Brake pulsate... I'm stumped!

[sunofogun]

Okay guys, so like a month ago my steering wheel started pulsating when I was braking like a month ago, so I figured I should cut them or replace them soon. Well, I work in a shop so I replaced the front pads and did the shoes and drums in the back about two weeks ago. I was going to cut the rotors later when my boss wasnt at work Well on my test drive, the pulsation was still there and a little more severe than before. Two days ago I put new rotors on, thinking it would fix the problem, it made no change whatsoever! Im pissed! haha My rims are not bent and I just put the tires on maybe 6 months ago. I shook down the front end and its all good. I don't think its the bearings because there is never a sound from my wheels. Could the calipers be hanging up in the piston area? Also, about every other time I do a drum brake job, the drums end up making this clunking noise as they slow down to a stop. I usually clean the drums with solvent and sand down all the surfaces and it goes away. Well, thats not doin the trick on my car! What the heck is going on?

[sunofogun]

Okay here's an update: Today I took all the tires off and notice some weird movement on the balance machine. I put 4 new tires on and theyre still acting weird. The rims dont look bent, maybe they do have some lateral runout though. I also noticed my front upper ball joints have some play. They dont make any noises yet or really affect the steering. I doubt that they are causing the brake shudder, they primarily would affect my steering and handling on a regular basis.

[Oldblueaccord]

Well there several threads about brakes just on this page review them when you can.

I think any loose part will make a shudder when you brake. Make sure the upper arms bolts to the body are tight as well.

As far as the rears are your brakes adjusted all the way to the drum so it just slips on ? You want the E-brake to be nice and tight at 4 clicks.

wp

[Kelvin]

Read this:

http://www.stoptech.com/tech_info/wp...rakedisk.shtml

It's written by Carrol Smith, the guy who wrote "Engineer to win" and "Tune to win" some of the most famous books on setting up a race or street car in the world.

Basically, you're going to need new rotors, by the cheapest ones you can, as long as they're new, and then spend the money on PADS. Buy the best pads you can afford, with the highest maximum operating temperature. Think Axxis Ultimates, or Axxis Metal masters. Maybe Hawk or Greenstuff, but I haven't tried them, but they should both also work. This will avoid uneven pad deposits, thus avoid uneven wear, thus avoid pedal pulsation.

[2ndGenGuy]

Read this:

http://www.stoptech.com/tech_info/wp...rakedisk.shtml

It's written by Carrol Smith, the guy who wrote "Engineer to win" and "Tune to win" some of the most famous books on setting up a race or street car in the world.

Basically, you're going to need new rotors, by the cheapest ones you can, as long as they're new, and then spend the money on PADS. Buy the best pads you can afford, with the highest maximum operating temperature. Think Axxis Ultimates, or Axxis Metal masters. Maybe Hawk or Greenstuff, but I haven't tried them, but they should both also work. This will avoid uneven pad deposits, thus avoid uneven wear, thus avoid pedal pulsation.

Dude, quit it! Stop linking people to this article, and now acting like you're a brake expert because you've read it. You're giving advice for a RACE CAR! RACE CARS only need to get through a single race.

This advice is fine if you don't plan on daily driving your car, and swapping out rotors and pads between races. Cheapo rotors tend to be already AT the minimum service limit when you buy them, they can't be turned and that's typically why cheap rotors suck. They're thinner and can warp and wear out quickly. Again, fine for making it through a few lapping days or race day.

Metallic pads cause HORRIFIC rotor wear compared to ceramics or organics. Add in some cheap-o rotors and you've got a combination for new rotors every few thousand miles... They're also still going to likely leave deposits in the EXACT same manner that a regular pad will if they get hot enough and you come to a complete stop with hot brakes.

In case you didn't read the original problem, he noted that the upper ball joints are loose, and that he already put new rotors on! What do you suggest? He just toss some metallic pads on and call it good? I doubt that will fix the problem.

[sunofogun]

Yeah the pads I put on are ceramic, front and rear. Theyre like 2 weeks old on new cheap rotors. Im wondering if that week or so I drove with the new pads and the old rotors if that was enough to wear the new pads unevenly and ruin them? Oh yeah and I fixed the rear brake problem . I had to loosen the shoes the whole way just to get the drum on and then I adjusted it tight from the back access hole. Now theyre almost too tight! One click on my parking brake! Oh well theyre pep boys brakes so theyll wear down soon enough lol!

