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Discussion Starter #1 (Edited)
In an attempt to mitigate any flaming, I have been reading through dozens of threads on brakes, and generally feel that I understand the benefits and limitations of most of the kits. I am generally a fan of stock parts in general, and like the durability of stock solid rotors, but reasons for the switch are listed below.

Up front, I don't plan on tracking my M5, but plenty of spirited driving and the occasional autocross. My main concern is when I get out of the Army and drive my M5 back home to the SF Bay, I'm going to take HWY 1 from LA up to Santa Cruz (yeahhh... you Cali guys know what I'm talking about, it's going to be a blast. Gas will be used in a highly inefficient manner.) So the name of the game is Heat Dissipation- it's a long drive. Also will be taking routine drives up 9 to Alice's.

Research has yielded the general consensus that converting over to M-Tech style brake ducts don't actually cool the brakes all that much unless you install added flexible tubing/ducting straight to the hub- I don't want to do that. Daily Driver car.

Simply put, I don't have the capital to go after a full Stoptech or Brembo BBK, or do the BMW Performance brake conversion- that money would instead be spent on my 240Z racecar.

Simple and inexpensive upgrades are the Euro-style floating rotors (~$520/pair at @ ECS) or the StopTech Sport Slotted rotor (~$200/pair @ RockAuto). Yes the slots are generally accepted as giving better "bite", but my interest lies in StopTech's claim of having a superior cooling vane design for improved cooling (but these are 1-piece rotors). I REALLY like the look of StopTech's AeroRotor- best of both worlds... 2-piece, slotted, "Aero Vane" (whatever that's supposed to mean), but can't seem to find them for E39 M5 application. As such, a by-vehicle search on StopTech's website yielded the following options:

<table class="Centered" rules="all" id="PartIntDataGrid" border="1" cellspacing="0"><tbody><tr class="alternate" valign="top"><td align="left">High Carbon Cryo Treated Rotor</td><td style="width:150px;">125.34062CRY</td></tr><tr valign="top"><td align="left">StopTech Sport Cryo D&S Rotor Left</td><td style="width:150px;">127.34062CL</td></tr><tr class="alternate" valign="top"><td align="left">StopTech Sport Cryo Drilled Rotor</td><td style="width:150px;">128.34062CL</td></tr><tr valign="top"><td align="left">StopTech Sport Drilled and Slotted Rotor</td><td style="width:150px;">127.34062L</td></tr><tr class="alternate" valign="top"><td align="left">StopTech Sport Slotted Brake Rotor</td><td style="width:150px;">126.34062SL</td></tr><tr valign="top"><td align="left">StopTech Sport Slotted Cryo Rotor</td><td style="width:150px;">126.34062CSL</td></tr><tr class="alternate" valign="top"><td align="left">StopTech Sport X-Drilled Brake Rotor</td><td style="width:150px;">128.34062L</td></tr></tbody></table>
we'll just nix any drilled options due to structural integrity, leaving Cryo treated or slotted as the only 2 viable options.

I plan on getting Hawk or StopTech street performance pads unless there's a recommendation for something clearly superior for my needs. Car came with fresh Nitto NT555's, which is what she will be riding back to the Bay (for the record, they seem like good tires from the limited idiot-driving I have done so far. I had Hankook Ventus V12's on my E39 540i/6 that I really liked. Dunlop Direzza Z2's on the 240Z for autocross, really like them but wear faster than what I'd want on a daily. Pilot Sport PS2's on my M3- no comment needed.)

I will likely do SS braided lines when I do the rotor swap, may as well, although I see it more as a preventative maintenance piece than anything else (I didn't notice much of a difference when I put them on my 540, had a full GT1 bleed at the Stealership in conjunction.) But again my emphasis is on heat dissipation rather than bite- but having some oomph for emergency stops is always nice.

Circling back to original question, haven't seen much of a comparison between these two OE-sized rotors (or really any at all talking about how well the StopTech's slotted rotors deal with heat instead of bite.) I plan on keeping the rear rotors stock (for reference, only have seen Euro rears that are drilled... wtf?)

If I really have to go with the brake ducting, I will- that would probably limit me to StopTech's instead of Euro's simply from a cost standpoint (ducts plus wheel well liners in the neighborhood of 200-300$, would cut the front plastic grill to give it a E36 M3-style look with the ducts). But I like the idea of increased aerodynamics by not adding extra holes to the nose of my car- however minimal it may be.

Thanks in advance.
 

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I have been running Euro floating rotors - SS line , etc See signature. The floating rotors are lighter which is a huge plus, and I have tracked my car with wonderful results.
 

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Discussion Starter #3
I have been running Euro floating rotors - SS line , etc See signature. The floating rotors are lighter which is a huge plus, and I have tracked my car with wonderful results.
No ducts? Didn't see it in signature, just wanted to confirm.
 

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Research has yielded the general consensus that converting over to M-Tech style brake ducts don't actually cool the brakes all that much unless you install added flexible tubing/ducting straight to the hub- I don't want to do that. Daily Driver car.
Where did you find said consensus....the M tech ducts work quite well at dissipating rotor heat for the type of driving you're doing.
 

