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2014-08-29
Featured Article

How to Replace Disc Brake Pads on a Jeep Wrangler

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How to Replace Disc Brake Pads

Seriously, this is a very easy process and is the same for both the front and rear disc brakes on a Jeep Wrangler TJ. Particularly on a Jeep Wrangler, there is NO reason at all to pay dealers more than $100 in labor fees for doing this. One of the only reasons to contemplate paying a dealer to do it is if your calipers are laced with a crazy amount of electronic sensors for traction control or ABS ... but even then, it's not hard, as the pads themselves are expected to be replaced regularly. The real reason to pay is if you absolutely suck at all things mechanical - because failure to do a simple task like this means you'll die when your brakes don't work. Push up your sleeves, grab your tools and just do it.

Resources Required:

  • Flat Blade Screwdriver
  • 13mm Ratchet
  • 19mm Tire Iron
  • Jack Stands
  • Chock Blocks
  • Bottle Jack
  • C Clamp
  • 5 Gallon Bucket
  • Brake Pads
  • Brake Grease

Making It Happen

Make sure you've chocked your front wheels. This doesn't need to be a fancy chock block - I used a really big chunk of wood. The parking brake is really just a drum brake inside the rear rotors. Since you'll be lifting the rear end up, at best, only half the braked wheels are holding the Jeep in place. Thus, you should always use extra precautions to prevent your vehicle from rolling especially whenever you have the risk of your vehicle falling off a jack stand and crushing you into a grease spot. The chock blocks help make sure the Jeep is secure in place so it doesn't move and fall off the jack stands later.

Now, before you actually jack up the Jeep, you should loosen the lug nuts. Once the tire is elevated in the air, the tire may just start to spin freely (if you didn't use the parking brake or if its a front tire) when you apply an appropriate amount of pressure to break the torque on the lug nuts. This is especially true if you've previously allowed mechanics to simply air ratchet the nuts back on in their shops without using a torque wrench. You'll need to apply enough force to break them free that it will require the weight of the Jeep on the pavement to keep the tire in place.

Use the 19mm tire iron to loosen the lug nuts before you jack up the Jeep.

Using the stock bottle jack, place it below the differential and elevate the axle. Then slip the jack stands underneath the axle to support the Jeep. Now lower the Jeep back down onto them. Using jack stands is more stable and safe than leaving the Jeep on the bottle jack. Another best practice is to put the jack stands on top of some wood or sturdy platform to distribute the weight across a wider surface area. Why? On a hot summer day, the sheer weight of your Jeep could push the jack stands down into your driveway's softer asphalt leaving you some nice holes to commemorate your work. (sad facepalm).

Lift the Jeep up safely and support it on jack stands.

Spinning lug nuts is grunt work. This is a handy time to enlist the help of a small assistant to remove them. Hopefully your children will be successfully brainwashed into a lifetime of Jeep maintenance while embedding the idea that Jeep's are awesome. If nothing else, this sort of training prevents my little girl from being helpless on the side of the road years from now. Girls (and boys) should know how to change a tire.

Teach your children auto maintenance with the easy stuff.

At this point, you can pull the tire off the Jeep and set it aside. I personally find big Jeep tires to be a great seat to work from and just lay it right where I'm going to sit. You'll notice in my picture an additional component; the blue disc is my Spidertrax spacer. Unless you've something similar installed, you'll just be looking at the rotor and the axle on yours.

With the wheel off, you should be looking at your caliper and the rotor.

Look on the backside of the caliper for the two mounting pins. The caliper itself slides on these pins as it squeezes and releases the disc. If you are applying an enormous amount of force to remove these pins, you are probably not on the right ones.

On the backside of the caliper are the mounting pins.

Once the bolts are loosened and removed, you can simply lift the caliper off the Jeep. Sometimes, however, the caliper will be "stuck" to the disc. You can pull really hard on it and then bloody your knuckles against other metal parts when it suddenly comes free. Oooorrrrr, you can simply use a C-clamp. Attach the clamp so that it presses against the caliper behind the pads. This should only take a half turn of of pressure on the clamp. What this will do is essentially press the piston in just a little bit and create enough of a gap that the pads are no longer squeezing tightly.

