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?
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.
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
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.
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.
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...
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.
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.
sorry if i jacked the threat, my bad
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?
Originally posted by The EuroTour:
BFH.
Hum, I'm guessing that means, Big F_ Hammer. Correct?
Correct.
Caliper (and both caliper bolts) is completly off the rotor, then there is nothing else holding it on.
Try some PB Blaster.. soaked two or three times every 15 minutes (optimally, leaving the last one 12 hours over night, then re-applying a 4th time for 15 minutes of soaking) then go at it with the BFH. Since you are replacing it (IF you are) then no worries in that respect.
Ray
when i changed my rotors and pads about a year ago the drivers side was frozen on so bad that even the BFH wouldnt break it loose. we had to drill 2 holes into the center hub of the rotor and then pry it off. i hope you dont have to do that it sucks
Make sure that you use a wire brush to clean the rust off the hub face and then apply some anti-sieze between the hub and rotor, including the area around the center hole so that it comes apart easier next time.
Unless you enjoy the frustration of needing top hit things with big hammers.
Some sort of rust penetrator....and a hammer...if the hammer doesnt work, get a bigger hammer.
Originally posted by posthuman63t:
Some sort of rust penetrator....and a hammer...if the hammer doesnt work, get a bigger hammer.
All right, a hammer it is. I have already soaked and resoaked them with PB Blaster... I'll let it soak overnight again, and then go at it with a hammer.
Thanks !
Originally posted by posthuman63t:
Some sort of rust penetrator....and a hammer...if the hammer doesnt work, get a bigger hammer.
...And if that hammer still doesn't work???
DON'T BEAT ON ROTORS WITH A BFH UNLEES YOU WANT TO REPLACE THE WHEEL BEARING IN A FEW WEEKS
Not smart!
If you need to get it off and some persuasion with a reg ular hammer doesn't work. Don't go pulling out the sledge. You will need to cut the old rotor off with a diegrinder.
Cut down through one whole side of the friction srface and part way through the hat, avoiding cutting trhrough the hub itself. Then insert a chisel into the cut and hammer it in - the rotor will crack easily and you will be able to remove it.
Beating on it will a mallet will Brinnel the wheel bearing sand then a simple brake jobs ends up in a wheel bearing replacement.
Bummer....You really know how to ruin a guys fun
Originally posted by mean'tour:
Originally posted by posthuman63t:
Some sort of rust penetrator....and a hammer...if the hammer doesnt work, get a bigger hammer.
All right, a hammer it is. I have already soaked and resoaked them with PB Blaster... I'll let it soak overnight again, and then go at it with a hammer.
Thanks !
Well I'm half-way there. Passenger's side pulled and replaced. PB B'laster, for about 24 hours- multiple applications and a 1 lb. rubber mallet seemed to do the trick. The driver's side is giving me a little more trouble though.
Thanks for the suggestions.
what stazi said inst always true. i had a rotor that warped badly and i was beating it with a bfh for about 45 minutes till it came off. and that was over two years ago and my wheel bearings are fine. so there is a chance you will need wheel bearings. but maybe you wont.
Well of course don't break a sweat wailing on the rotor with a hammer...A hammer is step 2 when it will not just "pull" off with your hands. Rust penetrator and a whack or two usually will break the rusty bond the rotor has. Give it a half-a$$ed whack and it should come loose. Never use a sledge or similar to try and remove it. It will work eventually, but then you'll have additional repairs, like Stazi said.
When I had a bad wheel bearing we took a sledge to the rotor, soaked it in PB blaster, nothing worked. Next morning I said the heck with trying to get it off in one piece and grabbed the Sawzall and My dremel. Took 4 metal cutting blades but I got 'em off...
Even when the rotor was cracked in two it was still hard to get broken loose...
Heh ask Christine's husband and Brian about my car... took 5 hours to get both rotors off. They were both beating them at the same time with a hammer, and PB blaser, and everything. They eventually kept dremmeling the hub down a tiny bit and beating it, and finally the thing came off, hit the catch pan, and blew dirty brake fluid and rust chunks all over them and everything else.
