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I did some searching, came across this:
From the Brake FAQ stickies:
***********************************************************
While braking, you feel a pulsation or strong vibration in the pedal.
-Most often, this is cause by warped rotors. You can either replace the rotors or have then turned. If you just recently had new rotors installed, turn them. If you are at the end of your pad cycle, get new ones.
-But that is not always the case. Rotors are know to have pad build-up which can cause pulsation. This link contains information on brake pad build-up and other useful braking facts.
************************************************************
I think rotor warp is my problem. I have a lot of pedal feedback when braking, the harder I brake the more vibration and feedback I can feel through the brake pedal.
My question is about diagnosing. How do I know which rotor it is? Is there a way to diagnose while they are on the car?
MUST SELL - ECM computer new for a 98 V6 mtx + pats
Now trolling in a Red Nissan 4 x 4
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On my warped rotors and others I have seen you can actually see pad prints on the rotor. If you see these prints that is what is causing your pulsing. Most likely it is both of the fronts.
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just thought i would add my perspective, sorry for the length, though take it for what it is worth - not to mention i concider myself a "modern jack-ass" so i maybe way off but this is what was introduced to me...
my father claims he has been using disk brakes since they came out (about early/mid 50's i think). ever since he had a car equipt with them, he used to do all of his own work and until the 70's came around (or when he was even more lazy) he finaially let someone work on his car including brakes. ever since he trusted someone with his disk brake system, every few years a mechanic would come up with, "oh your rotors are getting warped we need to "turn" them". my father would refuse claiming that turning rotors was a stupid idea and weaken rotors of you take a chunk off to aquire a "clean and level surface". he claims that it is basically a scam in a way because if you get into this habbit of "turning" rotors then eventually you would have to buy new ones over time after taking a chunk off regularly. when a mechanic says that your rotors are "warped" that is not necessarily a bad thing (this is all what i have been taught, dont hate me if i am wrong). as long as you change your pads when they are toast, a warped rotor will allow the pad to shape to the rotor after proper brake-in period; eliminating shutter under hard braking.
with my fathers knowledge in mind, i have used his car that he currently uses as a daily driver, 95' saab 9000 aero w/ 240,000 miles, and the brakes feel terrible (not pulsating but lack of feel and feel exactly like the are not assisted by power) but they work! and work well! you just need to push your foot down hard (and pedal travel is same as it ever was). when he takes his car in to the dealer for oil change or whatnot occasionally a technition will say, "geeze your rotors look awful you need to buy new ones or have the rotors turned," and the reply always comes out, "i have been using disk brakes since 1950-whatever and i have never ever had any rotors turned or replaced EVER and never have had a braking problem ever..."; contradicting basically every mechanic's rule of thumb.
now i dont necessarily agree with my father, but i think he has a small point that should be adressed. i recently bought new rotors for me car (maybe 15,000 miles ago) and the only reason i needed to have this done was because the previous owner adimently turned the rotors regularly until it came to the point they were starting to crack/crumble because the rotors were so thin and weak.
like i said, i am confused but compelled to the argument that my father, MIT grad (in other words a major geek), has never had the need turn or replace a rotor ever in the 50 odd years he has been using them. ALSO i find it amazing after driving a saab w/ origonal rotors that have almost 240k miles on them and the brakes work just fine; and your leg gets a fine work out too!
-a
koni kit - hpp rstb
camber/plates - cf (yikes!)
polyroll resistors - TCA's
WR headers/ypipe -TB hiflow cat
SFC's - XCal2
-dreaming of 3L-
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If the rotors are pulsing and you just change the pads then it will start pulsing again soon. If it has never pulsed I could see how just changing pads could result in still smooth braking the pads would just bed to the rotor the way it was. It just seems like a better idea to start with a fresh smooth surface on both. I would be a little scared to be driving on rotors that have seen 240k miles. They must be past the min thickness for the disc just from wear. Who ever was turning your cars rotors to the point they couldn't handle the braking definetly went past the min thickness. It is quite scarey how some people handle there brakes. The problem is some rotor pad combinations are prone to warping but if you find the right combination you don't end up with problems. The stoptech article in the sticky is good information and what I have seen on some rotors.
