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Discussion Starter #1
Hello All,

First post and sort of new to the list, been in lurk mode for a while, but my question comes in relation to the brake configuration of the STI. Does anyone know if they (being the engineers) seperated the brake system front to rear or if they cross connected the system (ala suzuki, kia, some honda's)? The STI would be my first Japanese car, and would require selling my "baby" BMW for the new purchase.
This question comes directly from being able to install line locks on the braking system to assist in cornering on track situations, or when you wanna scare your passengers a bit. I have a feeling that I'll have some significant adjustment necessary to my current driving style going from a RWD to an AWD... This question was spurred from reading the info on the DCCD, and in the manual it stated that when pulling the hand brake would cause the diff to enter in to the "free" position. This interested me simply because of the fact that they (again the engineers) accounted for hand brake usage, which is something typically not seen in car user manuals.
So if any of the insiders know to layout of the braking system it would be great, so I can get another order of line locks shipped over to the house before the car arrives. :)
 
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I believe your answer is in Subarus "complete STi Story", the link is
http://impreza.subaru.com/microsites/impreza/main.jsp

anyway for those that don't want to leave to read it I have posted the Baking and Handling portion here:

HANDLING/BRAKING
Power coupled with confidence and control

The joy of driving WRX STi is not only in the power, but also in the ability to control it. The Impreza WRX STi features competition-proven handling. A super-stiff Ring-Shaped Reinforcement Frame body structure with a hydroformed front subframe form the basis of the high-integrity Impreza platform. The four-wheel independent suspension inherits technology from the Impreza World Rally Championship competition car, but has been strictly optimized in the WRX STi for high cornering performance on paved roads. Compared to the standard WRX, the STi version has been lowered by 0.4-inch, yielding a lower center of gravity. New inverted struts in the front and rear suspension reduce unsprung vehicle weight and increase bending resistance for quicker and more consistent performance under hard cornering.

The WRX STi employs a quicker steering ratio than the standard WRX model-15.0-to-1 for compared to 16.5-to-1 for the WRX. As standard equipment, Subaru equips the WRX STi with 17 x 7.5-inch BBS aluminum-alloy wheels and 225/45 ZR17 Bridgestone Potenza RE070 directional performance tires

To help ensure stopping power and consistency commensurate with the vehicle's extreme performance capability, Subaru has equipped the Impreza WRX STi with one of the most advanced and performance-optimized braking systems on the market today. The powerful Brembo Performance Brake System employs ventilated four-wheel disc brakes to help ensure stopping power and consistency. The front discs measure 12.7 inches in diameter and 1.2-inch thick and utilize four-piston, fixed-position calipers. The rear discs are 12.3 inches in diameter and 0.8-inch thick and make use of two-piston, fixed-position calipers.

A combination of Electronic Brake-Force Distribution (EBD) and a new Super Sport Anti-lock Braking System (ABS) helps to reduce stopping distances and understeer when compared to conventional ABS systems. Conventional ABS systems control the rear wheels as a pair, reducing the braking force to both wheels when a loss of traction is detected at either wheel. Using input from a lateral g-sensor, Super Sport ABS can independently control the braking forces at each wheel, optimizing the braking ability during hard cornering-resulting in reduced understeer. EBD also provides a more precise control of braking pressure between the front and rear wheels based on the vehicle load to improve stopping distances and stability.
 

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Discussion Starter #3
Excellent thanks for the link. However, do you read it as 4 individual lines or 2 hard lines that split front to rear?
 

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Discussion Starter #5
EBD also provides a more precise control of braking pressure between the front and rear wheels based on the vehicle load to improve stopping distances and stability.
That was the section that confused me. I'm thinking 4 independent lines from an ABS hub (or what ever the true name is) and if thats the case the line locks just need to be tied in together electrically. No biggy, just have to order two.

Thanks.
 

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dealer deposit

any car not equipped with a bottom-of-the-barrel, make-it-as-cheap-as-possible ABS system has individual lines running to each wheel from the ABS pump / HCU (hydralic control unit).

I do not think that the el-cheapo diagonally linked ABS systems have been used on many production cars for quite a while, but I might be wrong. they would certainly not be used on the STi.

as for adding linelocks or the like to "play" with the car while on track, I think that would be an extremely foolish idea. the ABS system would freak out as it would sense a locked wheel and it would also likely be a potential problem for the driveline in general.

unless you're a stunt driver & need to do handbrake turns for the cameras or something, I don't see needing to have control of individual brakes. what sort of BMW do you have such a system currently installed on ? let us know when & where you are on track so we can stay away from the track. it's stressful enough to have to worry about the guy in front of you spinning off on his own, let alone with the assistance of some sort of goofy braking system. :D



Ben
selling two BMW"s to get STi
 

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Discussion Starter #7
Ha. :) The BMW in question is a 325is with a few little things here and there. ABS is easily disabled on a Bimmer, so no worries there. It would seem, in accordance with car and driver's article (See September 2002 the article where they installing different braking systems on a 2003? WRX- Interesting that stoptech's win over the Brembo F50's- guess that's another thread though), ABS is also easily disabled on the WRX, which must share at least some components with the STI. While the BMW's computer does bitch, and your ABS light on your dash stays on all the time its well worth it for being able to control skids without having to worry about some computer telling you the way it thinks you should be braking. The line locks are just an easier, and safer way, of using your hand brake to assist in tight corners while attempting to keep speed. No worries about staying off the track I'm on, cause I'll probably be lapping you anyway. :)
 

