Truth about using STI Brembos on the twins

[dejxx]

i have looked into this matter so many times... UNTIL at the last track day my car (now turbo with 290whp) got to 230kmh (around 140mph) on the main straight and i felt my brakes fading... i didnt loose brakes, just felt them fading, and let me tell you... past week i order a AP Racing Sprint kit, which shipped to Argentina costs A SHIT TON OF MONEY. But i couldnt have that happening again... it was not fun. When it comes to safety on the track, would you rather risk it on an STI swap or just get the brakes designed for this car by a major company that knows whats it is doing? just my 2. cents

[protpibe]

Originally Posted by dejxx

i have looked into this matter so many times... UNTIL at the last track day my car (now turbo with 290whp) got to 230kmh (around 140mph) on the main straight and i felt my brakes fading... i didnt loose brakes, just felt them fading, and let me tell you... past week i order a AP Racing Sprint kit, which shipped to Argentina costs A SHIT TON OF MONEY. But i couldnt have that happening again... it was not fun. When it comes to safety on the track, would you rather risk it on an STI swap or just get the brakes designed for this car by a major company that knows whats it is doing? just my 2. cents

So you were running STI calipers?

Also, what pads and fluid were you running in your STI calipers that caused you to form this first hand account of life with STI calipers on the track?

[solus]

So...

to randomly jump into this thread. Background: I do not track my car. I occasionally do spirited driving around some canyons. I do not autocross or anything else. I basically drive my car on the street as a daily driver for my personal needs.

I have a full set of 2011 STi calipers (F/R). I also have a set of DBA rotors, SS lines, pads and brake fluid.

I want to run these on my DD.

Will these brakes perform better or worse aggregate across all categories that determines brake performance? I understand rear bias... and can't imagine a situation where this would effect me on the street.

Am I going to kill myself with these brakes? Lol ��

Remember I DON'T track. I'm turbocharged at about 320hp.

I just want to know if I'll be okay or should I sell everything... and maybe buy a wilwood kit.

[wootwoot]

FML...

[CSG Mike]

Originally Posted by solus

So...

to randomly jump into this thread. Background: I do not track my car. I occasionally do spirited driving around some canyons. I do not autocross or anything else. I basically drive my car on the street as a daily driver for my personal needs.

I have a full set of 2011 STi calipers (F/R). I also have a set of DBA rotors, SS lines, pads and brake fluid.

I want to run these on my DD.

Will these brakes perform better or worse aggregate across all categories that determines brake performance? I understand rear bias... and can't imagine a situation where this would effect me on the street.

Am I going to kill myself with these brakes? Lol ��

Remember I DON'T track. I'm turbocharged at about 320hp.

I just want to know if I'll be okay or should I sell everything... and maybe buy a wilwood kit.

Braking performance is first and foremost determined by your tires. Barring that, I personally would not risk it, but I wouldn't run Wilwoods either.

Honestly, running your stock calipers with just some upgraded pads and fluids are a better idea.

[calispec]

Front brembos off an STI:
4 piston 40mm and 46mm
1/2 piston area = 2918.5 mm^2
Effective diameter = 268mm

Brz OEM calipers front:
2 piston 42.8mm and 42.8mm
piston area = 2877.44 mm^2
Effective diameter = 247mm

If both see the same line pressure the brembos will see 6.74% more stopping [force] (edit: torque) than the OEM calipers.

I didn't bother doing the rears because I knew it was going to be way worse and didn't want to spend the time trying to find the information on them.

With stickier tires you will see more weight transfer because you are stopping faster. Probably somewhere in the 4-7% range. I think it's safe to assume with sticky tires the brembos on the front will work out to be pretty great.

That's what I did. I have a lot of hours on track with them and so far I love it.

Hopefully we can figure out how to put those calculations on the first page so people don't have to sort through 5 pages to get it.

[CSG Mike]

Originally Posted by calispec

Front brembos off an STI:
4 piston 40mm and 46mm
1/2 piston area = 2918.5 mm^2
Effective diameter = 268mm

Brz OEM calipers front:
2 piston 42.8mm and 42.8mm
piston area = 2877.44 mm^2
Effective diameter = 247mm

If both see the same line pressure the brembos will see 6.74% more stopping force than the OEM calipers.

I didn't bother doing the rears because I knew it was going to be way worse and didn't want to spend the time trying to find the information on them.

With stickier tires you will see more weight transfer because you are stopping faster. Probably somewhere in the 4-7% range. I think it's safe to assume with sticky tires the brembos on the front will work out to be pretty great.

That's what I did. I have a lot of hours on track with them and so far I love it.

Hopefully we can figure out how to put those calculations on the first page so people don't have to sort through 5 pages to get it.