Various other guides talk about using a hammer to knock the caliper off. Do you really want to hit your brake caliper, the device that keeps you safe with stopping power, with a hammer?

A stuck caliper can be loosened with C-clamp.

At this point, your caliper should be removed. If this is the first time you've ever taken it off your Jeep, it's probably disgusting - covered in dirt, grease, and flaking rust everywhere. Notice at this point that it is only attached to your vehicle via a rubber hose brake line. It is important to not just dangle the caliper from this line!!

Your caliper looks like this once you remove it.

Rest the caliper on top of something so the brake line has slack. A five gallon bucket is just the right height for this. The moment you set the caliper down, all the dirt and rust will really start flaking off. At this point, you'll probably start feeling like you totally neglect your Jeep and are a bad owner.

This particular guide is just about pad replacement, but at this point, it's very easy to replace your rotors. In my case, that step would require removing those SpiderTrax spacers. However, generally speaking, once the caliper has been removed, the rotor can simply be pulled off over the wheel studs and the replacement can be slid right back on. Rotor replacement is necessary periodically for many reasons such as wear, warping, or simply upgrading. But regardless, that process is as easy as I've just described. (NOTE: If you do replace a rotor or caliper, do it in pairs.)

A five gallon bucket makes a perfect caliper support.

Start the pad replacement by removing the pad furthest away from the piston. This will be the pad held on just with retaining clips. Just use a flat-blade screwdriver to lift the metal tabs securing it in place. It may resist moving due to rust, age, and whatnot. However, there's no need to be careful about it - you're throwing this old pad away.

Pry that worn down pad off with a screwdriver.

If the rusty condition of your caliper doesn't make you feel bad, the condition of your pads will. I admit, I allowed these pads to go waaaaaaaay too long. Stop judging me!

See the difference between a new and used pad?

Now that you've recovered from your shock at not taking care of your Jeep, prepare to remove the other pad. Before you take the piston's pad off, you can use it to push the piston back. Looking at the picture below, you can see how far the piston is extended outward. It is effectively out as far as the pads have worn down. With fresh pads in place, you'll be unable to put the caliper back on over the disc unless the piston is retracted.

Notice the extended piston.

It's easy to push the piston back in, but you won't be able to do it with your thumbs. Grab your C-clamp and get it positioned against the old pad and the rear of the caliper. Again, it doesn't matter that you're pushing against the pad because you're going to throw it away.

Use a C-clamp to retract the piston.

There are two schools of thought on piston retraction and what to do about the fluid. Obviously, since the piston is extended, the cavity behind it is filled with brake fluid that has to go somewhere. Some folks will argue that you should open the bleeder valve so that when the piston retracts, that excess fluid is pushed out of the system altogether to include contaminants. Of course, doing this will require you to properly bleed your brakes at the end since you may have introduced air into the system. That is certainly not a "wrong" answer.

Others will argue that if the piston is full of contaminants and sediment that you have bigger problems. First, how did sediment get in there in the first place in which case you may have pushed some out, but obviously your whole line must have it somewhere requiring a complete flush. Second, if there is sediment inside the piston, you've probably just ground the piston over some of it leading to the possibility of it getting stuck on sediment later. You'll have to replace your caliper in that case (in pairs) anyway. Thus, the other half of the folks argue that if the lines are clean, what difference does it make just pushing the fluid backwards some? (NOTE: This happens anyway when you remove your foot from the brake pedal ... just not a full piston's worth.) You can read these arguments on-line ad nauseum and see the points made by mechanics for both.

This guide, which is not covering brake bleeding, simply covers piston retraction by pushing the fluid back into the system. Before you begin squeezing the clamp on that piston, it is recommended to remove the cap from your brake fluid reservoir at the master cylinder. When you push the piston back in, you are also pushing the brake fluid in the piston back through the brake lines into the reservoir. If you've topped off your fluid before this, there's a chance your reservoir could overflow when that fluid is pushed back. Having the cap removed, allows you to address the excess fluid without an airtight seal fighting against you. Be prepared with some rags to wipe up any fluid spillage - it will eat through your paint.

Relieve air pressure and allow the excess fluid somewhere to go.

