This is true up to a point. Try this when given a chance. Drive to 50mph and stand on the brakes. It will take a few monents until the ABS kicks in. Try it with a BBK and the time until the ABS kicks in is greatly decreased. That is the benefit. And as stated before, most kits are much lighter than stock even while increasing the pad size.

Another analogy.....take a sheet of paper and hold it between you thumb and finger. Squeeze them together and try to slide the paper from between them. Now try the same thing but instead of between your fingers place the paper between your palms and press together. Much harder to slide the paper out.

 

Nope. Pad size plays no role on brake torque. Large pad, small pad, doesn't matter. The clamping is the same pressure via the piston pushing on it. Where the pad is on the radius does play a small role but for comparing one to another; small pads just wear out quicker.

Try this: if your wife weighs 110lbs, is she heavier in high heals of flip flops??

While MAX Torque is generated sooner with the BBK, the total torque required to stop the tire from rotating would be less. The distance will remain the same (or very, very close). Numerous tests have shown the BBK to provide no significant change in cold stopping distances. Differences of a couple feet one way or the other can be attributed to driver and suface changes alone.

Use the bias calculator to show it:
http://www.tceperformanceproducts.co...alculator.html
Pick a max tq rating and call it SKID. The default will work. Then change the rotor OD to 14". Note the total tq has gone up? Call that 'post skid', now reduce the amount of leg with a 14" rotor until you hit the original number from default. All the bigger rotor did was require less pressure to get to SKID.


It's really hard to wrap your head around this I know. Like the guy on the NASIOC board who insisted he has more "brake power" with a larger master cylinder. No, only a firmer one and less pressure requiring he push it harder.

Do that driving test over and over and heat things up, then the BBK will stay for more consistant.

 

But if it takes less pressure to get to SKID, than wouldn't you get there faster by applying the same pressure as oem. Wouldn't you get more torque if the pressure is the same and the area is greater? In this scenario, aren't the tires the weak point? If what is being said about the BBKs is true, then is it only because the OEM rotors are big enough for the weight of the car/brake hydraulics.

It seems to me that the bigger the rotor/pad surface, the less pressure it takes to lock up the tires. If the hydraulics were the weak point, then the bigger surfaces would help. So the main benefit of a BBK is in the design of the rotors/pads and the materials used...not the size. Is this correct?

 

Thanks todd !

I was just simplifying what I had seen on a tuner show of some kind I saw a while back where they were doing side by side tests of mods done to a street car. They claimed, and showed the results of tests, that by going to a larger pad size (ie BBK) you would get to the ABS quicker than with stock pads. Thereby getting shorter braking distances.

I know from my own experience that after my brake upgrade (same size parts) I could get the ABS to kick in much sooner than I could with stock.

But then again I haven't ever slept in a Holiday Inn.........

 

+1 on the ABS/tire traction concept. If you can engage ABS at all, buy better tires before touching the brake system.

On my Subaru with Brembo's/Hawk HPS pads/2pc rotor setup, I could engage the ABS even with 245 width Goodyear F1's on a moderate stop from 40mph. That means the brakes were overkill for the street, but my reasons for doing the swap were 100% about feel - the stock pedal travel was not confidence inspiring.

 

The point of SKID is related to the combo of piston diam, pad Cf and rotor diameter. How you mix and match these things changes the final torque.

But...this is why I suggested the target SKID value. Make it 60k in lbs. In the default calculator that's 62lbs of leg. Now achieving the same 60k on a 14" rotor takes only 51 leg. Forget the bias stuff and populating MINI specs, just change the values to example the change you require.

Rotor tq is rotor tq is rotor tq. Thus SKID is the same regardless of changes in the math values used to get there. Suppose you put a 16" rotor on the default- 44lbs.

Think of it being a breaker bar the nut is still tq'd to 150lbs, but using the longer bar you still tighten to 150 but with less effort.

The pad size is base on PSI. A larger pad has the same pressure behind it as small pad. If a 40yr old man tightens the nut does he exert more effort than a 5yr old boy to get the nut tight?

The main beneifit is efficiency and what I've come to call "duty cycle" meaning the same effort is being done but in a more efficient way. The SKID will always be the slid- where the tire can no longer interact with the road surface. The BBK can achieve this quicker, longer and be more manageable.

