Edmunds.com | Inside Line | Auto Observer Your Account | Help | Directory
You are here:
![[F]](http://a332.g.akamai.net/f/332/936/12h/www.edmunds.com/media/townhall/webxicons/site.gif){kind=small}
Forums
SUVs Jeep Liberty and Jeep Liberty Diesel Jeep Liberty/Liberty Diesel Brakes
74 messages, Last post on Oct 05, 2009 at 1:22 PM
You are in the Jeep Liberty and Jeep Liberty Diesel Forum. Your Hosts are steve_ & tidester
|
Replying to: john81 (Jan 08, 2006 2:06 pm) Maybe someone over in Stop here! Let's talk about brakes can expound, but I don't why there'd be any difference. Steve, Host
|
|
|
Replying to: steve_ (Jan 08, 2006 4:26 pm) 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
|
|
|
Replying to: john81 (Jan 08, 2006 2:06 pm) 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
|
|
|
Replying to: tidester (Jan 08, 2006 6:50 pm) 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 |
|
|
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"
|
|
|
Replying to: rreidt (Jan 08, 2006 7:36 pm) 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
|
|
|
Replying to: john81 (Jan 09, 2006 9:16 am) You can always ask to see any parts removed during service too. Steve, Host |
|
|
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 |
|
|
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
|
|
|
Replying to: john81 (Jan 18, 2006 5:36 pm) 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
|
|
You are here:
Forums
SUVs Jeep Liberty and Jeep Liberty Diesel Jeep Liberty/Liberty Diesel Brakes
New? Join Now!
Forum Tools
Search Forums
Browse by Vehicle
2010 Jeep Liberty
Browse by Board
Browse by Topic
