Ok, stoptech really plugs the balance of their systems, compadability with oem abs, and how this means safer and shorter stoping distances.

I was wondering what other bbk manufactures have to say about this? (stoptech makes it seem like no one elst does this)

Im sure you guys do testing, but what do you do?

Thanks,
Jonathan

 

We thrash ours on the track...

But before that, Dr. Mike did a bit of math to ensure we ordered the right calipers - with the right bore/piston sizing. Second, we tested different pad compound combinations on the front and rear under all kinds of conditions...

There are really two components to ensure balance in our opinion - first is ensuring the calipers are right, and second is coming up with recommended pad combinations for the front and rear. You can hose your brake bias either way. It's a bit easier to do the math and get close on the calipers - the pad testing just takes time, plenty of pads to muck about with, patience, and access to a track and AX course (or test-and-tune days).

 

Thanks for the info

 

In short, yes, Stop-Tech makes a big marketing deal about it... But, anyone that does their homework provides the same thing.

 

Well, Im not a manufacturer, but in case I can post to this thread, let me first remark that I like your play on words, highlighted above! Secondly, I wonder if a BBK does, or should, effect the ABS. I have a BBK, and the ABS seems to work perfectly with it. On uneven pavement, I trigger the ABS because the wheels lock up, ever so momentarily, as the wheels hop over the ridges in the pavement near a stop light. Yet, on the track, under heavy braking, the ABS never engages, due to great grip between tires and track. I guess I never even noticed the ABS as a problem with a BBK.

 

I started reading these articles by stoptech's parent company that got me thinking in the first place. I found them to provide new light on alot of points!

http://www.centricparts.com/techsupport.htm

-Jonathan

 

Interesting reading, thanks. Of course, we here on NAM often like to compare "theory" with practice, so would anyone like to post who has experienced what the good Dr in the White Paper referenced is talking about? As I said, I've tracked my car, and daily driven it, and while I rarely get into bad situations, so far I've never experienced problems with my BBK and ABS system. I've not had gallons of spring water emptying from barrels thrown at me from a truck at 75mph, though, so I can't say how my system would respond. Anyone care to share?

 

In practice, brake bias dramatically affects the attitude of the car under heavy braking - and especially if you trail brake into corners. Front bias will tend to lock up the fronts, and rear bias, well, lock up the rears sooner.

If I've got my head straight yet (just got back from a vacation in Mexico con mucho rum y tequila): Both tend to cause the rear to get unsettled under heavy braking on a FWD car with all that weight transferring to the front, and you can't get the car settled well before turning in - and, trail braking, well forget about it. If it's severe enough on a FWD car, the front will push badly... On a RWD car, slowing the rear down faster can cause you to swap ends very, very quickly (almost before you can even think about it) - and as we all know, going backwards around the track isn't the fastest way! Slowing down the front faster on a RWD car makes for a bad push in some situations.

If you watch a lot of racing, you'll see many guys fiddling with the brake bias **** on the dash at times with in-car shots if they're not happy with the setup... And, they will change it from track to track. On a street driven car, though, and especially one with ABS, this isn't very practical. Still, some cars (especially old muscle cars with upgraded brakes like Baer's stuff) will require a proportioning valve to be installed to get the bias set right...

While testing our BBK, we noted that the front and rear pad combination is critical - the compounds need to be matched well in order to ensure that the car doesn't go where you don't want it to go. Even though some 80% of the braking is done by the fronts, too light a compound in the rear will cause some VERY uneasy feelings when you step on the pedal at the end of a straight... Especially if you're braking deep... Nothing's worse than having the rear-end step out unexpectedly or not having it setup when you enter a high speed sweeper (turn 1 to 2 and 2a at Texas World Speedway comes to mind!). On the street, it's less critical but still important in panic stop situations.

This is why we suggest running R4's in the rear if you plan on swapping from a 'street' pad like the R4-S to either the R4 or ST-43 pads in the front with our BBK for AX or track work. R4-S pads in the rear will cause the rear to get a bit light and waggle under heavy braking with either the R4 and ESPECIALLY the ST-43 up front. For the street, though, R4-S pads all around works great.

So again, it's important to match both the piston size and the compounds...

I'll ask Dr. Mike to weigh in, too. Especially since I'm not sure if my head's right yet...

