Big Brakes Finally!

[122 Vega]

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[122 Vega]

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[Knox Joe]

Do they bolt on?

No modification?

Nice hair on the son, BTW.

I've got one on the way, should be here around March. I'm really wanting a boy.

 

[122 Vega]

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[nazgul350r]

How is the car coming along as far as national competion.

 

[sm76]

I can't see the pictures here at work (all picture hosting sites are blocked) so I can't comment on the install.
Are you switching to track days or still doing autocross? If autocross, why big brakes?

 

[Tom03es]

Interesting.

 

[Jeff@Tri-Point]

There is more to a Big Brake Kit then to just slapping on a Bigger Rotor and a 2 piston Caliper...

Lets talk about Britt's setup for example:

If you were to take the MSP verus Britt's BBK New setup

I've ran the car without ABS and on good sets of street tires that are fresh (Bridgestone RE-01R, Falken RT-615 and RA-1's). The car works great with the current pad setup that I have now which is a Axxis Ultimate Fronts and C-tek Semi Metallic Rears. Under threshold braking if I went any farther, the car would instantly lock up the front's at the intial bite and then continue to brake.

What am I getting at? I think our car (Mazdaspeed Protege) out of the factory is pretty well balanced. A couple of pad changes can get the car to be better.

http://www.stoptech.com/tech_info/formulas%20_vehicle_braking_dynamics.pdf

Please visit this site for the formula

1. Torque created by the caliper on the rotor (at the wheel) = TW

TW = PS x AP x x 2 x RE

PS = Pressure of system; AP = Total Area of pistons in one half of caliper (one side of
opposed type or active (piston) side of sliding or floater type); = Friction Coefficient; x 2, since
there are two sides of the rotor that the pads are exerting force against;
RE = Effective Radius of clamping force.

This formula will give us a rough # of how much torque increase there is between the two brake setups...

We can assume the Pressure of System (Same Car) and Also the Pad Friction Coefficient (Same Pads Used) are the same.

Now we are left with

TW = AP x RE

AP = Total Area of pistons in one half of caliper (one side of
opposed type or active (piston) side of sliding or floater type)

RE = Effective Radius of clamping force.

Mazdaspeed Protege
Single Piston Front Caliper Size: ~57mm
Brake Pad Height (Acutal Contact to Rotor): ~56.5mm
Torque created by the caliper on the rotor (at the wheel): 3220.5

New BBK Setup
Dual Piston Front Caliper Size: ~40.5mm x 2 = 81
Brake Pad Height (Acutal Contact to Rotor): ~51.6mm
Torque created by the caliper on the rotor (at the wheel): 4179.60

That is roughly a ~22.9% increase of Torque created by the caliper on the rotor!

The Protege factory brake system is very well balanced for a stock system. I wouldn't want to change it for the worse just to save some money.

The amount of Stopping power might be increased in the front but that just means lock up will happen MUCH sooner. Trying to threshold brake will be impossible to acheive. Of course you can always change this with tire compounds and brake compounds but you are only putting bandaids on the braking issue and the car is suffering on other aspects of handling because of these changes. Don't get me wrong, there are ways to make this kit work but it's going to require more parts (Brake Bias, Master Cylinders and etc) and an extensive amount of testing to get it to match stock performance.

 

[Crazee D]

Ouch my head hurts.

 

[sm76]

Jeff, the problem is the stock brakes are only well balanced if both sets of pads are not aggressive, like your setup. Once you go to aggressive track pads like the Carbotech XP-10s that I use the rear requires a very week pad to prevent lock-up at threshold braking. I have used Axxis Metal Master and Carbotech Bobcats with good results. Carbotech Panther+ in the rear locked up at almost every corner.
The larger rotors would not change the brake balance because you are already threshold braking with the rears and not the fronts, but the added thermal mass and larger diameter would allow for less abuse of the front pads. That would be ideal for the track.

 

[Jeff@Tri-Point]

Jeff, the problem is the stock brakes are only well balanced if both sets of pads are not aggressive, like your setup. Once you go to aggressive track pads like the Carbotech XP-10s that I use the rear requires a very week pad to prevent lock-up at threshold braking.

So you are stating that our stock braking system will change from a front lock up to a rear lock up, vice versa from a brake pad change which is roughly less than a 3% change. With that said, how would you balance it with a ~22% increase in front torque?

I have used Axxis Metal Master and Carbotech Bobcats with good results. Carbotech Panther+ in the rear locked up at almost every corner.

I would have to agree with you because I experience the same thing.

The larger rotors would not change the brake balance because you are already threshold braking with the rears and not the fronts, but the added thermal mass and larger diameter would allow for less abuse of the front pads. That would be ideal for the track.

The formula that I used was in regards to the Brake Calipers. A Larger diameter rotor means more pad contact which will change brake balance... Wheter its a huge difference or not, it's hard to say. By stating that you would want a "less abuse of the front pad" What kind of pad were you thinking? Even using a simple pad like Hawk HPS with this kit, the balance won't be right and you would still lock up easily, but then you would heat fade the pad then.