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if you want i could go outside and take a picture of the brakes (even though coverd by wheels). they certianly dont look like the result of 240K miles worth of city driving. i have been driving that car all week while svt gets new suspension. the whole car runs fantastic, and my brother and myself both agree that after 240k miles the entire car is just broken in; it has never run this well in its long and hard life full of punishing roads in the north east and many burnouts. besides from the fact that the pedal has horrible feel much like non-power brakes and to get the preassure on requires heavy footwork, they work very well. it brakes hard in a straight line and you never ever hear a squeek, squeel, hum, grumbling or anything; they just work. i am no long turning my rotors to see if the theory is actually true becuase it does seem plausable to me.
at more then one dealer i have asked mechanics about the "theory" of turning rotors and all said i was BSing. also when i explain just the one example about the 9000's rotor longevity i would consistantly get the response, "oh well thats a saab, its not a ford".
also my rotors started to crack/crumble after 40k miles i put on after i recieved the car. the privious owners turned the rotors two or three times before i had a chance to use them.
koni kit - hpp rstb
camber/plates - cf (yikes!)
polyroll resistors - TCA's
WR headers/ypipe -TB hiflow cat
SFC's - XCal2
-dreaming of 3L-
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Posts: 5,621
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Originally posted by mean'tour:
My question is about diagnosing. How do I know which rotor it is? Is there a way to diagnose while they are on the car?
Well, I replaced mine twice within the last 6 months - first it was KVR cross/drilled and then FSVT ones - and I was told - including all the Brakes Forum gurus - that u never replace one but always a pair...
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Hard-core CEG'er
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Hard-core CEG'er
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Originally posted by mean'tour:
I did some searching, came across this:
From the Brake FAQ stickies:
***********************************************************
While braking, you feel a pulsation or strong vibration in the pedal.
-Most often, this is cause by warped rotors. You can either replace the rotors or have then turned. If you just recently had new rotors installed, turn them. If you are at the end of your pad cycle, get new ones.
-But that is not always the case. Rotors are know to have pad build-up which can cause pulsation. This link contains information on brake pad build-up and other useful braking facts.
************************************************************
I think rotor warp is my problem. I have a lot of pedal feedback when braking, the harder I brake the more vibration and feedback I can feel through the brake pedal.
My question is about diagnosing. How do I know which rotor it is? Is there a way to diagnose while they are on the car?
Since this thread was hijacked, I quoted the original question.
It is proper to service rotors in axle pairs. That is both fronts or both rears.
You can pin down if the problem is from the front or rear by braking with the parking brake (under controlled conditions of course). If you still have the vibration/pounding when the park brake is applied, rears are bad. The fronts may be as well, but you can't isolate them. It is very uncommon to be both front and rear, but possible. If the braking is smooth when applying the park brake, the problem is with the front brakes.
Sometimes you can tell based on how you feel the vibration. If the vibration is felt strongly in the steering wheel, it is the front brakes. If the vibration is more strongly felt in the seat, the vibration is probably from the rear.
Some cars are just plain rougher on rotors than others. Most of the time, rotors can be machined multiple times before they need to be replaced. Some cars, especially if they have an agressive pad, wear out rotors nearly as often as they wear out pads.
Part of the judgement on if a rotor should be machined or not revolves on the remaining thickness of the rotor. They should always be measured before judging if they should be machined or not. If they will clean up with a light cut and there is plenty of material remaining, it makes sense to do so. If they will end up close to or under minimum thickness, they should be replaced.
In many cases, a used rotor that has a light cut is better than a new rotor because it has gone through many heat cycles and will be more stable.
