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Motorsports & Track Forum
From Auto-X to Trackday to Racing and Professional Motorsports this is the place to discuss making BMWs fast

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Old 07-04-2005, 12:19 AM   #1
gbn
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Inexpensive Brake Upgrades

I have a '02 325i with sport package. I have Axxis Metal Master pads and need new rotors. I can't afford a big brake kit but would like to have a little more stopping power. The OEM rotors were ok. I've done a little research into slotted, cross drilled (staying away from them), frozen and combinations. Anybody have any "real" test data with stopping distances? If not do the frozen rotors really last 2 to 3 times as long?

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Old 07-04-2005, 09:06 PM   #2
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Metal braided brake lines will help alot with feel but will not shorten your distances noticeably if at all.
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Old 07-05-2005, 01:25 PM   #3
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If you go to 17" or 18" wheels The rotors & calipers from a 330 E46 should fit. You'll need the mounting hardware also. A possilble source would be from someone how installed a big brake kit.
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Old 07-05-2005, 08:40 PM   #4
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I already have steel brake lines and the sport package (17" wheels). Has anyone done the 330i brake upgrade? How much better is it really? Should I save my $ for a big brake kit instead? Also, how effective are the slotted rotors anyway, any experiences out there folks?
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Old 07-05-2005, 09:27 PM   #5
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Nothing much will give you shorter stopping distances. The main thing youll get from ugraded calipers and rotors(330 or BBK) is less fading from repeated hard stops.

Yes people have done 325-->330 upgrades. I beleive changing some of the suspension is also necessary.
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Old 07-07-2005, 03:07 AM   #6
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I believe UUC came out with an OE brake upgrade.
Check it out http://www.uucmotorwerks.com/rotors
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Old 08-14-2005, 11:45 AM   #7
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If the low dust ceramic pads that UUC is refering to are the HPS, then I would advise you to stay away from them (for the track usage).

I've gone through a set of Hawks HPS, one set of Hawks HP+, and now on my 2nd set of Hawks HP+ since may.

HP+ >>>>>>> HPS on the track.

As for slotting the rotors, I don't really find it necessary. Maybe with Hawks Blues?


Now for your original question. If you want better stopping power, get Hawks HP+. They squeal like there is no tomorrow, are dusty like crazy, but you will stop a lot harder.
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Old 08-15-2005, 02:01 PM   #8
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Hawh HPS pads are NOT designed for track use. The HP are. Slotted rotors are nice. They will help disapate gasses between the pad and rotor which does decrease stopping distance, but you're only talking a few feet at 60mph. Slotting also helps to disapate water off of the disc in the rain. Drilled rotors are more for looks than real benefit IMO. They are also more prone to cracking. Larger brake kits decrease stopping distance in two ways: First, the amount of brake pad and rotor area is increased which increase the amount of area that the pads and rotors contact each other, hence, more friction. Second, the larger area and better cooling characteristics of upgraded rotors helps to disapate heat. Cool brakes are happy brakes.
If you want to increase your stopping distance significantly, you will want to look into a big brake kit. If you want to increase your overall performance, a good slotted rotor and pad will work nicely. I have Disc Brake Australia 4000 series slotted rotors and Hawk HPS pads. Like I said, it decreases distance by a few feet at 60 mph, but the brakes hold up much better after repeated braking. I have no direct experence with Cryo treated rotors.
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Old 08-15-2005, 09:00 PM   #9
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In my opinion, BBK ought to be the last thing you do.

There are plenty of pads that will offer more stopping power than you need.

As pointed out by rnitti and myself, HPS are not for track. They are an OEM pad with no dust.

HP+ will bite a lot harder, wear out your rotors faster (2 sets pads per rotor).

HP Blue (you best be tracking to use these)

Then there is Gransport with their GS4, GS3, GS2 and GS1 pads. GS3 might be interesting to look at.

rnitti:

I know the argument for slotting rotors, but i don't think we are using pads that require them.
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Old 08-15-2005, 11:26 PM   #10
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Quote:
Originally Posted by rnitti
Larger brake kits decrease stopping distance in two ways: First, the amount of brake pad and rotor area is increased which increase the amount of area that the pads and rotors contact each other, hence, more friction. Second, the larger area and better cooling characteristics of upgraded rotors helps to disapate heat. Cool brakes are happy brakes.
Larger brakes dont make you stop quicker. Actually in some tests they increased the stopping distance. Your car can only stop as quickly as your tires allow. The stock brakes have plenty of power to lock up.

The main benefits of BBK are seen on the track after repeated hard braking
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Old 08-16-2005, 09:36 AM   #11
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Quote:
Originally Posted by vaio76109
Larger brakes dont make you stop quicker. Actually in some tests they increased the stopping distance. Your car can only stop as quickly as your tires allow. The stock brakes have plenty of power to lock up.

