Vibrating Brakes

[cherrington17]

and before anyone picks the smartass answer... No, i do not have abs.


my brakes have been vibrating pretty bad lately. i'm pretty sure they are warped, but i've never felt warpage this bad before.... and they are only like 2.5-3 years old.

other then hard braking, which i don't do... what causes this and how is it avoided?

[[ion] C2]

shit quality oem rotors

R1.

[lonnie]

Here's an article I found: Warning long read!

Automotive Braking Systems and Brake Linings and Roughness and Vibration Service and Corrective Procedures
One of the most common brake system customer vehicle performance complaints is brake roughness, pulsation and vibration. As common as this complaint is very few people, including many service technicians, actually understand the true cause of it and what to do to correct it permanently. This leads to misdiagnosis, unnecessary repairs and parts replaced and the likely re-occurrence of the problem a short time later. Brake roughness can be defined as vibration that is felt in the steering wheel, brake pedal and/or seat during vehicle braking. This does not include the normal pulsation that occurs when anti-lock brakes are activated during a panic stop or when on wet, snow or ice covered roads, which can activate the anti-lock brakes.
What typically happens is the customer experiences this type of vibration and pulsation and thinks something is wrong with their brakes and then takes their vehicle into a repair facility. The customer explains the problem and the repair facility technician or service writer either takes the vehicle out for a test drive to confirm the symptoms or pulls it into the shop and starts right in on the brakes. Then they come out to the customer and inform them that their brake rotors are "warped" and they need new rotors and pads (and sometimes hubs), or they can machine the rotors on their bench lathe if there is enough rotor material remaining to meet the manufacturers minimum thickness requirements.
The problem with this diagnosis and repair procedure is that first of all is that brake rotors do not warp. The second problem is that replacing a brake rotor with a new brake rotor or machining the rotor on a bench lathe will only fix the problem temporary. The problem will almost always re-occur after a period of time, thus necessitating further repairs. Brake rotor disc thickness variation or excessive lateral runout, as well as drums that are out of round can cause vibrations and pulsations in the brake pedal and/or steering wheel. Brake lining material transfer onto the rotor can also have an effect on this as well.
Here's what really occurs: all brake rotors and hubs have an associated Lateral Runout (LRO). LRO occurs when two axes are not parallel to each other, such as the axes of the rotor and the hub or the spindle and the rotor/hub. LRO may be caused by manufacturing tolerances, improperly torqued wheel nuts (uneven or excessive torque), corrosion between the brake rotor and the hub, hub with excessive runout, worn or improperly adjusted wheel bearings or any damage or wear. This is what is commonly referred to as "warped" rotors. These so called "warped" rotors do not in and of themselves cause the vibrations and pulsations. Any machined component, such as brake rotors and hubs, are going to have manufacturing tolerances, which include runout. Typical original equipment new rotor runout specifications are in the range of 0.0015-0.002 in. while low quality aftermarket rotors can be significantly higher. In addition to excessive manufacturing tolerances, cheap, low quality aftermarket rotors can have increased impurities and porosity in the metallurgy. I recommend using either the OEM rotors or a high quality aftermarket rotor.
New rotors and hubs are machined to precision tolerances from the auto manufacturers. Aftermarket rotors and hubs are usually not machined to the same tolerances, as the aftermarket manufacturers do not know the OEM specifications, although some are much better than others. Auto manufacturers will either match mount the rotor and hubs or machine the rotor on the hub unit as an assembly. Match mounting is matching up the low spot on the brake rotor with the high spot on the hub. This match mounting process minimizes the runout of the assembled components, but is only a production process. A service technician cannot effectively determine where the high and low spots are in order to match mount the components. Machining the rotor on the hub (and/or spindle) with the proper on-vehicle machining equipment is the very best method and almost completely eliminates runout. But, if they do not effectively prevent rust and corrosion in the joint, over a period of time it will induce runout and eventually brake roughness.
What can occur over a period of time is that whatever runout is in the system coupled with improperly torqued wheel nuts and/or misadjusted or loose wheel bearings and rust and corrosion forming between the rotor and hub surface leads to increases in runout. As you drive your vehicle without using the brakes, such as on the highway, every rotation of the rotor high spot or multiple high spots contacts your brake linings in the caliper, even when you are not using the brakes and wears the high spot or multiple high spots off the rotor which causes a thin spot or multiple thin spots. Over a period of time this repeated process causes what is called Disc Thickness Variation (DTV). DTV is when the rotor thickness is not the same all the way around the rotor. DTV is typically caused by lateral runout. DTV can only be measured with very specialized laboratory testing equipment or with special on vehicle capacitance probes.
