The front brakes are disc brakes on all modern cars. The front brakes usually provide 80% of the braking force and, for this reason, they tend to wear more quickly than the rear ones. Replacing the entire block yourself - pads, calipers and disc - is pretty straightforward if you know what you're doing, and it saves you a lot of money. The instructions you will find in this article will guide you through replacing the entire front brake block. Having the workshop manual for your car on hand will keep you from going crazy, and will save you time and money. If you want to replace only the pads, or the pads and discs, but not the calipers, skip the part about replacing the calipers.
If you have a friend already knowledgeable in this kind of work, talk to him about what you are going to do after studying all the steps in this article, and ask someone to stay with you to keep you company or to talk while you work, perhaps someone who is just standing there reading a book; this is especially helpful if this is your first time engaging in operations of this type.
Steps
Step 1. Determine which parts and what tools you will need, and put safety first
Keep in mind that breathing in or ingesting asbestos dust released from older car brakes is a health hazard. Remove the dust or residues with rags or absorbent paper (impregnated with a solvent, which can also be simple alcohol) and get rid of it (read the "Warnings" section below for more information). Try to understand what the problem is with your brakes based on the symptoms they present, for example:
- If the front brakes whistle, you may only need to replace the pads.
- If the car or the brake pedal vibrates during braking, you may need to have the surface of the discs grinded or turned, or replaced completely.
- If the car tends to skid to one side when braking but continues straight ahead in all other situations, you may need new calipers. It is a clear sign of the uneven wear of the pads between one side of the car and the other, and this is due to the different pressure inside the two different lines of tubes.
- If the brakes make a scraping noise, the discs are gone, and you will need to replace them.
Step 2. Buy more pieces than you think you need
You can always return what you have not used (keep the receipt aside and avoid using or damaging the pieces to be returned). If you find yourself running out of something while the car is still under the knife, you may not have any means of transport to reach the auto parts and buy what you need.
Step 3. Park your car in a clean, well-lit, hard-floored location
Block the rear wheels with something heavy (such as bricks or wooden blocks small enough to fit under the tires) to prevent the car from rolling while it is raised. Pull the handbrake to lock the rear wheels. (In the case of an automatic gearbox, the "PARK" gear will block only one of the driving wheels so, if your car has front-wheel drive, it will only hold one of your two front wheels stationary while, if it is rear-wheel drive, it will only take care of one of the two rear wheels).
Step 4. Loosen the wheel bolts before jacking up the car (don't remove them completely yet)
If you skipped this step, loosening the bolts later would be quite inconvenient, although not impossible. In addition, loosening the bolts with the car raised could become dangerous.
Step 5. Raise the car with a nice sturdy jack on a solid surface (such as the floor, if you are working on concrete) and slowly lower it until it rests on jacks
Attention: jacks with wheels must be able to move, as the jack must be able to move slightly. Therefore, avoid soft surfaces where the wheels could sink or get stuck.
Step 6. Never work without jacks being firmly fixed on solid, flat surfaces, such as stone slabs or hard wood planks, to prevent the jacks from sinking, tipping, tipping or fall
Make the jacks lean on well resistant parts of the car - support frame or frames. Doing otherwise could end up damaging the underside of your car, or breaking something.
- Give the car some nice side thrusts; if it tends to slip or fall off the jacks, or if they tend to sink into the asphalt, gravel or dirt, or even simply fall, it is better to find out now that the car still has the wheels than later, when you have part of your car above you, and without the wheels mounted.
- Finish removing the wheels, and place them under the car, just behind the jacks. In the event that the car slips, the wheels underneath it would prevent it from falling on you, since it could not touch the ground.
Step 7. Make sure you have all the tools you need
There are two nuts to hold the calipers in place, and two to connect the brake block to the steering joint. If you don't have the tools to unscrew them, it's time to reassemble the wheels and go and buy them - you may need a wrench that fits your bleed screws and a set of hex or torx wrenches, or a set of bits of that. guy.
Step 8. Remove the grips leaving the hoses connected:
Remove the calipers from the brake block if necessary - some small calipers fitted to cheap cars are held in place by clips, and it's easy to remove the pads and squeeze the pistons without further complications. The calipers in larger cars, pickups, vans and trucks are much more massive, and are held in place with bolts. The pads may come off with the pliers, or remain anchored to a bracket, depending on the car. Place the caliper on the steering joint, or hang it somewhere else with a wire from a hanger or other so that its weight is not supported by the brake oil hose, and it does not fall.