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I would also say that opening the brake ducts into the wheel well is very helpful and all you'd need to do. I would also steer away from the Stoptech street pads and use something like the Centric semi-metallic pads instead. The stock front rotors will be fine for your application, just have fresh fluid, oh and the next step would be to just use Ti plates between the pad backing plate and piston. The first things you need to worry about are too much heat transfer to the fluid (conduction into piston) and baking the piston dust covers and seals -- the Ti plates work wonders to greatly reduce those two concerns especially as pad thickness goes down.
 
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Discussion Starter #7
Where did you find said consensus....the M tech ducts work quite well at dissipating rotor heat for the type of driving you're doing.
About 15 threads or so here on M5Board. Its definitely increasing airflow in the wheel well, but it seems to be only a fraction as effective as using flexible hose/ducting to continue straight the hub area in addition.
But if just the stock ducts work, they work. I just don't want to do it if there is little to no gain- cost/benefit analysis.

CSBM5- thanks for the head's up on the Stoptech pads. Ti plates is a good suggestion- I hadn't actually seen that mentioned in Any of the threads I went through. Do you know of a brand for those?
I had seen Centric also mentioned, just hadn't read as much feedback as the other two.
I am generally of the mentality of wanting a softer pad, to wear the pad out as opposed to the rotor- especially if I do go with the Euro rotors, they're quite expensive compared to pads. I'm guessing the OEM pad is also semi-metallic, so I will definitely look into the Centric. Any opinion on Hawks?
I would predict that a reputable brand ceramic pad with slotted rotors might be a good combo.
Regardless, I want those Ti plates!
 

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I would also say that opening the brake ducts into the wheel well is very helpful and all you'd need to do. I would also steer away from the Stoptech street pads and use something like the Centric semi-metallic pads instead. The stock front rotors will be fine for your application, just have fresh fluid, oh and the next step would be to just use Ti plates between the pad backing plate and piston. The first things you need to worry about are too much heat transfer to the fluid (conduction into piston) and baking the piston dust covers and seals -- the Ti plates work wonders to greatly reduce those two concerns especially as pad thickness goes down.
Do you have experience using these? Was always curious about there effectiveness in real world scenarios.
 

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Why do you believe that the stock brakes will not have enough ability to dissipate heat during driving on the street?
 

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Do you have experience using these? Was always curious about there effectiveness in real world scenarios.
Yes, and on track they have a dramatic effect at shielding the dust covers from radiation heat transfer in addition to increasing insulation in the conduction heat transfer path between the backing plate and piston (i.e. you pick up two thermal interface resistances plus the small contribution of the low conductivity Ti...say small since the Ti plate thickness is small). This is especially effective as pad thickness decreases since that is a major insulator between the rotor/pad interface and the piston. Many years ago, on track using R-comps, I melted a piston seal and roasted the dust cover of the stock calipers (before Stoptech BBK) using PFC 01 pads. They were down to maybe 1/3rd thickness.

I ended up going to the Stoptech BBK, using PFC01 still, and using Ti plates with the BBK...zero issues after that with anything brake related, BUT I do believe that simply using Ti plates with the stock calipers, race pads, Motul brake fluid, open brake ducts, is likely fine for even heavy tracking with a nicely setup car on R-comps for a typical 20min session.

Zeckhausen sells the Ti plates/shims and also hardbrakes.com. You need to make sure the ones you use with the stock pads have a relief for the spring clip btw.

Cheers,
Chuck
 

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Discussion Starter #11
Why do you believe that the stock brakes will not have enough ability to dissipate heat during driving on the street?
Santa Monica to Santa Cruz on HWY 1 is roughly 400 miles of twisty, fun canyoning roads (especially between San Louis Obispo and Carmel.) I expect to make at least 1 gas stop during the drive, but other than that, it's a lot of acceleration & braking, little cruising (especially "spirited" driving.)

Do I think the stock brakes will fail me? Not especially. Do I want to safeguard and make sure my fun won't be compromised during the long drive? Of course.

I don't see why wanting to protect against brake fade is a bad thing? Unless you know of a downside to improving brakes? Especially if I'm going to replace pads and rotors anyways, why would I NOT want to go with the best option for my parameters?
 

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Who said it was bad? Do your parameters include cost or longevity? The best option might be the stock components.

If you think you will be doing 400 continuous miles that will fade the stock brakes for the duration of the drive then you have a lot of other issues with the car that will need to be managed ;)

Good luck and have a great trip.
 

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The best option might be the stock components.
Says the guy who replaced the stock drive train with parts from a Chebby truck, and buys his oil from Walmart....
 

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Says the guy who replaced the stock drive train with parts from a Chebby truck, and buys his oil from Walmart....
I was fairly confident about what parts would meet my criteria :)

I only have 2 parts from a truck :eek:
 

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I was fairly confident about what parts would meet my criteria :)

I only have 2 parts from a truck :eek:
Wait...I thought it was a Thomas school bus that supplied that stuff?
 
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