Jim Johnson
98 SVT
03 Escape Limited
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Hard-core CEG'er
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Originally posted by 111R:
just thought i would add my perspective, sorry for the length, though take it for what it is worth - not to mention i concider myself a "modern jack-ass" so i maybe way off but this is what was introduced to me...
my father claims he has been using disk brakes since they came out (about early/mid 50's i think). ever since he had a car equipt with them, he used to do all of his own work and until the 70's came around (or when he was even more lazy) he finaially let someone work on his car including brakes. ever since he trusted someone with his disk brake system, every few years a mechanic would come up with, "oh your rotors are getting warped we need to "turn" them". my father would refuse claiming that turning rotors was a stupid idea and weaken rotors of you take a chunk off to aquire a "clean and level surface". he claims that it is basically a scam in a way because if you get into this habbit of "turning" rotors then eventually you would have to buy new ones over time after taking a chunk off regularly. when a mechanic says that your rotors are "warped" that is not necessarily a bad thing (this is all what i have been taught, dont hate me if i am wrong). as long as you change your pads when they are toast, a warped rotor will allow the pad to shape to the rotor after proper brake-in period; eliminating shutter under hard braking.
with my fathers knowledge in mind, i have used his car that he currently uses as a daily driver, 95' saab 9000 aero w/ 240,000 miles, and the brakes feel terrible (not pulsating but lack of feel and feel exactly like the are not assisted by power) but they work! and work well! you just need to push your foot down hard (and pedal travel is same as it ever was). when he takes his car in to the dealer for oil change or whatnot occasionally a technition will say, "geeze your rotors look awful you need to buy new ones or have the rotors turned," and the reply always comes out, "i have been using disk brakes since 1950-whatever and i have never ever had any rotors turned or replaced EVER and never have had a braking problem ever..."; contradicting basically every mechanic's rule of thumb.
now i dont necessarily agree with my father, but i think he has a small point that should be adressed. i recently bought new rotors for me car (maybe 15,000 miles ago) and the only reason i needed to have this done was because the previous owner adimently turned the rotors regularly until it came to the point they were starting to crack/crumble because the rotors were so thin and weak.
like i said, i am confused but compelled to the argument that my father, MIT grad (in other words a major geek), has never had the need turn or replace a rotor ever in the 50 odd years he has been using them. ALSO i find it amazing after driving a saab w/ origonal rotors that have almost 240k miles on them and the brakes work just fine; and your leg gets a fine work out too!
-a
I don't know where to start. You should have started a new thread.
There were a lot of things that I didn't agree with my dad about too. They seemed to make sense to him, but not to me.
When it comes to machining rotors, he has a lot to learn. Machining rotors is a routine practice when replacing pads on most cars. Many european car makes do not recommend machining rotors. Rather they say to install new pads on old rotors and replace the rotors when they wear too thin or if they warp or get hot spots. They use soft rotors and very agressive pads (very abrasive and very hard).
Other than on those car makes that don't recommend machining rotors, it has become routine for good reason. Mechanics hate come-backs, and so do customers. Replacing pads without servicing the rotors (called a "pad slap") very often will cause a come back for noise or vibration that could have been prevented by machining the rotors. If it is your own car and you are doing the labor and willing to take the risk, that is another matter. Personally, I don't enjoy doing a job twice, even on my own car.
Rotors don't wear out from being turned too many times. They wear from wear. It sounds like the prior owner was only admiting that he should have replaced them sooner.
By the way, my dad was very smart too. He hade a masters degree in engineering. He was an aircraft engineer. Amoung other things, he was one of the design leaders on the B-70. Perhaps that is part of why he felt that he knew better than the auto engineers.
Jim Johnson
98 SVT
03 Escape Limited
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sorry if i jacked the threat, my bad 
koni kit - hpp rstb
camber/plates - cf (yikes!)
polyroll resistors - TCA's
WR headers/ypipe -TB hiflow cat
SFC's - XCal2
-dreaming of 3L-
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Joined: Jan 2005
Posts: 1,593
Hard-core CEG\'er
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OP
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I narrowed it down to the fronts... I have the caliper off of the side I think is the problem. I'm having some trouble with getting the rotor off though...
Any tips and tricks from the pros? This rotor has been off this year, so it shouldn't be TOO frozen on... Am I missing something?
MUST SELL - ECM computer new for a 98 V6 mtx + pats
Now trolling in a Red Nissan 4 x 4
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