BBK for a 128i

[pj.rodriguez]

Originally Posted by Kgolf31

Have you driven on the track yet? Going full bore track pad will end up with you braking like crap. Braking on the track takes some work, and IMO if you run a HP+ or like pad for the first event or too, it might help you learn what to do and not to do.

If you're going to be removing pads, the bit of extra time to prep the rotor won't be the end of the world, IMO.

The first couple times on the track, you won't be able to use a track pad effectively.

I have not taken the 1er on the track yet, but I've tracked other cars here and there. I will definitely go stock pads for the first time out, but I have a feeling that I know when the limits will be had. I could then transition over to HP+ for a couple of track sessions and then we'll see where I stand. Right now winter just started and I'm extremely anxious to get up and get tracking.

[Kgolf31]

Originally Posted by Blacksport

I'm not going to argue with you, Kgolf, but just a couple of points: the BMW/Brembo BBK is heavier than the stock 128 setup: who cares? Yes, moment-of-inertia and gyroscopic effect have changed a little, but you won't feel it; but you'll definitely feel the better brakes.

"You will not stop any faster"? Think of it this way: you push the brake pedal firmly, but not activating the anti-lock, let's say the pressure on the brake line is 1000psi...that pressure has an EASIER time stopping a 13" rotor than an 11" rotor...it's simple physics...

Unsprung weight is equal to 4 to 10 times more of sprung weight. That is why it matters so much. Why do people go lightweight wheels when they are only shaving ~6lbs or so from each wheel?

It is rotating mass, when ever you increase weight on rotating mass YOU WILL FEEL IT. Especially more-so on a low HP car. Going like for like, before and after...your braking distance will INCREASE, not decrease.

If you're using the same brake compound before and after, you will not decrease braking distance. It really is simply physics. Static friction has more force than dynamic friction. So simply ditching the money that you are going to throw away with buying BMW "BBKs" (if you really want to call it that) you can upgrade tires and gain more traction, and thus brake harder/faster. There is still a reason why Bimmerworld runs stock brakes on their World Challenge Touring car.


Please, I know you think I'm some stupid guy...but just because I don't drink the purple kool-aid and go with majority doesn't mean I'm wrong.


Oh, and sources because I can back up my info:

http://www.modified.com/roadtests/07...t/viewall.html

[Blacksport]

Jeez, Kgolf, what is wrong with you???

If you drove 2 128's 1 with the BMW/Brembo setup and 1 with the stock setup, without seeing the brakes...you would NOT be able to tell which car had the slightly extra weight from the BBK...but you COULD tell which car had the better brakes, trust me on this....purple Kool-Aid and the majority have nothing to do with it.

A bigger rotor has more leverage than a smaller one.
A caliper mounted further from the hub will have more leverage.
An aluminum caliper will dispense more heat that an iron one.
4 or 6 pistons apply a more even pressure to the pads compared to 1 piston on one side of the caliper, plus they can handle a larger pad.

Still have trouble grasping the facts? Here's Car & Driver's report on the braking distance of the 128 and the 135, which has the BMW/Brembo BBK:

128 from 60mph: 134 ft

135 from 60mph: 105 ft

Yes, I really want to call the BMW/Brembo a BBK

[pj.rodriguez]

Originally Posted by Blacksport

Jeez, Kgolf, what is wrong with you???

If you drove 2 128's 1 with the BMW/Brembo setup and 1 with the stock setup, without seeing the brakes...you would NOT be able to tell which car had the slightly extra weight from the BBK...but you COULD tell which car had the better brakes, trust me on this....purple Kool-Aid and the majority have nothing to do with it.

A bigger rotor has more leverage than a smaller one.
A caliper mounted further from the hub will have more leverage.
An aluminum caliper will dispense more heat that an iron one.
4 or 6 pistons apply a more even pressure to the pads compared to 1 piston on one side of the caliper, plus they can handle a larger pad.

Still have trouble grasping the facts? Here's Car & Driver's report on the braking distance of the 128 and the 135, which has the BMW/Brembo BBK:

128 from 60mph: 134 ft

135 from 60mph: 105 ft

Yes, I really want to call the BMW/Brembo a BBK

But where are the control experiments? You can say how far something brakes, that's no issue. But you have to have a 128 without the Brembos. Those numbers really don't prove anything. I'm not trying to bash you, you obviously know more than I do, but I just need to see something that compares a 128 to a 128.

[Suprgnat]

Originally Posted by Blacksport

Think of it this way: you push the brake pedal firmly, but not activating the anti-lock, let's say the pressure on the brake line is 1000psi...that pressure has an EASIER time stopping a 13" rotor than an 11" rotor...it's simple physics...

