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Jeep Liberty/Liberty Diesel Brakes

john81john81 Posts: 60
Keep an eye out and see which SUV's or Trucks (imports) start installing rear drum brakes instead of rear rotor and caliper brakes. It is widely known that drum brakes are more "mpg" friendly, but lack the stopping power of rear rotor/caliper style brakes. I am wondering if efforts of making a better braking system has accidently invited additional heat. Weight, momentum and size determines the style of braking system, this according to most mechanical engineers.
Drum brakes are less costly. They worked OK during the 1950's and 60's when cars were iron tanks with huge engines. So what's so different now, only body shape and lighter materials. Lets go back to rear drum brakes. Any retro-fitted drum brakes out there that I could swap out with my rear brakes. Maybe others might be interested also.
John
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Comments

  • threept82threept82 Posts: 1
    Hi Guys.
    This is my first post and I hope it's not a silly question.
    My wife has a 2002 Jeep Liberty, I purchaced a repair manual for it when I bought it and I'll be darned if I can locate it in my house.
    I need to change a bulb for the break light on rear driver side, I opened the rear door
    and removed the 2 inside screws. Everything seems loose but I can't remove the housing is there something somewhere else I missed to loosen? I don't want to just pull on it for fear of snapping something. Any help would be greatly apprecheated. Thanks.
  • libertyinctlibertyinct Posts: 15
    Threept82,
    What a weird coincendence. I just changed mine myself, and ran into the exact same situation. I had the same worry about snapping of some plastic part off and ruining the tail light for good.
    Here's the solution from my experience;
    The outside (for the driver side brake light, it would be the left hand side of the taillight as you are looking at it) of the taillight is held onto the body by (2) prongs roughly .25 diameter that snap into (2) holes mounted into the body. The prongs are located (1) at the top and (1) at the bottom of the taillight. The best way to remove it is to first remove the two inside screws as you did before. Second, you need something to pry the taillight off. I used a large flat screwdriver, sticking it in at the middle of the taillight between the body and the light. It's important that you work it slowly and gently. I do recommend using a cloth or something to cover over the blade of the screwdriver in order to prevent scratching the body or cracking the light. Thank God, I got lucky and didn't do either.
    Good luck. Let me know how it goes.
  • tqqlintqqlin Posts: 3
    I had the same problem...the trick is to give it a good pull after the screws are out, don't worry it won't break. There are clips that help hold it in tight to the body, they release with a good pull.
  • steverstever Viva Las CrucesPosts: 40,990
    I like rear drums too, but why are drum brakes are more "mpg" friendly? You mean they go more miles before you need to replace the brake shoes?

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  • john81john81 Posts: 60
    The brake pad is located inside the brake drum. Brake pressure is applied which pushes the brake pad against the inside wall of the drum. There is only one surface which actually makes contact during braking. The caliper, on the other hand applies pressure from both sides of the rotor.
    Now, the rotor is exposed to the elements, road salts and rocks. I am trying to find if this situation exists. Ok, take an ironing board, put some water on it and then slide a hot iron over the wet spot. Steam is created and the iron slides across the ironing board. So, when water is heated to a steam state, it becomes a lubricant (of sorts) and reduces surface friction. Does this happen with rotor/caliper brakes in wet weather?
    John
  • steverstever Viva Las CrucesPosts: 40,990
    Dragging brakes will affect your mpg, but properly adjusted discs or drums shouldn't drag. If they aren't dragging they wouldn't be creating heat (and thus steam).

    Maybe someone over in Stop here! Let's talk about brakes can expound, but I don't why there'd be any difference.