Originally posted by mean'tour:
Originally posted by mean'tour:
Originally posted by posthuman63t:
Some sort of rust penetrator....and a hammer...if the hammer doesnt work, get a bigger hammer.
All right, a hammer it is. I have already soaked and resoaked them with PB Blaster... I'll let it soak overnight again, and then go at it with a hammer.
Thanks !
Well I'm half-way there. Passenger's side pulled and replaced. PB B'laster, for about 24 hours- multiple applications and a 1 lb. rubber mallet seemed to do the trick. The driver's side is giving me a little more trouble though.
Thanks for the suggestions.
After several hours today I finally got it off. I was hitting at if from beneath/ behind with a regular hammer, then pried the front and back sides apart. Finally got some chunks loose, then some pieces of the backside. Kept hitting at it, and all the time soaking and resoaking with PB Blaster. Finaly got all the braking surface off. Took a drill to the cap, and weakened any cracks. Drilled or hammered at the cracks... Finally the cap came loose. Wow it was an ordeal. See photo, when it was all said and done.
*** NEW PROBLEM***. I can't get the caliper back on with both pads in it. It seems like maybe the brake pedal has been pressed and the inside pad been psuhed in. How do I release the pressure? I opened the bleed and let out some fluid thinking that might release the pressure and let me push the inside pad out, but no luck.
Any suggestions? Once I can get the caliper back on, this project will FINALLY be over... PLEASE HELP ! ! !
Take a clamp or something along those lines to the caliper. You want to loosen up the bleeder screw and then squeeze the piston inwards, so you will have more room to work. Then tighten the bleeder screw back up. This is what I did when I did my brakes, worked great. It may be a tight squeeze even with it opened up but it will work.
Originally posted by 99Mystique ATX:
Take a clamp or something along those lines to the caliper. You want to loosen up the bleeder screw and then squeeze the piston inwards, so you will have more room to work. Then tighten the bleeder screw back up. This is what I did when I did my brakes, worked great. It may be a tight squeeze even with it opened up but it will work.
This is correct.
A common tool to depress the caliper piston is a 6" woodworking "C" clamp. It is best to depress the piston before removing the caliper. You want to push it back evenly. If it get cocked to one side it will bind.
If indeed, someone did press on the brake pedal and extend the piston out too far, that could be another matter. If it has come out too far, I would expect there to be a severe fluid leak from around the piston so since you didn't say anything about that I would guess that you are OK.
If it has been extended too far, all is not lost. It isn't that hard to put back together, but it would be wise to buy a seal kit and replace the seals while it is apart. There are two seals. The boot seal that you can see, and the square cut "O" ring inside the caliper around the piston. Pull the piston out (or blow it out with compressed air with an old brake pad or block of wood to catch it), clean out the bore and piston with brake clean, replace the seals, lubricate well with fresh brake fluid, and reassemble.
To get the piston back into the boot seal, you may need a bent paper clip to help pull back the edge of the seal. Another method is to use compressed air blown gently through the hole where the hose attaches as you move the pistone toward the bore. If you figure out the right airflow and slow movement of the piston insertion, the boot seal will move aside from the air pressure and allow the piston to slide in "like it had eyes".
Originally posted by 99Mystique ATX:
Take a clamp or something along those lines to the caliper. You want to loosen up the bleeder screw and then squeeze the piston inwards, so you will have more room to work. Then tighten the bleeder screw back up. This is what I did when I did my brakes, worked great. It may be a tight squeeze even with it opened up but it will work.
Ok. So I was right, I just wasn't pushing hard enough. Good to know. I will try it out tomorrow.
Thanks for your suggestions. I will update this thread, if you care.
Thanks again !
I'm interested in hearing how you make out...
Make sure you loosen the bleeder screw before compressing the piston. Mine, once the bleeder screw was loose, I could compress them by hand. At least I think thats what I did.
Originally posted by 99Mystique ATX:
I'm interested in hearing how you make out...
Make sure you loosen the bleeder screw before compressing the piston. Mine, once the bleeder screw was loose, I could compress them by hand. At least I think thats what I did.