"Easier", but not any faster. The limiting factor is the tires.

Originally Posted by Blacksport

Here's Car & Driver's report on the braking distance of the 128 and the 135, which has the BMW/Brembo BBK:

128 from 60mph: 134 ft

135 from 60mph: 105 ft

Please link to where you're getting your data. Car and Driver does 70-0 tests.

128i: 163 feet http://www.caranddriver.com/reviews/...take-road-test

135is: 158 feet http://www.caranddriver.com/reviews/...ed-test-review

A 5 foot difference, all in the tires.

[Kgolf31]

Originally Posted by Blacksport

Jeez, Kgolf, what is wrong with you???

If you drove 2 128's 1 with the BMW/Brembo setup and 1 with the stock setup, without seeing the brakes...you would NOT be able to tell which car had the slightly extra weight from the BBK...but you COULD tell which car had the better brakes, trust me on this....purple Kool-Aid and the majority have nothing to do with it.

A bigger rotor has more leverage than a smaller one.
A caliper mounted further from the hub will have more leverage.
An aluminum caliper will dispense more heat that an iron one.
4 or 6 pistons apply a more even pressure to the pads compared to 1 piston on one side of the caliper, plus they can handle a larger pad.

Still have trouble grasping the facts? Here's Car & Driver's report on the braking distance of the 128 and the 135, which has the BMW/Brembo BBK:

128 from 60mph: 134 ft

135 from 60mph: 105 ft

Yes, I really want to call the BMW/Brembo a BBK

Isn't a straight apples to apples comparison...is it?

Lets start.

First, we will assume that the 128i and 135i are base models, with no other packages added.

So, with that being said:

The 128i has 205/50/17 run-flat all-season tires.
The 135i 215/40/18 front and 245/35/18 rear fun-flat performance tires.



Point made.

Once again, we go back to static friction. The 135i has MORE tires on the front wheels (and rear) ANNNND high performance tires versus the all-season (I like to call them no-season) tires on the 128i.

There is your differential on braking distance right there.




It is funny how you try and focus the variable being the brakes when throughout the model comparison there are SEVERAL different variables in play. Please, take some time and re-read my link and look at an actual comparison done on the same car

[Suprgnat]

Originally Posted by Blacksport

Here's Car & Driver's report on the braking distance of the 128 and the 135, which has the BMW/Brembo BBK:

128 from 60mph: 134 ft

135 from 60mph: 105 ft

How about Motor Trend? They do 60-0.

128i on 205-225 NCT5s: 108 feet http://www.motortrend.com/roadtests/...est/specs.html
135i on 215-245 RE050As: 102 feet http://www.motortrend.com/roadtests/...t/viewall.html

[Blacksport]

Sorry, it was Carsort.com, I thought they were quoting C&D, but was mistakened.

Hey, you know what? Everybody has basically proven me wrong...I guess the next IMSA car I build won't have 16" carbon rotors...I'm going to use stock 128 front brakes with their 11" mouse rotors and cast iron 1 piston calipers.

Enjoy your stock brakes...I wouldn't give up my BMW/Brembo kit for twice what I paid...my brake foot doesn't lie...

[Kgolf31]

Originally Posted by Blacksport

Sorry, it was Carsort.com, I thought they were quoting C&D, but was mistakened.

Hey, you know what? Everybody has basically proven me wrong...I guess the next IMSA car I build won't have 16" carbon rotors...I'm going to use stock 128 front brakes with their 11" mouse rotors and cast iron 1 piston calipers.

Enjoy your stock brakes...I wouldn't give up my BMW/Brembo kit for twice what I paid...my brake foot doesn't lie...

Oh boy.

You better call Spec E30, Spec Miata, Spec 944, World Challenge Touring, BMWCCA. CALL EVERYONE and tell them that stock calipers ARE NOT SAFE!

Call Bimmerworld, please let them know they are wrong!


Dude, get the ego out of your head. Just because you can use BBKs, or they are allowed within the rules, doesn't mean it is the best financial upgrade.


PS - Your brake foot doesn't lie...but your mind does.

[Suprgnat]

Originally Posted by Blacksport

I guess the next IMSA car I build won't have 16" carbon rotors...I'm going to use stock 128 front brakes with their 11" mouse rotors and cast iron 1 piston calipers.

Enjoy your stock brakes...I wouldn't give up my BMW/Brembo kit for twice what I paid...my brake foot doesn't lie...