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  • john81john81 Posts: 60
    Wow! Look at all those brake problems. I have to believe that its a "vendor", because it seems that these problems covers all models and manufacturers.
    Can you change the "temper" of the (rotor surface) outside laminate (which makes contact with the brake pads)? I found an old rotor and discovered the interior is not solid. Rotors warp from heat or the tempering of the steel in isolated areas.
    Even front rotors have problems with heat, warping and causing ball joints to fail. I have noticed this for some 20 years. I had a 1981 Dodge truck that was famous for bad rotors, bearings and ball joints.
    I have to believe its the vendor or there is an monopoly of bad technology in which the car manufacturers are forced to purchase from.
    I can't believe that everyone suffers from just caliper calibration problems. Look at all the recalls, even dating back to the 1980's about brakes. I have to conclude that all rotor brake products were defective, but its "theoretical" functionality and performance "trump'd" its failure quotient.
    Rotors are a "consumable item", which means they are suppose to be replaced. I would like to check the specifications standards for rotors, say made in 1985 and rotors made now. Are the "spec's" the same between the two or have changes been made since then.
    Can a caliper brake pads "weld" themselves to the rotor? This may be an extreme situation, but even if welding does not occur, look at the extreme temperatures which change the chemical temper of the steel surfaces.
    I have to thank you guys at edmunds.com/forum. Everyone can't be crazy if we suspect our brakes are bad. Then the only conclusion I have to draw, its a design flaw.
    John
  • tidestertidester Posts: 10,109
    Ok, take an ironing board, put some water on it and then slide a hot iron over the wet spot. Steam is created and the iron slides across the ironing board.

    In the case of fabric, liquid water (and steam) will remain trapped in the fabric providing a more or less steady supply of steam under the iron. The metal in your brakes is nonpermeable so any liquid water or steam is very quickly expelled.

    tidester, host
  • rreidtrreidt Posts: 15
    I have an '03 Limited with 33,500 miles. I had my brakes checked at a good shop and the mechanic said it looked as though they haven't even been broken in yet-yes he showed me too. I don't think my driving habits are any worse or better than anyone else. Why are mine in such great shape and others with less miles are having trouble--no noises at all-just solid braking. It is got to be more than driving habits too. I live in a four season climate.

    -"Lucky Liberty"
  • john81john81 Posts: 60
    This principle of steam used as a lubricant has been successfully used on steam catapults onboard aircraft carriers since the 1960's. A metalic "shuttle" rides on a wave of steam along a metal track driven by a pneumatic piston.
    Rotors in contact with metal brake pads goes along this same principle. This may be a monentary event, until the metal contacts exceed the temperature limits of water and it all evaporates away as steam.
    So, it steam is generated, we are talking the temperature of boiling point, or 100 degrees C. Now, what are the upper temperature limits in which a rotor can withstand? I am sure many people, if under severe braking have not bothered to check their rotors if such an event happened. They just keep driving.
    So, can rotors reach 1000 degree's. Smoking brakes reflect a breakdown of the hydraulic system and fluid gets on the hot metal. At 1000 degrees, hydraulic fluid is quite flammable. That's why hydraulic lines are metal instead of rubber (or should be metal). Not only worn brakes, but worn gaskets or seals in brake lines could rupture from the radiated heat.
    Anyone who has welded their brake pads to the rotor, I would be interested what temperature reading that would be. Maybe exceeding 2000 degrees?
    All these things are possible.
    John
  • john81john81 Posts: 60
    I have to agree that driving habits cause a huge impact on brake wear. My Jeep Cherokee went 132,000 miles without one brake pad or rotor change. I had a manual transmission, so braking was at a minimum. My 2006 Jeep Liberty also has a manual, no brake problems of any kind.
    I think it would be a good idea, like you said, the technician showed you the brakes. Like a doctor visit, have some visual idea what is happening under the car when you slam on the brakes.
    I don't know of any service shop who would invite customers into the work area, like on a guided tour to examine what is wrong with their car. Unfortunately, what most customers sees is their bill, with the prospect that the problem will reoccur.
    Doctor technician conference - Good idea?
    John
  • steverstever Viva Las CrucesPosts: 40,990
    Great idea; some of the newer dealerships feature glass walls between the customer waiting area and the service area so you can see a little of what's going on.

    You can always ask to see any parts removed during service too.

