Hamulce - klocki, tarcze itp.

[elmo]

 

 

maja dokłądnie 30kkm czyli szału nie

I to by się zgadzało. Przednie schodzą jeszcze szybciej - u mnie tak do 15-20kkm. 

[AdaSch]

sprawdziłem też przód,

 

kupione miesiąc później a mają z 5mm mięsa (jeszcze to sprawdzę), przebieg 30kkm, tarcze TRW. Czyżby jednak większa powierzchnia i wolniej się zużywały?

to trochę dziwne bo balans mam 68% przód 32% tył

[tzd]

balans mam 68% przód 32% tył

 

Adam, jak to zmierzyłeś? szczególnie po zmianie zacisków? 

[respect]

@@AdaSch, średnica tłoczka jest teraz większa niż w zacisku seryjnym ?

I faktycznie skąd masz ten rozkład 68/32 ?

[AdaSch]

z forum www.subaruforester.org

 

 

**warning** This is a LONG post. A VERY long post. VERY VERY long. I'll CN it at the bottom. If you are a dork, you'll read it all. Data for this thread came from the Subaru Factory Service Manuals and my friend Josh Colombo.

Below is all of the information about brake bias setups. For clarification, all we are doing here is assuming a pedal input pressure and then extrapolating data from that. Because we are only concerned with bias, the actual numbers don't have to have any real world significance, only the ratio really matters. That said, we can guess at a few things and still come up with a reasonably realistic bias guide. There are a few unknowns that we are forced to eliminate. Mainly, the proportioning valve split point. Pressure IS split 50/50, however above a certain threshold the prop valve dramatically limits the pressure flowing to the rear lines. Up until that point, bias will be the same no matter the pedal input. After that point, bias will shift forwards. Since I didn't originally design the system, I have no idea what that point is. Still, these calculations will give us a general idea of how the brakes will feel when paired with different front brake setups. The calculations aren't difficult, just tedious. To cut back on this, we will keep a few things constant. Master cylinder size, brake pad coefficient of friction, and pedal pressure. Keeping these constant will make some bits of the equation constant and save time. When looking at the numbers, there is such a thing as too much rear brake. It's like riding a bicycle. Too much rear brake and the rears lock up and you don't stop nearly as well as you could. Too much front brake and you lose rear wheel traction putting even more stress on the front brakes. The ideal bias is tough to determine and varies for everyone. To get an idea of what you MIGHT like, you could go ride a bicycle and experiment with lever force. Ideally you'll have enough rear bias to not lock the rear tires, but not so much front bias that you dive excessively. This ties a significant amount into suspension setup, tire choice, and alignment settings. All of these things will impact the "right" brake bias for you. Really soft suspension and a front biased setup will make the rear brakes inefficient. Really stiff suspension and not enough front bias, and you'll overload the rear tires and make trail braking difficult. It's kind of a slippery slope and the best thing you can do is look at the stock numbers and then think to yourself how you might like to change it. If you are unhappy with stock, and would really like more rearward bias, then go that way and judge the amount of bias you'd like.

Brakes are a system. You have your pedal input and the associated pressure applied to the master cylinder. The master cylinder applied force across an area giving you some line pressure. The pressure in the lines and the area of the piston give you some force output. The friction between the pad and the rotor with the force applied and the distance from the center of the pad to the center of the hub all compile to produce torque. The actual torque applied to the hubs is not the focus of this discussion. This post is all about ratios. The ratio of front to rear torque, and to some extent, the ratio of one setups brake torque to another. Since we are keeping so much constant, we can assume that if one system produces X brake torque, and another produces 1.25X brake torque, then the latter is proportionally "stronger" by that amount. I wouldn't expect numbers that large. Also, one thing that we will choose to ignore is tire coefficient of friction and its relationship to stopping the vehicle. This gets into mathematical models far beyond the scope of this thread. Since this is a brake comparison and not a tire comparison, the figures to calculate theoretical stopping distances would be constant and directly proportional to brake torque within reason (it's possible that the torque produced at our theoretical pedal pressure is beyond the torque required to stop the vehicle).

So let's begin by laying the ground rules. We need to assume our constants.

