Abnormal brake pad transfer (deposit)

[racingbrake]

This notice is posted for all prospective customers who may involve in track racing to read, so they become a more knowledgeable and understandable in tracking their cars.

NOTICE FOR TRACK RACING

RB two-piece rotors are made from specially formulated alloys and high carbon cast ion, and are proven in the race tracks that they are highly resistant to wear, warping or thermal cracking under extreme heat cycles than OE or others.

Since our disc material is made harder (190-230 BHN) than stock, the same racing pads (compounds) you used to know or use that work on OE or competitions' rotors may not work well on our rotors. One of the most common issues is the pad deposit which is a substance emitted from the pad under high heat and transferred to the rotor surface that can cause vibration, pedal pulsation and hot spots on rotors surface resulting in thermal cracks and/or pre-mature brake failure.

It's individual racer's responsibility to ensure that a right pad compound is chosen can resist to the temperature he/she expects w/o emitting the deposit.

Understand that pad deposit comes from pad and stays on rotor, not originated or part of rotor. When it happened it can cause ill effect of braking performance which is beyond our control as a rotor manufacturer.



We have sold thousand sets of high performance rotors (one piece, two piece and brake kits), so far we received two complaints resulting from the pad deposit (build up):

First customer used RB one piece rotor for his front EVO and he used Ferrado 2500 pad:
http://www.evolutionm.net/forums/sho...d.php?t=155348

Second customer used RB two piece rotor for his front STi and he used Carbotech XP10 pad:
http://forums.nasioc.com/forums/showthread.php?t=936395

Both cases were well discussed on their respective forums. However other customers with the same combination could produce satisfactory results.

Brake is a rather complicated system to optimize:
http://www.iwsti.com/forums/showthre...=30353&page=20

We also consulted a racing pads expert dealing with NASCAR racing teams, and his comments on brake pad deposit (build up):

"There are several reasons that an unusual pad build up can occur on a rotor. It is important that the rotor be machined well with good parallelism, flatness, and run out. From our experience the RB rotors meet this standard and this should not be a concern. Some pad compounds are more prone to leaving build-up on rotors than the other. This especially occurs when the pad is used at temperatures outside the operating range the pad was designed for. It is important for racers to have an idea of what temperatures their brake systems are operating in at any given event and choose an appropriate pad for that temperature range."

Always check your pad suppliers, talk to your friends and make sure the pad you choose is appropriate for your braking temperature range and use (handle) them properly.

If you experience brake deposit, we recommend to clean it rather than resurfacing the rotor, although it may appear like rotor surface is grooved but actually it's metallic compounds emitted from the pad and it's removable. Per recommended procedures below.

[youngturk]

Question

Thank you for your article regarding abnormal pad transfer. One part of the article states the following:

"If you experience any malfunctions such as brake vibration or pulsation resulting from any pad deposit you should consult your brake pad supplier, remove the excessive build up and replace a more suitable pad rather than resurfacing the rotor. " (bold emphasis mine)

My question is: What is the proper material and method to remove pad material build-up?

Thank you!

[racingbrake]

1. Remove the deposit (Suggested items are available from Home Depot).

Use the steel wool and brake cleaner such as Acetone to scrub off the build up. Since this deposit was emitted from the brake pads at higher temperature, therefore it may not be easy to remove the deposit at room temperature, in this case you will have to heat up the rotor surface with a torch and repeat the scrubbing process with a coarser steel wool until all deposits are cleaned up from the rotor.



2. Replace the brake pads.

Do some research, talk to your your friends and pad suppliers, find a brake pad compound that can adequately handle the heat of your track activities. If the pad replaced can't handle the job you have to repeat this cleaning process.

3. Re-bed the pad and rotor.

[usa35]

Additional information

Since this is a sticky thread, I thought I'd add the following experience.

I use my 05 STi (mostly stock) on the track with Pilot Sport Cups and had the stock Brembos which were subsequently upgraded with the RB 4-pot front kit. The reason for the kit change was basically cooking the front OEM Brembo calipers. A few things became clear after the switch:

* The RB 4-pot caliper isn't much of an upgrade - but the rotors are (cooler)

* The STi is essentially under-braked for significant track use (as I imagine the Evo and others are) when using any sort of track tires (e.g. Victoracers, PSC's, Advan's)

* There is very poor airflow to the front rotors on the STi, causing a host of problems (including pad transfer and worse). This can be remedied in a number of ways, all of which should probably be done for tracking an STi:
- Remove the backing plates on the front (rear stays cool enough)
- Upgrade to 2-piece rotors (and the RB calipers if you are so inclined)
- Add cooling ducts (easier said than done)

Even with the backing plates off and 2-piece rotors, there simply isn't enough airflow to the rotors. You can actually leave the backing plates on if you add airflow to the area (and possibly cut the backing plates to fit your ducts).

The airflow is the key! The pads won't matter until you get airflow under control.

A nice upgrade for the STi would actually be the 6-pot/4-pot RB upgrade AND cooling ducts to get air to the front. If you are doing to do DE or club racing events at places like MPH, Road America, Brainerd, Laguna Seca, etc., it's practically a must.

-Mark

[racingbrake]

How a warped rotor is different from pad deposit

"Warp" in a proper term is:

"Something become or cause to become bent or twisted out of shape, typically as a result of the effects of heat or dampness"

To a brake rotor the warp was caused from the result of heat cycles during expansion (hot) and contraction (cold), that the rotor can no longer restore to its original form due to the nature of metallurgical structure, some rotor can be more resistant to warpage than the other.

Brake deposit on rotor surface is a substance emitted from the brake pads when the brake pad exceeds it's temperature limit, same as rotor some higher quality compound is more resistant than the other.

If the vibration is caused by the pad deposit, it's correctable but you don't need to turn the rotor. Just try to clean the surface with some brake cleanser with sand paper or steel wool.

The thread created more than 10 years ago in RB brake forum still is the most referenced article in the brake performance circle today.

Abnormal brake pad transfer (deposit) is what described above.

Pad deposit is correctable as suggested in this thread. However if the rotor is warped usually turn the rotor doesn't help because you only fix the surface but not the internal metallurgical structure, and it will warp again even sooner than before (because the rotor is now thinner), so replacement is a better solution.
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