hellspare

Hey guys I got a question. After a few hard braking sessions, my pedal seems to pulsate when I step on the brakes. This never happens just driving around town, only when I'm pushing the car, so the problem isn't that severe. Is this due to warped rotors or just bad pads? After I get down the mountain or whatever and drive a couple minutes the pulsating goes away.

Thanks.

mr5parkle

from my experience, warped rotors also cause shaking in the steering wheel when braking as well.

slalom44

You don't have warped rotors. That's a myth. Rotors don't warp. What you have is an uneven transfer of brake pad material on your rotor surface. This results in varying thickness of your rotors at different locations. This can be caused by getting your rotors really hot, then stopping (for example at a stoplight) and continuing to apply your brakes. A thicker layer of pad material gets applied to a small section of your rotor. .

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

The best way to fix the problem is to get your rotors turned or replace your rotors. It's possible for the chatter to go away by itself over time, but not likely.

INTJ

As has been posted 1000x: Rotors do mechanically warp...why else would turning help them? But then you have spent 15 bucks and your time to take mass off of warped rotors and you will get warpage faster. And, yes, put a disk on a cutter and you can see the METAL warped, it cuts off metal.

Now pad transfer, such as slalom describes is common in racing pads and a very light cut will take off a fine layer of pad material. That would be very unusual for Honda pads. I have only had that with a few racing brands, and it comes right off with hard braking, it does NOT go from good to worse.

slalom44

You obviously didn't read my link. No, rotors don't warp. And yes, you will see a severely deposited rotor with different thicknesses removed when it is turned because the difference in thickness between the deposited sections and the other areas can be significant.

The link I posted specifically talks about the observation you mention.

tof

According to your source, slalom, rotors don't warp. There is, in fact, a good bit of disagreement on this topic with plenty of smart degreed professional engineers on both sides. Some say pusling of the brake system is caused by warped (distorted) disks. Others blame uneven transfer of brake pad material to the rotor surface that is described in the article you linked to.

And I don't buy the argument that physically warped rotors won't cause pedal pulse in cars with sliding calipers (which are nearly universal in passanger cars). Sliding calipers don't always slide as readily as they were originally designed to do. This is especially true on systems that are subject regularly to excess heat.

And INTJ, turning rotors would correct a problem of material transfer and thus "flatten" the high spots on the disk surface. It would also result in in metal being 'cut off' even if the surface is uniform and the brake disk is undistorted.

A few thing are generally agreed upon. Unbalanced tightening of rotors can cause them to deform. And heat can cause both the conditions generally attributed to brake pulsing. But here is the important point. Regardless of what is causing pedal pulsation, the real source of the problem is most liely improper use of the brakes in high performance driving or use of pads not designed for such conditions, or poorly made rotors and/or pads. "Turning" the rotors on a lathe desinged for the purpose, when done correctly, can often cure the pedal pulsing but the reduced mass of the rotors and the fact that pads are usually replaced with comparable pads means the problem will return.

I used to own a v6 Accord and ran it at the local drag strip fairly regularly. It was fun and the automatic made it easy to kick butt in bracket racing and win a few bucks. When braking at the end of the quarter mile the pedal would pulse badly. And, no, I wasn't braking nearly hard enough to engage the abs. But after driving for a few minutes the pulsing would go away. Even during hard driving I never had a problem. It was only when braking from 90+ mph that the problem ever occurred. I have no idea what this means but I thought I'd throw it into this thread.

pgss2k

Is it possible you're just getting the abs engaging when you are pushing the system? Might explain why it only happens when aggressive.

INTJ

Nope. I read your post and disagree for the reasons I cited:

"As has been posted 1000x: Rotors do mechanically warp...why else would turning help them? But then you have spent 15 bucks and your time to take mass off of warped rotors and you will get warpage faster. And, yes, put a disk on a cutter and you can see the METAL warped, it cuts off metal.

Now pad transfer, such as slalom describes is common in racing pads and a very light cut will take off a fine layer of pad material. That would be very unusual for Honda pads. I have only had that with a few racing brands, and it comes right off with hard braking, it does NOT go from good to worse."

I have used a rotor cutting machine several times. I gave up on using it because it was a failure. Why? Because once rotors warp and if you trim mass off they have less mass and warp again, more severely. You can SEE the metal come off the high spots. Not compounding, metal. I have far less warping with Brembos and if they warp, I throw them in the bin.

If I use a new brand of racing pad, I do a superficial light cut, it takes off the pad transfer. You can see that it is NOT METAL. There are deposits from pad transfer and there is the base metal of the disk. The carbide cutter doesn't lie. I have even stopped cutting racing pad because I can just burn it off with hard braking or use a set of blues between.

hellspare

No because when they are heated up even if I step on the brakes lightly it'll pulsate.

Thanks for the responses though. What are some blanks you guys recommend?

ShiftGearAP1

brembo blanks- not too expensive either