Time for Brake System Upgrade

[BiscottiGelato]

So I have finally beaten the stock pads to sh_t and it's time for a change... Summarizing what I know regarding the 135i Brake System before asking further questions...

Compared to the major rivals in the class, 135i have some of the weakest brakes, thinnest rotors and the worst aftermarket support. The piston issue doesn't lend any help in the situation.

135i - 338 x 26mm Front, 324 x 22mm Rear.
335i - 345 x 30mm Front, 336 x 24mm Rear.
Subaru STi - 326mm x 30mm Front, 316 x 20mm Rear.
Evo X - 348 x 32mm Front, 328 x 22mm Rear.

There have been a few discussions on trying to fit bigger rotors on the 135i without going for 3k+ BBKs over the past year, but nothing have came to fruition. Yet, there doesn't seem to be a very major outcry or real traction in putting something together other than a few's individual efforts. Afterall 90% of the posts on this subforum is still pre-dominantly on discussion over Suspension rather than Brakes. So my question is, have we deemed that the 135i braking system is sufficient given minor upgrades, such as pads, backing plates/piston replacements, or even stock sized aftermarket rotors? Or have everybody already went for real deal BBKs due to the lack of any options?

On a slightly different note, if I say that someone might be able to mass produce caliper brackets like the Dieselboost ones, which allows fitment of the Z4 M ZCP/M3 CSL rotors (345mm x 28mm), how much interest would there be? If there's sufficient interest, it might actually be possible.

[chachacha28]

I still havent forgotten about you guys, and will do a dieselboost write-up/review when i get my car back.

I am very interested in a similar solution for the rears as well, either a 335i rear rotor with the stock 135i caliper, or a complete 335i rear brake solution. I tried to find some info on piston sizes, but couldnt. I think they would compliment each other very nicely.

edit: i cant believe the sti has such weenie brakes! another brembo product.

[BiscottiGelato]

For the STi, I think the additional 4mm thickness makes a bigger difference than the diameter of the rotors? Thicker rotors allows more air to be sucked inside for cooling?

[chachacha28]

Originally Posted by BiscottiGelato

For the STi, I think the additional 4mm thickness makes a bigger difference than the diameter of the rotors? Thicker rotors allows more air to be sucked inside for cooling?

i was comparing it to the evo.

I wish we werent so limited with our calipers, as far as rotor thickness went though.

[BiscottiGelato]

Originally Posted by ezeedee

i was comparing it to the evo.

I wish we werent so limited with our calipers, as far as rotor thickness went though.

Yeah. The Evo definately seems to have nice sized brakes. I think it's one of the few OEMs that actually gets calipers that have the actual 'Brembo' branding on the front. The MR option package also gives them 2 pieces front rotors stock.

[BiscottiGelato]

Bigger rotors seems to be going no-where. The lack of aftermarket (cheap non-cross-drilled) options at the 345mm x 28mm size is also a problem. Unless we can start fitting 345mm x 30mm rotors (e90/e92) into the caliper then that's a whole different ballgame...

So here's what I'm thinking as a 3 stage brake upgrade.

1. Power Slot rotors at stock sizes, Ferodo DS2500 pads, F30 backing plate. Planning to go without Ti Shims...

2. Piston and seal change, either to Turner's solution, or whatever solution RacingBrake is able to churn out in a month or 2 down the road.

3. See if there's a cheap way to upsize rotors half a year to a year down the road.


Feedbacks? Comments? Anybody got any experience with power slot rotors? Any reviews on their directional vane design? Thanks!

[Focusedintntions]

I'll be testing a 350 x 28 mm rotor along with the piston rebuild kit RB is making...

Sadly w/o changing calipers a wider rotor isn't possible. I'm betting this is the last real thing we can try w/o having to go to a true BBK.

Originally Posted by BiscottiGelato

Bigger rotors seems to be going no-where. The lack of aftermarket (cheap non-cross-drilled) options at the 345mm x 28mm size is also a problem. Unless we can start fitting 345mm x 30mm rotors (e90/e92) into the caliper then that's a whole different ballgame...

So here's what I'm thinking as a 3 stage brake upgrade.

1. Power Slot rotors at stock sizes, Ferodo DS2500 pads, F30 backing plate. Planning to go without Ti Shims...

2. Piston and seal change, either to Turner's solution, or whatever solution RacingBrake is able to churn out in a month or 2 down the road.

3. See if there's a cheap way to upsize rotors half a year to a year down the road.


Feedbacks? Comments? Anybody got any experience with power slot rotors? Any reviews on their directional vane design? Thanks!

[BiscottiGelato]

Originally Posted by Focusedintntions

I'll be testing a 350 x 28 mm rotor along with the piston rebuild kit RB is making...

Sadly w/o changing calipers a wider rotor isn't possible. I'm betting this is the last real thing we can try w/o having to go to a true BBK.

When will you have some results? I have to change my pads/rotors very very soon. It's running so thing that I can't run another HDPE without a new set of pads/rotors...

[Focusedintntions]

Well i'm waiting on the parts so soon as I get them. Right now I should be getting stuff end of July/early august. Next event I can do is August 27/28 in that month.

[BiscottiGelato]

Have you already custom fabricated a caliper bracket/adaptor?

[uberschnell]

Originally Posted by BiscottiGelato

For the STi, I think the additional 4mm thickness makes a bigger difference than the diameter of the rotors? Thicker rotors allows more air to be sucked inside for cooling?

I think you may be off here. Think of a breaker bar. The lower you grip it the more force it takes to loosen a bolt. The higher you grip it the less force it takes to loosen that same bolt.

