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      05-22-2010, 07:40 PM   #221
JB135MDCT
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Is there a Smiley for, "THIS THREAD IS WORTHLESS"?
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      05-25-2010, 09:18 PM   #222
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Here are comments from my driver Ralph Warren after using the titanium shims at Buttonwillow and Auto Club Speedway:

“With the TI Speed backing plates installed, we noticed overall improved braking performance in the H-Stock 135i car immediately. With one of the heaviest and most powerful cars in BMW CCA Club Racing, brak performance is very important to us. Although our Hawk DTC-70 brake pads handle the heat quite well, we now have less fade, lower caliper temps, shorter braking distances, more driver confidence and the pads last longer.”
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      06-29-2010, 05:51 PM   #223
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After completely destroying my OEM Brembos in only three track days, I replaced them with 355mm 6-pot Stoptechs. I'm appy to report that, coupled with Hawk DTC-70 pads and Titanium shims, the Stoptechs performed flawlessly, with no fade whatsoever in run sessions up to 25 minutes. Also, I could can swap pads back and forth in just a few minutes. Very pleased.
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      06-29-2010, 10:40 PM   #224
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Quote:
Originally Posted by bradford View Post
After completely destroying my OEM Brembos in only three track days, I replaced them with 355mm 6-pot Stoptechs. I'm appy to report that, coupled with Hawk DTC-70 pads and Titanium shims, the Stoptechs performed flawlessly, with no fade whatsoever in run sessions up to 25 minutes. Also, I could can swap pads back and forth in just a few minutes. Very pleased.
Looks like shims and rotors are 2 major factors to keep heat off the calipers. I haven't found any drop in 2-piece rotors. I started this thread but seems to be dead: http://www.1addicts.com/forums/showthread.php?t=391102.

I think with shims, pads, better rotors, hi-temp fluid and some form of air ducting might work with oem calipers.

Bradford, Any chance you can make some simple measurements to see if a stoptech rotor can fit with oem calipers? I now the diameter is larger but that can be turned down. How do the offsets/thickness compare between the 2 rots? Thanks.
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      06-30-2010, 08:00 AM   #225
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I think with shims, pads, better rotors, hi-temp fluid and some form of air ducting might work with oem calipers.

Bradford, Any chance you can make some simple measurements to see if a stoptech rotor can fit with oem calipers? I now the diameter is larger but that can be turned down. How do the offsets/thickness compare between the 2 rots? Thanks.
The problem with the OEM calipers is that the throat is too narrow. You simply can't get a rotor with sufficient thermal mass in there. The Stoptechs would be too thick. I don't have the exact specs on the OEM throat width but it is very visible looking at the OEM rotor. It's a decent diameter at 13.3" but it's skinny as hell. Looks like a record - makes the Stoptech one look like a manhole cover.

If you want to stick with the OEM setup (I sure didn't want to drop the 3 Gs on Stoptechs, but I'm a very aggressive track driver) your best bet is good fluid, Ti plates, try to stuff a duct in there (not really an option for me on a daily driven car that needs to be able to parallel park and still fit 245mm R-comps up front), and remove the OEM dust shields (or trim them and fashion a flange to use with the ducts to deliver air to the center of the rotor)
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      06-30-2010, 06:08 PM   #226
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Originally Posted by bradford View Post
The problem with the OEM calipers is that the throat is too narrow. You simply can't get a rotor with sufficient thermal mass in there. The Stoptechs would be too thick. I don't have the exact specs on the OEM throat width but it is very visible looking at the OEM rotor. It's a decent diameter at 13.3" but it's skinny as hell. Looks like a record - makes the Stoptech one look like a manhole cover.

If you want to stick with the OEM setup (I sure didn't want to drop the 3 Gs on Stoptechs, but I'm a very aggressive track driver) your best bet is good fluid, Ti plates, try to stuff a duct in there (not really an option for me on a daily driven car that needs to be able to parallel park and still fit 245mm R-comps up front), and remove the OEM dust shields (or trim them and fashion a flange to use with the ducts to deliver air to the center of the rotor)
Assume you have stoptechs up front and oem rear?

