More brakes......

[odepaj]

Again.....

I wasn't looking to use Brembo's, I was looking at the WRX 4-pots. I now know they can not be used.

I wasn't looking at them for larger rotors, I was more interested in reducing unsprung weight and having a more balanced and accurate caliper.....

I know the Brembo's need a larger rotor and in one of my posts even said I wasn't looking for the purpose of larger rotors.

I know fluid is one good way to reduce brake fade.....I also know about the different pad materials.

Biasing the pads sounds like it could work nicely, figuring out the best combination will be the only tricky part.



Dustin

[YourConfused]

Haven't you driven marisa's car? she has um, I forgot, akebono ceramic pads, s.s. lines and fancy rotors... What do you think of the way her car brakes? I thought it was a firmer pedal and slightly better braking.

[TomsSVX]

Originally Posted by odepaj

Again.....

I wasn't looking to use Brembo's, I was looking at the WRX 4-pots. I now know they can not be used.

I wasn't looking at them for larger rotors, I was more interested in reducing unsprung weight and having a more balanced and accurate caliper.....

I know the Brembo's need a larger rotor and in one of my posts even said I wasn't looking for the purpose of larger rotors.

I know fluid is one good way to reduce brake fade.....I also know about the different pad materials.

Biasing the pads sounds like it could work nicely, figuring out the best combination will be the only tricky part.



Dustin

Dustin, I was not pointing it out to you...

Tom

[odepaj]

Originally Posted by YourConfused

Haven't you driven marisa's car? she has um, I forgot, akebono ceramic pads, s.s. lines and fancy rotors... What do you think of the way her car brakes? I thought it was a firmer pedal and slightly better braking.

Yeah, she has ceramics. I didn't get to drive it hard because we were just listening for a rattle. I did like the feel of the S.S. lines though!



Dustin

[YourConfused]

yeah, they are a nice upgrade. I was late for a job interview today and had to do about four 0-90-0 in a matter of 2-3 minutes and my brakes never once induced anit-lock, but rather just faded a little. The pedal wasn't as mushy as in my truck, but not really great either.
So when you coming up to austin to go for a fun drive?

[odepaj]

Originally Posted by TomsSVX

Dustin, I was not pointing it out to you...

Tom

I'm lost as to the reason for your post then? I know I jumped the gun and retaliated alittle "harshly" but with how many times I said I wasn't looking to use the Brembo's I just couldn't see why the fitment of the Brembo's kept coming up?

As of now my stock brakes will stay just that (aside from fluid and S.S. lines).

I thought it would be nice to have the WRX 4-pots for weight reduction, better heat transfer, and a more balanced caliper.

4 pistons (2+2 layout) will be more balanced and precise along with having a better "clamping" force to act on the rotor/pads.

Example: Four 10" speakers will have better response and clarity then two 12" speakers because the four 10's (while being smaller in diameter) add up to a larger cone area than the two 12's.


More can be done with a smaller 4-pot caliper then with a 2-pot. It also can save weight while still adding mass (for cooling)



Dustin

[TomsSVX]

Believe me, i would like opposing calipers simply for more precision in my braking, but right now the stockers are fine.

I had said that because Chris had stated that all one would need is a custom rotor to make the Sti Brembos work, which is not the case and that should be crystal clear to anyone reading this.. Otherwise people are going to buy them and be awful pissed off when they find out the hard way.

Tom

P.S. I am not 100% but the clamping force/friction surface of the 4 pots might not even be up to snuff against our slider 2pistons so before looking too far into mounting make sure it would indeed be an upgrade

[odepaj]

Originally Posted by TomsSVX

Believe me, i would like opposing calipers simply for more precision in my braking, but right now the stockers are fine.

I had said that because Chris had stated that all one would need is a custom rotor to make the Sti Brembos work, which is not the case and that should be crystal clear to anyone reading this.. Otherwise people are going to buy them and be awful pissed off when they find out the hard way.

Tom

P.S. I am not 100% but the clamping force/friction surface of the 4 pots might not even be up to snuff against our slider 2pistons so before looking too far into mounting make sure it would indeed be an upgrade

Ah! Ok, sorry about the confusion then.

Yeah, I've actually already given up on the Subaru 4-pots. Eventually I will look into different 4-pot calipers but thats a long ways down the road still. The pads for the 4-pots did look bigger than ours though, I would think they have greater force. Some of the guys with older WRX's ('02-'03 with the 2-pots in front) seem to like the 4-pots as an upgrade. The '02-'03 calipers are similar to ours (2-pot sliders) but look alittle smaller.




Dustin

[odepaj]

Originally Posted by YourConfused

yeah, they are a nice upgrade. I was late for a job interview today and had to do about four 0-90-0 in a matter of 2-3 minutes and my brakes never once induced anit-lock, but rather just faded a little. The pedal wasn't as mushy as in my truck, but not really great either.
So when you coming up to austin to go for a fun drive?

Pretty soon hopfully! I need some koni's and GC's (or Mychailo's springs) first though!

