[SpiralOut]

Thanks for the info Mr. 5..... I just ordered a full set for my e92.

Originally Posted by Mr. 5

Just to let you know guys...

http://www.autoindividual.com/ is having a 15% off coupon for the month of February (coupon code is pano210).

[Turkeybaster115]

Anyone got any coupons for F/R cool carbons? Please PM me.

[Mr. 5]

Originally Posted by Turkeybaster115

Anyone got any coupons for F/R cool carbons? Please PM me.

Email info@autoindividual.com
They might be able to help you.

Remember that EAS is also selling these now at a great price.

[Mr. 5]

Originally Posted by Turkeybaster115

Anyone got any coupons for F/R cool carbons? Please PM me.

Email info@autoindividual.com
They might be able to help you.

Remember that EAS is also selling these now at a great price.

[mid-corner fun]

sigh....after 1 bedding cycle with new coolcarbon pads and new slotted brakeperformance rotors I'm getting the dreaded vibration at high speeds, even without braking.

Should I even attempt to finish the bedding procedure? (2 more cycles). I did follow the bedding instructions/did not stop between runs/let the brakes cool down at the end, or at least I think I did it right. I'm having it checked out tomorrow morning.

[Mr. 5]

Originally Posted by PeterM1

sigh....after 1 bedding cycle with new coolcarbon pads and new slotted brakeperformance rotors I'm getting the dreaded vibration at high speeds, even without braking.

Should I even attempt to finish the bedding procedure? (2 more cycles). I did follow the bedding instructions/did not stop between runs/let the brakes cool down at the end, or at least I think I did it right. I'm having it checked out tomorrow morning.

I hate to say it, but it sounds like the rotors are warped.
Did you ever come to a complete stop when you were doing the bedding procedure?

Also another thing to consider...If you are getting vibration at speed without applying the brakes then your wheels need to be rebalanced.

[AP Racing - Chris_B]

Originally Posted by PeterM1

sigh....after 1 bedding cycle with new coolcarbon pads and new slotted brakeperformance rotors I'm getting the dreaded vibration at high speeds, even without braking.

Should I even attempt to finish the bedding procedure? (2 more cycles). I did follow the bedding instructions/did not stop between runs/let the brakes cool down at the end, or at least I think I did it right. I'm having it checked out tomorrow morning.

The procedure should definitely be finished. As you mentioned, one of the most critical issues with bed-in is a proper cool down. You want to make sure you are driving at least a mile or so without using brakes at all, if possible. The pad transfer layer that is put down on the rotor needs to "freeze" in a virgin state during cool down. If this gets screwed up, it can usually be fixed by re-bedding -- if caught right away!

Stopping when the rotors are still hot can lead to pad "print off" -- a heavy concentration of pad material in one spot. This can often be seen by a light outline of the pad friction puck on the rotor. This can be cured by re-bedding if it is not severe. Severe cases require scrubbing the friction surfaces with Scotch-Brite or, better still, using a Flex-Hone. I do NOT recommend sandpaper as it removes iron and surface flatness cannot be guaranteed if done by hand. Also, the pad surfaces are usually glazed (the resin binders in the pad compound have melted and the surface now has shiny areas), so they must be cleaned up as well. The easy way is to use 180 grit sandpaper on a flat surface (glass works very well) and oscillate each pad face down until the surface is dull again. Once the rotors and pads are cleaned up, do the full bed-in procedure all over again.

If the car is stopped with a foot on the brake pedal when the rotors are extremely hot, carbon molecules can transfer from the pad to the rotor. This will convert some of the iron on the local surface into cementite, which is much harder than the remaining surface. This will lead to uneven wear down the road as one spot will have a much greater resistance to wear. Service techs will measure the resulting runout and call it a "warped rotor", but in reality you can't get iron hot enough on a car to warp iron as the brakes would catch fire well before that occurred. But if you could, the results would be nearly the same, hence the misnomer for so many years. Cementite can be removed by turning if the rotor is not worn much. If it is worn more than 50%, it's new rotor time.

Chris

P.S. I also agree that if you are getting a vibration without applying the brakes, you have other issues. If it wasn't occurring before, most often the wheels need to be removed and re-torqued in a star pattern (NO AIR TOOLS!). Other than that there is a long list of items that will cause vibration.

[e90pilot]

Could it be possible that the pad compount just isn't compatible with the rotor surface? When my brother used to race he and the rest of the drivers always hated going on after the Atlantic cars because the Yokohama rubber didn't mix with his Michelin rubber. Could the same phenominon be observed in brakes?