The main benefits of BBK are seen on the track after repeated hard braking
Yup. Although if you could exert more pressure to the disc, then you would slow down faster if the tires would allow it. I think that this might be true at very high speeds.
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Old 08-16-2005, 12:25 PM   #12
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Bigger brakes will, and do, decrease stopping distance on the track. So to say that big brakes may actually increase distance is only half correct. You are correct with saying that big brake kits are for very high speeds with racing tire/slicks. Racing slicks/tires will loose traction at a much higher thereshold that street performance tires will; thus, the car will stop more quickly due to the tires being able to maintain grip. Big brake kits will serve no real purpose on the street other than to look nice. The reason that big brake/high performance kits may increase distance on the street is because the brakes don't generate enough heat to take advantage of the aggressive pad compounds. Also, street compound tires will skid far sooner that racing tires/slicks will.

Last edited by rnitti; 08-16-2005 at 12:35 PM.
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Old 08-16-2005, 02:48 PM   #13
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Quote:
Originally Posted by jmsanders78
Yup. Although if you could exert more pressure to the disc, then you would slow down faster if the tires would allow it. I think that this might be true at very high speeds.
The stock calipers have no problem exerting enough pressure on the pad/disk to lock up the brakes/tires. The tires are the limiting facotrs here.
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Old 08-16-2005, 02:59 PM   #14
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Quote:
Originally Posted by rnitti
Bigger brakes will, and do, decrease stopping distance on the track.
For the first couple of hard stops no, the braking distance will be relatively the same. Its after several repeated hard stops that BBK come into their own because the stock brakes are fading/faded, thats when the BBK will give roughly the same stopping distance as the stock brakes gave originally. The braking might be even better at this point because if you have track pads(which take a while to get up to optimal temp) theyll be up to temp...
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Old 08-17-2005, 09:48 AM   #15
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Quote:
Originally Posted by vaio76109
The stock calipers have no problem exerting enough pressure on the pad/disk to lock up the brakes/tires. The tires are the limiting facotrs here.
Then why do race pads stop the car faster?

For STREET applications I agree with you. For track applications I believe that the stock calipers are great, and a BBK isn't on my list of stuff to buy.
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Old 08-17-2005, 11:07 AM   #16
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Race Pads stop the car faster than street pad simply because the pad compound has a higher coeficient of friction.

Higher friction = stop 'faster' = shorter lifetime

I find that the stock calipers are good for some track, but they need time to properly cool down between sessions. I'm already on my third set of calipers up front since may.
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Old 08-17-2005, 01:24 PM   #17
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Quote:
Originally Posted by Asmodeus
Race Pads stop the car faster than street pad simply because the pad compound has a higher coeficient of friction.
Yes, I know this. I was making a point. If more friction in the brakes can stop the car faster, then the tires aren't always the limiting factor. Such as under track conditions at track speeds with r-comp tires.

Quote:
Originally Posted by Asmodeus
I find that the stock calipers are good for some track, but they need time to properly cool down between sessions. I'm already on my third set of calipers up front since may.
Yeah. I didn't look to see what kind of car you have, but I find that the calipers don't last too long. It's not actually the calipers but rather the dust boots. I replace my front calipers in the middle of last season and they needed it again at the beginning of this season. But instead of buying new ones this time, I rebuilt them myself.
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Old 08-17-2005, 11:36 PM   #18
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Quote:
Originally Posted by rnitti
Bigger brakes will, and do, decrease stopping distance on the track.
No they do not. If the brake pad compound is the same (as well as tires and rotors), it won't matter. The difference will be the amount of heat absorbed/dissipated. While that can translate into the brake pad being a little more effective, it really comes down to picking the right pad compound for the job. Use the wrong pad with any sized caliper and it's not going to matter about anything else; fade is fade.

http://scirocco.dyndns.org/faq/brake...n/pfpage1.html

Quote:
The Wheels and Tires
Time to get down to business--and time to stop the car. Because the wheel and tire are mechanically bolted to the rotor, the torque is transferred through the whole assembly: rotor, hub, wheel and tire. And now, the moment we have all been waiting for: It is the interface between the tire and the road that reacts to this torque, generating a force between the tire and the road that will oppose the motion of the vehicle.

Ladies and gentlemen, this is what stops the car--not the brake pads, not the rotors, not the cool stainless steel brake lines. It's the road reacting against the tire.
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Old 08-18-2005, 12:21 AM   #19
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More force = more friction. Higher friction coefficient = more friction. A couple of ways to skin the cat. If you don't have the tires to take advantage of it, it doesn't matter.
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Old 08-18-2005, 07:55 AM   #20
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Quote:
Originally Posted by jmsanders78
More force = more friction. Higher friction coefficient = more friction. A couple of ways to skin the cat. If you don't have the tires to take advantage of it, it doesn't matter.
Bigger brakes don't offer more force. You aren't changing the proportion of the braking force from the brake master cylinder. The same force is just spread over a wider pad, but it's the same force.
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