ANNOYING SOUND #3: SQUEALING - EEEEEEEEEEEEEEE!
You pull up to a stop light in your freshly detailed shiny GT-R, with a nice long fierce brake squeal. Everyone parked at the stop lights looks side to side expecting to see a crapy old beater minivan, instead they have to do a double take when they realize it some kind of fancy new sports car. How embarrassing!
To eliminate this noise we have to understand what causes it.
Most average modern cars today use ceramic compound based brake pads, with low metallic composition.
They are designed for the average driver - one who will ride the brakes to come to a slow gradual smooth stop; will never warm up the brakes despite the outside temperature or wet conditions; will occasionally do a hard cold stop, usually in an emergency situation, when the brakes are also cold and expect excellent results (cold bite); one that will expect the lowest dust and noise possible; and want the brake pads and especially rotors to last forever.
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| Pad Material Transfer But Fading after 3 weeks of daily Driving |
The GT-R uses semi-metallic compound based brake pads with a high metallic composition. They are designed for very quick hard stops and absolute last minute braking, not a gradual stop. They are meant to work well under extreme temperatures, dissipate heat quickly and in fact work better when warmed up. Every stop is basically an emergency stop and no design thought is given to the life of the pads or the rotors. They are absolutely horrible when wet. (Recall the brake feel immediately after coming out of the car wash.)
There is a compromise scale in play here:
More metallic composition = greater squeal = greater hot stoping power = worse cold emergency stopping power.
I now use Endless MX72 pads with stock rotors, which are slightly more aggressive than stock and believe this is what Nissan should have delivered with the car. As a comparison, the Endless ME20 pads have a higher metallic compound and have better bite for track but squeal way more on street. And the Hawk HPS have lower metallic compound, low dust, great cold stopping power but do not last on the track. Is the pattern of what traits go together slowly developing?
If you use the GT-R for daily driving, the OEM pads are abrasive enough, due to the high metallic composition, that the pads actually grind down the rotors ever so slightly (fractions of micro-millimeters). This metallic pad compound to metal rotor grinding is actually what causes the squealing noise. Mystery Solved.
How do we stop it? Simple. We stop it by Bedding-In or Burnishing the pads against the rotors. This means putting some pad material onto the rotor by heat transfer.
- I assume you start with a clean washed wheels all brake dust removed, and at least 50% pad life.
- Find a nice long country road with no traffic and a 10 minute route for no stopping right afterwards. Read the rest of the instruction to realize why.
- Turn your MFD Screen to "B".
- Check your front and rear view mirror for traffic. Accelerate to 70 mph quickly and slow down very quickly to 10 mph, and DO NOT STOP completely. It should be hard enough braking that you can almost feel the ABS kick in. It's okay if it does, but avoid it next time. My MFD braking "B" screen with the G-meter shows almost 1g of braking force.
- Check for traffic! Do it again 4 more times for a total of 5 times. You might smell some burning and even see smoke from the wheels. This is normal. DO NOT completely STOP the car. You will notice the GT-R brakes bite more progressively i.e. 1.1-1.3g and result in shorter stops.
- Now drive at 50-65 mph for 10-15 minutes to cool the brakes down. This should not be stop-and-go traffic as it will scrape off pad material that was just laid down.
- Of course if at any time you need to use the brakes to stop or in an emergency, use them.
- I have noticed that the brakes might still squeal a little, but will absolutely stop squealing after the GT-R has been parked and the brakes are back to ambient temperature.
I have done this procedure countless times, especially the evening before the track day to optimize the braking, or if the squealing is very bad, and it has stopped the squeal every time. The rotors should have a nice bluish (MX72) or brownish color (Stock) on them instead of the shiny silver color or new rotors. As per the pictures below.
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| Pad Material Transfer But Fading after 3 weeks of daily Driving |
However, what happens over time with daily driving is that, with the repeated cold stops and gradual stops, the burnished layer get scrapped off the rotors slowly exposing the shiny naked rotor surface again, essentially the semi-metallic pads are turning the rotors and now we are back to the squeal. Time for a repeat of the procedure. You can minimize the "un-burnishing" by making harder daily driving stops, but you run the very likely risk of someone rear ending you.
Also one might wonder if re-bedding-in or re-burnishing is eating up pads, indeed that is true, but relatively speaking each front rotor (one side) is about $1100 (stock) and set of pads (one side) is about $245 for MX72. I would rather go through 4-5 sets of MX72's before having to pay for complete rotors and avoid the noise combined with exceptional stopping power.
Also one might wonder if re-bedding-in or re-burnishing is eating up pads, indeed that is true, but relatively speaking each front rotor (one side) is about $1100 (stock) and set of pads (one side) is about $245 for MX72. I would rather go through 4-5 sets of MX72's before having to pay for complete rotors and avoid the noise combined with exceptional stopping power.
Once you understand these braking concepts, you may actually be okay with moderate squeal, as I am now, on a daily basis and recognize what needs to be done to solve the problem if it becomes too much.