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  • john81john81 Posts: 60
    http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml
    Check out this website on brakes, brake characteristics, rubbing, overheating and such.

    Submitting a new electronic braking system based on old technology, magnetic amplifiers.
    Hyraulic fluid, according to the above website, can overheat and boil inside the brake lines creating bubbles.
    So, could I substitute brake lines with electrical wiring feeding a magnetic amplifier. The mag amp might cause the caliper to close when opposing "N" and "S" fields are present thus closing the pads against the rotor. Pads are off the rotor by putting a "N" and "N", same pole charges thus repelling the pads keeping them clear of the rotor.
    The rotor is a spinning iron wheel, so could I use this as a reverse clutch to stop the vehicle via opposing torque?
    The only problem is that magnetic amps need alot of power to create the magnetic fields necessary to stop a vehicle.
    Could incorporate a separate alternator to supply all the required power necessary.
    How difficult would this be? Mag amps can control large servo's, so how hard would it be to stop a car? I'll draw up a skematic and work out the math.
    John
  • john81john81 Posts: 60
    I did the math on the magnetic calipers. My reference was based on normal hydraulic brakes which reaches up to 2000 psi (fluid) during braking and transfers 500 ft/lbs of force onto the rotor via the brake pads.
    In a magnetic situation, I would need a magnetic field, on each wheel's caliper about the size of a large car to produce that amount of force. If you buy a computer hard drive, it says, keep it way from magnetic sources like monitors or large magnets. So magnetics are not very practical and potentially dangerous to you car's computer.
    What I did learn is that "if" a caliper does not have an internal value to equalize the pressure or a faulty equalizing valve, then the hydraulic 1500 psi will be distributed unequally over the rotor. If one caliper plunger sticks out more than the other, so putting pressure to one side of the rotor causing the rotor to bend while its still turning.
    Now, you put on the brakes with 1500 psi hydraulic pressure with 500 ft/lbs going to the brake pads via the caliper, but what happens when you release the brakes? Where did that 1500 psi go to? Does it go back to zero psi or is there some residual pressure left which still causes the brake pads to make contact with the rotor. Then I would think that a hydraulic value was bad. Your maintenance dept has on hand a 3000 psi gage and a 1500 psi gage to test the hydraulic pressure going to the calipers. Now, I would ask, when the brakes are released, how much of that remaining pressure can be called out of tolerance? There should be a valve which creates a negative pressure to pull the caliper plungers away from the rotor.
    Should there be a dashboard light to indicate higher than normal hydraulic psi under no brake conditions.
    John
  • I have replaced my front disc pads twice and rotors once, both by myself. At almost 100,000 miles, my rear brakes are starting to go in my 2002 Liberty Limited. Anyone have pointers for doing such a repair myself...like is it much more complicated than the front brakes?
  • tidestertidester Posts: 10,109
    I would need a magnetic field, on each wheel's caliper about the size of a large car to produce that amount of force.

    I don't know how you arrived at that conclusion but it's not the physical size of the field that matters, it's the size and energy requirements of the magnet that matter (assuming you go for an electromagnetic rather than a permanent magnet!).

    Technically, magnetic fields continue far out into space but they typically fall off very quickly with distance.

    Also, I advise against storing your computer hard drive near your brake pads! ;)

