salsa-king

What do bigger brakes do?

Eg-
My car is was 215bhp and I upgrade power to 350 and get told get bigger brakes to stop better. But have kept with std 4pot and change to grooved discs and better pads.

Or another car is 600bhp has bigger brakes cus I have big bhp.


Scenario...

Both the above cars are the same make and model.
And are travelling at the same 90mph and need to stop.

Why does bigger brakes make any difference when both cars are doing the same speed?

banny sti

iTrader: (68)

You will stop quicker without the brakes fading

Maz

iTrader: (34)

More power usually means your car will gain speed quicker and in a shorter distance. Ergo it needs to stop quicker too. QED.

BULLITT

In that scenario no, bigger brakes won't make a difference.

But bigger brakes are needed on more powerful cars to overcome the power of the engine.

Ie. You should in theory be able to have your foot on the brakes and press the throttle and the car should not go anywhere.

If the power of the engine is enough to overcome the friction force created by the braking system, then the brakes are not strong enough and will not efficiently stop the car when driven to it's potential.

This is why bigger brakes usually have much higher operating temperatures than standard brakes as they create more frictional stopping force capable of stopping a much more powerful vehicle.

scubbay

iTrader: (61)

Its also not so much the stopping from 90mph thats the issue. Its the fact that with more power, especially big power, everything happens a lot quicker. In a car with over 500bhp it doesn't take long to cover a good distance when accelerating so even if you "plan ahead" things can come up quicker and big brakes can help cope with this.

Don Clark

Roughly..........

"Bigger" brakes have a larger pad/disk area/more pistons and thus can exert more braking force for the same pedal pressure, allowing you to stop in a shorter distance/quicker time.

As the disks are usually of a larger diameter the "effective braking radius" is larger meaning less force is required to get the same effect.

LUCKO

iTrader: (3)

the OP is winding us up ??

been on subaru site over 10 years and has to ask this question lol

high quality brakes and tyres will save your life one day thats a fact if you didnt know this i would surrender your licence back to the dvla as you will probably kill someone in the near future

Turbodanc

iTrader: (1)

I completely agree with this. I think exactly the same, its like when people do engine conversions in small cars and they instantly say "you NEED to upgrade the brakes before you drive it.." I always say you dont need to as the old ones will work just fine still, BUT you really should do as bigger brakes would work allot better and so its adviseable.

But i completely understand what your saying And i also understand what everyone else has said on here too, all makes sense.

myblackwrx

iTrader: (1)

http://forums.nasioc.com/forums/show....php?t=1998265

Possibly a controversial read (as it sort of says in the title of the thread)

Turbodanc

iTrader: (1)

Love that thread! He sums it up prefectly.

stonejedi

iTrader: (51)

Anyone that thinks that you can chuck another couple hundred brake horse power at there car and be fine with the standard brakes,is living with the fairies and need to get back to reality.increased bhp and torque puts a load on the brakes you won't believe until you try a couple of hard stops with power and notice your standard pads falling apart.O.E brakes is just that brakes that were designed to deal with a specific amount of power and torque that an engine left the factory with,when you come out of that parameter you need to uprate to deal with the increased power.keep standard brakes with increased power at your peril,Simples.SJ.

T5NYW

iTrader: (4)

Agreed QED

Tony

Although more speed and less brakes = gains or death.

T5NYW

iTrader: (4)

better scenario is less weight = better PTW ratio = less cornering inertia = faster braking = faster.

Tony

RedScoob

Big brakes disperse heat more effectively.
You obviously need no more braking power than is required to lock the wheels, but larger brakes mean that you can repeat the process more before fade becomes an issue.
You'll probably be travelling faster, more of the time if you have more power, so QED..

his-n-her-scoobs

iTrader: (5)

That's true on cars were the brakes worked in the first place, automatically excludes the Scooby

cuprajake

iTrader: (11)

The op mustn't have drove a newage wrx as the standard brakes are pant with the power the car has from factory.

burbling1

iTrader: (1)

I must be missing something on this post surely a car with bigger brakes will stop sooner and in less distance at 90mph than a car on standard brakes.

bustaMOVEs

iTrader: (31)

A lot of misconception here IMO.