 

The critical point to make here is that the torque provided at the four corners of the car under braking should be complimentary to the dynamics of the vehicle, and to the available friction at each of the four corners. Regarding front to rear bias, the variables that can affect this include:

1. Tire size, compound, inflation, and condition
2. Weight transfer under braking load
3. Pad-to-rotor friction coefficient, which is a function of temperature
4. Rotor size (width, diameter)
5. Pad area
6. Caliper piston area
7. Hydraulic pressure at each caliper

TSW chose items 3 and 6 to match the other parameters when we developed our BBK. Of course, we have no control over the tires on a customer's car, but the kit is naturally matched to a set of equal tires. The caliper piston area was chosen to work with the existing MINI brake hydraulic system. Also, choosing the brake pads based in part on the pad friction coefficient is a very effective way to tune the balance of the brakes without resorting to the addition of a new brake bias valve.

 

Different suppliers have different agendas. Sticking with known product from known vendors with a reputation for both design and build will assure you of a well built kit.

While Stoptech produces a fine product and has done a nice job on research and production of supporting documents they don't remain the only company to produce well balanced product. And truth be told; the MINI does not present a very difficult platform for near any supplier to work from. Given the vehicles short wheel base there's little gains to be had from the rear and just about any front kit can enhance the overall stopping. However poorly designed, some kits can become over taxing of the front while doing so.

No BBK should have a direct negative effect on the ABS. ABS is simply measuring the lack of rotation and modulating pressure based upon that. It's not aware of the brand of product in use. However making a final kit that makes the threshold of ABS "touchy" can be a problem at times. The right mix of some of those items drmike notes above can make or break you.

Having researched many of the products on the market here a few years ago most are proving to be fine kits. A few have "issues" and generally they are the ones you don't hear much about. Probably due less to anyone having real negative things to say but less positive things to share!

You can do your own calculations on this and all vehicles on the TCE web page as well as learn more about how these changes effect your vehicle.
http://www.tceperformanceproducts.co...alculator.html

 

Width just for temperature relation right? I am unaware of how width can effect braking bias or toruqe other then temperature related issues. If i am missing something i would like to know thanks.

 

You are correct! Width affects only the temperature of the brake surfaces for a given energy input, wheel speed, ambient condition, airflow, etc.

 

Pad size has an impact on brake bias and torque. But not pad area.

A larger pad spreads the same loads over a greater surface but does no more work than a smaller pad assuming the piston area behind it remains the same. Larger pads simply wear longer. There's no gains in torque by having larger pads.

That being said, the results can in fact vary a bit by the pad size depending upon how it's placed on the rotor. Most oem pads go for long life and greater swept area. This often results in a more stable feel given that larger rotors are more prone to dealing with run out issues.

What effects both torque and ultimately bias to an extent is the height of the pad. This is viewed normally as width but the proper term is height. Example: an FSL pad is 4.75 by 1.75 roughly (friction material, don't be mislead by pad plate dimensions!) so the height is 1.75". In this case you'd factor half this as the average "effective radius". The exact location can vary a real small amount depending on piston placement but for the most part ER=PH/2.

ER is the point of average contact and piston centers. This is where torque values are calculated from actually, not the total rotor diameter. Racing calipers and pads tend to run a "tall skinny pad" or one with a lot of height that creates a greater ER. The down side to this is that it puts greater pressure on the outer edges of the rotor and can make the outer edge run very hot. They are also more touchy to run out. However they remain far more effective in the braking world than the short fat pads of oem parts as they run a bit cooler as they do the same work on a greater rotor.

Side by side a greater rotor diameter is always a winner hands down. They offer greater mass, greater swept area and in short: more bang for the buck. The down sides are that they take up more room, weigh more and cost more.

 

Side-by-side, a wider rotor with the same diameter = better, too. More mass, same swept area, but greater cooling as well...

 

Absolutely. As you know I offer this as well on both a small kit as well as the larger 13 and 14" kits. In the case of the 14 you reach the point of diminished return but the casting is only available as such!

My comment on larger rotors was only to try to make it clearer that the larger rotor offers improvements in efficiency. When you do this and pick up those gains it's required that you reduce the clamping power and aspect of the equation so to achieve the same or close final rotor tq values.

For those not fully following us here:

A smaller rotor needs more clamping. A larger rotor needs less clamping as the leverage aspect of the value is greater. Just like when you torque a wheel, brakes are the same. A longer breaker bar makes life easier. Same with the rotor/caliper relationship.

 

Fair enough on pad height and position vs. pad area. I agree with what you wrote, Todd. I didn't want to go into full-on lecture mode regarding energy transfer and swept area (tired, lazy...)