Pulsating Brakes

[JBDive]

So I am a huge believer in changing pads on a regular basis, long before they go out, usually just as the chamfer levels out. So I just did this on Thursday, new pads, inspected the rotors and they looked perfect. Prior to changing out the pads my only complaint was a slight squeak on cold pads as well as very hard breaking when they had been sitting or gotten wet from the morning commute and say all day.

New pads, smooth as silk, no issues at all other than these pads are clearly different in stopping than the prior, smoother and less hard grab upfront.

So I'm driving down a long grade this weekend and everything was fine up till they started getting warmed up. Once I had been on the brakes for an extended period I started getting all types of pulsating, pulling, grabbing and vibration as if my rotors were massively warped.

Once I got off the long grade and back to basic driving I have no grabbing, pulsating, etc no matter how hard I apply the brakes.

I really hate to have the rotors trued when I don't feel they need it based on normal driving.

 

[Aztimer2]

Had that same experience, I took my Liberty in to have them trued. Works great now.


Sent from my iPhone using Tapatalk Pro

 

[HoosierJeeper]

Rotors don't warp, it's uneven brake pad deposits. So they probably self cleaned up. If I do a few panic stops with mine, it smooths the rotors out quite a bit.

 

[tjkj2002]

Rotors don't warp, it's uneven brake pad deposits. So they probably self cleaned up. If I do a few panic stops with mine, it smooths the rotors out quite a bit.

Oh yes they do,seen some so bad you can see the wobble on a brake lathe.

Best to replace rotors when you replace the pads,turning rotors just makes them heat up faster since your removing material that it needs to dissipate heat.There cheap enough,in most cases cheaper than a good set of pads.

 

[tommudd]

Yes always change the rotors and pads
With the amount of dirt, rust, etc that you go through/ etc while wearing out a set of pads well worth it

 

[TomB985]

From the sounds of your post, I don't think there's anything wrong with the rotors. This stuck out to me, though:

So I'm driving down a long grade this weekend and everything was fine up till they started getting warmed up. Once I had been on the brakes for an extended period I started getting all types of pulsating, pulling, grabbing and vibration as if my rotors were massively warped.

So the issue happened when you were riding the brakes down a long hill? If so, this is one of the worst things you can do to your brakes, and can make stopping at the end problematic at best as the brakes overheat. This is the whole reason we've got downshift positions in the shifter; the engine is meant for controlling speed down such hills. That way your brakes are fully functional, even at the bottom of the hill, should you need to complete a panic stop. You'll also avoid glazing your pads and prematurely replacing brake parts.

Just my two cents, they really drove this into me when I was learning to drive big trucks. wavey.gif

 

[Tog]

From the sounds of your post, I don't think there's anything wrong with the rotors. This stuck out to me, though:



So the issue happened when you were riding the brakes down a long hill? If so, this is one of the worst things you can do to your brakes, and can make stopping at the end problematic at best as the brakes overheat. This is the whole reason we've got downshift positions in the shifter; the engine is meant for controlling speed down such hills. That way your brakes are fully functional, even at the bottom of the hill, should you need to complete a panic stop. You'll also avoid glazing your pads and prematurely replacing brake parts.

Just my two cents, they really drove this into me when I was learning to drive big trucks. wavey.gif

I agree to a point some of the heavy gradients here in Oz there is no where enough engine braking available with the Auto transmission that you still need to use alot of brake pedal

Sent from my SM-G960F using Tapatalk

 

[JBDive]

Rotors don't warp, it's uneven brake pad deposits. So they probably self cleaned up. If I do a few panic stops with mine, it smooths the rotors out quite a bit.

Terminology, we all know, or should, that what we mean is uneven.

Yeah as I said once they cooled all braking afterwards was and is fine. First braking may have had a bit of bump to it but after that nothing.

Now how to stop that from happening? I can't be coming off ski mountains this winter with these NAPA pads and have them go nuts like this. Last pads didn't, Wagner I think. I like the softer braking of these generally.

