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      07-21-2016, 06:06 AM   #1
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Brakes 101

What components of the braking system are most important to improve your stopping distance?

Size of rotors, design, brake pads, calipers, etc?? My OE brakes seem not to have any bite or as much as I would like. Pad sensors say 4600 miles left on rears and 10,000 left on fronts. Not tracking just want something better. No squeaking , little dust ok. What's the best bang for the buck and why for an upgrade? StopTech, R1, Hawk pads???
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      07-21-2016, 09:34 AM   #2
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Changing to larger rotors and/or different calipers is a non-trivial project.

Pads are the biggest thing that's going to affect your braking performance, that's the main thing you should focus on. Most of my experience with aftermarket brake pads is on other cars. Some pads that seem to be popular around here are Hawk HPS 5.0, StopTech, Performance Friction, and Cool Carbon, among others. I can tell you that if you want low noise and dust, stay away from Hawk HP+. They stop great but are very loud and dusty.

For rotors, the BMW rotors and similar replacements are good. Holes and slots in rotors don't do really anything performance-wise. They can help shed water off the rotors in the rain, but our cars have a feature called Brake Drying where they lightly pulse the brakes when the wipers are on to clear water off the brakes. So holes and slots are mostly a cosmetic upgrade. If you do want one of these, I'd recommend slots over holes, as holes drilled into the rotor can make them weaker. Another option is if you want to reduce weight, you can get Z4 35is front rotors that are the same size as 335i but a 2-piece design with aluminum hats (the part in the middle) that saves a couple pounds each.

You can make the pedal a lot firmer by going with braided stainless brake hoses. Whenever I've put these on a car I've always liked the firmed up pedal. This is more an upgrade about feel than decreasing your stopping distance. The hoses for the 335xi are unique. StopTech makes a hose kit for the 335xi.

You should also go for a higher-temperature brake fluid. If you get too much heat in the BMW brake fluid and it starts boiling, you get a mushy pedal and brake fade. This is more of a concern on the track, but fluid is a cheap way to give yourself an extra safety net. There's a sticky thread at the top of this forum with boiling points of a whole bunch of brake fluids. Of those, a couple good and not-too-pricey options that you can find without much trouble are Motul RBF600 and Wilwood Hi-Temp 570.
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      07-21-2016, 11:14 AM   #3
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Quote:
Originally Posted by AtlasM View Post
Changing to larger rotors and/or different calipers is a non-trivial project.

Pads are the biggest thing that's going to affect your braking performance, that's the main thing you should focus on. Most of my experience with aftermarket brake pads is on other cars. Some pads that seem to be popular around here are Hawk HPS 5.0, StopTech, Performance Friction, and Cool Carbon, among others. I can tell you that if you want low noise and dust, stay away from Hawk HP+. They stop great but are very loud and dusty.

For rotors, the BMW rotors and similar replacements are good. Holes and slots in rotors don't do really anything performance-wise. They can help shed water off the rotors in the rain, but our cars have a feature called Brake Drying where they lightly pulse the brakes when the wipers are on to clear water off the brakes. So holes and slots are mostly a cosmetic upgrade. If you do want one of these, I'd recommend slots over holes, as holes drilled into the rotor can make them weaker. Another option is if you want to reduce weight, you can get Z4 35is front rotors that are the same size as 335i but a 2-piece design with aluminum hats (the part in the middle) that saves a couple pounds each.

You can make the pedal a lot firmer by going with braided stainless brake hoses. Whenever I've put these on a car I've always liked the firmed up pedal. This is more an upgrade about feel than decreasing your stopping distance. The hoses for the 335xi are unique. StopTech makes a hose kit for the 335xi.

You should also go for a higher-temperature brake fluid. If you get too much heat in the BMW brake fluid and it starts boiling, you get a mushy pedal and brake fade. This is more of a concern on the track, but fluid is a cheap way to give yourself an extra safety net. There's a sticky thread at the top of this forum with boiling points of a whole bunch of brake fluids. Of those, a couple good and not-too-pricey options that you can find without much trouble are Motul RBF600 and Wilwood Hi-Temp 570.
Excellent information! So it sounds like pads is really all I need to start. Dealership just replaced the fluid so I'm good there. I might possibly look at the brake line kit as well. Makes sense anyway.
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      07-21-2016, 11:48 AM   #4
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Quote:
Originally Posted by 550i Beast View Post
Excellent information! So it sounds like pads is really all I need to start. Dealership just replaced the fluid so I'm good there. I might possibly look at the brake line kit as well. Makes sense anyway.
z4 are 0.8lbs lighter each and not worth thew money.
ATE 200 is best brake fluid for the money, I get it locally for $10
m3 master cylinder, used or new aftermarket
performance friction pads are the best
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      07-21-2016, 11:58 AM   #5
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Quote:
Originally Posted by AtlasM View Post
For rotors, the BMW rotors and similar replacements are good. Holes and slots in rotors don't do really anything performance-wise. They can help shed water off the rotors in the rain, but our cars have a feature called Brake Drying where they lightly pulse the brakes when the wipers are on to clear water off the brakes. So holes and slots are mostly a cosmetic upgrade. If you do want one of these, I'd recommend slots over holes, as holes drilled into the rotor can make them weaker. Z4 35is front rotors[/URL] that are the same size as 335i but a 2-piece design with aluminum hats (the part in the middle) that saves a couple pounds each.
Holes/dimples or slots help air ventilation and expel heat so rotors will run cooler and cool off faster because the hot gas will be allowed to escape.
Shortly > not only for decoration.
Z4 are 0.8lbs lighter each.
http://www.e90post.com/forums/showthread.php?t=627141
(same issue as with GC, ECS need to fix their website )
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      07-21-2016, 11:59 AM   #6
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Quote:
Originally Posted by feuer View Post
z4 are 0.8lbs lighter each and not worth thew money.
ATE 200 is best brake fluid for the money, I get it locally for $10
m3 master cylinder, used or new aftermarket
performance friction pads are the best
Ok...performance friction pads...what brand and model do you recommend?
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      07-21-2016, 12:09 PM   #7
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Originally Posted by 550i Beast View Post
Ok...performance friction pads...what brand and model do you recommend?
for track PFC08 for everyday ST SP
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      07-21-2016, 12:57 PM   #8
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Quote:
Originally Posted by feuer View Post
Holes/dimples or slots help air ventilation and expel heat so rotors will run cooler and cool off faster because the hot gas will be allowed to escape.
Shortly > not only for decoration.
Z4 are 0.8lbs lighter each.
http://www.e90post.com/forums/showthread.php?t=627141
(same issue as with GC, ECS need to fix their website )
Fair enough on the weight of the Z4 35is rotors.

Slots and holes might have a small benefit but essentially no modern pads really produce outgassing anymore, so gas is not a concern. As for cooling, the OE rotors are already vented front & rear.

Personally I like slotted rotors and have had them on multiple cars. I like them because the coating keeps the hats from rusting, they look cool in general, and the slots help a bit in the rain. But Brake Drying on our cars minimizes the rain benefit of slots. There aren't many downsides to slotted rotors other than potentially increasing pad wear, but quality of drilled rotors is hit-or-miss. Too many of them end up cracking around the holes.

I'm still planning on slotted rotors for my 335xi when the time comes, but they're really more of a cosmetic upgrade than anything else.

Pretty sure we can agree that in terms of priority of what is going to make the most difference in braking performance, it's pads > fluid > hoses > rotor gimmicks.
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