Step 9. Remove the pads and check for wear
You may need to pour some brake oil from the master cylinder to fill the gap that has been left by the caliper pistons now that they have been pushed out. To do this you should remove the cap from the brake fluid reservoir and cover it with a rag to prevent something from getting inside; in this way the liquid would be free to flow in the area where it is missing, making the pistons easy to put back into position. Some calipers have ceramic or other delicate material pistons, so simply pushing them back with a screwdriver could damage them, making it necessary to replace the entire caliper. Consider using a small clamp or piece of wood to push the pistons into place and then be able to free the pads, as described later for installing new calipers. If one of the two pads has gotten to the metal, you will need to have the brake discs turned, or replaced.
- This is also an excellent opportunity to compare the wear of the right brake pads with that of the left brake. If there is a big difference, you may need to replace the calipers or discs.
- Some discs will come off easily by removing the flared bolts that connect them to the wheel post, while others are part of the wheel hub and to remove them you will have to extract the hub bearings and then re-grease them and reassemble everything, as you will see later.
Step 10. Apply anti-slip paste to the new pads, but do not fit them yet
Make sure that neither brake oil nor any lubricating substance comes into contact with the lining of the pads. Some cars, especially some Ford SUVs, use special lubricants for the moving parts of the brake calipers, and these lubricants are not commercially available (you will need to ask for heat resistant brake grease). Try not to remove them if you can. If you find that some components are not lubricated, you may need to replace the calipers etc. as this could be a sign of some bigger problem.
Step 11. Inspect the brake discs:
if there are any grooves or they are too shiny, fix them by turning or grinding them, or replacing them.
Step 12. Inspect the brake hoses:
If they have leaks around the fittings or if they are damaged, you will need to replace them - but this article will not go into detail on this topic. If you are just changing the pads, skip to the step that starts with: Clean the pins on which the caliper slidesotherwise, read on.
Step 13. Remove the brake discs if you want to have them turned / grinded or if you want to replace them
In most cases, the discs are separated from the hub. Simply slide them off after unscrewing them. You may need to remove grains and / or use a rubber mallet to loosen them. You may also need to hit the wrench used to unscrew the dowels counterclockwise with the mallet if they are particularly stubborn.
In case the brake disc and the wheel hub are one piece, remove the cup with the grease, the pin and the castle nut from the drive shaft to be able to disassemble it. (Only if necessary, disconnect the brake lock from the steering joint. The bolts holding them together tend to jam, so you may need a hammer, lever, or flame to loosen them.)
Step 14. Have your discs grind (or turn) in a repair shop or auto parts repair shop that also does these types of jobs
Some auto parts have brake lathes, or a workshop inside them. Call them before you start putting your hand on the car in order to check their timetables; many workshops are only open until noon on Saturdays, and closed on Sundays. The discs and discs integrated into the hub can be ground (or turned) if they are not too worn or damaged, but consider replacing them if they have too deep grooves on their surface. The workshop should refuse to rectify them if they are already too thin or if they are damaged.
- Although replacement parts could be expensive, especially if you have to replace the hub and various bearings instead of reassembling the old ones. However, not all new hubs with a built-in disc include bearings (although they may already have the outer race, so you will only have to insert them on the inner race already equipped with balls and grease present on the drive shaft). You may need to install from the raceways and other bearing components, and also think about the grease. For this reason it may also be necessary to buy bearings before starting work.
- If possible, you could take the opportunity to grease the bearings of your front wheels. Look for the instructions in your car's workshop manual. You will need new pins and grease suitable for the wheel bearings, as well as a pair of long nose pliers.
Step 15. Fit the new or ground (turned) discs in reverse order of when you removed them
New discs have a slight oil patina on their surface; is applied to protect them from corrosion during the months spent on the shelves. Remove it with a carburetor / injector cleaner; in this case it will work better than the brake disc cleaner. Refitting brake caliper and pads. If you don't plan on replacing the calipers as well, skip to the step that starts with: Clean the pins on which the caliper slides.
Step 16. Replace the calipers if necessary:
Make sure the brake fluid reservoir is tightly closed, especially if you opened it in the previous steps to allow the oil to expand. Remove the characteristic fitting that connects the oil hose to the caliper. It is a hollow bolt that allows the oil to flow inside; do not damage it and do not lose it. Mark its position and the direction in which it is oriented to avoid bending and damaging the tube during reassembly.