Can you elaborate on shield mods without using air pipe? Remove completely or just lower half?

Iv'e seen a 300zx with air guides/funnels mounted to control arms. Anybody try this?
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      06-30-2010, 07:09 PM   #227
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I bought a set of brake spoilers from a Porsche GT3. They are plastic and are meant to snap to the control arm. They are relatively cheap as well (~$30). I didn't get a chance to fit them yet, as they will require some trimming. I think they work better attached to the tension rod, but seem to fit nicely on the wishbone. Both methods will require zip-ties to secure, but shouldn't affect turning the wheels. This seems like an easy way to get some more air-flow to the brakes without a hardcore duct that may be limiting on the street. Hopefully I'll get a chance to try it out.

http://www.suncoastparts.com/mm5/gra...akespoiler.jpg

http://2.bp.blogspot.com/_mmF7kG1eqN...0/DSCN3218.JPG

(Pictures borrowed from suncoastparts.com and blogspot.com)

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      06-30-2010, 10:53 PM   #228
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Quote:
Originally Posted by JB135MDCT View Post
Assume you have stoptechs up front and oem rear?

Can you elaborate on shield mods without using air pipe? Remove completely or just lower half?

Iv'e seen a 300zx with air guides/funnels mounted to control arms. Anybody try this?
That was something I was considering before we ended up going with hoses.

I think part of the problem is the size of the front brakes vs. the rears. The front calipers/pads are huge compared to the rears and probably end up doing too much of the braking, while the rears have too easy a time of it. So one advantage of going with aftermarket brake upgrades is being able to get more rear brake.
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      06-30-2010, 10:58 PM   #229
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Quote:
Originally Posted by scottn2retro View Post
I think part of the problem is the size of the front brakes vs. the rears. The front calipers/pads are huge compared to the rears and probably end up doing too much of the braking, while the rears have too easy a time of it. So one advantage of going with aftermarket brake upgrades is being able to get more rear brake.
The physical size of the rotors and calipers has little to do with "how much" braking is done by that particular set of brakes. Piston size determines brake bias. And I'm pretty sure that the engineers at BMW understand how to compute optimum bias.

The rear brakes do not do little braking because they're small. They're small because they do little braking.
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      06-30-2010, 11:31 PM   #230
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bradford, Did you put stoptech on all 4? Did you calculate the bias before and after brake mods? My experience with e34 M5 is that adding more bias to the rear made a huge difference.
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      07-01-2010, 08:18 AM   #231
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Quote:
Originally Posted by JB135MDCT View Post
bradford, Did you put stoptech on all 4? Did you calculate the bias before and after brake mods? My experience with e34 M5 is that adding more bias to the rear made a huge difference.
I did front only. The Stoptech kits are designed to be balanced when combined with the OEM rear setup as well.

http://stoptech.com/Products/BBK/balance.shtml

While doing the Stoptech rear kit may yield some benefit, it's definitely a case of diminishing returns for the money spent. There are certainly more effective ways to spend $2k+ on this car.
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      07-01-2010, 05:53 PM   #232
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Bradford, Thanks, Hope you will update us with any more improvements.
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      07-03-2010, 04:25 PM   #233
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Quote:
Originally Posted by bradford View Post
The physical size of the rotors and calipers has little to do with "how much" braking is done by that particular set of brakes. Piston size determines brake bias. And I'm pretty sure that the engineers at BMW understand how to compute optimum bias.

The rear brakes do not do little braking because they're small. They're small because they do little braking.
Hehe, have you owned a car with the same sized brakes on all 4 corners? We do.
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      07-05-2010, 05:29 PM   #234
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Quote:
Originally Posted by bradford View Post
The physical size of the rotors and calipers has little to do with "how much" braking is done by that particular set of brakes. Piston size determines brake bias. And I'm pretty sure that the engineers at BMW understand how to compute optimum bias.
This is not quite correct. Piston size is one variable but there are so many others including; ratio of master cylinder piston to slave cylinder pistons, number of slave pistons, the distance these pistons are acting out from the centre of the wheel/disc carrier, pad material etc, etc.