You may have missed the point others were making. Big brake kits are not about stopping distance, they are about heat capacity; a perfectly valid reason to put a BBK on your next IMSA car.

Here's an article: http://www.autos.com/aftermarket-par...ar-stop-faster

Or from Stop-Tech: "StopTech® Big Brake Kits exceed stock performance in two key areas: First, larger rotors increase heat capacity, allowing a driver to brake harder stop-after-stop with reduced chance of fade. Second, stiffer calipers and stainless steel lines reduce system compliance, providing consistent pedal feel and confidence-inspiring responsiveness." http://www.stoptech.com/products/big-brake-kits

Wilwood: "Most modern stock brake systems work well for average daily street driving and an occasional 60-0 or 80-0 stopping. Typically performance enthusiasts who occasionally compete in racing events, push the stock brake system beyond its capabilities. Driving style, and other performance modifications such as increased horsepower, tire and suspension upgrades, etc., can quickly overwhelm stock brakes. A big brake kit will provide increased heat capacity, which means substantially more resistance to brake fade and caliper distortion with multiple stops from high speed. A firmer pedal due to stronger and stiffer components, as well as better modulation characteristics are also benefits of a properly balanced brake upgrade." http://www.wilwood.com/TechTip/TechFaqs.aspx

Stop-Tech, Wilwood, Brembo, AP Racing, Racing Brake. Not one claimed a car would stop any faster with their products.

[Blacksport]

You should have read the article in autos.com, Supernat....Here's a quote from the article: "Upgraded calipers and rotors will result in MORE BRAKING TORQUE, the stopping force applied to the wheels. This will bring about wheel lockup or ABS intervention sooner than with the stock system."

So it's the ABS controller sensing impending lockup and releasing pressure to the affected wheel that's keeping a BBK from substantially shortening the stopping distance. Without ABS, a BBK would kill a stock setup; of course, the tires would be flat-spotted.

I raced in the days before ABS...if you think I never flat-spotted a set of $1500 racing slicks, or went thru a corner backwards because I locked the brakes trying to slow for a turn, well let's just say it happened too often.

The simple fact is, and your article backs me up on this, a BBK will result in more braking torque.

[Suprgnat]

Originally Posted by Blacksport

Without ABS, a BBK would kill a stock setup; of course, the tires would be flat-spotted.

You're joking, right? If you're skidding and flat-spotting, you're not stopping. To further quote the article "As the physics lesson states, under braking, your car absorbs the most kinetic energy (movement) right before the tires lock up."

Formula 1 banned ABS because it was too good a drivers aid, not because ABS sucks. "Formula One previously allowed anti-skid braking systems (which would reduce the brake pressure to allow the wheel to turn again and then continue to slow it at the maximum possible rate) but these were banned in the 1990s. Braking therefore remains one of the sternest tests of a Formula One driver's skill." http://www.formula1.com/inside_f1/un...port/5284.html

Originally Posted by Blacksport

"Upgraded calipers and rotors will result in MORE BRAKING TORQUE, the stopping force applied to the wheels. This will bring about wheel lockup or ABS intervention sooner than with the stock system."

The very next sentence reads: "This should not be interpreted as a shorter stopping distance."

More braking torque does not equate to shorter stopping distances, which is what you were trying to say. If you wish to back-step and limit your statement to "big brakes have the potential for more braking torque" then I agree, too. But as the article states: "this equation states that the only way to make a car stop quicker is to either increase the coefficient of friction with the road, (e.g. upgraded tires) or decrease mass by lightening the vehicle. Note, both of these things have little to do with brakes."

I'm done. Unsubscribed. I vowed last time not to get sucked in to this argument as it's tiring dealing with the cognitive dissonance.

[Iron Man]

Originally Posted by Blacksport

You should have read the article in autos.com, Supernat....Here's a quote from the article: "Upgraded calipers and rotors will result in MORE BRAKING TORQUE, the stopping force applied to the wheels. This will bring about wheel lockup or ABS intervention sooner than with the stock system."

So it's the ABS controller sensing impending lockup and releasing pressure to the affected wheel that's keeping a BBK from substantially shortening the stopping distance. Without ABS, a BBK would kill a stock setup; of course, the tires would be flat-spotted.

I raced in the days before ABS...if you think I never flat-spotted a set of $1500 racing slicks, or went thru a corner backwards because I locked the brakes trying to slow for a turn, well let's just say it happened too often.

The simple fact is, and your article backs me up on this, a BBK will result in more braking torque.

I like how you conveniently only quoted part of the paragraph.