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What? You've gotta be kidding. You can't beat an STi with a 325, I'm sorry...it's the STi that'll be running circles around you! Maybe if it was heavily modded and you dropped in an XI tranny and ripped out all the seats, audio system, A/C, etc, you might be able to keep up :lol:
 

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Discussion Starter #9
I wasn't implying that a 325 could beat an STI... unless the STI was a shotty driver and the BMW was a GT3 god or something... The question was about what car I currently had and used the line locks on. But the 325 isn't your average BMW... Supercharger, lighten flywheel, replacement rear, exhaust, chip, cold air intake, larger injectors, cross braces here and there, race clutch, brembo replacements w/ carbon metalics, and a little other good fun stuff makes it slightly quicker than most of the stockers out there. But there again, the Porsche C4's that dual it out on the track with us enjoy that AWD, which is what got me hooked on the STI concept initually. Not looking for the Porsche tweak $$$$ in the process though. My Bimmer's been beaten to a pulp, and needs a new home, ala no more money is getting dumped into it to keep everything running the way I like it.... So, welcome STI...
By the lapping on the track I was implying an STI with line locks installed and using sliding tactics (not sure if possible the way I learned them on a RWD with an AWD but that's what those tire barriers are for right? :) ) versus an STI driver who didn't employ those driving tactics. Would an STI kill a stock 325is, oh my god yes... With that I have no issue.
 

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(not sure if possible the way I learned them on a RWD with an AWD but that's what those tire barriers are for right? )
I believe a RWD car will be easier to use slide techniques b/c you are already biased toward the rear. What I mean to say is that sure line locks and even using the handbrake on an AWD car will make the back slide out, but you will have a harder time (I would think, but then again it is 300hp/300trq stock) than with a high powered RWD car that has a tendency to overstear naturally.
 

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Discussion Starter #11
The "Additional US STI Specs" thread just answered my brake questions.... Although, I thought we were getting vented rotors front and rear? Hmm, guess not cause there was a size difference listed. 1.2" versus .8" Ah well, still should brake rather well regardless. 8)
 

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Yeah I don't believe they are vented rear.

As far as braking goes..yeah it brakes very well. The German dealer quoted 100-0km is 35meters..or about 115-120 feet. That's some braking force, but we'll see when they actually test this sucker.
 

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new_sti_lvr - I see your point now. You don't sound like a dumb guy which is why I was confused as to your lapping comment :lol:
 

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Wow... that's 911 Turbo braking distances (60-0 112 ft) You sure? Dang.
That's what I was told, BUT I don't fully believe it. I do know that the braking ability was simply amazing on the car we drove. I am looking forward to Motor Trend, etc to test this and the Evo. I wanna see numbers.
 

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Discussion Starter #16
WTF!!!

SnowbordrWRX said:
new_sti_lvr - I see your point now. You don't sound like a dumb guy which is why I was confused as to your lapping comment :lol:
Well thank ya. :) You just don't know me yet, I have my brilliant moments of being a dumbass from time to time, more frequently than I would care to admit.

So, when is the first comparison coming out? (STI versus EVO) Anyone know?
 

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Discussion Starter #17
I believe a RWD car will be easier to use slide techniques b/c you are already biased toward the rear. What I mean to say is that sure line locks and even using the handbrake on an AWD car will make the back slide out, but you will have a harder time (I would think, but then again it is 300hp/300trq stock) than with a high powered RWD car that has a tendency to overstear naturally.
Excellent point. Isn't it true that with DCCD it is possible to bias as much as 65% of the torque to the rear? With 300 ft lbs, it should be more than enough to break them free (even better if you could lock the LSD somehow in the process to make the break complete and uniform in nature), but what I'll need to get used to is the front attempting to continue to track in the correct direction. Something I currently do not have the luxury thereof. Those AWD Porsche's seem to do pretty good under the right kind of driver, ala drive it like you stole it, mentality. Hmmm, wonder how much the rear seats weigh, or if there is any lining in the trunk. Do we get a full size spare? Just thinking of weight to drop from the rear of it to help it along in the process. :)
 

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New STi pics and updates on official website

Excellent point. Isn't it true that with DCCD it is possible to bias as much as 65% of the torque to the rear? With 300 ft lbs, it should be more than enough to break them free (even better if you could lock the LSD somehow in the process to make the break complete and uniform in nature), but what I'll need to get used to is the front attempting to continue to track in the correct direction.
True DCCD will go up to 65% to the rear. I would think it that is enough to break the rear lose. As far as understeering, a lot has to do with the suspension setup. Honestly, for track use the stock STi suspension is a little soft and high. If you got competition coil-overs you shouldn't have a problem setting up the car to overstear on command, especially with enough power to the ground.
 
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