 

[JBDive]

From the sounds of your post, I don't think there's anything wrong with the rotors. This stuck out to me, though:



So the issue happened when you were riding the brakes down a long hill? If so, this is one of the worst things you can do to your brakes, and can make stopping at the end problematic at best as the brakes overheat. This is the whole reason we've got downshift positions in the shifter; the engine is meant for controlling speed down such hills. That way your brakes are fully functional, even at the bottom of the hill, should you need to complete a panic stop. You'll also avoid glazing your pads and prematurely replacing brake parts.

Just my two cents, they really drove this into me when I was learning to drive big trucks. wavey.gif

Brakes were pumped as needed during the downhill run, not riding them. Trust me, I have driven that hill and others for 40+ years in a probably a dozen rigs including pickup trucks loaded with wood, furniture and so forth, I know how to come off the hills. There was no need to "downshift" as a few pumps here and there kept me under 60 except for one section.

Prior pads on the same hill just weeks before did not suffer the same effect.

 

[tjkj2002]

Prior pads on the same hill just weeks before did not suffer the same effect.

With old rotors(non-prepped surface) the new pads can not properly "bed in"

 

[tommudd]

With old rotors(non-prepped surface) the new pads can not properly "bed in"

And why we replace pads and rotors
( and then properly seat the new pads in )

 

[wycowboy]

Rotors don't warp, it's uneven brake pad deposits. So they probably self cleaned up. If I do a few panic stops with mine, it smooths the rotors out quite a bit.

Yes they do, lol. I've seen some so bad I wasn't able to true them up and keep them safe to use. Rotors have gotten cheap enough and finding a place to true them, at least here in Sheridan Wyoming, is so hard that I usually buy new ones every brake job now.

 

[JasonJ]

Even if rotors are warped, there are wear patterns engraved into the rotor surface that correspond with the old set of pads- the new pads will get eaten up into this same wear pattern instead of having freshly machined surfaces to mate against.

Rotor and pad life is then reduced significantly, in addition to possibly causing pulsations and noise.

 

[Charlesthe2nd]

Seems like the consensus is to replace pads/rotors every brake job. I was on the fence because my rotors look fine but the pads are at end of life, just over 40k on them. Should the drums be replaced as well?

This is on the same topic but deviating from the original question. I've had an issue with the rear brakes making a squeak when letting off the brake pedal, and when releasing the e-brake. Any ideas on what this could be?

 

[ltd02]

Seems like the consensus is to replace pads/rotors every brake job. I was on the fence because my rotors look fine but the pads are at end of life, just over 40k on them. Should the drums be replaced as well?

This is on the same topic but deviating from the original question. I've had an issue with the rear brakes making a squeak when letting off the brake pedal, and when releasing the e-brake. Any ideas on what this could be?

I still have one vehicle with drums even though my 02 is gone.

I usually just hit the drums with emery cloth or even sandpaper unless you get that rumble in the seat when stopping. They're pretty cheap these days too so wouldn't hurt to change them. After a while you'll where a lip on the edge too. As for the squeak, I had that one time when a wheel cylinder was starting to leak and the shoes got contaminated and another time when there was just a ton of brake dust in there and I needed to relube the contact points where the shoes rub the backing plate. They were struggling to release. Could always be a spring getting lazy too. I change hardware every time I change the shoes.

 

[Charlesthe2nd]

I still have one vehicle with drums even though my 02 is gone.

I usually just hit the drums with emery cloth or even sandpaper unless you get that rumble in the seat when stopping. They're pretty cheap these days too so wouldn't hurt to change them. After a while you'll where a lip on the edge too. As for the squeak, I had that one time when a wheel cylinder was starting to leak and the shoes got contaminated and another time when there was just a ton of brake dust in there and I needed to relube the contact points where the shoes rub the backing plate. They were struggling to release. Could always be a spring getting lazy too. I change hardware every time I change the shoes.

The drums are definitely old school! Have thought about throwing an '03 axle on there but it's not worth the time. I don't mind having the drums though, they never give me any issues (sans the annoying squeak).

I'll be replacing rotors up front and the drums in the rear. Along with a good set of pads and shoes with hardware. Thanks for the direction on what to look for. Hope to do this soon before it gets too cold up here.