[A20A1]

Interesting article, and well worth the read and I'm sure it's true, but there is a point where you have to step back and ask what you know to be true in one area and how you apply that knowledge across the spectrum of automotive parts. Not all parts are created equal, it could be dangerous to assume so. It's not a good idea to suggest anyone buy cheap parts just to prove a point, although this puts "quality = price" in the mix and thats not always true either.

An extreme and odd example: I could sell you a block of the highest quality aluminum with holes drilled in it with a hand drill, and sell it at a cheap price, or sell you a block of aluminum precesion milled into and engine block at a higher price. It's made from the same material but the quality in manufacturinig makes a difference, it's not just the material that counts.

[DBMaster]

My mechanic told me that sometimes worn out front bearings can cause the shuddering. I had it myself. The solution was resurfacing the rotors myself, on the car, with a "Brake-tru" kit and replacing the pads with ceramics from Raybestos (QuietStop). It has been fine for a year and a half now.

http://www.autosupplyco.com/content....d=autosupplyco

[Kelvin]

Interesting article, and well worth the read and I'm sure it's true, but there is a point where you have to step back and ask what you know to be true in one area and how you apply that knowledge across the spectrum of automotive parts. Not all parts are created equal, it could be dangerous to assume so. It's not a good idea to suggest anyone buy cheap parts just to prove a point, although this puts "quality = price" in the mix and thats not always true either.

An extreme and odd example: I could sell you a block of the highest quality aluminum with holes drilled in it with a hand drill, and sell it at a cheap price, or sell you a block of aluminum precesion milled into and engine block at a higher price. It's made from the same material but the quality in manufacturinig makes a difference, it's not just the material that counts.

Thanks. But again, I've never had a problem with $11-15 rotors. Just get good pads, and they'll last a long time, and avoid uneven pad deposits if you bed them correctly.

[86AccordLxi]

Honestly, I have to agree. My autozone blanks on both of my 240s (coupe had axxis metal masters, fastback has hawk hps), have held up with 0 problems.

I put brembo blanks on my accord with some performance friction carbon metallic pads (higher end autozone pads) and after one long spirited drive (and probably turning the car off with my foot on the brake haha) I managed to leave uneven pad deposits and had shuddery BRAND NEW brakes (honda calipers, new fluid, p.f. pads).

Alex

[2ndGenGuy]

Yeah, cheap rotors will stop your car just fine. I don't think that they will be as durable or last as long as a good rotor, but the costs of good rotors is really expensive. This is why people who actually race (not street race), or run lapping days will buy the cheap rotors. They will be destroyed by the end of one race, while a better rotor might have lasted 3 or 4 races. Still, the cheap rotors can be replaced at a lower cost, cheaper than buying an expensive set that will last through multiple races.

Many metallic pads even say on the box: "May cause excessive rotor wear"

[86AccordLxi]

They buy cheap rotors b/c a lot of them have lifetime warranties

That + really abrasive pads = win.

Alex

[2ndGenGuy]

Oh yeah, like those cheap-ass pads that have the lifetime too... Hmm that's not a bad idear.. :-P

[Ichiban]

I posted that link ages ago...somebody didn't search.

https://www.3geez.com/forum/showthread.php?t=58260

Oh and BTW, with my limited knowledge and experience, I DISAGREE with the theory that the brake rotors don't warp. Also, failed bearings most often make noise when turning, and will cause the brakes to "artificially fade". IE the rotor moves with the slop in the bearing to force the pads back and away, and push the caliper pistons back into the body. The result is you having to pump the pedal to take up the clearance before any braking actually happens.

Barring bizzare things like tire issues or broken suspension parts, chances are your rotors are at fault. Buy "better" OEM style replacements. High performance pads and such generally aren't worth it for normal driving. Maybe look at your driving habits as well, I know if I tried on the roads around here I could destroy new rotors in about 10 minutes. Drop a gear and stay off the brakes on hills.

[Kelvin]

with my limited knowledge and experience, I DISAGREE with the theory that the brake rotors don't warp.

Of course you do, you didn't understand what he was talking about. Basically uneven pad deposits from crap pads or overheated good pads can alter the cast iron rotor's surface, chemically. It will change the cast iron into 'cementite', which then spreads basically like rust, somewhat, through the rotor. Cementite is harder and more brittle than cast iron, so if you have UNEVEN pad deposits, this cementite forms UENVENLY, and thus the rotor WEARS unevenly.