Unfortunately, I don't have access to my FSM right now so I don't exactly know the stock MC size. I seem to recall it being 1.00" since I KNOW it's not the 1.0625" STi size and I doubt it's the 0.9375 of the LGT. That's important. Right away, we encounter our first tidbit. Larger MC's mean greater pedal pressure required for the same line pressure. So if you feel like your brakes have to light of pedal pressure, a bigger MC is for you.

We also need to assume a few other things. Mainly piston travel for sliding calipers (.025"), and roll back. These will be constant, since in reality I think they are. We won't get into caliper flex and such, because they aren't necessarily important.

Now we need the following brake data for each of our interests; effective disc diameter, piston area, and number of pistons.

This is where it gets complicated. A fixed caliper has all pads pushing with the same pressure. A fixed caliper has the same pressure for each piston. A sliding caliper, however, applies the pressure from the piston twice (once on each side of the pad). So a 2-piston sliding caliper effectively applies the force from 2 pistons on each side, making it have twice the area. Confused? The pistons in a sliding caliper push the pad into the rotor. When the pad contacts the rotor, the caliper pulls the outboard pads into the rotor. Negating caliper flex, it pulls the outboard pad into the rotor with exactly the same force as it pushes the inboard pad to the rotor. We COULD simply ignore half of the fixed caliper pistons and focus on half of the braking system, or we could multiply the sliding piston calipers by two. Doesn't really matter. Let's do the latter because it makes for more easily handled numbers. This is funny. A sliding caliper actually acts like it has twice its actual piston area. Funny to think, huh? That a fixed caliper and a sliding caliper can have exactly the same effective piston area. No wonder the M3 has never come with monoblock calipers!

Also, outside diameter does not impact brake torque. On the contrary, effective diameter is what matters. The effective diameter is provided in the FSM. It is the average diameter of pad swept area. If you look at the swept area of a rotor, the smaller diameter of the inside and the larger diameter of the outside would produce different torques at each point. The effective diameter can be thought of by the average of these two points, and as such is slightly higher than the center point of the swept area. Funky, I know. But the FSM provides this, so it doesn't REALLY matter how they got it. It is also not rotor specific, but has to do with the pad shape as well. The FSM provides it, so we go with what they give. We will only make one assumption, and that is the effective diameter of the RB 316x18 rear rotors. We will assume that they have the same effective diameter as the STi rotors. It won't change much if they are slightly different.

Another thing to consider is pad compound. There are a bunch of different compounds. Standard pad coefficient of friction ranges from 0.38 to 0.40. Performance street pads range from 0.45 to .050. Race pads range from 0.60 to 0.65. We'll use performance street pads because that's what most of us will run. We'll simply average the values and use 0.475.

The last thing to consider (I promise) is the brake booster. There is some data out there, but we will make some generalizations. Accurate or not, it would give us a good range for where our line pressure should lie. We'll basically ignore this and just make an assumption for the pressure applied to the rear of the MC. We'll call it 100 pounds to try and keep numbers as manageable as possible.

OK, I think we've gone over everything. Now let's do some math!

We'll start with stock FXT brakes. They are easy and give a good base line. I'll only do the front end calculations once and then just post the numbers for the other setups. I'll post the data though, incase anyone wants to double check my math. I'll show the steps as well so that you can play with different MC sizes if you so desire.

Data needed:

FXT front brakes-
Outer Disc Diameter - 11.57" (294mm)
Effective Disc Diameter - 9.72" (247mm)
Caliper piston diameter - 1.685" x2
Caliper piston area - 4.460sq.in
Effective caliper piston area - 8.915sq.in

FXT rear brakes-
Outer Disc Diameter - 10.47" (266mm)
Effective Disc Diameter - 9.06" (230mm)
Caliper piston diameter - 1.5" x1
Caliper piston area - 1.767"
Effective caliper piston area - 3.5325sq.in

The 1" master cylinder has a surface area of 0.785.

So we start by finding line pressure. 100lbs of input force divided by the surface area will give us line pressure.

100pounds/.0785sq.in = 127.3885 psi (so much for keeping simple numbers).

With this, we are armed with our first constant. Line pressure = 127.3885psi. Yay!

Now areas from above. Pressure times area.

Front: 127.3885psi * 8.915sq.in = 1135.69lbs of clamping force on the front rotors
Rear: 127.3885psi * 3.5325sq.in = 450lbs of clamping force on the rear rotors.