When you apply your brakes, and a brake rotor has DTV, the thick and thin spots on the rotor cause the brake pads to move in and out. This in-and-out pad motion causes increases and decreases in brake system pressure, which the driver can feel in the brake pedal. This in-and-out pad motion causes a varying brake force, which is passed to the steering wheel. As the rotor gets hot, it is much more likely to increase thickness variation, thus increasing pedal pulsations as well as steering wheel and other vehicle vibrations. This phenomenon is what many technicians refer to as "warping", however they actually think the rotor warped and needs replacement.
Typical acceptable values for DTV are around 0.0004 in. That's 4 ten thousandths of an inch! As DTV increases beyond 0.0004 in., brake pedal, steering wheel and vehicle vibrations and pulsations will almost always occur.
Replacing a rotor with excessive DTV with another new rotor will only correct the problem temporarily, because eventually the associated LRO with the new rotor will lead to DTV over a period of time, and the problem repeats itself all over again. Machining a rotor with excessive DTV on a bench lathe will only temporarily correct the problem because the rotor is being machined true to the bench lathes spindle and not the spindle on the car, plus the spindle on the bench lathe has its own runout.
The correct method is to machine the brake rotor on the vehicle using an on-vehicle brake lathe. For applications where the rotor is separate from the hub (loose rotor) make certain that both surfaces are free of rust and corrosion and be sure to put a thin layer of nickel anti-seize on the mating surfaces. This will prevent rust induced increases in LRO over a period of time. Rust can form in-between the mating surfaces and exert tremendous forces which will cause increases in tension of the wheel studs and resulting clamp load variation which creates LRO. The LRO will then eventually lead to DTV, brake roughness and vibration. For vehicles with adjustable wheel bearings, be certain to properly adjust the bearing preload prior to machining the rotor.
Brake drums still must be machined on bench lathes as there is no method to machine a drum on-vehicle. Drum brake systems are less sensitive in terms of tolerancing that can cause vibrations and pulsations. Most newer model vehicles these days have 4-wheel disc brake systems. Both front and rear rotors can be machined on-vehicle. Note that I recommend machining new rotors on vehicle as well. That way you can be 100% assured that the entire assembly (rotor, hub and spindle) is a matched and perfectly machined rotating assembly. In addition, make sure the caliper slides freely on the caliper pins or slide mechanism, which will minimize off-brake contact of the brake pads with the rotor.
The on-vehicle brake rotor machining equipment that I recommend which performs the absolute best job is the Pro-Cut On-Vehicle Brake Lathe. It is simply the absolute best on-vehicle brake lathe on the market; the competition doesn't even come close to the results achieved with the Pro-Cut. The Pro-Cut is recommended and approved by Ford, GM and Daimler-Chrysler as well as many other car companies.
I have measured finished LRO values of less than 0.0005 in. with the Pro-Cut, which is less than the tolerances on new rotors. In addition the Pro-Cut uses special cutting bits that produce the proper non-directional micro-finish. The Pro-Cut lathe attaches to the hub and is computerized in order to measure runout of the entire system automatically and compensate for it prior to machining so that a perfect cut is achieved every time. Do not allow a caliper mounted brake lathe to be used on your vehicle. Caliper mounted brake lathes mount on the caliper mounts which are machined in different planes with different cutting tools, therefore a few thousandths difference at the caliper mount will produce a finished machined rotor with runout machined in which will eventually lead to DTV and brake roughness.
Now you know what to do next time a repair facility or anyone else tells you your brake rotors are warped. You can explain to them that brake rotors do not warp and that you want your rotors machined with a Pro-Cut On Vehicle Brake Lathe. If they don't have one then call around to find a facility that has one, or contact Pro-Cut directly at 1-800-543-6618 and they will tell you where your nearest service center is that has a Pro-Cut

[pawzbear]

wtf is all that stuff? ^^^

Just resurface your rotors but they may need replacing depending on how thick they are. 2-3 years, youre due for that. cmon now cherry! jeeeezzz. Its basic maintainance and will happen regardless over time... and only put quality rotors on it. I always had Raybestos rotors and ceramic pads on mine and never had a problem. They dont cost a fortune either, and their 'parts plus raybestos' line is even cheaper and still good quality.

thats a bunch of bs crap there Lonnie, they just want to brainwash and sell. Rotor resurfacing is no big deal, we charge $41 for two rotors, theyre just making the process sound way too fancy.. lmao it cracks me up.