[AP Racing - Chris_B]

Originally Posted by e90pilot

Could it be possible that the pad compount just isn't compatible with the rotor surface? When my brother used to race he and the rest of the drivers always hated going on after the Atlantic cars because the Yokohama rubber didn't mix with his Michelin rubber. Could the same phenominon be observed in brakes?

This can be the case when switching between two incompatible pad compounds without scrubbing the rotors first. Racers find out pretty quickly which compounds can follow which other ones. The only issue I've seen with rotors is that some high-tensile ductile iron is not compatible with overly aggressive pads. Very few rotor manufacturers use this material for performance rotors as its other properties are also less than ideal.

Chris

[Mr. 5]

Originally Posted by e90pilot

Could it be possible that the pad compount just isn't compatible with the rotor surface? When my brother used to race he and the rest of the drivers always hated going on after the Atlantic cars because the Yokohama rubber didn't mix with his Michelin rubber. Could the same phenominon be observed in brakes?

If this were the case then we would all have the issue.
I also agree with Chris about the previous pads putting a layer on the rotor where the new pad cannot bond with, but peterM1 said that the rotors were new.

[David1]

I have seen many many new rotors in my day that were not true right out of the box.

[mid-corner fun]

Originally Posted by Mr. 5

I hate to say it, but it sounds like the rotors are warped.
Did you ever come to a complete stop when you were doing the bedding procedure?

Also another thing to consider...If you are getting vibration at speed without applying the brakes then your wheels need to be rebalanced.

you're correct, sadly it's warped rotors, I confirmed today. I did not come to a full stop at any time during the cycle but in retrospect I may not have driven enough after the end of the cycle to let the brakes cool down enough.

On the vibration issue at high speed, the cause was a caliper that was not fully retracting, this started to occur after the bedding cycle as well.

[mid-corner fun]

Originally Posted by AP Racing - Chris_B

The procedure should definitely be finished. As you mentioned, one of the most critical issues with bed-in is a proper cool down. You want to make sure you are driving at least a mile or so without using brakes at all, if possible. The pad transfer layer that is put down on the rotor needs to "freeze" in a virgin state during cool down. If this gets screwed up, it can usually be fixed by re-bedding -- if caught right away!

Stopping when the rotors are still hot can lead to pad "print off" -- a heavy concentration of pad material in one spot. This can often be seen by a light outline of the pad friction puck on the rotor. This can be cured by re-bedding if it is not severe. Severe cases require scrubbing the friction surfaces with Scotch-Brite or, better still, using a Flex-Hone. I do NOT recommend sandpaper as it removes iron and surface flatness cannot be guaranteed if done by hand. Also, the pad surfaces are usually glazed (the resin binders in the pad compound have melted and the surface now has shiny areas), so they must be cleaned up as well. The easy way is to use 180 grit sandpaper on a flat surface (glass works very well) and oscillate each pad face down until the surface is dull again. Once the rotors and pads are cleaned up, do the full bed-in procedure all over again.

If the car is stopped with a foot on the brake pedal when the rotors are extremely hot, carbon molecules can transfer from the pad to the rotor. This will convert some of the iron on the local surface into cementite, which is much harder than the remaining surface. This will lead to uneven wear down the road as one spot will have a much greater resistance to wear. Service techs will measure the resulting runout and call it a "warped rotor", but in reality you can't get iron hot enough on a car to warp iron as the brakes would catch fire well before that occurred. But if you could, the results would be nearly the same, hence the misnomer for so many years. Cementite can be removed by turning if the rotor is not worn much. If it is worn more than 50%, it's new rotor time.

Chris

P.S. I also agree that if you are getting a vibration without applying the brakes, you have other issues. If it wasn't occurring before, most often the wheels need to be removed and re-torqued in a star pattern (NO AIR TOOLS!). Other than that there is a long list of items that will cause vibration.

thank you for the detailed explanation, it certainly helps explain what I'm seeing. I think I've made quite a severe pad print off as I have several visible friction lines on my front rotors (not just the outline line) and a blue'ish hue on the outer layer...I take it 2 days after the 1st bedding cycle would not quite qualify for "catching it on time" and re-bedding. I'll get the rotors turned and pads cleaned asap before I resume the bedding process.

Originally Posted by AP Racing - Chris_B

The procedure should definitely be finished. As you mentioned, one of the most critical issues with bed-in is a proper cool down. You want to make sure you are driving at least a mile or so without using brakes at all, if possible. The pad transfer layer that is put down on the rotor needs to "freeze" in a virgin state during cool down. If this gets screwed up, it can usually be fixed by re-bedding -- if caught right away!