    tidester, host
  • john81john81 Posts: 60
    You should know that magnetic energy is hard to contain because it radiates into space and most of it is lost. So to generate the same amount of force (as in hydraulic brakes) your immediate field would have to be that large, to compensate for any field loss. Not to mention the weight needed to hold those thousands of coils of copper wiring. This was why magnetic amplifiers were ditched in the 60's and 70's because the advent of transistors.
    You know that an automatic transmission is another hydraulic unit. So what if one hydraulic unit is fighting with another hydraulic unit, say in putting on the brakes and forcing the automatic transmission to stop, What are the odds something might snap? One of the common elements is the differential. The automatic transmission is pushing the axle to sustain speed while the brakes are trying to stop the axle. Wow, aren't we having fun with physics!
    So, until another day at science class, keep learning about those FUBAR brakes from Jeep. If they can't figure it out, then they're out of business.
    John
  • john81john81 Posts: 60
    Wow, where did you find this, this is awesome!
    I would have more confidence in motor controlled hydraulic valve rather than a hydraulic pressure valve.
    The main computer would have alot more control in braking input and feedback response.
    I am reading over this website, and I'm thinking its not the weekend do-it-yourself'r. The addition of accelerometers and the various sensors would have to be aligned just right for maximum performance.
    I'm going to find out if someone around here in Southern Ohio or Northern West Virginia sponsors Continental Automotive system.
    If Jeep negotiated a contract with Continental to reconfigure their 2007 models or could retro-my 2006, I would seriously consider driving over to my dealership Service Dept and let them have a crack at it.
    Thanks!
    John
  • caribou1caribou1 Posts: 1,350
    I've read a few lines about this in the past year. Peugeot and Citroen were trying this system on their compact cars. They were using compound (multiple piston) brake jaws.
    There is one thing I would like to find on 4x4 trucks: it's a disk brake directly mounted onto the transfer case. This would be a great deal for those who have to tow and slow down heavy loads because the 4 wheels can spread the braking effort mechanically, and braking before a set of reduction gears calls for less power because this disk would spin faster.
  • john81john81 Posts: 60
    On smaller cars, braking is immediate. On larger trucks, I saw something similar to a brake time enable. This is a hydraulic valve enabled by an electronic signal. The electronic signal is only enabled once the computer receives a signal from the brake pedal for more than 2 seconds. This eliminates any signal which the computer might confuse from a momentary push on the brake pedal during normal driving. In an emergency, the computer receives the 2 second signal, then tells the hydraulic valve to engage the caliper plungers onto the emergency brake rotor, wherever the rotor is located along the drive system or on the trailer itself.
    The hydraulic pressure would imitate the pressure of the other brakes so not to create an unbalance.
    Yes, this would be an additional braking system, not to be confused with the braking system already on the truck and hydraulic lines feeding to the trailer's brakes.
    This new system opens up a whole new set of possibilites on where to put emergency braking systems because the computer has full access to its function and control.
    John
  • After about 48K miles, the front rotors warped on me. I replaced the pads and rotors with Bendix parts and was very careful to ensure that everything was properly lubed and used scotch bright to get the lose rust from behind the rotor. After about 2K miles, the passenger front warped again, so I got another rotor (different manufacturer) and replaced it. After 500 miles, it's back. At this point, the jerking makes it seems like both rotors are warped again. I couldn't find any performance brakes or rotors for the Liberty, so what can I do the third time around to make sure they do not warp again? I've seen something about the calipers here, but my untrained eye could not spot any issues with them anyway. I saw someone mention something about recalibration (whatever that is) of the calipers. HELP! I'm losing my mind over the warping.
  • john81john81 Posts: 60
    How about this, a single plunger caliper. What does a single plunger caliper mean? Only one plunger is activated to push the pads against the rotor, while the other pad reacts accordingly. So, is the rotor receiving unequal forces between the two pads? Then one side of the rotor may be "hotter" than the other, thus creating a warp. What type of brakes were incorporated in the 2002 Liberties, and is this the same for the 2005 or 2006?
    Front end alignments make sure the rotors are exactly 90 degrees, perpendicular to the ground. If the angle is slightly off, you get a gyroscope effect where the rotor wants to move off axis, creating an opposite force against the ball joints/yoke and CV joint.
    I would check the front end alignment in the 2002 liberty mentioned above. Wow, too bad Jeep wouldn't just buy your liberty to investigate "what's not suppose to happen!"
    Does this make sense?
    John
  • I dont see how a front end alignment can cause rotor warping. The bearings that the rotor spin on should prevent any undue movement of the rotor by external forces-be it the geometry of the front end alignment or the road conditions themselves. Warpage is caused by overheating of the rotor-plain and simple. I would check the rear brakes. If they aren't providing any braking action, the front would have to take up the responsibility for the whole vehicle. Since the user is stating that BOTH rotors are warping I would assume that both front calipers aren't sticking, holding the pads against the discs. If it's a rear drum setup, possibly underadjusted brakes can result in the same conclusion.
  • john81john81 Posts: 60
    I agree with you 100%. Once the rotors became warped, then a mis-alignment may become an issue. Yes, rotors warp from heat.
    Now, I read that the front Caliper is equiped as a dual plunger or piston model. The rear (by what I've read) is a single piston caliper.
    The calipers are essentially a hydraulic valve with multible chambers, depending if its one piston or two. In the maintenance manuals, it mentions to check to see if the hydraulic connections to the caliper or the pistons are leaking.
    How often are caliper changed or checked? Air can get into the system from boiling fluid during excessive heat. Can hydraulic fluid degrade chemically under heat stress? Hydraulic valves do not operate properly if the fluid is dirty or contains air pockets. Any fluid under high temperatures expands, thus creating more outward force. This outward force causes the caliper pistons to push out that much more creating unwanted friction against the rotor.
    Is there a way to keep a constant pressure between cold fluid and hot fluid?
    Are warped rotors "the" cause or a symptom from another source? Rotors are a consumable item, but calipers seemed to be overlooked as a possible suspect. Which should be examined first under situations of premature brake failure?
    The problems with Jeep Liberties, I guess only in automatics has existed since 2002. I would assume that after 5 years, someone would have figured it out and fixed it. The last people I want to argue and become frustrated with are the good folks at the Service Dept. Besides putting up with the customers, they have to fix the problems coming from the factory, which shouldn't be their concern.
    John
  • Tried changing my Liberty's tail lights and they are a pain. The info. posted here is correct. For the drivers side taillight assembly remove the two screws on the side of tailight assembly. You need a special star screw driver made specifically for Chrysler vehicles. Don't strip the screws. If you do you will be in a world of hurt trying to remove these screws. You have to swing the tailgate open to see the screws. Once those screws are removed you have to pry the taillight assembly from the vehicle. Pry it straight out using a couple of large screw drivers as pry bars. Be careful not to scratch the paint. There are two plastic shafts that clip into the body. They run along the outside edge of the light assembly. Apply steady pressure with the pry until they come loose. It will take some force to break them free. Do not try to pull the assembly out with your hands from outside the vehicle as you will probably break the assembly.

