subaru 4pot/2pot brake upgrade

[chochocho]

hello all,

been reading up on the stickies and i may have missed the information.

got a 91 legacy and wanted to look into upgrading to the 06-07 wrx red subaru 4pot/2pot calipers or equivalent.

from what i understand the front 4pot needs the following:

calipers from 06-07 wrx 4pot
rotors from 06-07 wrx
brake lines from 06-07 wrx
brake pads form 06-07 wrx

wonder if our 91 legacy ss stainless steel lines work?

Rear 2pot
calipers from 06-07 wrx 2pot
brake pads from 06-07 wrx
brackets from kartboy or another manufacturer

What rotors would i need to make this work with the e-brake? DBA 2657 rotors work. read it in another thread.

thanks in advance.

yat

[mike-tracy]

The 06-07 WRX rotors have the right size "hat" for our e-brake setup. I have no information about the 91 brake lines as I used the ones that came with 4/2 pots on my 91.

I like the setup, but if I hadn't paid $300 for everything, I'd say it's not worth it. Compared against 03-05 WRX front and 05+ LGT rears, costs alot more but has the same size rotors. Biggest difference is pedal feel (which isn't as big as you think, coming from 2/1 pot brakes). Don't want to dissuade you if you have your heart set on it, but this is my opinion.

[Legacy777]

I would agree with Mike on his comments. I've got the 02 WRX front brakes with LGT rear brakes and while it would be nice to have the 4/2 pot brakes, I just don't know if I can justify the cost, plus the fact I couldn't use the 02 WRX wheels I have as spare wheels. Looks and pedal feel (which is questionably small) are really the only reason I'd suggest the 4/2 pots over the 02-05 WRX fronts with LGT or H6 rears.

As for the brake line quesiton, I really don't see a reason why you couldn't use the brake lines that are currently on your car, but I haven't seen the 4 pots up close to say yes or no they would work.

If there is a difference it is likely to be whether there is an angle on the fitting so the brake line clears the wheel. I ran into somewhat of a similar issue with the rear calipers. Mine were actually overseas Legacy B4 rear calipers (which is probably the same as the new LGT rears) where the positioning of the opening that the brake line is supposed to go through wouldn't work for my brake lines and I just rotated the brake line fitting and tightened them down.

You can see what I'm talking about in these pictures

http://www.main.experiencetherave.com/s ... P_3659.JPG

http://www.main.experiencetherave.com/s ... P_3784.JPG
http://www.main.experiencetherave.com/s ... P_3788.JPG

Rest of the pictures are here
http://www.main.experiencetherave.com/s ... b4calipers

[originalcyn]

I like the setup, but if I hadn't paid $300 for everything, I'd say it's not worth it. Compared against 03-05 WRX front and 05+ LGT rears, costs alot more but has the same size rotors. Biggest difference is pedal feel (which isn't as big as you think, coming from 2/1 pot brakes). Don't want to dissuade you if you have your heart set on it, but this is my opinion.

Damnit Mike, how'd you get away with only 300? I tried to be as frugal as possible and still ended up over 5. and you have 4/2 pots. sigh.

[mike-tracy]

I wheel I deal lol.

[oldscoobyturbo]

I reused my brake lines with the wilwood 4 pots no issues with fitment and its a big upgrade from the stock 2 pots in stopping power and feel
I have newer stock rear brakes with ate pads and wagner vented rotors

[Lego22T]

To weigh in on the matter... I have the early '02 WRX fronts (left overs from 2nd Gen LGT & 2.5RS) and the H6 rears with s/s braided brake lines installed on my car for autocross purposes I'm running Hawk HPS front pads with Power Slot rotors and OE rear pads with OE rear rotors. I took a run in my buddy's '06 WRX with OE rotors front & rear and Carbotech pads in the front and s/s braided lines and his 4 pot / 2 pot setup was far above my car's braking ability. Yes the two cars are like comparing apples and oranges. So I took out another friend's car ('01 2.5RS) who had swapped over to the 4/2 setup and its still a beast when you plant your foot.

Now I'm not saying that the WRX/H6 brake combo isn't worth while, because it certainly is. It's a huge improvement over the stock LSS setup by far. I drive my wife's '07 Impreza 2.5i wagon with completely stock brakes and I can tell immediately that my Legacy has superior braking ability.

My $.02 on the matter is that the 4/2 pot setup is worth the purchase if you can get a complete setup for $500 or under. If not, "settling" for the WRX/H6 package isn't something to cry about. I do plan on swapping over to the 4/2 setup once I can pry them from his death grip.

[James614]

I plan on getting the 4pot 2pot setup. Like others have said, I wouldn't pay out the wazoo for it. I see them for $1200 on NASIOC and laugh hysterically. For that money I would definitely have some Brembos. Keep in mind a lot of GC STIs from overseas used the setup with black insteadof red calipers, that can help you find a better deal.

[jamal]

What rotors would i need to make this work with the e-brake? DBA 2657 rotors work. read it in another thread.

thanks in advance.

yat

That rotor is for rear brembos and a 170mm parking brake. You would just want 06-07 rotors.