The "The rear brakes do not do little braking because they're small. They're small because they do little braking." is certainly correct. Weight transfer under braking means that there's little weight over the rears so little force needed before lockup.
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      07-05-2010, 09:25 PM   #235
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Hehe, have you owned a car with the same sized brakes on all 4 corners? We do.
Please elaborate. Sounds like an expensive corner weight that reduces your suspension dynamics.

Last edited by JB135MDCT; 07-05-2010 at 10:25 PM.
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      07-06-2010, 10:51 PM   #236
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Quote:
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Please elaborate. Sounds like an expensive corner weight that reduces your suspension dynamics.
I also own this car which has the big StopTech kits on all 4 corners. Car stops like it has a parachute The fronts are still doing more work than the rears (for reasons mentioned above), but they aren't getting overworked.

Large size
http://www.bimmerfest.com/photos/sho.../size/big/cat/

http://www.bimmerfest.com/photos/sho...14310/size/big

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Last edited by scottn2retro; 09-10-2010 at 04:39 PM.
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      07-07-2010, 04:36 AM   #237
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Quote:
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The "The rear brakes do not do little braking because they're small. They're small because they do little braking." is certainly correct. Weight transfer under braking means that there's little weight over the rears so little force needed before lockup.
And to add to that, they "can" be small because they do less braking than front brakes. Less braking means less heat, and that means a smaller rotor "can" be used as the rotor size is purely a function a heat, not braking performance. Same for caliper (not piston) and pad size. Larger caliper and pads do not equal better braking performance per se. They just generally insure great thermal consistency during braking, which means harder braking for longer.
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      07-07-2010, 08:38 AM   #238
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Quote:
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I also own this car which has the big StopTech kits on all 4 corners. Car stops like it has a parachute The fronts are still doing more work than the rears (for reasons mentioned above), but they aren't getting overworked.

Large size
http://www.bimmerfest.com/photos/sho.../size/big/cat/

Assume the rear are 4 pot? Do you no the brake bias between front and rear for stoptech and oem? By adding more bias to rear should take some heat off the front and/or shorter stopping distance
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      07-07-2010, 08:54 PM   #239
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Assume the rear are 4 pot? Do you no the brake bias between front and rear for stoptech and oem? By adding more bias to rear should take some heat off the front and/or shorter stopping distance
All 4 corners have the 4 pot 355 kit (the calipers can barely clear the 18" wheels). The mod class cars are allowed to have adjustable brake bias, but we just have the OEM ABS setup.
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      08-18-2010, 08:46 AM   #240
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random thought. the front rotors and calipers sound like they are more suited for the rear of the car, anyone consider doing a big break front and just swapping the OEM front breaks to the back of the car? the bias shouldn't change much as that's pretty controlled by the lines used by the manufacturer and the amount of break bias they choose for the car. it would just be a beefier break on the back.... unnecessarily so, but it would work.
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      08-18-2010, 11:08 AM   #241
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random thought. the front rotors and calipers sound like they are more suited for the rear of the car, anyone consider doing a big break front and just swapping the OEM front breaks to the back of the car? the bias shouldn't change much as that's pretty controlled by the lines used by the manufacturer and the amount of break bias they choose for the car. it would just be a beefier break on the back.... unnecessarily so, but it would work.
Don't agree with your bias theory. But, since you came up with the idea, we all decided that you can see if it will fit.
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      08-18-2010, 11:44 AM   #242
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Don't agree with your bias theory. But, since you came up with the idea, we all decided that you can see if it will fit.
anyone have a doner set of 135 front calipers for me to try this with as i'm unwilling to part with 3000 for the stoptech brakes this week?

i have a lot more i want to do before i get to my breaks. however if there were a donor set, i would actually try this.

P.S. i'm glad you were all able to come together and discuss this so quickly and voluntell me :P
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