 

I spend a lot of time abusing Todd's BBKs and running with other MINIs using various combinations of stock, modified stock and various sizes of BBKs. Here in TX, high temps (105+) are common.
In a 20 minute session on a hot day, the BBK cars are in the lead at the end of the session every time. Even in the worst heat and on the fastest tracks, my brakes are consistent from the first stop to the last. With the OEM size brakes, I always had fade at the end if the sessions.
What I gained with the BBK was better heat management.
A second benefit is that I seem to get more mileage from the bigger pads than those using OEM size so there could be a minor savings there.
Another benefit is the ability to change the front pads in less than 5 min per side. Try that with OEM parts!
I have found it really difficult to get more air to the MINI front brakes. I'm still looking for a good solution.
Keep in mind that adding a BBk is only part of the solution. Choosing the right pad compound for the situation is critical.
If you don't race or participate in DEs then the ONLY reason you would ever get a BBK would be for bling. Not that bling is bad.

 

Truth spoken. I missed this statement earlier. Adding larger mass rotors is the same net result as 24s on a truck which everyone complains requires more brakes to slow. I can speak from experience having taken to putting 18s on my old F150 three years ago. Yea they looked good. One trip to CO for a race weekend and I pulled them off and sold them

For the MINI you have (IMHO) no need for some of the massive rotors on the market other kits use. I balance the need for mass and tq by way of the 13" x .81 rotor and that's a LOT of rotor for a car of this weight. The larger (and comp to other kits) 1.10" rotor weighs nearly 15lbs ea without the hat! Now the mass thing begins to really come into play. Not to mention the need for wheel spacers....

 

How does the warping issue come into play? It seems like there have been more reports of rotor warping with large rotors with narrow widths. I have the DT BBK (width 1.2") and was initially concerned because the rotors weigh more than some other BBKs on the market but about the same as the OE set up. The DT BBK fit my wheels easily without spacers. I think the calipers are narrower.

 

The warping issue is due mainly to pad build up on the rotor from the wrong pad comound and improper use. Driver error you might call it.

The most common vehicles I hear complaints on are those with an automatic trans. The need to keep ones foot on the pedal after stopping only goes to bake the pad to the rotor. When this happens the pads adhere to the iron and create a high spot.

The bad thing about the larger rotor is that it excentuates (sp?) this build up more as the radius is greater. A bit of build up on a smaller rotor may not be noticed but as it gets larger there's more movement in the caliper as the pads are pushed back with each rotation.

The use of the stock floating caliper design also helps prevent this as the caliper when clamping is still able to float on the slide pins and "follow" the rotor. On a fixed caliper it cannot do so and you feel the high spots push back the pads.

 

A friendly reminder to not sit on your brakes when you come into the pits after a session, or sit on them after finishing an autocross run!

Park the car, using the brakes as little as possible, put it in gear, turn it off and let out the clutch - and don't set the parking brake!

 

Question.
How many people have Todd's 13 kit with the big calipers and what size spacer and type of wheels do you have.
Thanks

 

I have the 13" BBK, Konig Holes wheels 17x7 et45, No spacer required.

 

Thanks

 

Anyone else running the TCE 13in kit. Need help to clear calipers. What wheels and offset are you using. Thanks.
Any pics of the setup would be nice.

 

Now forgive me if im misinterpreting, but a BBK with larger pistons or more pistons does increase the break torque on your disk. The constant here isnt the total force applied from the break system, but the pressure that the master cylinder can apply. If the pressure is maintained then an increase in piston area will be proportional to the increase in force. P=F/A

 

More area is more area and more clamping load.

Pressure being constant yes that means more torque. What if you can get the same tq for less clamping?

And in the end tire tq will dictate road max tq useable. How you get there is what makes the BBK and how you can increase its efficiency and thus decrease its duty cycle is how you'll keep it all day long.

BTW; that would be BRAKE torque not break torque.

 

without getting too technical, i can simply say that stomping on the brakes at say 80+ mph with stock brakes and stomping on the Stoptechs at the same speeds, the Stoptechs will put you through the windshield if you're not wearing your seatbelt, the stopping feel is drastically improved in what i've felt.

autocrossing it this past Sunday (yesterday) at Moroso, showed me how well they performed, I was only a second behind the fastest time of the day, 57.38 my best time on 300 treadware 17" street tires vs 56.40 which was accomplished by a Mini with shaved R compound tires on 15" wheels.

I sat up in the stands watching where this faster guy was breaking and it was nowhere as deep as where i was standing on the brakes, so yes, good brakes will improve times because simply put, you can brake later.

 

530i has vented front disc brakes by diverting some air from the front bumper to the front brakes. Maybe we can drill a hole on each side on the front bumper?

I did a brake bed-in process with 10 stops from 60mph to 10mph without rest. After that I checked the front brakes, amazingly, the rotors were nowhere close to as hot as the mini. I guess ventilation did play a big role here.