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  • Hello Everyone, I have a 2005 Jeep Liberty with less than 7000 miles. I am getting moaning or grinding sounds from the wheel area. (Its hard to tell the where the sound is coming from) Usually I get these sounds when I first start driving after the car as sit for a while. I think it is coming from the front wheel base. I am also getting a popping sound coming from the rear end when the car is in reverse and I step on the brakes. Any ideas?
  • bvcrdbvcrd Posts: 196
    Hard to say about the popping noise, but the moaning is probably the brake thing that we are all having. It is a problem with the pads and/or rotors and the dealers all have a fix for it. Under warranty if you are under 12,000 miles.
  • craigk1craigk1 Posts: 6
    I inquired about this same problem about 20 pages back and the answer I got then was it was a quirk of the Liberty braking system and something you had to live with. Those who answered my question also said it didn't appear to cause any damage.

    What's this latest about dealers now correcting the problem under warranty?

    Just what exactly causes the problem and what should I tell my dealer?

    craig
  • bvcrdbvcrd Posts: 196
    All I know is I called the dealer, and he said that they were aware of the brake noise thing, and to bring it in and they would let it sit overnight to deplicate the cold rolling start and also they would spray the brakes with water to duplicate the noise after I wash it in the driveway. All of this is just to verify it. Then, I understand that they turn or replace the rotors, and replace the pads with some that are quiet. I opted to wait until closer to the 12,000 mile mark to get a free brake job since there are no safety issues and I live in the desert so it is dry here most of the time. Mine only does it when they are wet, and cold.
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