Good! Now we can figure out torque, and from that bias information.

What we need to do is this:

Fluid pressure * effective diameter of the disc * coefficient of friction * Effective piston area.

Front: 127.3885psi*9.75in*0.475*8.915sq.in = 5259.664313lb-in of force
Rear: 127.3885psi*9.06in*0.475*3.5325sq.in = 1936.575 lb-in of force

Now, we find the ratios.

5259.664313/(5259.664313+1936.575) = .730891 Front and 1-.730891 rear

That means a stock FXT has 73% of its braking force up front and 27% in the back. Good!

Easy, huh?

So, fluid pressure is the same for all setups as is the coefficient of friction. So we can combine these into one constant term we will call M. 127.3885*0.475 = 60.5095

Now, to find torque we just multiply piston area times effective diameter times M.

So here's the info we need.

Legacy GT

LGT front brakes -
Outer Disc Diameter - 12.44" (316mm)
Effective Disc Diameter - 10.28" (261mm)
Caliper piston diameter - 1.685" x2
Caliper piston area - 4.460sq.in
Effective caliper piston area - 8.915sq.in

LGT rear brakes-
Outer Disc Diameter - 11.42" (290mm)
Effective Disc Diameter - 10.00" (254mm)
Caliper piston diameter - 1.5" x1
Caliper piston area - 1.767"
Effective caliper piston area - 3.5325sq.in

Torques -

Front: M*10.28*8.915 = 5545.469176
Rear: M*10.00*3.5325 = 2137.499412

Bias is 72.1787303% front and 27.8212697% rear

Notes: That was easy because of piston diameters being the same between the LGT and the FXT.

4-pots/2-pots

Subaru 4-pots -
Outer Disc Diameter - 11.57" (294mm)
Effective Disc Diameter - 10.04" (255mm)
Caliper piston diameter - 1.591" x4
Caliper piston area - 7.9482sq.in

Subaru 2-pot rear brakes-
Outer Disc Diameter - 11.42" (290mm)
Effective Disc Diameter - 10.00" (254mm)
Caliper piston diameter - 1.5" x2
Caliper piston area - 3.5325sq.in

Torques -

Front: M*10.04*7.9482 = 4828.670308
Rear: M*10.00*3.5325 = 2137.499412

Bias is 69.3160015% front and 30.6839985% rear

Notes: The rear pistons are the same size as the 1-piston rear brakes of the LGT. Effectively, the 4-pots provide LESS clamping force than the 2-piston brakes. This shifts the bias rearward which is why people see braking advantages from the 4-pots. Stiffer calipers and more rearward bias. Ultimate front brake torque is actually less with the 4-pots than with the stock FXT brakes.

Brembo

Front Brembos -
Outer Disc Diameter - 12.83" (326mm)
Effective Disc Diameter - 10.55" (268mm)
Caliper piston diameter - 1.575" x2 and 1.811" x2
Caliper piston area - 9.043743.in

Rear Brembos-
Outer Disc Diameter - 12.44" (316mm)
Effective Disc Diameter - 10.55" (268mm)
Caliper piston diameter - 1.417" x2
Caliper piston area - 3.15238573sq.in

Torques -

Front: M*10.55*9.043743 = 5773.305191
Rear: M*10.55*3.15238573 = 2012.406197

Bias is 74.1525713% front and 25.8474287% rear

Notes: This is a perfect example of two different outer diameters with the same effective diameters. The STi front caliper is tricky because of the different piston sizes. Still, it works out well and the bias is pretty good.

OK, so that's it for stock calculations. We have:

Stock FXT -
Front = 73% Rear = 27%

Stock LGT -
Front = 72% Rear = 28%

Stock 4/2 pot -
Front = 69% Rear = 31%

Stock Brembo -
Front = 74% Rear = 26%

Now, the calculations for the rear brake torque numbers of the RB big brakes

290x18mm BBK:
Outer Disc Diameter - 11.42" (290mm)
Effective Disc Diameter - 10.00" (254mm)
Caliper piston diameter - 1.5" x1
Caliper piston area - 1.767"
Effective caliper piston area - 3.5325sq.in

Rear torque: M*10.00*3.5325 = 2137.499412

Notes: Same as LGT rears! In fact, this is the same effective brake torque as the standard 'H6' upgrade. The benefit you have is vented rears over solid rears, allowing for a greater heat holding capacity and better cooling.

