legacycentral bbs

My budget is about $500 for everything.

The car is a '93 L AWD, 4eat, non-ABS.


I wish I could afford the 4/2 setup, or even Brembos, but, I cook for a living, so money's tight.

The car is being transformed from a completely stock car, to being built to the absolute limit of the STX class rules, for autoX. The brakes on the car currently are absolute garbage. I even tried swapping out the pads, and it seems like even still, the brakes take WAY too long to stop. I've got 17x7" ADR wheels, with 225/45-17 Kumho Ecsta AST's on it for my DD setup, and a set of '02 WRX wheels that are getting Dunlop Star Specs on them, so grip isn't the issue.... it's the brakes themselves.


I have a pair of brand new cryo-treated '03 WRX rear rotors already, that I got from a friend.


So, please help me figure out a front/rear caliper solution, front rotor solution, master cylinder solution, brake line solution.

Thanks!


Also... looking for some rear trailing arms to bolt a swaybar to, and a swaybar itself, too.

I've had pretty good luck w/ WRX two-pot fronts and turbo rears with EBC pads all around. ~$200 for all of it. I don't auto-x that car, though. If I was going to, I'd add cryo treated rotors in front.
If you're looking for more pedal pressure, you can swap in a SVX master.

Evan,

I think you need to define your braking requirements. Do you want better pedal feel/control, do you want more stopping power, reduced pedal travel, etc.

Each component you swap on will affect the entire brake system differently. I can't see you getting up to very fast speeds or long braking durations with auto-x, so you really don't need a very high temp pad. You would want something in the middle that has very good initial bite, and decent temp range so it doesn't overheat.

The cheapest option is probably to get WRX brakes. They will add more stopping force and better heat sinking capacity, which helps resist fade. On my car, which started life as a 90 L, I noticed an increase in pedal travel with the WRX brake setup due to additional volume requirements. The non-abs cars only have a 1" bore MC. So to move the same amount of fluid, the piston has to travel further. I did not desire this, so I upgraded to a 1-1/16" bore MC. The FWD SVX is the only Subaru vehicle to get a 1-1/16" bore 4-port MC (non-abs). Check out this thread for more info.

http://bbs.legacycentral.org/viewtopic.php?f=8&t=47710

Stainless braided lines are a good an inexpensive item to do, which will improve pedal feel.

Brake pads, I'd probably recommend starting with the EBC red stuff pads. I run them on my Impreza as a daily driver, and they work good, have good initial bite. If you find they are not agressive enough, you can go with the yellow stuff pads. I think I'm going to try them next time on my Impreza.....or the Legacy.

If you don't like the brake pedal feel, about the only significant thing you can do to change it is to replace the brake booster. Our cars have a tandem diaphragm brake booster, and it tends to provide an "over assisted" feel to the brakes. The early imprezas came with a single diaphragm booster, which provides much more linear brake pedal feel and a much firmer pedal. It's a good upgrade. Also, there are some braces that can be fit to the cars to brace the MC. They help a little bit, but aren't really a substantial improvement.

Brake/car balance. If you upgrade to the WRX brakes in the front, I think you will find that the car is overly front biased with the braking. If you want to balance the car out a little bit or shift some rearward, a common upgrade is to put the H6 Legacy rotor on the rear. This larger diameter rotor increases brake torque in the rear. The other thing I did was install a wagon proportioning valve. The wagon's proportioning valve has a slightly higher split point which allows more pressure to the rear brakes under hard braking.

I'd suggest checking out my brake math spreadsheet. You can play with different pads & calipers to determine what the changes would be, etc.

http://www.main.experiencetherave.com/s ... kemath.xls

If you have any questions, let us know. I think the only thing original with my brake setup is the hard lines on the car. Everything else has been replaced/swapped with something else.

Even with the SVX m/c and wagon prop valve, the balance was still front heavy with WRX brakes?


And if I ended up getting WRX brakes, what SS lines do I need? Legacy or WRX?

The MC has no affect on the balance of the braking. The MC will only affect pedal travel and feel.


There's a TON of calculations and vehicle dynamics that go into determining the correct brakes for a car. Obviously, we do not have that information, so we have to make some generalizations and assumptions. That's essentially what I'm doing if you look at my brake math spreadsheet.

There is a difference between brake torque change and brake bias change. Brake torque is a calculated value and should remain pretty static regardless of how fast the car is moving or whether it's stopping, turning, etc. Brake bias will change depending on vehicle dynamics. Also, based upon some rough calculations I did, about a 10% shift in brake torque nets you around a 1% change in bias.

To answer your question regarding the balance, with just the WRX brakes on the front, yes the car was overly front brake biased. When I put on the larger diameter LGT rear brakes, that balanced out the car and brought the front & rear brake torque values back to within 0.05% of the original brake setup. The thing with this though, is the original brake setup desirable? That is a more subjective question. You may think it's great, while someone else may think it's too front biased. So that is what you should be asking yourself before you do any swapping of the brake system. If you're happy with how the shift in braking is between the front and rear, get a combination of brakes that will get you back near the original setup. If you think the original setup is too front biased, get something that will up the brake torque.

There is however a practical limit on how much "rear" brake shift you should go for. I wouldn't suggest going more than a 10% shift in rear brake torque when compared to your original brake setup. Plus there are a limited number of calipers you can use to increase brake torque without down sizing the front calipers, which you really don't want to do. So the option there would be to run more agressive brake pads in the rear.

With all that said.....I would recommend you go with the 2-pot WRX front brakes and the Legacy "H6" rear brakes. That setup will give you the largest rotor diameter without stepping up to the brembros, and keep your overall brake bias similar to your original brake setup.

Either SS lines will work. If you still have struts meant for the legacy get the Legacy SS lines. If you swapped in WRX struts, get ones for the WRX. The mounting to the strut is what is different, but most people just use zip ties.

As far as what I want, I want to be able to tap the brakes, and peel my eyebrows off of the windshield.

Probably the best bet then is to build a Locost 7.