"Upgraded calipers and rotors in a big brake kit will result in more braking torque, the stopping force applied to the wheels. This will bring about wheel lockup or ABS intervention sooner than with the stock system. This should not be interpreted as a shorter stopping distance. In many instances the larger brakes confuse the stock ABS system which is not tuned to the different pressures required to engage and disengage the brakes."

By the way, you car has ABS, so the no-ABS argument is not valid on the vehicle you are driving.

[Iron Man]

Originally Posted by Suprgnat

You're joking, right? If you're skidding and flat-spotting, you're not stopping. To further quote the article "As the physics lesson states, under braking, your car absorbs the most kinetic energy (movement) right before the tires lock up."

Formula 1 banned ABS because it was too good a drivers aid, not because ABS sucks. "Formula One previously allowed anti-skid braking systems (which would reduce the brake pressure to allow the wheel to turn again and then continue to slow it at the maximum possible rate) but these were banned in the 1990s. Braking therefore remains one of the sternest tests of a Formula One driver's skill." http://www.formula1.com/inside_f1/un...port/5284.html

The very next sentence reads: "This should not be interpreted as a shorter stopping distance."

More braking torque does not equate to shorter stopping distances, which is what you were trying to say. If you wish to back-step and limit your statement to "big brakes have the potential for more braking torque" then I agree, too. But as the article states: "this equation states that the only way to make a car stop quicker is to either increase the coefficient of friction with the road, (e.g. upgraded tires) or decrease mass by lightening the vehicle. Note, both of these things have little to do with brakes."

I'm done. Unsubscribed. I vowed last time not to get sucked in to this argument as it's tiring dealing with the cognitive dissonance.

Sorry, you just beat me to the punch.

[Blacksport]

WRONG, WRONG, WRONG...no one, nor any article will ever convince me that more braking torque would not equal shorter stopping distance; yes other factors come into play; ABS, tire width, compound, diameter, temperature, road condition, pad compound, rotor condition, etc, etc.

But all things being equal, and in the absence of ABS and the absence wheel lockup, a BBK will simply kill a stock brake set up, because, like the article said, a BBK has more braking torque...

Since many of you guys are so enamoured with the stock brakes, I have a set you can have for FREE!!!! Paypal me $40 for shipping and they're YOURS!!! FREE!!! Only used for 180 miles, I didn't even give them a chance to break in....why would I?? I've included a picture so you can see them in all their cast iron, 1 piston, 11" mouse diameter glory....

[Kgolf31]

You pick certain parts of an article to try and make a point...but when the next sentence goes against that said point you want to point back and say it is wrong?

Ironic.

[TheSt|G]

Originally Posted by Blacksport

WRONG, WRONG, WRONG...no one, nor any article will ever convince me that more braking torque would not equal shorter stopping distance; yes other factors come into play; ABS, tire width, compound, diameter, temperature, road condition, pad compound, rotor condition, etc, etc.

Not our problem. The only thing getting screwed over here is your wallet.

[Blacksport]

I think my wallet can handle it, STG

My M Roadster has over $10,000 in it...3 piece OZ wheels, Eisenmann stainless exhaust, differential bracing and finned cover; those Wilwood calipers were not a kit, I adapted them and made the brackets.

Same with my Durango...that was a Yukon kit that I adapted to the Durango...Wilwood had a pic of the job on their home page for a few months, and their engineer called me with some questions he had.

Even my Yamaha FZ1 has 6 piston calipers adapted from an R1....that's over $3500 worth of Ohlins forks and rear suspension.

[pj.rodriguez]

Don't turn this into a competition.

[TheSt|G]

Originally Posted by Blacksport

I think my wallet can handle it, STG

My M Roadster has over $10,000 in it...3 piece OZ wheels, Eisenmann stainless exhaust, differential bracing and finned cover; those Wilwood calipers were not a kit, I adapted them and made the brackets.

So you have wheels that vibrate in the rain, an exhaust that has a high likelihood of being a knockoff(and I know first hand is a drone-o-matic), and an unbalanced brake kit? Am I supposed to be impressed that you are capable of financing your poor decisions?

[Dafttt]

Oh snap!

[Blacksport]

Originally Posted by Blacksport

Since many of you guys are so enamoured with the stock brakes, I have a set you can have for FREE!!!! Paypal me $40 for shipping and they're YOURS!!! FREE!!! Only used for 180 miles, I didn't even give them a chance to break in....why would I?? I've included a picture so you can see them in all their cast iron, 1 piston, 11" mouse diameter glory....

SOLD! Wait, I was giving these away....GIVEN!

Anyway, someone snapped them up...glad they'll be used instead of rusting away in my warehouse.....