316x18mm BBK:
Outer Disc Diameter - 12.44" (316mm)
Effective Disc Diameter - 10.55" (268mm)
Caliper piston diameter - 1.5" x1
Caliper piston area - 1.767"
Effective caliper piston area - 3.5325sq.in

Rear torque: M*10.55*3.5325 = 2255.06188

Notes: Effectively an LGT caliper with STi rotors.

Now, bias calculations with the various RB kits:

FXT w/ 290x18 rear kit:
Front: M*9.75*8.915 = 5259.664313
Rear: M*10.00*3.5325 = 2137.499412

Bias is 71.1037918% front and 28.8962082% rear

FXT w/ 316x18 rear kit:
Front: M*9.75*8.915 = 5259.664313
Rear: M*10.55*3.5325 = 2255.06188

Bias is 69.9914241% front and 30.0085759% rear

LGT w/ 316x18 rear kit:
Front: M*10.28*8.915 = 5545.469176
Rear: M*10.55*3.5325 = 2255.06188

Bias is 71.0909185% front and 28.9090815% rear

4-pot w/ 290x18 rear kit:
Front: M*10.04*7.9482 = 4828.670308
Rear: M*10.00*3.5325 = 2137.499412

Bias is 69.31600% front and 30.683998% rear

4-pot w/ 316x18 rear kit:
Front: M*10.04*7.9482 = 4828.670308
Rear: M*10.55*3.5325 = 2255.06188

Bias is 68.16562% front and 31.8343751% rear

Brembo w/ 290x18 rear kit:
Front: M*10.55*9.043743 = 5773.305191
Rear: M*10.00*3.5325 = 2137.499412

Bias is 72.979999895% front and 27.0200001% rear

Brembo w/ 316x18 rear kit:
Front: M*10.55*9.043743 = 5773.305191
Rear: M*10.55*3.5325 = 2255.06188

Bias is 71.91132567% front and 28.0886743226% rear

So, that about covers it.

We just did calculations for Stock: FXT, LGT, STi, 4/2-pots

We also did the 290x18 with stock: FXT, STi, 4-pots

We also did the 316x18 with stock: FXT, LGT, STi, 4-pots

All of these combinations put you fairly close with an ideal 70/30 split and any of them would work really well.

One thing I would consider when choosing is your style of driving and your suspension setup. If your car is stiffly sprung and you don't mind the tail stepping out a little, then the 316 rears would likely be ideal. More rear bias will take advantage of your suspension and you'll notice far less dive.

I'd say for most people with stock front brakes, the 290x18 kit would work out really well.

For those with 4-pots, it's a tough draw.

Brembo's should definitely get the 316x18 kit.

LGT fronts, I'd go with the 316x18 rear kit.

Also note, RB DOES have a 316mm front brake upgrade for the WRX/FXT which will then turn your numbers into those for the LGT w/ 316 rears.

I hope this has been informative and has helped you make a decision. If you have any questions, please let me know and I'll do my best to answer them.

Also, I'll ask to confirm the effective disc diameter on the RB 316x18mm rotors. I'll correct this post if I find that EDD to be different than the STi rotor.

Thank you for reading!

[kamilgt]

ile mniej więcej km "docierać" nowe tarcze i klocki (wszystko oem subaru) z przodu? zakładając jazdę po mieście i przedmieścia

[KamilP]

200km?

[matt1992]

Tarcze do wrx 2006, przód to 294?

[SOpEL]

tak

Edytowane 15 Kwietnia 2016 przez SOpEL

[matt1992]

Strasznie kiepsko to hamuje.

[Bartek1986]

Co kiepsko hamuje?

[Mike85]

ile mniej więcej km "docierać" nowe tarcze i klocki (wszystko oem subaru) z przodu? zakładając jazdę po mieście i przedmieścia

Najważniejsze to nie przegrzać ich podczas pierwszych hamowań.