Lose, lose situation in my opinnion.

 

[sm76]

I've never once experienced front brake lock-up on my car. Ever. Maybe that is why I don't see a problem with more front brake and you do. Anytime my brakes have locked, it has been from the rear.

 

[122 Vega]

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[low_psi]

Looks good, its cool that you picked a caliper that has plenty of pad choices. While I agree with Jeff that the stock system is pretty balanced if you find the right pad combination, the larger rotor will definately help out at the track.

I've thought about fitting 3 brakes on the front but I have no idea how much work it'd take. Have you driven much with the new setup?

 

[Jeff@Tri-Point]

Obviously the is no alternative but to set the car up exactly like Jeff's.

Don't worry Britt, we'll see whose car is setup better next year at the san diego national tour. (wink) After all, I will have more driving experience than 3 months under my belt and the car has been developed ALOT more.

 

[122 Vega]

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[rocketr2]

how much was the total $$ for the big brake upgrade?

 

[122 Vega]

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[gavin_leslie]

Ok Jeff, whatever. My results are due to only autocrossing three times (three National events) in the last two years and none the preceding four years, doesn't have much to do with the car.

There is a world where enough just isn't good enough for some.

I heard the same bs about "good enough" with my Vega, but I wanted more out of life and got a car that not only outhandled, out ran and out braked Viper ACRs and Z06's at the track, but was also published in a book dealing with building high performance cars. But since I'm a nurse and don't work at a shop, I guess I don't know anything. What is it you do exactly? Just a year ago you were texting me everyday asking about set-ups and such.

So I guess then I shouldn't put the Viper brakes on my Dakota, I'm sure the stock brakes are just fine too.

Is this actually what Jeff said? I took it as some good natured ribbing from another brother-in-arms STX MS protege owner. Maybe Im wrong though <shrug>.

This is an interesting discussion as I am actually involved in a factfinding mission regarding brake bias in the 88-92 MX6. The end result is to readjust the stock braking bias for better usage of the rear brakes with the benefit of better braking and shorter stopping distances.

Heres some interesting tidbits I have found (both anecdotal and tested). I have a friend who has access to a brake dynamometer. With a bit of testing he has tested the brake torque of the 88-92 MX6 at a 90%/10% split front to rear(we will be doing more individual baselines for the disk/drum and disk/disk cars as well). This is a pretty big split considering that some newer FWD cars are closer to 75/25. This friend also as a set of willwoods on one of his car. It consistently tests at a 92/8 split. This should be no surprise as the willwoods can achieve a higher clamping force than stock....but why would increasing the front brake torque on a car that comes stock with such a forward biased setup be a good thing?

Ive gone through some anecdotal archives about the 2nd gen 93-97 MX6s that (for a while) dominated GS in the late 90s. It seems that many of them ran with stock rear pads and something stronger in front. This was also confirmed by Inspector24 on this board when we chit chatted about his old GS setup. It would seem that Mazda changed the bias for the 2nd gen cars, perhaps learning something from the 1st gen setup. While the change was good for the streets (magazine articles consistently praised the cars excellent stopping ability) it was a bit more difficult under racing conditions and locked the rears.

I mention this because it seems that Mazda used the basic setup (chassis, brakes, drivetrain, suspension) of the 93-97 MX6 and used it with minor tweaks for the 99+ Protege. I recall that JeffW complained early in his autocross endeavors of rear lockup and I seen that echoed in other threads on this site.

Yes, In the final assessment an improvement to the 2nd gen MX6 and Protege would be less rear line pressure or more front brake torque. To the 1st gen MX6 it would be to add more REAR bias but I cant tell you how many people believe that big brakes is the "fix" for the 1st gen MX6. Its just not so.

When I see Jeffs statements I dont see an outright challenge to what you are doing. They are there, I imagine, as reminder that brakes are curious things where small percentages, car type, piston size/number, master cylinder sizing and bias play very important roles. Its just not enough to say "X will work" when it comes to brakes. It has to be how well will it work and will it work for this car.

Im sure you will make it work, but wouldnt it be a shame to go from whatever bias the stock protege came with, needing just a little more and then going too far to something disadvantageous.....like something closer to the 90/10 bias of the 88-92 MX6?

As for your Vega...I think that car kicks butt. A lot of history was made by that car and a lot of the cars of the 70s people attribute to "crapwagons" (Pinto with the 2.0 and 2.3Lima engine also come to mind). I have a friend who had a Vega and a Monza that he used to run in the old trans-am series. The guy is a font of cool racing tales of the good old days.

Other thoughts...maybe your driving is better than the other folks in the Vipers or vettes? True story..In another discipline, a friend had a car in a sorry state. Pure crap for a build. Some other friends and I took pity and rebuilt his ride from the ground up. We also taught him how to dial in his car, scales, rebuilding the shocks to get them matched, spring selection, etc. Then a funny thing started happening....he got fast. I mean really fast. Scary fast. All of a sudden we were looking at 2nd place all the time. We had created a monster. Some people catch on faster than others, and thats just how it is.

Gavin(talks too much)

 

[122 Vega]

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