new hoses as regular maintenance. The manual for the Ford Fiesta, for instance, states that those rubber pipes should be retired every 36,000 miles. But that'll add considerably

[Flashmn]

Holy crap, I'm not gonna read all of that.

I basically just change the pads when they wear out and check the rotors if they're still ok. Then every few years I change the whole fluid. Never had problems with brake systems.

[Excidium]

Take it easy on the cut/copy and paste. We already have some long threads going! No need to start a new long thread with only one posting LOL! Your rotors will almost always last longer than your pads. But if you do just change your pads, scuff up the rotor a bit with some sandpaper to remove some of the glazing. That way your pads seat better. Well that's my 2 cents!