1. A caliper that's upto the job wether it be 4/6/8 pot dosent really matter as 4 pot can be just as good with right set up e.g (ap 4 pots) no need for 8 pots IMO,
2. It all depends on disc size you can run on your car, I.e wheel clearance. But initially the bigger disc the better, just imagine a vynil record, if you put your finger on the inner circle to stop it, it will stop depending how kwik you want to stop it you put nessesery force to do so.
But if you placed your finger on outer edge and do the same it will stop quicker with less force.
3. The disc and pad will contribute to this massively, especially the pad compound if you want to stop quick.

All the above you will need to take into account for your set up and fitment, but IMO the biggest disc available to suit caliper, let's just say a 4 pot here and pads will suffice just as good as a 8 pot.
Caliper wise it's best going for the lightest one to save weight and one that will cope with extreme abuse too.
Hth

Berks-Jack

iTrader: (10)

^^^^^ the standard brakes on a blob wrx are disgraceful. Wtf were Subaru thinking.

Berks-Jack

iTrader: (10)

Agree with most of what you said there Busta but surely something like an AP 4 pot calliper is the equivebt of a cheaper biggercaliper?

MattyB1983

iTrader: (51)

My last impreza was far from a big power car but at under 1200kg and with circa 420bhp it was astonishing how quickly you would be on top of slower traffic.
I like to think im a pretty good driver but I openly admit it caught me out a couple of times. Hitting twice the national speed limit happens very quickly and a car doing half that comes up very quickly.

bustaMOVEs

iTrader: (31)

When you say bigger caliper, do you mean something like 8/10 pot?
But that surely would give more weight? Yes it would probably give you a bigger disc option but would depend on wheel to take the bigger disc, of course a bigger disc would need a slightly bigger caliper to cover disc (depending on size), but a 4 pot with BIG pistons on it would be good enough to cover the area or 6 pot maybe with BIG pistons.
Couple that with my example above with a good combination it will work just as good a a big caliper if not better. And AP 4 pot are definatly upto the job as is the brembos with right combination. A lot of it is down to the biggest disc size you can get for your set up, good pads and a acceptable caliper.

Oh and of course the type of tyres used too don't forget

salsa-king

cheers, tnx


I'm not talking about cars doing track days.. quick acceleration and fast reactions to stop, then re accelerate.

I'm on about normal road driving, day to day.

car (A) with standard Subaru 4pots (having better grooved discs and better pads --- not bigger discs)

then a car (B) with bigger all round brake set up.


Both these cars will be driven day to day... not hitting speeds more than the legal road speed limits.... 30, 40, 50, 60 & 70mph.

Does car (B) brake any better than car (A) on the normal day to day drive?






I totally understand about heat dispertion/brake fade on track and better larger surface area to brake with

cuprajake

iTrader: (11)

Drive a wrx then drive an sti, there's your difference and its a big difference in my opinion,

Having had both cars, the wrx standard brakes are pants, they inspire no confidence, they feel like they fade very quickly with no real bite. Updating the pads does make a big difference, it gives the initial bit also adding a brake stopper it will stop the flex in the bulkhead,

Move onto the sti with the bigger discs and brembos all round and you'll quickly notice what a good setup it is, the initial bite and feel is a lot more reassuring. I've upgraded my pads again and they feel even better,

I'd say for fast rd the brembos with a good pad/disc combo is ample, if your doing multiple track days. Then upgrading the disc to a bigger disc would be good to for more rotational force.

bustaMOVEs

iTrader: (31)

In this case then, one will require more pressure then the other and i would think the bigger disk would stop quicker but not much in it imo at that level of driving, you say the standard brakes had good pads right?
Tyre dependant as earlier link.

BoozyDave

iTrader: (8)

i agree with the stuff above, but one thing that i have wondered about is brakes on push bikes. if bigger is better and brake force, etc, why have bikes gone to tiny brake discs instead of using the rim like they used to?

F1 CJE UK

iTrader: (8)

To look cool!

APs front and back on my WRX and its night and day, of you use the car as a day to day then pads and brake lines would be perfect as long as you don't drive it hard.

Tyres play their part in this!

Brun

Ran a uk turbo on standard brakes at 215bhp a upto 320bhp and never got into a position where I would consider better brakes necessary!

veerinder9

iTrader: (1)

Aren't the std subaru 4 pots upto the job? Im sure theres a bigger disc conversion for the std 4 pots andthe use of a good pad would help? Do you really have to change them?

salsa-king

that's interesting too