 

[JBDive]

And why we replace pads and rotors
( and then properly seat the new pads in )

I have NEVER had pads act in this way and heck no you don't replace rotors when replacing pads, you don't even need to turn them each time. At most a surface prep is needed, nothing more than sanding down the surface to remove any material left by the old pads. Once completed you need to go through a few days of seasoning the pad by normal driving alternating with some fairly aggressive stops. This is the process I have used for 30 years.

This is the first time I have used these NAPA Adaptive One pads and the way they performed with the apparent buildup on the rotor during this downhill drive was something I've not experienced before. Maybe I did not get them seasoned in well enough before the trip. Driving around town ever since has been just fine, normal breaking to hard breaking although as I said before I find these pads do create a far softer breaking.

 

[tommudd]

I have NEVER had pads act in this way and heck no you don't replace rotors when replacing pads, you don't even need to turn them each time. At most a surface prep is needed, nothing more than sanding down the surface to remove any material left by the old pads. Once completed you need to go through a few days of seasoning the pad by normal driving alternating with some fairly aggressive stops. This is the process I have used for 30 years.

This is the first time I have used these NAPA Adaptive One pads and the way they performed with the apparent buildup on the rotor during this downhill drive was something I've not experienced before. Maybe I did not get them seasoned in well enough before the trip. Driving around town ever since has been just fine, normal breaking to hard breaking although as I said before I find these pads do create a far softer breaking.

Myself, Professionally started doing brakes and suspension work in 1972. Been to school , worked for various companies both doing it and management. SO, Been doing it since then off and on .
SO........................the way you do a COMPLETE brake job is all new pads, rotors, hardware, anything else is a slap on quickie. Rotors today are usually so thin to begin with there is nothing to turn.
So while you may have used one method for 30 years for your own rides, well..................

 

[tjkj2002]

I have NEVER had pads act in this way and heck no you don't replace rotors when replacing pads, you don't even need to turn them each time. At most a surface prep is needed, nothing more than sanding down the surface to remove any material left by the old pads. Once completed you need to go through a few days of seasoning the pad by normal driving alternating with some fairly aggressive stops. This is the process I have used for 30 years.

This is the first time I have used these NAPA Adaptive One pads and the way they performed with the apparent buildup on the rotor during this downhill drive was something I've not experienced before. Maybe I did not get them seasoned in well enough before the trip. Driving around town ever since has been just fine, normal breaking to hard breaking although as I said before I find these pads do create a far softer breaking.

Not prepping these for re-use.

You must be registered for see images attach

Or these...................

You must be registered for see images

Definitely not these...............

You must be registered for see images

Don't skimp on your safety and others around you,buy new rotors for the best results when doing brakes.I have over a 160 certifications from Ford,GM,Chrysler,Cat,Cummins,Detroit Diesel,AM General,Allison,and many many more and no one wants you to re-use old brake parts.

 

[JasonJ]

I have NEVER had pads act in this way and heck no you don't replace rotors when replacing pads, you don't even need to turn them each time. At most a surface prep is needed, nothing more than sanding down the surface to remove any material left by the old pads. Once completed you need to go through a few days of seasoning the pad by normal driving alternating with some fairly aggressive stops. This is the process I have used for 30 years.

This is the first time I have used these NAPA Adaptive One pads and the way they performed with the apparent buildup on the rotor during this downhill drive was something I've not experienced before. Maybe I did not get them seasoned in well enough before the trip. Driving around town ever since has been just fine, normal breaking to hard breaking although as I said before I find these pads do create a far softer breaking.

Yeah, I'm sorry JB but I have to disagree in the same line as Tom and Troy here. I changed my first set of brakes exactly 30 years ago this year, as well. I would say that instead of "At most a surface prep is needed..." really it's more like "At MINIMUM, a surface prep is needed."

I've seen exactly two vehicles where the rotors were in good enough condition where a non-directional scuffing with emery cloth or sandpaper was good enough with new pads and no issues came about from it. Only two.

When rotors for most vehicles can be had for as cheap as they typically can nowadays, no reason not to replace them. The tolerances for wear are so low; you're usually within a few thousandths from min spec thickness anyhow.

And if there are ANY grooves, pitting, rusting, or discoloration indicating excessive heat, forget about it. Front rotors for a KJ are generally $40 a side everywhere. Much safer to just budget an extra $80 into the brake job.

But you do you, and we'll do us. Drive your own drive, I guess.