The "Warped" Brake Disc and Other Myths

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bugnout

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MYTH # 6 - The brake fluid reservoir should be topped up during routine service.

Interesting. Thats one I would have disputed, but his point is valid. When the brake pads wear to the point they need to be replaced, you'll also get a low fluid event. Makes lots of sense if your wearing out your brakes in a year, but for those that don't put a lot of miles on thier vehicles or maintain them well, brake fluid can disappear in other ways.
 
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Dave

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Ry' N Jen

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I have watched many a person "top up" the brake fluid because of low fluid level due to the brake pads being worn down.
Only then when they replace the brake pads, the brake fluid over flows and dumps all over the inside of the engine compartment.
 
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jnaut

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MYTH # 6 - The brake fluid reservoir should be topped up during routine service.

Interesting. Thats one I would have disputed, but his point is valid. When the brake pads wear to the point they need to be replaced, you'll also get a low fluid event. Makes lots of sense if your wearing out your brakes in a year, but for those that don't put a lot of miles on thier vehicles or maintain them well, brake fluid can disappear in other ways.


Yeah, that's why most manuals for working on your brakes suggest you remove some fluid before compressing the piston all the way back-- to avoid overflows. If you've kept adding brake fluid over time, it'll overflow when you change the pads.

Or yeah, what Ryan said.
 

LibertyTC

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Brake fluid level is generally used as a wear indicator, or caliper leak indicator, and should not be topped up unless at or below minimum line, then it is time 4 inspection.
IMHO brake inspections should be done once a year or every 30,000 miles, which ever comes first. The safety of your passengers and vehicle depends on this.
Fact: Many home DIYers do not have a micrometer or run out dial indicator or understanding of proper bleeding/pad & caliper inspections. In these situations they should leave brake inspections/replacement to licensed professionals, and not guess what may be wrong or required.
Brake fluid in DOT3 & 4 should be bled once a year. Owners should understand the difference between ABS and standard disc braking and associated fluids.
In closing, I would like to state a new set of pads and rotors and caliper inspection with bleeding will give you the best overall results.
Do not take chances with your brakes, have them inspected frequently.
 
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tjkj2002

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Lots of crap in that web page,some is valid but most is crap.

1st it's not the '60's anymore and brake pads do not "outgas" like older pads.The temps required to make modern pads "outgas" is far beyond what the system can handle and will boil the brake fluid and melt any aluminum caliper/mounts in seconds.

2nd water in the brake fluid is not a concern anymore as most modern DOT 3/4 brake fluids have twice as high boiling points then brake fluid from the '80's and the amount of water needed to drastically reduce the boiling point is very high,much more then 3% nowdays.The biggest concern today is corrosion(not caused by water) that naturally occures when brake fluid and internals of ABS components are in contact for a long time.This is measured in copper content,when the copper content is 200ppm or greater it's time to flush the brake fluid.

3rd there are 2 forms of a "warped" rotor,1 is stated in that web page where pad material is melted on the rotor but is more commonly known as "hot spotting" and can not be turned,very easy to spot as you will see black "spots" on the rotor surface.The other is when the actual rotor actually warps beyond the max runout spec,and yes metal can actually warp when subjected to high heat then cooled often without material transfer in a friction type application like brakes.There is alot of vehicles out there that you must use a "on the car" brake lathe or you will get a shaking pedal/steering wheel,the KJ is not one of those vehicles.


4th is a "soft" brake pedal can be caused by much more then boiled brake fluid,more so if you have rear drums.

Oh and lastly your never "top off" the brake fluid level,this leads to very costly brake repairs if done.If you have a noticable reduction in brake fluid level between oil changes you have a leak,plain and simple as that much fluid loss is hundreds the amount that naturally will leak from a brake system through seals over time and I mean a long time as in years(10+).
 
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Cafe Red

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Okay, I have a question about brakes and "brake juddering".
My 05 Liberty (80,000 miles +)has experienced this rattle when brakes are applied. It wasn't all the time till recently. I have replaced pads at both ends and, at the direction of my mechanic, replaced the front rotors. Now the vibration seems to be all the time. At first I thought it might be worn front shocks,as I still have the originals. Someone had suggested that this juddering is normal for the ABS on this year. I really don't feel it in the brake pedal, but this morning I felt it in the floor. My wife drives the Liberty 90% of the time and I know she is ******* brakes. I'm planning a 600 mile trip in June and will be replacing tires before. Is the juddering normal for my Liberty?
 

tjkj2002

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Okay, I have a question about brakes and "brake juddering".
My 05 Liberty (80,000 miles +)has experienced this rattle when brakes are applied. It wasn't all the time till recently. I have replaced pads at both ends and, at the direction of my mechanic, replaced the front rotors. Now the vibration seems to be all the time. At first I thought it might be worn front shocks,as I still have the originals. Someone had suggested that this juddering is normal for the ABS on this year. I really don't feel it in the brake pedal, but this morning I felt it in the floor. My wife drives the Liberty 90% of the time and I know she is ******* brakes. I'm planning a 600 mile trip in June and will be replacing tires before. Is the juddering normal for my Liberty?
No,not normal.

It could be alot of different things like worn tie rod ends,tires,bearings,driveshaft(s),and bad bushings.
 

05kj6spd

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Had a problem like that after changing pads once. Turns out the bolts holding the bracket to the knuckle worked loose. No I didn't forget to tighten them they just worked loose after a little while. Now I check them whenever I am under there.
 

moparman

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Overtightened or unevenly tightened wheels can make a rotor wobble.

Rotors need to stay clean when re-assembling. Use rubber or latex gloves to keep fingerprint oil off of them and/or use brake cleaner on both sides after you handle them.
 

tjkj2002

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Overtightened or unevenly tightened wheels can make a rotor wobble.

Rotors need to stay clean when re-assembling. Use rubber or latex gloves to keep fingerprint oil off of them and/or use brake cleaner on both sides after you handle them.
Under-torquing will only result in the wheel coming off,over-torquing ruins wheel studs.Yes un-evenly torqued lugnuts will actually "warp" the rotors.

You can use brake cleaner to wash off the coating new rotors come with and wash any grease/oils off but then they need to be scrubbed with hot water and soap then rinsed with clean water to wash off the brake cleaner residue.
 

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