[sunofogun]

Guy hates my car: I am gonna try better rotors and a fresh set of pads. That will be the first thing I try. I do use the brakes more than downshifting, cause I'd rather replace my brakes than a clutch! ha One other thing I noticed, my steering has some play I think . I jsut noticed the other day a clink sound when I turn my steering wheel back and forth right near the straight ahead position. Its coming from down near the rack, possibly the joint or the rack itself. i havent had a chance to check it out again. I know the tie rods have no play. This might be part of the problem I dont know.But the pulsation is also in the brake pedal, so its probably brake related/

[guaynabo89]

From personal experience I have noticed that some of those cheap rotors are very poorly cast. Even when turned you could see strange brittle areas on the rotor surface.
Some cheap rotors might be good, but from personal experience there has been some poorly casted cheap rotors and some decent ones.

That surely would need to be taken into consideration.

I agree that higher heat range pads will ultimately keep your rotors from warping. (not pad deposits) Case in point, My wifes 6th gen cord was constantly warping rotors. (she likes to go fast and is real hard on her brakes) I upgraded to AEM pads. She still managed to warp the rotors again but greatly increased the time they were not warped. Now these rotors were turned 3 times, (not at the same time) and I also used some emery cloth coarse sandpaper to take the glaze off the pads. Each time I did this the brakes were perfect again for another 6 months or so till they warped again.

So from my experience my rotors did warp and were able to be resurfaced with no vibrations afterwards. Im not doubting that pad deposits wouldnt cause pulsating brakes but that its not a fact for every single time.



Back to the original question

Dude you need to go back and double check everything that rotates basicly. I mean have you ever hiit the bottom of the car on a curb or such? I figure if you wacked one of your driveshafet it might cause that.

Go back and chec wheels, rotors, bearings cv axels.

As for the drum klicking issue. Did you try lubing up the parts of the brake shoes that slide back and forth that touch the backing plate of the drum? (where the cylinder is) I could also see if they were adjusted wrong and too loose making a clicking sound.

for the rack thing check the bushings that hold it to the body and jack the front of the car and turn the wheels back and forth slightly to see if the play is in the rack.

[Kelvin]

Case in point, My wifes 6th gen cord was constantly warping rotors. (she likes to go fast and is real hard on her brakes) I upgraded to AEM pads. She still managed to warp the rotors again but greatly increased the time they were not warped. Now these rotors were turned 3 times, (not at the same time) and I also used some emery cloth coarse sandpaper to take the glaze off the pads. Each time I did this the brakes were perfect again for another 6 months or so till they warped again.

That's because they were never warped. What happened, was that your wife maybe braked really hard, and let the pads cook onto the rotor. This uneven pad deposit will cause CEMENTITE. Cementite.

"Regardless of pad composition, if both disc and pad are not properly broken in, material transfer between the two materials can take place in a random fashion - resulting is uneven deposits and vibration under braking. Similarly, even if the brakes are properly broken, if, when they are very hot or following a single long stop from high speed, the brakes are kept applied after the vehicle comes to a complete stop it is possible to leave a telltale deposit behind that looks like the outline of a pad. This kind of deposit is called pad imprinting and looks like the pad was inked for printing like a stamp and then set on the disc face. It is possible to see the perfect outline of the pad on the disc. (FIGURE 5)

It gets worse. Cast iron is an alloy of iron and silicon in solution interspersed with particles of carbon. At elevated temperatures, inclusions of carbides begin to form in the matrix. In the case of the brake disk, any uneven deposits - standing proud of the disc surface - become hotter than the surrounding metal. Every time that the leading edge of one of the deposits rotates into contact with the pad, the local temperature increases. When this local temperature reaches around 1200 or 1300 degrees F. the cast iron under the deposit begins to transform into cementite (an iron carbide in which three atoms of iron combine with one atom of carbon). Cementite is very hard, very abrasive and is a poor heat sink. If severe use continues the system will enter a self-defeating spiral - the amount and depth of the cementite increases with increasing temperature and so does the brake roughness. Drat!"

So from my experience my rotors did warp and were able to be resurfaced with no vibrations afterwards.

Yes, but only for a short time period. You've effectively sliced off some of the rotor's surface, making it 'true' again, but the problem is you have sections of 'cementite' would still exist on that rotor, and after a short time period, the 'pulsating brake pedal' would reappear again, like you said it did.


Basically, everything you've said concides perfectly what Mr. Smith's braking article. I have had ZERO pedal pulsation on all three of my cars for the past 3-4 years, after switching to fresh, cheap rotors and high quality pads with a high maximum operating temperature.

