brake shudder at high speed

[Cardiobuck]

For some time now I've had an issue with a vibration or shudder in the '07 accord when traveling at highway speeds and the brakes are first applied. By the time I decelerate to 60mph or so the problem is gone. It never happens at 'around town' speeds.

I disassembled, cleaned and lubricated the brakes looking for the source. I found a caliper slide pin on the passenger rear to be frozen--and the inboard pad was unevenly worn. Also the inside surface of the rotor was uneven.

So I replaced the rear rotors and pads, installed new caliper hardware, and re-lubricated the heck out of the caliper slide pins so they move freely. I am disappointed today to find that I still have the same shudder at high speed when first applying the brake. It is less severe but still there. Any ideas on where this is coming from? --there was nothing I could find wrong visibly with the fronts.
Also, I took time to wire brush and clean the hub so the rotor would have a smooth/clean surface to rest against.

 

[morepwr]

Since you have replaced the rear rotors I would check the fronts. I have seen cars shudder at higher speeds due to warped rotors but not really cause the steering wheel to shudder much. Sounds weird but it can happen.

 

[CharBaby]

I think the shudder is coming from the front. And it's the Front Rotors. This isn't something that you can see with the naked eye. And the rotor(s) may not be warped but, there could be heavy brake pad deposits impeded in the rotor(s) surfaces.

 

[tig1]

Replace the front rotors and pads.

 

[Mykl]

My bet would be for uneven pad deposits on the rotors. I'd consider installing new pads and rotors, but the pads might be fine and it's possible that you could turn the rotors if they aren't too old.

 

[anonobomber]

Before spending another penny try rebedding the brakes. In many cases this will fix your braking issue without having to replace parts and should always be tried as a first step: http://www.zeckhausen.com/bedding_in_brakes.htm

 

[tig1]

Originally Posted By: anonobomber
Before spending another penny try rebedding the brakes. In many cases this will fix your braking issue without having to replace parts and should always be tried as a first step: http://www.zeckhausen.com/bedding_in_brakes.htm


That's for new brakes. His front brakes are older and need replacing.

 

[ShotGun429]

You have overheated,and warped Front rotors, Very common. It;s possible to have only 1 hard overheat event on a set of NEW Rotors and they can be ruined. Gregg M.

 

[threeputtpar]

Had the same issues on the A6 for almost 80k miles. A couple of brake jobs and even a new set of tires didn't cure the problem. New control arms, tie rod ends, front CV axles, and wheel bearings and hubs, none of which helped.

I finally got a resolution a couple of weeks ago. Ponied up the money to have my wheels road force balanced on the fine setting and the problem is gone. My dealership is so good they didn't even charge me the $20 that it would have cost. 50% discount because I bought the tires from them.

 

[tig1]

Originally Posted By: ShotGun429
You have overheated,and warped Front rotors, Very common. It;s possible to have only 1 hard overheat event on a set of NEW Rotors and they can be ruined. Gregg M.


Also all disc brake wheels need to have the lug nuts torqued to the proper torque so the rotor has even pressure all the way around the rotor. Most all tire shops don't do this.

 

[RF Overlord]

My buddy has a 2003 Taurus that had bad brake shudder. Turned out to be heavy amounts of pad transfer on the front rotors, because he's one of those people who doesn't brake gently and likes to rush up on things and jam the brakes on at the last minute. Installed new rotors and his brakes are fine now. (for a while...

)

 

[Cardiobuck]

Thanks for the replies.
I have ordered new front rotors/pads. Will install when they arrive & time allows. Hopefully that works.

 

[anonobomber]

Originally Posted By: tig1
Originally Posted By: anonobomber
Before spending another penny try rebedding the brakes. In many cases this will fix your braking issue without having to replace parts and should always be tried as a first step: http://www.zeckhausen.com/bedding_in_brakes.htm


That's for new brakes. His front brakes are older and need replacing.