Stopping when the rotors are still hot can lead to pad "print off" -- a heavy concentration of pad material in one spot. This can often be seen by a light outline of the pad friction puck on the rotor. This can be cured by re-bedding if it is not severe. Severe cases require scrubbing the friction surfaces with Scotch-Brite or, better still, using a Flex-Hone. I do NOT recommend sandpaper as it removes iron and surface flatness cannot be guaranteed if done by hand. Also, the pad surfaces are usually glazed (the resin binders in the pad compound have melted and the surface now has shiny areas), so they must be cleaned up as well. The easy way is to use 180 grit sandpaper on a flat surface (glass works very well) and oscillate each pad face down until the surface is dull again. Once the rotors and pads are cleaned up, do the full bed-in procedure all over again.

If the car is stopped with a foot on the brake pedal when the rotors are extremely hot, carbon molecules can transfer from the pad to the rotor. This will convert some of the iron on the local surface into cementite, which is much harder than the remaining surface. This will lead to uneven wear down the road as one spot will have a much greater resistance to wear. Service techs will measure the resulting runout and call it a "warped rotor", but in reality you can't get iron hot enough on a car to warp iron as the brakes would catch fire well before that occurred. But if you could, the results would be nearly the same, hence the misnomer for so many years. Cementite can be removed by turning if the rotor is not worn much. If it is worn more than 50%, it's new rotor time.

Chris

P.S. I also agree that if you are getting a vibration without applying the brakes, you have other issues. If it wasn't occurring before, most often the wheels need to be removed and re-torqued in a star pattern (NO AIR TOOLS!). Other than that there is a long list of items that will cause vibration.

Is there any way I can PM you I have a technical question to ask.

[David1]

You know, you can just drive normally to bed them in as the instructions state. I did it this way since I was not going to do any hard driving real soon after the install. I did do some moderate braking and my cool carbon pads are smooth as glass. Just takes 200 to 300 miles. I did my install with rotors that had 2k miles on them.

[AP Racing - Chris_B]

Originally Posted by index1489

Is there any way I can PM you I have a technical question to ask.

Yes, you can -- now that I'm back in the country! If I can help, then great. If not, there is a good chance I might know who to direct you to.

[boilerdan33]

I'm curious what kind of pad life you gentleman are seeing out of a set of pads. I did two track days and about 9K miles on the OEM pads before switching to CC. The OEM pads were probably about 60% used when I replaced them with the CC.

I only did TWO track days at Road America plus about 4K of VERY easy street driving, and today at the pre-tech, the mechanic said I need new pads before I go to the Autobahn Country Club track. They were down to 20% or less. I love the pads, they are definitely a huge improvement over stock, but I don't think I can afford two hundred bucks for two days of track time. Each day was four twenty minute sessions. There are three very hard braking zones of about 130 mph to about 40 mph on the track. I haven't checked the pads myself, but was wondering if it was me or the pads.

The service manager said he would have no problem replacing DE used pads with more factory pads. He specifically stated, "I don't work for BMW." Wink. Wink.

D

[dbjb]

Thanks for the great review.

I wasn't considering switching to Cool Carbon pads but after reading the reviews, I may just pull the trigger.

As of now, I have Centric pads installed. I got them primarily for the low dust properties. I have no idea how well they'll perform on a track though. During the bed in process, I do not recall fade but they did have less bite similar to what the Cool Carbon reviews show.

Anyways, maybe I'll switch out to the Cool Carbons on my next change out. I just hope there IS less dust because OEM is horrific.

Question: During my last free maintenance service, the SA made a comment about using non-OE pads. He said it would void the warranty (mechanical or free maintenance) on the rest of the brake components. Now, I'm not worried about not covering the pads but I still want my calipers covered and I still want my free rotors til 100k miles. Has anyone else experienced an SA making such a comment?

Also,
I want to chime in on the talk of warped rotors. This may be obvious but should be mentioned. Whenever your brakes heat up, you want to refrain from coming to a complete stop which puts the pad in contact with the rotor. THIS INCLUDES SETTING THE PARKING BRAKE AFTERWARD. If you participate in track events, take some wheel chocks along. Use them instead of the parking brake. Definitely worth the cheap investment.

[335i_4D]

Originally Posted by dsbj

THIS INCLUDES SETTING THE PARKING BRAKE AFTERWARD.

Isn't the parking brake a drum-like system inside of the rear rotor on the e9x cars ?

[David1]

Originally Posted by 335i_4D

Isn't the parking brake a drum-like system inside of the rear rotor on the e9x cars ?

Correct, it is drum brake parking brake.

[dbjb]

Originally Posted by 335i_4D

Isn't the parking brake a drum-like system inside of the rear rotor on the e9x cars ?

Maybe I should have said hand e-brake.

[sandyeggo325i]

anyone experience squeaking w/ oem (centric) rotors?