[lonnie]

Originally Posted by pawzbear

wtf is all that stuff? ^^^

Just resurface your rotors but they may need replacing depending on how thick they are. 2-3 years, youre due for that. cmon now cherry! jeeeezzz. Its basic maintainance and will happen regardless over time... and only put quality rotors on it. I always had Raybestos rotors and ceramic pads on mine and never had a problem. They dont cost a fortune either, and their 'parts plus raybestos' line is even cheaper and still good quality.

thats a bunch of bs crap there Lonnie, they just want to brainwash and sell. Rotor resurfacing is no big deal, we charge $41 for two rotors, theyre just making the process sound way too fancy.. lmao it cracks me up.

I said it was an article I found. I will say that I don't believe half the crap these auto shops do is necessary at all. Its cheaper to replace both rotors then to resurface them. I paid less then 40 bucks for new rotors, haven't had a problem yet...Knock on wood! As soon as he takes them in and ask to resurface the rotors they'll think of a million other things to do to them. Just to avoid doing a 40 dollar job. I shouldn't have included the last part cause I don't want that to come across like that, only showing other causes.

[[ion] C2]

Originally Posted by lonnie

brake rotors do not warp.

Eliminates all credibility of the article. Epic failure on their part.

[cherrington17]

use only quality parts, eh? i replaced the oem with bendix. (pads, rotors) now what?

if they get bad enough, i might consider r1....

[super white alero1]

WTF is that? A how-to for overhauling the entire brake system? Paws nailed it. Change your rotor far cheaper and longer lasting.

[cherrington17]

if i decided to get new brakes....

i know ion posted this http://store.r1concepts.com/Items/co...10?sck=7251907

for the r1concept rotors... not that i'd mind changing, but i definitely do NOT need rear rotors. (i have drums) anyone know any other good places to order them from?

granted, this will be sometime down the line, just looking for sellers.

[[ion] C2]

You can buy just fronts from them.

[Cliff8928]

Originally Posted by [ion] C2

Eliminates all credibility of the article. Epic failure on their part.

They can warp if the wheels aren't torqued correctly. However that article is basically right. At the first signs of vibration if you make a HARD stop, usually you can get the vibration to go away. Sometimes you can get deposits of pad material on your rotor and/or hot spots, etc.. depending on how you drive.

[lonnie]

Originally Posted by super white alero1

WTF is that? A how-to for overhauling the entire brake system? Paws nailed it. Change your rotor far cheaper and longer lasting.

Read again, I said change the rotor she said to get them resurfaced. Next time read the article then you would know what it was about!

[freeze12]

Get "Napa" premium rotors as they have a lifetime warranty.

[cherrington17]

well... i think i found my problem....

what would cause degeneration like that in only 3 years?? and i've always heard bendix is good stuff... wtf. if i'm going to be having this kinda breakdown, i'll just buy the cheap shit and replace it every couple years!






not happy with these brakes at all... and even my caliper is a little rusted...

[freeze12]

3 years..Your lucyk as I have to replace rotors every year or so.If You get the cheap Chinese Rotors (around $18.00) my price,they will look like that after a year.Also use ceramic pads as the metallic & high perf. pads are brutal on the rotors.Go to Rock Auto on the net & they have Monroe Ceramic pads with a $20.00 rebate.

[Bmorezcmunee]

are both the pad wearing evenly? if not the caliper could be bad. other than that...alero's are heavy in the front. most of the stopping is happening there. invest in premium rotors and pads

[cherrington17]

those were premium rotors and pads!

both pads are shown.. besides the one on the floor, starting to fall apart, i'd say the thickness is about even.