A najlepiej jest pojezdzic w cyklu miejskim i dac im sie wystudzic. 2,3 takie jazdy ( jakies 100km) i po docierce ;-)

 

Wysłane z mojego SM-N910F

[kamilgt]

dzięki we wtorek z samego rana zmieniam zestaw na przodzie a w środę jest SJS... będę jeździł cały wtorek, odwiedzę chyba wszystkich znajomych

Edytowane 17 Kwietnia 2016 przez kamilgt

[saszynski]

wiesz, ze masz dotarte heble kiedy podczas hamowania pedal jest twardy a auto hamuje... bez uczucia gumowatosci...

[AdaSch]

Nowe tarcze trw miały jakby rowki na płycie gramofonowej. Klocki omp odotarly się w może Max 20km chociaż już po 7km czyli pod domem było już bardzo dobrze

 

Wysłane z mojego HTC One dual sim przy użyciu Tapatalka

[pablosik]

Macie namiary na tani sklep z CL5+ do WRXa GD na tył (290mm)?

[matt1992]

Co kiepsko hamuje?

Wrx 2006 Hawk.

[KamilP]

sprawdzales czy tloczki niezapieczone?

[ADK90]

Przeglądam temat od jakiegoś czasu ale nadal jestem głupi ile ludzi tyle opinii na temat skutecznych klocków i tarcz do WRX'a. Zbliża mi się wymiana wszystkich tarcz i klocków oraz szczenek w moim robalu. Chciałbym mieć mocne hamulce lecz bez żadnych pisków, buczenia czy innych hałasów. Używam auta do szybszej jazdy ulicznej oraz okazyjnych wypadów na tor to hamulce muszę mieć mocne. Co polecacie aby to dobrze hamowało i nie piszczało? Zaciski mam 4pot i 2pot.

Obecnie z przodu mam tarcze brembo które przy wyższych prędkościach biją oraz klocki Ferodoo premier ale ten zestaw nie hamuje... Z tyłu siedzą jakieś twarde nacinane tarcze oraz klocki, które kupiłem wraz z zaciskami.

 

Podsumowując potrzebuje Waszej opinii co i jakie mam wybrać:

-tarcze na przód (294mm)

-klocki do przodu

-tarcze na tył (290mm?)

-klocki na tył

-szczęki ręcznego (średnica bębna 180mm?)

 

Dzięki za każdą sugestie.

[AdaSch]

Jak to powiedział mi dzisiaj mój rajdowiec, mechanik, serwisant w w swoim wyczynowym RA ma RC5+ bo nic innego nie hamuje, tyle że puchną tarcze, a w swoim evo x, cywilnym potworze ma rc6 i to jest zabójcza zyleta.

 

Pytanie: na jaki kompromis chcesz pójść?

 

Wysłane z mojego HTC One dual sim przy użyciu Tapatalka

[ADK90]

Jeździłem takimi samochodami z takim klockiem i hamuje to na prawdę rewelacyjnie, tak jak powinno wychodzić z fabryki. Odstrasza mnie jednak jak w Twoim przypadku przy cl5 byczenie i wibracja przy wyższych prędkościach. Nie ukrywam zdarza mi się rozpędzić 160+ i taki dźwięk przy takiej prędkości jest okropny. Moim kompromisem jest jak najcichsze odgłosy przy hamowaniu z połączeniem hamulca żylety oraz ich żywotnością co w przypadku cl5 jest okropnie szybka.

[markos007]

klocek EBC Green Stuff, jak to się sprawuje na co dzień?

[sredniaq]

Jaka największa tarcza hamulcowa wchodzi na 14" stalówki? Rozważam upgrade hebli, ale nie chcę wymieniać zimówek...

Na razie

 

Albo inaczej: jaka najmniejsza felga na tarczę:

- 277mm (nie wiem jakie zaciski występowały z tą tarczą, dwutłoczek z GTka? )

- 294mm (zacisk NIE 4-tłoczek)

Edytowane 5 Maja 2016 przez sredniaq

[Crazy_Ivan]

 

 

klocek EBC Green Stuff, jak to się sprawuje na co dzień?

 

W mojej opinii tak samo jak brembo za 1/4 ich ceny. Nie warto.

[leon]

 

 

Jaka największa tarcza hamulcowa wchodzi na 14" stalówki? Rozważam upgrade hebli, ale nie chcę wymieniać zimówek...

 

260.