Hypothetical question

[skid542]

I got to thinking the other day, I've got turbo rear calipers and rotors and as such my braking is rear biased. While this is nice and fun in a lot of cases, in some it's really bad. Although I really have got used to it and like I don't get that pitched down feeling braking hard. I'm going to be upgrading the fronts very soon, should start work next week , but when I upgrade the fronts it will be front biased, more so than what I would prefere. I know a wagon prop valve will help under heavy braking but it's still going to be forward biased.

So I was wondering, can you put turbo front calipers over NA rotors? If the stock NA braking was front biased and all I have done is put more force on the back, it should just take an equal addition to the front to bring it back right? Since the bracket for the turbo is for a larger rotor I would expect that the caliper would have to be transfered to the NA bracket. Do you think it'd fit?

I'm just kinda thinking aloud and wondering what you all think.

[Legacy777]

No you can't put turbo calipers over n/a rotors. You must use the correct size rotor.

[Imprezive]

Do you mean put front turbo calipers on the rear??

Or did you want to put turbo calipers on the front? Aside from the fact that they aren't the right size there would be no point in keeping the front N/A rotors, are those even ventilated?

[All_talk]

Sounds like you need to install a driver adjustable proportioning valve like the rally boys.

Gary

[skid542]

I meant put turbo front calipers on my na front rotors, that are vented.

But Josh confirmed what I kinda figured, thanks.

And yes I need a portioning valve, but I also need other things first including time and money .

[jamal]

No you can't put turbo calipers over n/a rotors. You must use the correct size rotor.

they're the same width, aren't they? Or do turbo calipers not fit on n/a brackets?

[BAC5.2]

My Legacy stops just fine with WRX front brakes, stock rears with hotter pads in the rear than the front, and a Wagon Prop Valve.

It's level enough for me.

Remember, the WRX has the same brake size in the rear, ours are just vented. I think piston diameter is the same, but I'm not 100% on that.

[Legacy777]

Sounds like you need to install a driver adjustable proportioning valve like the rally boys.

Gary

You can't add any adjustable valves like the rally guys use because we have a dual circuit (at least plumbed that way) and the prop valve is a single inlet, and could only control one circuit.

You're only option is to play around with different subaru prop valves.

[Legacy777]

No you can't put turbo calipers over n/a rotors. You must use the correct size rotor.

they're the same width, aren't they? Or do turbo calipers not fit on n/a brackets?

The discs are the same width, but the turbo rotors are larger diameter, and no the the turbo calipers probably don't fit on the n/a brackets.

[Legacy777]

Remember, the WRX has the same brake size in the rear, ours are just vented. I think piston diameter is the same, but I'm not 100% on that.

You're correct. The SS has the same size rear piston.

The n/a sedans were the only ones to get gyped. The caliper piston diameter was 1.374" instead of 1.5"

[ultrasonic]

My Legacy stops just fine with WRX front brakes, stock rears with hotter pads in the rear than the front, and a Wagon Prop Valve.

What pad options have you found for turbo Legacy rear brakes?

[BAC5.2]

Remember, the WRX has the same brake size in the rear, ours are just vented. I think piston diameter is the same, but I'm not 100% on that.

You're correct. The SS has the same size rear piston.

The n/a sedans were the only ones to get gyped. The caliper piston diameter was 1.374" instead of 1.5"

And a smaller piston diameter equals a firmer pedal feel.

The full SBS lineup is available for the SS rear caliper, so is Carbotech. I'm running the SBS GS5's in the rear. I'll probably go one step hotter next time. I've been really happy with them. Tire Rack carried them.

[skid542]

Can anybody confirm though that they won't fit on the NA brackets?

I'm sure I'll be looking for a wagon prop valve come spring sometime but that still only changes the split point and not the bias before the split. I'm sure I'll be plenty happy with the stock turbo setup but it just feels so good not having an excessively (I know it's not excessive, but how many people want it changed?) front biased braking. On older suspension it really makes a difference braking into corners and such.

Phil, do you notice much difference running different pads once you get it all warmed up? I know I feel a difference with Mintex's on the rear and OEM's up front. What do you run up front?

[Imprezive]

Whats the point of the wagon prop valve then if it doesn't change the bias?

[skid542]

It changes the bias after the split point, under heavy braking the bias changes and favors the fronts a little more. The wagon prop valve changes this from around 520 psi to 640 psi, that's the pressure at the rears when it changes. Josh has a nice spreadsheet that has it all.

[Legacy777]

And a smaller piston diameter equals a firmer pedal feel.

That small of a change isn't going to probably show itself. Even going from a 1" to 1-1/16" bore MC didn't affect the pedal feel. If anything it felt firmer, which went against logic, but hey..

If you go from the stock n/a single 2.252" dia. piston to two 1.685" dia. piston on the turbo leg or WRX, you'll probably feel a difference.

[Legacy777]

Can anybody confirm though that they won't fit on the NA brackets?

Lee,

I wouldn't recommend you do that, even if they do fit, which I doubt they will. The brackets are sized for the caliper, which places the pistons at the correct location to provide even force on the brake pad at it's horizontal center. By using the n/a brackets, the chances of that happening are pretty slim to none.

[Legacy777]

Whats the point of the wagon prop valve then if it doesn't change the bias?

The split point occurs around what I consider medium braking. I did a whole bunch of test with a scale on the brake pedal to measure input force, and correlated that data to factory manual info as to where the split point was, as well as what I considered light, medium, and heavy braking.

If you haven't seen it, check out my spreadsheet

http://www.main.experiencetherave.com:8 ... kemath.xls

[BAC5.2]

Lee,

I'm running HAWK HPS+'s on the front and the GS5's in the rear.

Cold, they are OK. Kinda startling in the winter.

When they warm up, the car will haul down FAST. When they are blisteringly hot, the car squeaks to a stop and the only forward bias that is felt, is the significant G forces.

Sticky tires and light wheels help braking though. As well as driver input. I don't use ABS, and slowing to a stop on the threshold of 225 width RE070's is really something else. It's a cool feeling.

Stainless lines also help. Get those too.

[skid542]

The brackets are sized for the caliper, which places the pistons at the correct location to provide even force on the brake pad at it's horizontal center.

Valid point, I hadn't thought of that.

And thanks Phil, I'll look into the stainless come spring.

[Imprezive]

It changes the bias after the split point, under heavy braking the bias changes and favors the fronts a little more. The wagon prop valve changes this from around 520 psi to 640 psi, that's the pressure at the rears when it changes. Josh has a nice spreadsheet that has it all.

So then it kind of prolongs the brake system from favoring the front brakes? Josh's link wouldnt load.

[BAC5.2]

Imprezive - Yes. Exactly.

It requires higher total brake pressure, before diverting more pressure to the front system. Kind of nice in a sedan, less dive under most braking situations.

Full on the brakes, and it acts very similarly. Roll onto full-brake, and it's more level until you reach that pressure, then it dives forward.

[Legacy777]

Try the link again. If it doesn't work again, try this one

https://www.main.experiencetherave.com/ ... kemath.xls