Pulsating Brake Pedal...Again...What to fix Next??

[galaxy]

2014 IS350, F package. 6X,XXX miles on it. Did a really good break job first time; turned original rotors, EBC Red pads, completely flushed the entire system with Amsoil fluid. Within 20,000 miles, brakes were pulsating and felt like a warped rotor. Pads were still practically brand new.

This time, installed brand new rotors all around, cleaned up the surface of the pads on a very flat surface, and bled the brakes. Within 10-15,000 miles of this, pedal started pulsating again like warped rotor.

This time, brand new rotors checked (they were fine). Installed brand new pads (even though the Red's were still in great shape). Again, within 10,000 miles, the pedal is now pulsating again and it's horrible.

It's not the rotors. They are not warped. Pads are fine. The driver is not hard on brakes by any stretch of the imagination.

What would you do next?

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[Schwerin]

Any faults with the ABS?

 

[galaxy]

Nothing apparent. No warning lights or codes or anything. I would think an ABS problem would show up immediately or still be there after a brake job.

 

[Hack]

So, my take is that for you to get a pulsing there has to be an issue with the rotors, or the components the rotors mount to - hub/bearings something like that. Pulsing typically comes from the pads hitting an inconsistent or poorly aligned surface. I would think you would have noticed a wheel bearing issue or a problem with a hub, but that would be something to verify. My second assumption is you would have noticed and repaired if there was a brake fluid leak or some other contamination of the pads.

If you are buying top quality rotors and they are warping in so few miles, that points me to some other flaw in the system that is causing heat buildup. My first thought is there's a caliper hanging up on a slide or a caliper piston isn't moving freely. You should be able to see uneven wear or drive the vehicle and notice high heat on one corner of the vehicle versus the others.

 

[Hack]

More thoughts. If the problem temporarily goes away when the rotors are replaced or turned - that tells me that the rotors are getting warped. If the problem wasn't with the rotors, the pulsing would not go away when you replaced the rotors.

The way I read your posts above it sounds like the problem went away for a while after the brake services. So, that means to me that something is happening to warp your rotors.

 

[galaxy]

I would think if there was a problem causing heat or some other reason to warp a rotor, it would reveal itself. For example, a bad caliper creating too much heat would/should cause some type of negative driving conditions, no? Pulling one way or some other effect?

 

[kent0464]

Rotors typically do not warp, except in extreme cases. In nearly every case I’ve seen here at the shop it’s either the pads leaving deposites on the rotor or the pads getting glazed. Next time it happens, remove the pads and scuff them with either some 80 grit sand paper or 2-3 passes on some flat concrete, remember to slightly bevel both ends, put them back on and see how they behave. If this corrects the problem them you need to look into a different pad compound.

 

[Hack]

I would think if there was a problem causing heat or some other reason to warp a rotor, it would reveal itself. For example, a bad caliper creating too much heat would/should cause some type of negative driving conditions, no? Pulling one way or some other effect?

I agree with what you are saying. Maybe Kent's thoughts are correct and the pads are getting glazed. I've never ever seen that happen, but it sounds like he has a lot more experience with various cars than I do.

Rotors typically do not warp, except in extreme cases. In nearly every case I’ve seen here at the shop it’s either the pads leaving deposites on the rotor or the pads getting glazed. Next time it happens, remove the pads and scuff them with either some 80 grit sand paper or 2-3 passes on some flat concrete, remember to slightly bevel both ends, put them back on and see how they behave. If this corrects the problem them you need to look into a different pad compound.

 

[galaxy]

Rotors typically do not warp, except in extreme cases. In nearly every case I’ve seen here at the shop it’s either the pads leaving deposites on the rotor or the pads getting glazed. Next time it happens, remove the pads and scuff them with either some 80 grit sand paper or 2-3 passes on some flat concrete, remember to slightly bevel both ends, put them back on and see how they behave. If this corrects the problem them you need to look into a different pad compound.

So this is exactly what I did and it fixed the problem. This was also my first thought, and still is. Until (as stated) we replaced the pads with a different brand. I don't know what's on it now; I didn't install them. But the same thing happened with a second set. What are the odds? Or, if plausible, what's going on to make the pads keep doing this? All in, this has occurred with three different sets of pads over the course of dealing with this.

 

[kent0464]

So this is exactly what I did and it fixed the problem. This was also my first thought, and still is. Until (as stated) we replaced the pads with a different brand. I don't know what's on it now; I didn't install them. But the same thing happened with a second set. What are the odds? Or, if plausible, what's going on to make the pads keep doing this? All in, this has occurred with three different sets of pads over the course of dealing with this.

Do you remember what compounds those pads where made of? The weight or these cars combined with the heat generated in spirited driving will cause certain compounds to glaze.

 

[galaxy]

The first set were the stock ones, the second were EBC Reds, the third and current set IDK.

 

[kent0464]

The first set were the stock ones, the second were EBC Reds, the third and current set IDK.

I see some of the problem, you need to step up to a better pad.......as I said before the weight of the car and heat generated during spirited driving is causing the problem the compound gets hot and hardens causing the pads to glaze.
I see that you car is a 350gt (awesome), so right off the bat you are way past the compound of the EBC reds, see below. That compound is for smaller lighter cars under 250bhp....your car is waaaay past that! The proper pads for your 350 GT are going to be something like power stop, Ferodo DA2500, etc

 

[galaxy]

I see some of the problem, you need to step up to a better pad.......as I said before the weight of the car and heat generated during spirited driving is causing the problem the compound gets hot and hardens causing the pads to glaze.
I see that you car is a 350gt (awesome), so right off the bat you are way past the compound of the EBC reds, see below. That compound is for smaller lighter cars under 250bhp....your car is waaaay past that! The proper pads for your 350 GT are going to be something like power stop, Ferodo DA2500, etc

so you completely misread something, and I don’t know how. It is a Lexus IS350. Not a big heavy car and this car does not get any spirited driving by any stretch of the imagination. This car is an adult female mom driven DD. I know how this car is driven on a daily basis and that would not explain the pad condition. I agree with you about what is happening, but something else is causing it.

 

[kent0464]

so you completely misread something, and I don’t know how. It is a Lexus IS350. Not a big heavy car and this car does not get any spirited driving by any stretch of the imagination. This car is an adult female mom driven DD. I know how this car is driven on a daily basis and that would not explain the pad condition. I agree with you about what is happening, but something else is causing it.

Yikes! That’s completely my fault, I looked at your signature for the car. But your Lexus IS350 weights in (curb weight) at 3583lbs-3737lbs, depending on options, which puts it in the same weight class as your 350GT.

 

[galaxy]

no worries Kent...just wanted you to have the right picture in case it influences your diagnosis. I'm racking my brain on this one and tired of throwing parts at it.

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