Ever come squealing to a halt at a traffic light? Ever hear a horrific grinding noise when you apply the brakes? Chances are you have, and it is un-nerving to say the least. Of all the systems your BMW (or other "lesser" brand car) has, I doubt any are more important than your braking system. I mean, you can 0-60 in 3 seconds in a supercharged M3, top 190Mph in an M5, swing through curves like nobodys business in a ZHP, but if you cant stop; whats the point?
As I recently did some inspections on my car I realized it was about time for new brakes (great, there goes $300 bucks!) and I figured now would be a good time to talk about brakes, my preferences, tips, tricks, and where to find good deals on parts (hint: it isnt the dealer).
BMW brakes are exceptional. It only took me one or two fast stops after I bought my 323 to realize the incredible stopping power of the E46. I then came to find out that the BMW brakes are lighter than most cars for better balance, and larger than most cars for better fade resistance and more stopping power. I also learned that OEM pads give the 1930s "dust bowl" nightmare a run for its money! These truths span the entire line of BMW models 3s, 5s, and 7s (the ///M cars get even beefier units). The braking system is designed essentially the same on the E34s, E36s, E39s and E46s I have repaired. So as a general rule, the steps to change brakes on an E34 is largely the same as an E46. The main difference being rotor size. The E46 323 like mine for instance, comes with 286mmX22mm front rotors while the 330 has 325mmX25mm rotors. These much larger brakes are why I switched my 323 over to 330 brakes. And yes, those 39mms make a BIG difference in braking.
So where and what should you buy for brakes? Many people prefer OEM braking components (Brembo or Zimmerman rotors and Textar pads) because they work and a LOT of people think they have magical properties (dont even get me started on BMW coolant!). The reality is that the OEM spec stuff just plain works and you cant argue with a company like Brembo for brakes. But there are better options than textar or mintex for pads. This is where performance and driving style come in to play. If you like super aggressive driving, late, hard braking, and just plain having fun, a "bitier" pad like Hawk or EBC Reds might make your day. If you like low dust, but less aggressive stopping power (still excellent though) you might want to check out the ceramic offerings available by Hawk or Akebono. A friend has the Akebonos and they are great from a dust standpoint, but squeal in protest during a stop and this is something all ceramics I have experience with seem to have issues with. Another thought is that super aggressive pads also wear out your rotors faster (in addition to gobs of brake dust), so youll want to keep that in mind. Overall the best mix in my opinion is the Hawk Street pads with Brembo rotors (or Zimmerman). Turner Motorsport has some excellent packages on their website featuring these products.
Real quick let me address the inevitable question about cross drilled/slotted rotors. The answer is yes, they look cool, but no, they dont help you stop any better in an E46. In fact, if you buy the wrong cross drilled rotors you can get rotor warpage, cracking, or total failure. Recently I put ebay cross drilled rotors on a Mini Cooper for a lady that really wanted them. Within 5,000 miles they were warped and she had to replace them with regular rotors. If you must go with cross drilled, EBC or Zimmerman are the only two manufacturers I would use. Again, Turner Motorsport has them for you. You just cant abuse your rotors enough, even on track day, to need cross drilled.
Lastly, here a few tips/tricks concerning brakes:
- You dont have to replace the brake sensors (saves you $20) if your brake light doesnt come on in your instrument cluster. You really shouldnt be waiting that long anyways. Even if it does come on, I personally just twist the wires together to make the light go off and zip tie them out of the way. Why? Because the sensors on most BMWs are on opposite corners (drivers front and passenger rear) and on my car, the back drivers side went all the way to the rotor and I never got the light to come on. They are pointless. Inspect your car regular and it wont sneak up on you. (dummy lights are for......well.......dummies!)
- Make sure to use steel wool on your caliper guide pins to get them nice and clean. I use a 0000 steel wool. This is important for proper brake function.
- Use a liberal amount of anti squeal on the BACK of the pads, please dont put it on the pad surface!
- Use a small dab of anti-seize compound on the hub BEFORE putting the new rotors back on, you will thank me for this when you go to change them again. Also put some on the rotor hub so getting your wheels off will be easier.
- Lastly, spend the $4 and buy new rotor retaining nuts. They are notorius for stripping out and it is a hassle you can avoid. If your old ones are giving you problems try using a torx bit to help give you some extra "bite" in the threads.
And there you have it. Brakes in a nutshell. Yes, there is a lot I missed and/or skipped. But you get the ideas. I leave you with Shads list of links to places to buy brakes (I have used them all and they are all good):
http://www.turnermotorsport.com/
http://www.autohausaz.com/
http://www.bimmerworld.com/
