Wilwood BBK for WRX - Fit to BRZ

[SubieNate]

But if the front brake calipers themselves are identical stock, it follows that an aftermarket replacement should work identically as well, to keep the same bias in the original vehicle would keep the same bias in the new vehicle regardless of the actual pressures involved. If the BR-Z is pumping x % less psi to the fronts, then if the calipers apply the same torque per psi then it should be fine.

Now, if the Wilwood kit is designed to be in a 4 wheel kit, then running without the rears could be an issue, or, if the rears are different on the WRX. But I'm not sure about that.

Nathan

[Scooby South]

^^^^ exactly

Bill

[OrbitalEllipses]

Originally Posted by SubieNate

But if the front brake calipers themselves are identical stock, it follows that an aftermarket replacement should work identically as well, to keep the same bias in the original vehicle would keep the same bias in the new vehicle regardless of the actual pressures involved. If the BR-Z is pumping x % less psi to the fronts, then if the calipers apply the same torque per psi then it should be fine.

Now, if the Wilwood kit is designed to be in a 4 wheel kit, then running without the rears could be an issue, or, if the rears are different on the WRX. But I'm not sure about that.

Nathan

First, we have different rears from the early Impreza WRX so bias is already off. I believe we have 10+ Legacy rears or something similar. Second, piston diameter (or area) was not stated by the OP. I'm sure they're on Wilwood's site, but I'm too lazy to check. Third, related to second, we would need stock piston diameter/area of our brakes...which SHOULD be the same as the Impreza, but I'm not certain.

Note: it's possible the rear piston diameter/area hasn't changed from 2003 to 2012, but I wouldn't be sure about that.

[ABQautoxer]

Originally Posted by OrbitalEllipses

First, we have different rears from the early Impreza WRX so bias is already off. I believe we have 10+ Legacy rears or something similar. Second, piston diameter (or area) was not stated by the OP. I'm sure they're on Wilwood's site, but I'm too lazy to check. Third, related to second, we would need stock piston diameter/area of our brakes...which SHOULD be the same as the Impreza, but I'm not certain.

Note: it's possible the rear piston diameter/area hasn't changed from 2003 to 2012, but I wouldn't be sure about that.

How about you do the math and show me facts rather than speculate? I hate just because its brakes people lose their minds about basic facts. The factory setup is terrible so convince me this is worse and thus unsafe for street use.

[SubieNate]

Originally Posted by OrbitalEllipses

First, we have different rears from the early Impreza WRX so bias is already off. I believe we have 10+ Legacy rears or something similar. Second, piston diameter (or area) was not stated by the OP. I'm sure they're on Wilwood's site, but I'm too lazy to check. Third, related to second, we would need stock piston diameter/area of our brakes...which SHOULD be the same as the Impreza, but I'm not certain.

Note: it's possible the rear piston diameter/area hasn't changed from 2003 to 2012, but I wouldn't be sure about that.

Basically what I'm saying is that bias isn't just a matter of piston size/swept area. It's determined by the proportioning valve in the braking system as well. If the rear setup is different, who cares? If the front puts out the same torque as stock but increases the thermal capacity, it will improve the performance without affecting the bias.

So as long as the front setup retains the same torque output per psi, (Same balance of piston area, swept area, effective diameter etc) it doesn't matter that it's a different car. If our car has the same brake caliper as the WRX, and the same swept area and the same effective diameter, and the Wilwood caliper is designed to retain those things on the WRX, it will retain it on our car as well.

I'm not saying that's the case, but if the OE hardware is exactly the same then there's no reason to believe the Wilwood won't work if Wilwood did their homework the first time.

[OrbitalEllipses]

Originally Posted by ABQautoxer

lol @ devil's advocate. What a cop out...

From NASIOCs brake math spreadsheet, you ignoramus: the 2002-2005 Impreza WRX has 2x 42.8mm front pistons and 4.460"^2 piston area across 2 pistons. The linked Wilwood kit has 4.12"^2 piston area across 4 pistons (4x 1.62" piston diameter). Likely the '10 LGT just has a different caliper bracket in the front and ahs the same 42.8mm pistons out front and 38.1mm pistons out back.

[OrbitalEllipses]

Way to not quote the facts and now my post is edited too while I added MORE math for your consumption, ingrate.

And the Wilwood caliper has 4x 1.62" piston diameter.




Choke on a rock.

[Captain Snooze]

Originally Posted by ABQautoxer

The factory setup is terrible

In what way is the factory set up terrible?

[ABQautoxer]

Originally Posted by Captain Snooze

In what way is the factory set up terrible?

Yeah that was poor wording, mainly I hated the stock pads, it was very easy to fade them.

[bpracer]

The older WRX kit is 12"x0.81" rotor, the new BRZ kit is 12.88"x1.1" rotors. It's a pretty big difference in rotor thickness.

I've raced a 2750lb car with 12x.81" rotors, they are not going to have the heat capacity to hold up to real abuse. They would warp after a hard days use and I would change out rotors to complete the weekend.

Now if you were at a track that was easy on brakes and I can see using these to help acceleration. There are not that many people that change brake packages for different tracks other than pro race teams.

[SubieNate]

I don't understand how he's saying the diameter is larger... The diameter that is important is the outer diameter of the tire. That is the same (or nearly so) as every WRX that has ever been made in the states.

Nathan

[OrbitalEllipses]

Originally Posted by SubieNate

I don't understand how he's saying the diameter is larger... The diameter that is important is the outer diameter of the tire. That is the same (or nearly so) as every WRX that has ever been made in the states.

Nathan

Thickness = heat capacity. Thinner rotors will overheat quicker with abuse, ultimately ending in cracks or other failure.

[bpracer]

Originally Posted by OrbitalEllipses

Thickness = heat capacity. Thinner rotors will overheat quicker with abuse, ultimately ending in cracks or other failure.

Yes, thickness is important, they will cool faster.

Larger diameter will add mass, more heat capacity, but thinner rotors will not cool off as well.

It all a trade off of weight vs capacity.

These 12x.81 will work fine on the street, auto-x, but serious track use with some high friction pads will uncover their lack of capacity.

Edit- in simple term, two rotors of the same diameter but different thicknesses will stop the same for a while, the thinner has less mass/capacity and less airflow through the cooling vanes. The thinner one will get hotter faster and cool off slower.

[m.wood0213]

This is an excellent write up. Im seriously considering pulling the trigger on this setup.