So I've gone through 4 sets of front rotors on this car due to pulsating/shuddering brakes. Five if you count the ones on it when I bought it. That's over the course of about 150K miles. And many of those I kept on for a long time after they began pulsating. Some started pulsing as early as 5K miles. I'm not sure if it's a problem specific to my car or if it's intrinsic to the 4G TL. I'm not a newb when it comes to brakes. I've replaced pads and rotors on several vehicles with no problems whatsoever. My wifes '09 pilot has about 60K on her rotors and pads that I swapped out 4 years ago and they're still smooth as butter.
I've done everything to try to stop it but haven't had much luck:
- Cleaned the rust/debris off the hubs before installing the rotor
- Meticulously followed the bedding procedure (specific to the rotor manufacturer)
- Used a new set of pads for each new set of rotors
- Measured the run-out of my hubs to make sure they were true.
- Made sure all suspension components and wheel bearings are good.
- Made sure the calipers are in good shape - clean, no rust, guide pins were lubed up and freely moving, boots intact, etc.
- Thoroughly cleaned rotors prior to install - first with soap and water to remove the oil usually applied by the manufacturer to prevent rust followed by brake cleaner after install.
- Used anti-seize and brake grease where needed on all contacts of the brake pads.
Also, every set of rotors and pads have been a different brand. Centric (cryo-treated), Stop-Tech, Raybestos, Duralast (autozone) and Wagner. Still - no luck. :cuss:
Having researched ad-nauseum online, a common consensus among brake experts is that rotors don't generally "warp". They might warp if they're super hot, then cooled very quickly. Such as braking for a long time then running through a deep puddle. However, in general, most pulsating brakes are a result of uneven brake pad material deposited on the rotor. I've always been skeptical of this since I'm unable to visually see any sort of uneven buildup on the rotor surface and I can measure run-out on bad rotors with a dial gauge (whereas they were fine when I installed them). New rotors should have a runout of around 0.002" at most. I've measured runout as high as 0.009" on "bad" rotors that were pulsating. This led me to believe that the rotor was warped. Especially when examining the area where the excessive runout was present and seeing that the surface didn't look any different than the rest of the rotor.
In browsing on the topic, I came across a BMW forum where M3 owners were having similar problems. It seems that it's chronic for them as well. Even worse, their rotors are around $200-$300 EACH :shocked:. You can get decent rotors for the TL for as low as $40 each. So needless to say, they wanted to figure out a way to prevent or fix the problem. One method to try to remove uneven pad buildup is to repeat the bedding procedure. But that seems to have mixed results. However, one poster on that forum found that if he repeated the bedding procedure with a set of metallic pads (semi-metallic racing pads in this case) that it ground all the old ceramic pad material off the rotor resulting in a relatively smooth surface. After that, he'd replace those with the previous ceramic pads and the pulsating was gone!
https://www.m3post.com/forums/showthread.php?t=1384226
The pads he used were Hawk Blue racing pads which is a semi-metallic pad specifically designed for racing. Semi-metallic typically burn up rotors quicker but have better heat dispersal and more bite. For run of the mill cars, ceramic is most popular since it creates less dust, is quieter, easier on the rotors and lasts longer. But in this case, the whole point was to grind down the rotors to remove the ceramic pad material build up so semi-metallic race pads are perfect :thumbsup:
I was unable to find racing pads for the 4G TL. And frankly, I'm not sure I'd be willing to pay the price. They can be well above the $100 mark. So I decided to go the cheap route. I purchased a pair of semi-metallic pads from Autozone then did the bed in procedure. Boom! Pulsing was gone.
Time will tell if the fix is long term. I left the semi-metallic pads on for now but will probably swap the Akebono ceramics back on after a few more hundred miles - just to make sure the old material is fully removed. I'll follow up later to post results.
I've done everything to try to stop it but haven't had much luck:
- Cleaned the rust/debris off the hubs before installing the rotor
- Meticulously followed the bedding procedure (specific to the rotor manufacturer)
- Used a new set of pads for each new set of rotors
- Measured the run-out of my hubs to make sure they were true.
- Made sure all suspension components and wheel bearings are good.
- Made sure the calipers are in good shape - clean, no rust, guide pins were lubed up and freely moving, boots intact, etc.
- Thoroughly cleaned rotors prior to install - first with soap and water to remove the oil usually applied by the manufacturer to prevent rust followed by brake cleaner after install.
- Used anti-seize and brake grease where needed on all contacts of the brake pads.
Also, every set of rotors and pads have been a different brand. Centric (cryo-treated), Stop-Tech, Raybestos, Duralast (autozone) and Wagner. Still - no luck. :cuss:
Having researched ad-nauseum online, a common consensus among brake experts is that rotors don't generally "warp". They might warp if they're super hot, then cooled very quickly. Such as braking for a long time then running through a deep puddle. However, in general, most pulsating brakes are a result of uneven brake pad material deposited on the rotor. I've always been skeptical of this since I'm unable to visually see any sort of uneven buildup on the rotor surface and I can measure run-out on bad rotors with a dial gauge (whereas they were fine when I installed them). New rotors should have a runout of around 0.002" at most. I've measured runout as high as 0.009" on "bad" rotors that were pulsating. This led me to believe that the rotor was warped. Especially when examining the area where the excessive runout was present and seeing that the surface didn't look any different than the rest of the rotor.
In browsing on the topic, I came across a BMW forum where M3 owners were having similar problems. It seems that it's chronic for them as well. Even worse, their rotors are around $200-$300 EACH :shocked:. You can get decent rotors for the TL for as low as $40 each. So needless to say, they wanted to figure out a way to prevent or fix the problem. One method to try to remove uneven pad buildup is to repeat the bedding procedure. But that seems to have mixed results. However, one poster on that forum found that if he repeated the bedding procedure with a set of metallic pads (semi-metallic racing pads in this case) that it ground all the old ceramic pad material off the rotor resulting in a relatively smooth surface. After that, he'd replace those with the previous ceramic pads and the pulsating was gone!
https://www.m3post.com/forums/showthread.php?t=1384226
The pads he used were Hawk Blue racing pads which is a semi-metallic pad specifically designed for racing. Semi-metallic typically burn up rotors quicker but have better heat dispersal and more bite. For run of the mill cars, ceramic is most popular since it creates less dust, is quieter, easier on the rotors and lasts longer. But in this case, the whole point was to grind down the rotors to remove the ceramic pad material build up so semi-metallic race pads are perfect :thumbsup:
I was unable to find racing pads for the 4G TL. And frankly, I'm not sure I'd be willing to pay the price. They can be well above the $100 mark. So I decided to go the cheap route. I purchased a pair of semi-metallic pads from Autozone then did the bed in procedure. Boom! Pulsing was gone.
Time will tell if the fix is long term. I left the semi-metallic pads on for now but will probably swap the Akebono ceramics back on after a few more hundred miles - just to make sure the old material is fully removed. I'll follow up later to post results.