Don't forget to also calculate in how far the force is from the axis of rotation

[calispec]

Originally Posted by CSG Mike

Don't forget to also calculate in how far the force is from the axis of rotation

That's the effective diameter. The sti rotors are slightly larger and that is shown in the difference of the effective diameter.

The diameter comes from the placement of the pad and assumes all the force is located in one spot. The perfect way to do it is by integrating but the difference between the two is about .01% so I'll just do the easy way 🍻.

To your point though. My post calculated the torque difference not the force difference (as I stated). Ill edit that now.

[acro]

If your turboed just do the right thing and get a proper kit

[cdrazic93]

Why is this such a heated topic? Better performance at the track=bbk.

Better performance on the street = pads, fluids and possibly different rotors. Getting less than 10% improvement over stock for $600, is questionable. how close would some fluid and pads be? I just dont see it.

[calispec]

Originally Posted by cdrazic93

Why is this such a heated topic? Better performance at the track=bbk.

Better performance on the street = pads, fluids and possibly different rotors. Getting less than 10% improvement over stock for $600, is questionable. how close would some fluid and pads be? I just dont see it.

You are looking at it wrong. You don't buy larger brakes because you need more stopping torque. If you can lock up your tires with the brakes you currently have then you clearly have enough or even too much.

You buy larger brakes because larger brakes have a larger thermal capacitance and can dicipate heat faster. It has absolutely NOTHING to do with brake torque.

The largest problem on track is overheating your brakes. When they overheat the pads don't work. I don't care how much force you put on an overheated pad. It's not going to stop.

The argument is are brembo brakes worth while. IMO YES but only the FRONTS. They are bigger. They do have a larger thermal capacitance. They will cool faster. They are floating piston as opposed to floating caliper. The bias only moves forward slightly over OEM.

DEFINITELY swap the bleeders and mount the caliper in the correct orientation!!!
DO NOT swap the rears.

If you do this then for $500 you can't get a better brake upgrade.

[cdrazic93]

I know larger diameter rotors are only for staving off brake fade. Thats why pads and larger replacment rotors on the track are probably better using the stock configuration.

[lead82]

Originally Posted by calispec

Front brembos off an STI:
4 piston 40mm and 46mm
1/2 piston area = 2918.5 mm^2
Effective diameter = 268mm

Brz OEM calipers front:
2 piston 42.8mm and 42.8mm
piston area = 2877.44 mm^2
Effective diameter = 247mm

If both see the same line pressure the brembos will see 6.74% more stopping [force] (edit: torque) than the OEM calipers.

I didn't bother doing the rears because I knew it was going to be way worse and didn't want to spend the time trying to find the information on them.

With stickier tires you will see more weight transfer because you are stopping faster. Probably somewhere in the 4-7% range. I think it's safe to assume with sticky tires the brembos on the front will work out to be pretty great.

That's what I did. I have a lot of hours on track with them and so far I love it.

Hopefully we can figure out how to put those calculations on the first page so people don't have to sort through 5 pages to get it.

I would think the Brembo's would see a little more torque than you stated. Only because I would assume the pads would have a higher coefficient of friction than stock pads.

As you did say in a later post, bigger brakes are primarily to dissipate heat, not to improve brake torque. I would be interested if you had taken temperature measurements during track days and also compared wear rates.

[calispec]

Originally Posted by lead82

I would think the Brembo's would see a little more torque than you stated. Only because I would assume the pads would have a higher coefficient of friction than stock pads.

As you did say in a later post, bigger brakes are primarily to dissipate heat, not to improve brake torque. I would be interested if you had taken temperature measurements during track days and also compared wear rates.

I had the same pad compound for the oem calipers and the Brembo's. I don't have any hard data or temperatures to show but i did experience fade with the oem calipers and didn't have it with the Brembo's (Same pad compound).

That being said I don't remember the temperature of the day for the runs but the sti rotors are heavier and larger so they must have a better thermal capacitance. I also like the feel of an opposed piston caliper vs a floating.

Changing the pads on the Brembo's are 1000 times easier and there is a wider range of compounds made for that pad size. There is also a pretty wide rage of aftermarket rotors for the STI so that opens some options up as well.

You will destroy rotors and with a 2 piece rotor you can replace the ring for relatively cheap. (Coleman)

Are the sti brembos the best brakes out there.. NO.. they are heavy compared to others. but for the price its a very good choice. JUST DON"T DO THE REAR.

on an aside..
be careful using different pad compounds for front and rear. each pad compound will have a different coefficient of friction as temperature raises. Cold you could have a rear bias.. as temperatures raises that bias could change to the front.. and then it could change back to the rear as you get them really hot..

you can also glaze the rear brakes first on a front biased car. There is more to it than just bias.