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Brake Time!

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  • Brake Time!

    DISCLAIMER: The author is NOT an ASE certified mechanic, just an idiot sharing his experience. If you lack the confidence, ability, or tools to do a proper brake job, pay for the labor. It beats being sued if you smash into somebody.

    This forum is full of discussions on lifts, tires, death wobble, fabrication, and GEARS GEARS GEARS. But as Jeepers, we seldom think about our brakes until they literally squeal for attention. Or they grind. Or worse yet...they don't work. Unfortunately, I've been victim to all three. As such, I've gotten rather familiar with my brakes.

    After a bad experience involving brakes that no worky on our old truck, I bought the Wife a 2001 Grand Cherokee (WJ). I love the body style and the rock solid reliable 4.0 and she loves that she can fit all of her Avon in it. Not long ago, I installed new pads and rotors. Not long after, we had some intermittent God-awful squealing. Truck stopped fine and I don't drive it daily, but it reportedly stopped. But then I started noticing a LOT of brake dust on the drivers's side front tire. Popped off the tires and discovered that the pads on that side were almost completely worn and the passenger's side was like new. This tells me that the drivers's side was doing the lion's share of the braking and the passenger's side was doing little or none. I knew it wasn't the caliper slides as I had cleaned them up and greased them. Looks like a bad caliper. Much light headlight bulbs, I don't like to replace just one. The driver's side rotor had grooves in it, and I had to use a hammer to get the passenger's side off. So those went on the shopping list too. Gotta have pads too. Bonus to all of this: Wife still can't drive stick, so I had only the hours of 5:00 p.m. on to get this done. And it needed to be done last night. So I figured of course I had time to take pictures and share this with all of you in case a brake job is in your future.
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    Here we have two brand new calipers. The calipers came complete with new caliper brackets (Not all vehicles have a separate bracket; for example, my TJ's calipers bolt directly to a bracket already on the unit bearing), bolts, and bleeder screws. I also picked up new rotors, pads, and a fresh bottle of DOT 3 brake fluid. If you don't have any, it's a good idea to grab a can of brake cleaner as things get nasty in there as well as a can of disc brake quiet. The tools I needed for this job were mostly wrenches. The caliper bolts on the WJ are 17mm. The bracket bolts are 18mm. The brake hose bolt is 14mm. I jacked up the front end and supported the WJ on jack stands and popped off the tires (19mm lug nuts on mine) with the handy dandy impact gun.

    Here's the ugly start.
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    First, I popped the calipers off. I removed the 17mm caliper bolts, then gently pried the caliper off using a large pry bar. If you're just doing new pads, be gentle on the rotor. Also, if you are just changing pads and rotors, the brake line does not need to come off. It's poor practice to just let the heavy caliper hang by the brake line as it can stress and break said line, leaving you with Step 8 and another trip to the parts store. I keep a bunch of cut wire hangers in the shop for this purpose (They're also handy to hold up parts that are being painted and dried). Tie the caliper up and out of the way.
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    I then removed the caliper bracket by loosening the two 18mm bolts holding it on. The bracket is where the brake pads live. They slide in and out on the bracket as they are pushed by the caliper. They rest on small metal clips. Both the pads and the calipers came with these clips. Here's a side by side of the old bracket and new bracket with the clips installed.
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    Before the new pads go in, I spray the back of the pads with the brake quiet. It goes on like red paint. The idea here is to reduce or eliminate any squealing from the metal on metal contact they make. Be mindful that it will remain tacky even hours after it is sprayed on, so handle by the edges if you can.
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    Once the pads are slid into the bracket, said bracket fits right over the new rotor and gets bolted in place using the old 18mm bolts. I used a thin coating of anti seize on these bolts because brake pads are a consumable part and I'm sure I'll be replacing them again some time.
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    Before that shiny new rotor goes on, it's important to clean it. They are shipped from the factory with a coating to prevent pre-mature rust. One way is to spray with brake cleaner and wipe them down real well. I actually take mine into the kitchen and scrub them with warm water and dish detergent. I forget where I learned this, but it works. I also use one of the lugs to hold the rotor on while I bolt up the bracket as it can be quite Step 8 inducing to do this while the rotor is wobbling around freely. Here's a shot of the old rotor. It's got deeper groves than an old vinyl album (But the vinyl album has way cooler grooves, dig it?)
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    Now we're ready for the caliper. If you are just changing pads and rotors, the new pads will have considerably more meat on them than the old ones. As such, you'll have a hard time trying to fit the caliper and pads over the new rotor. You have to spread the caliper's pistons open. I didn't have to do that because I was using brand new calipers, but here's the right tool for the job.
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    This tool can be used on one or two piston calipers. The shiny metal part that says "Face towards piston" backs up to the far side of the caliper so that the vice-like portion can push the caliper open. To use it, place one the the old, worn pads against the pistons and tighten agains them like so.
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    I used an old caliper for demonstration purposes, but this step is usually done with the caliper still attached to the brake line. If you are too cheap to buy a brake tool, or can't rent one at a parts store, a C clamp will work, but keep in mind that you might not have the room to maneuver this tool around under the Jeep.
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    At this point, if changing pads and rotors, simply place the caliper on the bracket and bolt it up. In my case, I replaced the calipers with new ones, so I'm going a few steps extra. My new calipers came with new caliper bolts, as well as a new bolt to hold the brake line to the caliper. I used a thin coating of anti seize on the new caliper bolts, but not on the new brake line bolt. Note the two new copper washers. These are extremely important! Don't lose or discard them.
    Chris Barnes - Former NJJC President, Wannabe Fabricator, Errant Mechanic
    I fix stuff by a little bit of trial, a lot of error, and a TON of bad words!
    2001 TJ, upgraded as broken

  • #2
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    I use an old coffee can to catch the old fluid. I then popped the brake line off the old caliper using the 14mm wrench. When bolting the line up to the new caliper, a new copper washer goes on top of the brake line and under the brake line between it and the caliper. These washers act as a gasket and prevent leaking. DO NOT reuse the old ones. Copper is a soft metal and forms a new seal.
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    Of course I forgot to get a pic of the new finished set up. So just look at the second picture above and picture it black and shiny.