[LX-incredible]

All hail the brake lord

[2ndGenGuy]

All hail the brake lord

Yess... I am wrong in my ways. Cast iron can't warp. Brake pads can't leave deposits without converting cast iron to cementite.

Can you forgive me oh brake lord.

[Kelvin]

Sure. The best thing is, when you adopt the ways of lord Carroll Smith, you too, will become a brake lord, and rise above the masses of ignorance and old wives tales. Just kneel before me and say "all thy brake rotors in all thy lands shall not ever warp; if any shall speak of warpage, inform them of thy uneven pad deposits".

[MessyHonda]

Sure. The best thing is, when you adopt the ways of lord Carroll Smith, you too, will become a brake lord, and rise above the masses of ignorance and old wives tales. Just kneel before me and say "all thy brake rotors in all thy lands shall not ever warp; if any shall speak of warpage, inform them of thy uneven pad deposits".

baby 3geezus> you

[Ls1-Inside]

Yess... I am wrong in my ways. Cast iron can't warp. Brake pads can't leave deposits without converting cast iron to cementite.
Can you forgive me oh brake lord.

Yeah - I agree... it is possible to have vibrations from unevenly deposited pad material w/o creating cementite... Especially considering most braking conditions don't heat the rotor up so much as to chemically change the molecular composition of the rotor...

When i bought my car, i had slight vibrations when braking from higher speeds... I posted about it on CorvetteForum. It was recommended that I do a series of long hard braking then drive around to cool the rotors. Sure enough - after that, the shuddering went away... The reason was the previous owner never used the brakes that hard, and never followed in a proper bed-in procedure for the pads/rotors. So over time a gradual build up of unevenly deposited pad material was on the rotor. That Doesn't mean it was BAKED IN, just deposited...

Kelvin - do YOU understand how brakes work? A properly functioning rotor should have a layer of PAD material deposited on it, bedded into the rotor. During proper operating temperature that material uses adhesive friction against the pad... almost sticking to the pad, then breaking away... creating a good bite. When you have an even layer of pad material you get optimal braking performance. That Pad material is SUPPOSED to be on the rotor, and will NOT turn into cementite. If your pads bedded in unevenly, then you will have an uneven layer of pad material on the rotor causing a slight vibration. You can correct this by heating up the brakes and rebedding them in with the correct procedure. Extreme overheating of the rotor however, will create the cementite and 'temper' the metal...

I've done it, it works, people i know have done it... people on corvette forum do it all the time... it is possible... the Pad Material on the rotor doesn't automatically mean you're fucked... unless you get the rotors heated up to an obscene temperature which is highly unlikely on daily driver applications.
In addition Rotors can and DO warp... just ask the people who have washed their cars right after some "Spirited Driving/Braking" or rally cars who hit puddles when at extreme braking temperatures. Anytime tremendous temperature changes happen, the metals in a rotor can and will warp... 2ndGenGuy is right... i'm sorry - rotors warp... and improperly bedded in rotors can be corrected...

-Dan

[Ls1-Inside]

May i point out the "EXCESSIVE HEAT" Portion to be critical. A rotor that has not been excessively heated will have a layer of pad material on it, that can move around... you can BED in the rotor, and relocate the pad material such that it is evenly distributed on the rotor... thus correcting the shuddering problem W/O replacing the rotor, AND w/o Creating Cementite ruining the rotor!

Do Not over heat your brakes!

Vibrations can be corrected as long as you have not overheated your brakes!

Rotors warp, it's physics... metal cools at different rates and changes shape. Obviously this guy has never washed his car... because People have ruined their rotors with water on a very hot rotor...

-Dan

[2oodoor]

who's your daddy who's your daddy.... lmao

un freakin believable......

Ok, the grade rotors you use and how well they work/last also depends on the type of vehicle. There may be poorley cast rotors for a certain type vehicle that the same brand would be fine on another vehicle.
You can warp rotors by torquing the wheels (lugnuts) incorrectley.
Cross drilled rotors recover best from heated stops. Rotors in racing applications get cherry red hot, and need to be made of a material that can retain it's shape to very close tolorances.
Pad choice is up to you, ultimately the best choice is whatever is as close to OEM as possible, If your car came with carbon metalics, use them. ANY other choices with pads or rotors involving aftermarket products or how to use them CAN NOT be held to a protocol of application that can be TAUGHT as FACT. Only opinions, shared experiences, and recommendations are usable communications for these subjects.
That said, we need to remain open minded to others shared experiences (real life) and not try to preach something that was written by someone else and then tell people they don't know what they are talking about when they share non-fictional recollections of factual events to back it up.