Step 17. Drain the fluid contained inside the caliper into a container in order to be able to dispose of it properly at the end of the work
Step 18. Together with the new calipers you will find two brass washers, two rubber bellows to protect the pins on which the caliper slides, clips to hold the pads (if this is the type of caliper that fits your car), perhaps some new pins for the sliding of the caliper and eventually the cable fitting to connect the caliper to the brake pipe
Be sure to mount the calipers so that the bleed screw is at the top when finished. If you accidentally swap the left caliper for the right caliper (which is easier than you think), the bleed screws would be at the bottom of the calipers, which would lead to air bubbles forming in the oil chamber at the bottom. inside the caliper, making it impossible to bleed the braking system. Remember, the bleed screws go UP!
Step 19. Reconnect the brake hose by placing a new copper or brass washer between the hose fitting and the hollow bolt, and one between the hollow bolt and the caliper itself
Reusing an old washer or misplacement of a new one could cause leaks in the future. Make sure you tighten everything tightly.
Step 20. Clean the pins on which the pliers slide, if you have not already done so, using a wire brush for the grinder, a hand brush with iron bristles or some fine grit sandpaper
Clean the parts along which the caliper or pad holder will slide. Apply silicone-based brake lube to all affected parts.
Step 21. Squeeze the caliper pistons or, as appropriate, screw them in
Yes, some pistons (like those of some Nissans), they are screwed and unscrewed to enter and exit the caliper. If you had pistons of this type, you would notice some notches on the head where you can insert a special tool. Trying to push these pistons, treating them like normal ones, would only damage the thread and ruin the caliper and pistons.
- Using a clamp: if you have normal pistons, take one of the old pads and place it inside the caliper, resting on the pistons, so as to offer the clamp a surface on which to act. Make sure you use a strong enough clamp (if not, you would end up deforming, bending or breaking it), and slowly and evenly compress the pistons so that they fit back into the caliper.
- An even simpler way to compress the pistons is to use a special tool (but inexpensive and readily available) called a "retractor". It was designed with this in mind, and is more effective and faster than any clamp!
- Note: Before compressing the pistons it is recommended to unscrew the bleed screw to allow the brake oil to escape from the caliper while compressing the pistons. Doing so will prevent dirty oil from rising up the brake lines and damaging the master cylinder and internal parts of the ABS system if your car has them. Also, you will avoid getting dirty in case the liquid gets to the master cylinder and overflows it.
Step 22. Wipe off any brake fluid in case it leaks from the reservoir
Check that there are no traces in the areas adjacent to the brake fluid reservoir. Be very careful, brake oil is corrosive and can damage and remove the paint on your car if it is not cleaned immediately!
Step 23. Fit the new pads
You may have to use a large flat-blade screwdriver again, but this time you'll need to be even more careful if you want to avoid damaging the pad clips.
Step 24. Refit the caliper to the bracket and tighten the bolts securely to lock it
Step 25. Bleed the brakes - if not you have replaced the calipers or loosened any fittings, JUMP to "Wheels, brake oil and test"; if you notice that the brake pedal is soft or goes down too much, you can always bleed the brakes later; to find out how, just resume reading the article from this point on.
You will need a helper, and only work on one side at a time
Step 26. Use a dedicated brake cleaner to remove any grease left on your fingers or skin and to remove any traces of oil that may have gotten onto the discs during assembly
If the pads showed traces of grease or brake oil, in fact, the friction with the disc would be compromised, making braking less effective.
Step 27. If your discs are not the ones integrated into the hub, reinstall the wheels to keep them straight
Step 28. Do not take the car off the jacks yet
Step 29. Remove the rubber plug from the bleed screw and loosen it 1/4 or 1/2 turn, or just enough to loosen it, being careful not to damage it (use a wrench of the correct size, not the pliers and do not an adjustable wrench)
Connect a clear or rubber hose to the screw, and dip the other end into a container of brake oil before depressing the brake pedal. Doing so will help prevent air from being sucked into the circuit if the pedal is released at the wrong time.
Step 30. Ask your assistant to slowly depress the brake pedal until it stops and hold it in that position until you tell him to release it
You may see oil or air bubbles coming out of the sheath you connected to the caliper. With the pedal fully depressed, tighten the bleed screw. Tell your assistant to slowly release the pedal. When the pedal has returned to its normal position, reopen the bleed screw.
Step 31. Repeat the entire process of depressing the pedal, tightening the screw, releasing it, loosening the screw, depressing the pedal again, etc. until you see clean (no air bubbles) brake oil coming out of the hose
Always remember to tighten the screw before releasing the pedal; and check that it is tight when you have finished bleeding. (In some brakes, the fluid will flow out due to gravity when you loosen the bleed screw; just loosen it and wait until you see clean oil, although the pedal procedure would work anyway).