I found an awesome highway just west of College Station that we could turn into a once-in-a-blue moon type drive.

Texas Highway 166, its 15.57 miles long and the speed limit is 65mph with most of the turns needing to be taken at 30-35mph to be civilized. It's mixed with some nice long straights aswell (one of them is nearly 2 and a half miles long!) Driving aggressively it took me 15-20mins to complete.

[YourConfused]

Originally Posted by odepaj

Pretty soon hopfully! I need some koni's and GC's (or Mychailo's springs) first though!

I found an awesome highway just west of College Station that we could turn into a once-on-a-blue moon type drive.

Texas Highway 166, its 15.57 miles long and the speed limit is 65mph (with most of the turns needing to be taken at 30-35mph to be civilized.

is it the yellow or red route?

[odepaj]

Originally Posted by YourConfused

is it the yellow or red route?

The red and white.

[shotgunslade]

Another issue to be wary of if you start changing calipers is changing the ratio of piston volume to master cylinder capacity. You could wind up changing the pedal travel distance from slight to full braking. This brake thing is really complicated. I heartily suggest anyone thinking of changing rotor size, or calipers read the article in this month's Grassroots Motorsport concerning brakes. It really covers the issue of brake improvements.

This is not an advertisement, but your $40 annual dues payment to NASA gives you a subscription to GRM, which is more than worth the entire dues amount.

[Boxersix]

Originally Posted by shotgunslade

Very interesting article in this month's Grassroots Motorsports on brake retrofits. Bottom line, if your current braking system can be put into anti-lock mode, then your rotors are big enough and your calipers are adequate. Obviously, whether or not you can do that depends on the tires you are running. If you are running 255 R-compound slicks, you might need more brakes. I'm running 245/40-17 Bridgestone RE01-R's (not quite R compound) and I can get into anti-lock mode (just barely). Changing the brake system (rotors and calipers) on the front only can throw off the braking balance for the car. Significant improvement can only be achieved if the stock front or rear brake system is significantly out of balance with the other end of the car.

Thermal mass (ability to absorb more heat for a given temperature rise) in the braking system (rotors and calipers) is really important for repetitive hard braking (the track). There is an obvious trade-off between braking system thermal mass and unsprung weight (it's all unsprung) related to handling. The SVX front calipers are medium sized, given that they are only 2 pistons.

I also seem to be using similar braking points (closer in many cases) to other faster cars (of course, they're hauling it down from higher speeds). They pass me on the straight and I'm right back with them going into the corners. They then leave me in the dust exiting the corner.

Don't go for drilled and slotted rotors. I have cracked a front drilled rotor all the way through one side wall (track overheating abuse). Get just slotted or dimpled and slotted. I'm running slotted Frozenrotors (cryo-treated). Even so, they show a pattern of hairline surface fractures from over-heating. Still going strong though.

If you are suffering fade, your need to look at your brake fluid and your pads. I'm using ATE Super Blue fluid, and Axxis Ultimate front pads, Axxis Metalmasters rear (Ultimates not available for rear). I have never suffered significant fade at the race track, although I have glazed the pads (melted the surface). This reduces your braking potential slightly and makes a funny noise when you put on the brakes, but wears off after a short time. Also, you might look at rebuilding (or having rebuilt) your calipers. There is a good chance that age has caused their operation to deviate from spec.

I'll jump in here and back this up about 98% here, with one crutch on the anti-lock theory being that initial bite on some setup may be enough to initiate the ABS sequence at low velocities but nowhere near enough once pad temperature comes up and ~75% of the rotors thermal capacity is met. My 965 had enough initial bite to initial antilock on stock rotors with PFB's in the calipers but ran out of thermal capacity up top. Upgraded to GT3 brakes with ceramic pistons and PFB's all around now to remedy that issue.

Aside from that, one of the most solid informative posts on braking I've read in awhile.

On a side note...........just in my opinion with dealing with my PCA/BMWCCA/Koni-GA race customers ditch that ATE super blue fluid. It's very hydroscopic and absorbs water vapor quite easily. It was common nature here to flush the system after every big race because that fluid would pull moisture and start to boil easily. Castrol SRF is what I run now, and although expensive I usually get a full season on one flush before it becomes water heavy and needs to go. I used to flush the ATE so much over the season I would easily exceed the cost of the SRF fluid. May not be the case in your situation or setup but just and FYI for you incase you start running into a soft pedal constantly.

[Nevin]

I cannot imagine why someone would need different calipers or larger rotors than the factory setup. Unless you are just doing hardcore, highspeed racing, the stock calipers have plenty of bite, and the rotors are large enough to dissapate a good amount of heat.

I have SS lines, ceramic pads, and drilled/slotted rotors and this thing just stops NOW! I'm very impressed by it's stopping power considering the cars heft.

[Tim]

Yea I had to slam on the brakes this weekend for a very hard stop. My friend's response was "Wow... those are some damn good brakes." It also helps to have some fresh fluid, SS lines, Axxis pads and slotted rotors... and the Koni/GC to minimize the brake dive