So theoretically the more force (energy) you need to slow down a rotor the more heat is generated. The further you move away from the fulcrum the less brake force you need to achieve the same result.

The thicker a rotor is the more heat it can absorb. The design (1 piece vs 2 piece, vane shape and form) effects how quickly it will cool down and how it will conduct heat.

Number of pistons is less important then overall piston surface area.

[uberschnell]

Here is some interesting info I found:


-The brakes function by converting the kinetic energy of the car into thermal energy during deceleration - producing heat, lots of heat - which must then be transferred into the surroundings and into the air stream.

- The amount of heat produced in context with a brake system needs to be considered with reference to time meaning rate of work done or power. Looking at only one side of a front brake assembly, the rate of work done by stopping a 3500-pound car traveling at 100 Mph in eight seconds is 30,600 calories/sec or 437,100 BTU/hr or is equivalent to 128 kW or 172 Hp. The disc dissipates approximately 80% of this energy. The ratio of heat transfer among the three mechanisms is dependent on the operating temperature of the system. The primary difference being the increasing contribution of radiation as the temperature of the disc rises. The contribution of the conductive mechanism is also dependent on the mass of the disc and the attachment designs, with disc used for racecars being typically lower in mass and fixed by mechanism that are restrictive to conduction. At 1000oF the ratios on a racing 2-piece annular disc design are 10% conductive, 45% convective, 45% radiation. Similarly on a high performance street one-piece design, the ratios are 25% conductive, 25% convective, 50% radiation.

-Repeated hard stops require both effective heat transfer and adequate thermal storage capacity within the disc. The more disc surface area per unit mass and the greater and more efficient the mass flow of air over and through the disc, the faster the heat will be dissipated and the more efficient the entire system will be. At the same time, the brake discs must have enough thermal storage capacity to prevent distortion and/or cracking from thermal stress until the heat can be dissipated. This is not particularly important in a single stop but it is crucial in the case of repeated stops from high speed

[BiscottiGelato]

Mtek. Make sense and great info!. I guess the STi rotors have their own sets of problems. At least their calipers allows for thicker rotors so if they do get some sort of bracket fabricated, they can mount nice big and thick rotors onto their axels.

I guess I'll stick with Power Slot and Ferodos for now. Hopefully FocusedIntensions will have some breakthrough late July which all 1 series enthusiast can model after.

And don't get me wrong Focused. Your spirit to explore is greatly appreciated!

[BiscottiGelato]

Focused, these are the ones you are trying to get fitted to the 135i front, correct?

http://www.ecstuning.com/Porsche-200...ear/ES2515722/

[Focusedintntions]

yes that rotor ring...but it's have our hat/offset to it.

[BiscottiGelato]

so short of bigger rotors and/or RB... what rotors did everybody get?

[andrey_gta]

I have seen some where 135i calipers used with e46 rotors from m3 or 330 zhp
i think it was a z3

[Focusedintntions]

Originally Posted by BiscottiGelato

so short of bigger rotors and/or RB... what rotors did everybody get?

I've been running with some ebc rotors very happily for over a year and they've taken quite a bit of track abuse. They're finally toast and no good for track, but they're fine for street. I have a set of really cheap R1 rotors sitting on the shelf to replace them for the street. They're slotted but nothing special.

[BiscottiGelato]

The EBC rotors aren't exactly cheap either. Are they really any better than stock blanks or cheaper slotted rotors?

[Focusedintntions]

http://shop.autoanything.com/brakes/61A3865A0A0.aspx

Those are the ones I use for the street and track use...and yeah last way better than the stock ones. If you shop around you might be able to find them a bit cheaper

If you really want to go cheap try the R1 rotors...they're about the cheapest I found. I just haven't tested them yet.

[tro-nik]

Originally Posted by BiscottiGelato

So I have finally beaten the stock pads to sh_t and it's time for a change... Summarizing what I know regarding the 135i Brake System before asking further questions...

Compared to the major rivals in the class, 135i have some of the weakest brakes, thinnest rotors and the worst aftermarket support. The piston issue doesn't lend any help in the situation.

135i - 338 x 26mm Front, 324 x 22mm Rear.
335i - 345 x 30mm Front, 336 x 24mm Rear.
Subaru STi - 326mm x 30mm Front, 316 x 20mm Rear.
Evo X - 348 x 32mm Front, 328 x 22mm Rear.

There have been a few discussions on trying to fit bigger rotors on the 135i without going for 3k+ BBKs over the past year, but nothing have came to fruition. Yet, there doesn't seem to be a very major outcry or real traction in putting something together other than a few's individual efforts. Afterall 90% of the posts on this subforum is still pre-dominantly on discussion over Suspension rather than Brakes. So my question is, have we deemed that the 135i braking system is sufficient given minor upgrades, such as pads, backing plates/piston replacements, or even stock sized aftermarket rotors? Or have everybody already went for real deal BBKs due to the lack of any options?

On a slightly different note, if I say that someone might be able to mass produce caliper brackets like the Dieselboost ones, which allows fitment of the Z4 M ZCP/M3 CSL rotors (345mm x 28mm), how much interest would there be? If there's sufficient interest, it might actually be possible.

I use discs (345mm x 28mm) for more than 4 months.
All great.

Ready to provide adapters for testing.
Without the money!

[BiscottiGelato]

Originally Posted by tro-nik

I use discs (345mm x 28mm) for more than 4 months.
All great.

Ready to provide adapters for testing.
Without the money!

So where can we get this? I have money ready in hand...