Step 32. Make sure the brake fluid reservoir does not drain completely during bleeding, otherwise you will be letting air into the brake system and, most importantly, the master cylinder
In that case, you should drain all the oil inside the system, and this is a much more exhaustive process than simply letting the air out of the tubes and cylinders of the calipers alone.
Step 33. Wheels, brake oil and tests:
Refit the wheels. Cross-tighten the bolts so that the wheel is straight. Example: If you have five bolts, tighten them as if you were drawing a star on a piece of paper, moving from one bolt to the opposite, and so on.
34 Check the brake fluid level and top up if necessary
35 Sit in the driver's seat and press gently on the pedal a few times
The first time, the pedal may go down a lot, but after two or three times it should come back high and quite stiff. The procedure just carried out serves to bring the pads back to the discs.
36 Check for leaks in the brake hoses if you have replaced the calipers
37 Put the car back on the ground and do a "mini" test drive, put the wheel stops a little further away from the front and rear wheels to allow the car to move forward and backward to test the brakes
If not, you may find that your brakes don't work at the wrong time. During a real test drive, make sure that the car is not jerking, that there are no strange rubbing noises, that you do not hear anything banging and above all that the brakes are working properly.
38 Tighten the wheel bolts again to make sure they are tight, and refit any wheel covers
39 Put your tools away and clean up
You will probably want to keep the old pieces aside for a few days, so that you can show them to friends and family before throwing them away. Use a mechanic's hand paste, as brake dust can contain asbestos, and brakes tend to be quite dirty.
Advice
- Never press the brake pedal when the calipers are detached from the disc. The pistons would come out, and you would find a nice and expensive puddle of oil and brake parts under each caliper.
- Remember to fit the new calipers with the bleed screw on top. If after fitting them you notice that the screws are at the bottom, it would mean that you have swapped the left and right calipers. At that point you have to disassemble and fix everything. Remember, the bleed screws go UP!
- Most vehicles will not need a bleed if the brake system has never been opened (e.g. by loosening a bleed screw, brake hoses, etc.), unless there are leaks. This will save you time and effort in case your bleed screws are very rusty or frozen.
- When you squeeze the pistons, if you notice that the brake oil is likely to overflow, you can remove the excess with a large syringe. Do not reuse the removed oil. If you need to add more, use new oil. A little, so don't try to save a few cents at the expense of your brakes. They may come in handy in the future.
- Buy the workshop manual for your vehicle. Plus, buy a pair of tarps to keep your greasy hands and brake oil off your car paint, and also buy a pair of washable mechanic's gloves. It is definitely worth it!
- Brake pads can contain asbestos, so don't use compressed air to clean your brakes or wheels before working on your car. Instead, use a rag you no longer need, and wear a mask when cleaning.
- Use an anti-friction spray on bolts and fittings, for example on the area where the discs fit into the hub, to make future disassembly easier. However, be careful not to use too much!
- Keep your workspace clean and organized so you don't lose any tools or parts. Keep some rags and paper towels on hand. Plus, remember to wear old clothes. Don't work in a tuxedo if possible.
- Even if you could have them rectified (or turned), buy new discs the first time. This way, the next time you need them, you can take your old discs to be rectified first so that you have them ready for when you take the car apart.
- Buy the best parts you can afford. You're already saving money by avoiding going to a mechanic, so spend on parts!
- Use your car jack if you have to, but a wheeled jack is much safer and not too expensive. Buying jacks is also not a bad idea. Never work under a vehicle held up only by a jack! Always use jacks or jack stands!
- Always replace the brakes in pairs. Pads on both sides, discs on both sides. Only the calipers can be replaced individually.
- Disc brakes naturally whistle. Using a high temperature resistant silicone based brake lube will help you avoid this or alleviate the problem, as will using house pads. It is easier for cheaper pads to whistle more frequently, but the whistle does not always indicate that the pads have been fitted incorrectly or that you are in danger.
Warnings
- Always keep in mind where all parts of your body are. Working in the confined space you will have under the car, perhaps to tighten some bolts, could easily cause you to hit your knuckles, elbows or head. Keeping this in mind will prevent certain blows from turning into far more serious injuries.
- Brake dust may contain asbestos. Be careful not to assimilate it by breathing it in, ingesting it, smoking cigarettes, or wiping the sweat from your forehead with dirty hands. Wash thoroughly when finished.
- Cars are not monsters, but they are big and heavy. Be very careful to lock the wheels, pull the handbrake, test the jacks with a few pushes and lay the wheels under the car with half raised, as if they were emergency stands.
- The risk of finding asbestos in brake pads is more real than people realize. Statistics show that cancer cases attributable to asbestos exposure are quite common among former auto mechanics (especially among those dealing with older car models).