[mike-tracy]

Lego22t, why not upgrade to 03-05 WRX front brakes - bigger pads, improved setup.

[Lego22T]

I've thought about it. I know the rotors are the same size but it's also the clamping force of the 4 pots that attracts me.

[Legacy777]

I've thought about it. I know the rotors are the same size but it's also the clamping force of the 4 pots that attracts me.

The 4-pots actually have less clamping force than the WRX 2-pots. This is why braking components in my mind are not fully understood and the motto, "bigger is better" isn't always the case. The main things most people comment on is brake feel, stopping power, and brake fade. I've listed them in that order because I think brake feel can have a more profound affect on the driver's ability to interpret the car's ability to brake than the car's actual stopping ability.

There is A LOT that goes into brake design and to simplify things, brake torque is the most common comparable measurement when looking at different braking setups. Brake torque can account for different rotor size, calipers, & pads.

When you look at the 4-pots vs. the WRX 2-pots, the 4-pots actually have smaller pistons, which give the 4-pots less overall clamping force and brake torque with the same given input brake fluid pressure. Another key difference between the 4-pots and the WRX 2-pots is that the effective rotor diameter is different. The effective rotor diameter is calculated by finding the centroid of the brake pad. This is something that really can't be calculated easily by hand, so we are left to the numbers provided by the factory manuals. What you see though is that the 4-pots have a greater effective disc diameter compared to the WRX 2-pots, and this is due to the pad design/shape. This also helps counter the smaller diameter pistons.

In my opinion, the benefit of the 4-pots (or any opposing caliper design) is that they provide a much more even brake force across the brake pad, which allows the pad to be more effective and stop the car better. The additional item as I mentioned before is that the brake feel is typically superior which allows the driver to better interpret the car's stopping ability, especially during heavy braking.

My brake math spreadsheet has all the numbers if anyone cares to look and haven't run across it yet.

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

[Lego22T]

Good info Josh. Being a mechanic I understood going into my upgrades that the 4 piston design would equate to more equal pad pressure and contact. As for over all rotor size, I wasn't sure if there was really much difference.

I have pics of my OE Legacy rotors next to the early WRX fronts and H6 rears and its pretty crazy how much larger they are. Obviously the H6 rears are larger in scale than the my buddy's '03 WRX rears, so I was quite glad to be equipping my car with them.

[Doaomo]

So I have a lead on a full 4/2 pot 07 WRX swap for $400. That lines, pads, calps and rotors. Is there anything you guys can think of that I would still need to get??? Putting this on my 91ss. Thanks in advance for the advise guys!

[Lego22T]

Adapters to fit them to the rear spindles. Kartboy makes adapter brackets.

http://www2.kartboy.com/x4/product.php? ... 260&page=1

[mike-tracy]

Yep^ I had to do some grinding on my hubs to get the cartboys to fit.

[jamal]

To expand a little on what Josh said, a big reason I really like the 4-pots is that they have smaller pistons than the 2-pot caliper. What that means is that it takes more pedal effort but less pedal travel to create the same braking force. That's a big part of improving brake feel because it is much easier to modulate pedal pressure than travel. Think of a brake pedal that provided zero feedback and braking power was only dependent on how far you pushed it. Would not be very easy to drive.

The other benefits are that you get a stiffer caliper which flexes less (further reducing pedal travel), better pad selection, and more rearward brake bias compared to the WRX 2-pots. A little more rear brake will shorten stopping distances and slightly reduce dive.

one of these days I'll buy a set.

[James614]

Think of a brake pedal that provided zero feedback and braking power was only dependent on how far you pushed it. Would not be very easy to drive.

Translation: imagine you're driving a '90s Mercury Grand Marquis

[Legacy777]

Good addition Jamal!

Yeah I would really like to pick up a set as well, but I'm not sure whether they'll fit under my current wheels, and even if they do, the spare 02 WRX wheels I have wouldn't fit.....so if I do the upgrade, it's certainly a snowball type effect.

[jamal]

Yeah nice thing for me is that they'll fit under both my sets of wheels. My current brakes are pretty decent though so I'm not in a big hurry.

[Legacy777]

I need new rotors in the front, so I'll have to decide what I want to do......but first I have to get the damn car running....

[PhyrraM]

A bit late to the party, but here is my 4 pot/2 pot installation.

You can see where I ground a bit from both the Kartboy brackets and the rear carrier on the car. I uses resurfaced OEM '06 rotors (front and rear).

http://bbs.legacycentral.org/viewtopic. ... 3&start=59

[originalcyn]

Back from the dead on this a bit, but the option of getting the brackets from kartboy is there, but what about the hub conversion? Mike and I were talking about it and thinking that it would be approximately the same price as the brackets, but i guess another more important question is how often to hubs come up for sale? it's not a single part that can just be ordered i don't think it is anyways...

[cj91legss]

I've seen the complete oem kits on ebay but they're about 900-ish. The rear hubs should be a direct swap. Maybe you can just find the rear hubs alone?

[86BRATMAN]

If I'm not mistaken all that needs to be swapped on the rear is the backing plate, at least that's it on the second gen legacy, for the 2 pots to bolt on.