Whichever method you've opted to use, now it's time to push the piston back. Sloooowwwwlly compress the piston back into the caliper using the C-clamp. When the old pad is flush with the caliper, you can remove the C-clamp. Then simply pull the old pad off the piston. Again, you can use a flat-blade screwdriver to pry it away. Sometimes, the metal prongs holding the pad to the piston may rust and break off so be sure to clear away the debris inside the socket.

When the piston is flush with the caliper, it is in the correct position.

Don't forget to put the cap back on the brake fluid reservoir as brake fluid becomes contaminated with prolonged exposure to air. If you forget to put the cap back on ... you'll pretty much need to flush all your brake fluid and may as well have gone with the bleeder approach from the beginning.

Don't forget to put the cap back on.

Now install the new pad onto the piston side of the caliper. Just center the prongs with the piston and push it on. If you're using tools for this ... you're trying to hard, you can do this with your bare hands. Just try to minimize your contact with the pad's surface to avoid getting greases and oils onto it. Obviously, that doesn't help you stop later.

Install the piston's new pad.

Now install the remaining new pad onto the caliper. Unlike it's rusty, old counterpart, this one will simply slide right on. Make sure the retaining clips are pushed all the way to their securing points. You'll know this because the pad is pushed all the way up the caliper but you can also tell because you can't slide it off without lifting up the clips. Your two pads should be aligned with each other now.

Install the remaining pad on the caliper.

Your caliper now looks much better with fresh pads. They clash nicely against the rusted, disgustingness of your caliper. There's always the option of purchasing high temperature paint specifically for brake calipers and making your rust problem go away. It should be intuitively obvious to the most casual observer that if you opt to paint the calipers, do it before ou put the new pads on.

Fresh pads on an old caliper.

Before you install the caliper back onto the Jeep, a little preparation is necessary. The caliper is held in place by only two pins and the pads themselves slide across two metal surfaces that look like little rails. Just as the condition of your caliper and old pads was terrible, the rails are probably in poor shape as well. If you don't take care of them, your pads can stick. This sucks a lot because your brakes will drag, heat up, smoke and fail.

Your caliper's pad rails are probably in terrible shape.

After cleaning the surface of those metal rails, finish the task with some disc brake lubrication. Lube makes everything feel better - treat your lady right.

There's ALWAYS time for lubrication.

Smudge that lube all over those rails. You'll also need to lubricate the smooth surfaces on the pins where the caliper itself slides on.

Grease the pad rails to keep them from sticking.

Grease the caliper pins to keep them from sticking.

At this point, the caliper can be placed back onto the Jeep. You'll notice each side of the pad ends are slightly different. One side has double tabs and one a single. The side with double tabs must be slotted against the rail first, after that, the other single tab side simply rests against the other rail. The caliper may feel very loose compared to when you removed it based on the increased space between the pads and the disc itself. This will be corrected in the end with the bedding procedure.

Place the double slot end of the pads onto the rail first.

Now the caliper is properly placed but it is not yet secured. You may have to slide the boot sleeves back and forth on the caliper in order for it to align properly with the mounts. Once everything is aligned, slide the greased pins into the mounts and torque them down. That's it, your caliper is mounted.

Secure the caliper with the two greased bolts.

But you're not done yet. Put those mammoth Jeep tires back on and torque those lug nuts appropriately to 115 ft-lbs.

Torque the lug nuts down to standard.

The labor part of the pad replacement is now complete, but now the brake pads must be appropriately bed. This process isn't too difficult and involves doing a few controlled stops. Different pad manufacturers offer specific procedures for bedding their pads. But in general, you need to do roughly five hard stops from 35mph. One of the simplest functions of this is to push the pads into the right seating position under pressure and to close the pad gap. But the more significant purpose is to produce just enough heat to burn off factory glazes and prime the pads for actually stopping. Failure to bed the pads properly may result in a significant loss of braking power during the first high speed stop when you really need it (since the glazes are still present).

Conclusion

Replacing the disc brake pads on a Jeep Wrangler is a remarkably easy task (and is pretty much the same for any vehicle with disc brakes). It may take awhile the very first time but once you've done it, the process reduces to about 30 minutes for two wheels. Save yourself an hour of labor fees and gain the prestige of bloody knuckles, grease stains, and I-did-it-my-mother-f'ing-self kudos.


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