I already tried that. I had it loosened enough that it was leaking a little bit of fluid, but only from the bleeder. I tried compressing it by hand, but no luck. Will get a clamp tomorrow and give it a whirl.
Thanks again !
YOu don't need to crack the bleeder open. Just use a clamp to compress the piston back.
-Todd
Originally posted by Silver Snake:
YOu don't need to crack the bleeder open. Just use a clamp to compress the piston back.
-Todd
Agreed. Most technicians don't as well.
However I believe that is is better that you do crack open the bleed port. If you have contamination in the fluid or if you push the piston back too quickly, you risk damaging the master cylinder.
I used a big assed C - clamp, or you can just go buy a caliper compressor for like 10-15 bucks.
Originally posted by mean'tour:
Originally posted by 99Mystique ATX:
I'm interested in hearing how you make out...
Make sure you loosen the bleeder screw before compressing the piston. Mine, once the bleeder screw was loose, I could compress them by hand. At least I think thats what I did.
I already tried that. I had it loosened enough that it was leaking a little bit of fluid, but only from the bleeder. I tried compressing it by hand, but no luck. Will get a clamp tomorrow and give it a whirl.
Thanks again !
Got it !!! I got a clamp today, and got it all together! Test will be tomorrow. I need to touch-up my caliper paint and then I'll throw the wheels back on and give it a whirl. I need to throw a little more brake fluid back in though, I lost some as I compressed the piston.
Thanks for all of the help. It did make a difference.
Good to hear!
I know you don't have to open the bleeder screw but if you risk damage otherwise, even if it *usually* isn't a problem why take the chance?? Especially for so little more work...
C clamps work wonders...
Originally posted by mean'tour:
Originally posted by mean'tour:
Originally posted by 99Mystique ATX:
I'm interested in hearing how you make out...
Make sure you loosen the bleeder screw before compressing the piston. Mine, once the bleeder screw was loose, I could compress them by hand. At least I think thats what I did.
I already tried that. I had it loosened enough that it was leaking a little bit of fluid, but only from the bleeder. I tried compressing it by hand, but no luck. Will get a clamp tomorrow and give it a whirl.
Thanks again !
Got it !!! I got a clamp today, and got it all together! Test will be tomorrow. I need to touch-up my caliper paint and then I'll throw the wheels back on and give it a whirl. I need to throw a little more brake fluid back in though, I lost some as I compressed the piston.
Thanks for all of the help. It did make a difference.
I actually didn't get a large enough clamp, so ended up doing compressing it by opening the bleed valve, and pushing really hard with 2 hands.
Originally posted by mean'tour:
Originally posted by mean'tour:
Originally posted by mean'tour:
Originally posted by 99Mystique ATX:
I'm interested in hearing how you make out...
Make sure you loosen the bleeder screw before compressing the piston. Mine, once the bleeder screw was loose, I could compress them by hand. At least I think thats what I did.
I already tried that. I had it loosened enough that it was leaking a little bit of fluid, but only from the bleeder. I tried compressing it by hand, but no luck. Will get a clamp tomorrow and give it a whirl.
Thanks again !
Got it !!! I got a clamp today, and got it all together! Test will be tomorrow. I need to touch-up my caliper paint and then I'll throw the wheels back on and give it a whirl. I need to throw a little more brake fluid back in though, I lost some as I compressed the piston.
Thanks for all of the help. It did make a difference.
I actually didn't get a large enough clamp, so ended up doing compressing it by opening the bleed valve, and pushing really hard with 2 hands.
ALL FINISHED ! I added some Brake fluid and then drove around a little. It was a little scary the first couple of stops as I built up pressure, but after I topped it off again, it is perfect now ! NO VIBRATION ! ! !
I'm so proud of myself ! ha ha
Tomorrow, one last attempt at getting my y-pipe off to change out the oil pan gasket. Then new front and rear roll resistors (stock) and I should be good to go.
I know I'm a little late to the party but a couple thoughts.
Make sure you torque your lugs evenly with a torque wrench. Uneven torquing of the lugs greatly increases the likelyhood of future warped rotors.
This would have been a great time to flush you brake fluid system. There is an FAQ with detailed instructions.
-Andy