    Now, because I installed new calipers, I introduced a little air into the brake system. These brakes are hydraulic, and the lines and calipers must be full of fresh fluid. This meant bleeding the brakes. Vice prez Joe recently showed me the right way to do this, and I I turn taught Wife how to assist me. I jacked the rear tires off the ground and pulled them off. Then, I loosened each bleeder screw. Forgot to take pics of these, but they are the small Zerk-like fittings on the calipers (Or on drum brakes, the wheel cylinder). Old bleeders are ridiculously difficult to open due to years or exposure to the elements, so it's not a bad idea to have new ones on hand to replace the old ones should you manage to strip them. It's also very important to use the right sized wrench. On my WJ, the fronts were 10mm while the rear were 3/8". Thanks a pant-load, Mother Mopar!

    The proper procedure is to have a helper pump the brakes while you bleed each individual caliper. You work from farthest from the master cylinder to closest (Passenger rear, driver rear, passenger front, driver front). The helper pumps the brake pedal until there is a firm or stiff pedal, then holds it ("Holding!"). The bleeder places a piece of clear tubing over the end of the bleeder; said tubing empties into a clear plastic bottle. When the helper says, "Holding," crack the bleeder open (About a quarter to half a turn is all that's needed, righty tightly lefty loosey). This is repeated until there is clear, clean fluid with no air bubbles coming through the tube to the bottle. Repeat for each wheel. It's important to check the brake fluid reservoir as you go; the fluid is being pushed out to the wheels and if you drain the reservoir completely you'll end up with more air in the lines and have to curse, throw wrenches, find the wrenches, and start over. I like to repeat the entire process twice. Then top off the fluid in the reservoir, put the tires back on, and test drive it.

    A note about brake fluid: As soon as you break the vacuum seal on the bottle, you need to use it immediately. You cannot use it a week, a month, or a year later. When exposed to air, the chemicals in brake fluid begin to break down and if you use old fluid, you run the risk of the brakes failing. So don't do it.

    Here's a shot of the old brake fluid versus new.
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    Note how nice and clean the new fluid is. You can see the old fluid in the bottle with the hose in it. The hose is from Napa and it is just clear tubing with a rubber boot to fit over the bleeder screws. You still have to physically hold it in place as the pressure will push the tube off. You can use any clear bottle for this, but I like to drill a hose-sized hole in the cap as this prevents a little extra air getting into the brake system.

    Remember how I said one caliper seemed to be working better than the other? Here's a shot of the old pads side by side. Click image for larger version

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    After bleeding, I took the truck out for a ride. Before I even got out of the driveway, I did several brake checks. Once I was confident, I cruised around the neighborhood and even did a few emergency stops. I did this because in addition to Avon, Wife also drives our son around in this truck. So keep in mind, before you do your own brakes: Are you confident enough in your abilities that you'd put the people you love most in the vehicle when you're done? If not, pay for the labor. There's no shame in keeping your family alive. But if you have the ability, pads and rotors aren't difficult to do. The second you have to crack open a bleeder, though...that's where you need to be certain.

    So there you have it. Brakes for dummies by an idiot! Happy and safe Jeeping, everyone!
    Chris Barnes - Former NJJC President, Wannabe Fabricator, Errant Mechanic
    I fix stuff by a little bit of trial, a lot of error, and a TON of bad words!
    2001 TJ, upgraded as broken

    Comment


    • #3
      Nice write up.

      Small addition - when changing just pads and pushing the caliper pistons in, this pushes fluid back up into the reservoir. Be prepared to remove some of the fluid (turkey baster works good) from the reservoir, else it will overflow and is very bad for paint.

      As the pads wear over time the piston gets closer to the rotor, this requires additional brake fluid to maintain the pressure, lowering the level in the reservoir. Replacing with new pads, they are thicker than the old, reducing the overall fluid volume in the system.

      This didn't occur in the write-up as the calipers were replaced.
      Dan M.
      Former President, Secretary, Treasurer
      48 days on trail in 2012!
      '85 CJ7 - 4.0L,T-18,4.10s,Locked F&R,35s,Caged,Winch
      '68 Kaiser Jeep M715 body transplant on '90 Dodge W350 in progress

      Comment


      • #4
        Thank you, Dan. Good info.

        Another note: WJs were built with two different styles of front calipers (Thank you AGAIN, Mother Mopar!). The ones pictured above in my Jeep are the Akebono style. The others are noticeable as they have a piece of wire along the outside of the caliper. Know what kind of brakes you have to avoid double trips to the parts store.

        Also, check your owner's manual before you buy brake fluid. I can tell you that for both my TJ and WJ it is DOT 3. It makes a difference; DOT 4 performs differently.
        Chris Barnes - Former NJJC President, Wannabe Fabricator, Errant Mechanic
        I fix stuff by a little bit of trial, a lot of error, and a TON of bad words!
        2001 TJ, upgraded as broken

        Comment

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