This works on old brakes too. A lot of times you'll get pad material embedded in the rotors an this can clean it out. I've done it many times in the past when I thought I would have to do work on a brake system and it solved the issue and brought the brakes back to working like new.

 

[The Critic]

The pulsation is almost always caused by disc thickness variation. Most disc thickness variation issues originate from excessive lateral runout.

When you install the new pads and rotors, be sure to clean the hub flange very very well. Use a wire wheel on a drill to really clean the hub flange. Ideally, you should also use a dial indicator to check runout on the installed rotor. The runout needs to be below 0.002", but less is better. With proper indexing, I can usually get most to 0.001" or less.

 

[sxg6]

As a couple of others have said, too much front rotor runout from brake pad deposits on the rotors that can't be seen by the naked eye. Proper brake pad/rotor break-in is critical to help prevent this from happening. Replace or turn your front rotors, and rebed them. If the front pads are worn, replace those as well.


http://www.powerstop.com/what-causes-brake-pulsation/

http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths

 

[The Critic]

Originally Posted By: sxg6
As a couple of others have said, too much front rotor runout from brake pad deposits on the rotors that can't be seen by the naked eye. Proper brake pad/rotor break-in is critical to help prevent this from happening. Replace or turn your front rotors, and rebed them. If the front pads are worn, replace those as well.


http://www.powerstop.com/what-causes-brake-pulsation/

http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths



Rotor runout isn't caused by pad deposits. Rotor runout is caused by improperly tightened lug nuts or rotors that were not properly installed (i.e. not fully cleaning hub flange, not indexing rotors). Disc thickness variation is what causes the issue, and runout is often the root cause. Sometimes, aftermarket pads, certain OE pad materials or certain driving styles will cause the rotors to wear unevenly thus resulting in pulsation issues.

The pad deposit theory seems somewhat believable, but it is a theory that originated from the automotive aftermarket. It is probably responsible for a very low percentage of pedal pulsation complaints.

 

[sxg6]

I disagree, pad deposits on the rotor can cause runout. The links I posted go into more detail on this topic.

 

[SteveSRT8]

Originally Posted By: sxg6
I disagree, pad deposits on the rotor can cause runout. The links I posted go into more detail on this topic.


IME here the deposits are the overwhelming majority of complaints.

Carroll Smith has worked with many OEM's to develop high performance braking systems, he may have forgotten more than most will ever know. Not really very respectful or accurate to label him as a simple "aftermarket" brake guy.

I know the northern climates face extra challenges but down here the runout thing is very rare if anyone knows what they are doing at all...

 

[The Critic]

Originally Posted By: SteveSRT8
Originally Posted By: sxg6
I disagree, pad deposits on the rotor can cause runout. The links I posted go into more detail on this topic.


IME here the deposits are the overwhelming majority of complaints.

Carroll Smith has worked with many OEM's to develop high performance braking systems, he may have forgotten more than most will ever know. Not really very respectful or accurate to label him as a simple "aftermarket" brake guy.

I know the northern climates face extra challenges but down here the runout thing is very rare if anyone knows what they are doing at all...


The fact that he has worked with OEMs as zip to his credibility in my book. I've worked with a number of individuals who claimed association to leaders within an industry, but their individual opinion was often quite far off-base.

Some of these pad deposits are from pad imprints on the rotors. Usually you'll see them from people holding the brakes at a red light after a long hill. It really isn't common on daily drivers, and I think this is a phenomena that is going to be very dependent on the type of driving usage as well as the pad material that is being used. Besides, most pad material isn't aggressive enough to clean off pad deposits from rotors anyway.

The runout issue is quite common from what I've seen. And yes, if the hub-flange isn't cleaned then it will be an issue. Even when it is cleaned, I will often see runout on the edge of the spec - usually 0.0015 or 0.002. So for all practical purposes, it should be "OK" in most situations. But less runout is better, and less runout will usually reduce the likelihood of developing thickness variation over the course of the rotor's lifespan.