What is the point on bigger disc setups?

[timmaaah 0]

My take is less effort for comparible or increased amounts of friction without causing then disc to be stationary, therefore no lock up and activation of the ABS. As stated all to do with leverage across the disc and increased pad contact either through larger pad and or more force being applied through more pistons..

 

In short they just are better, thats why super cars have brakes that are bigger than our wheels...

 

Please explain how better leverage or less friction can increase the mechanical grip of the tyres. Thanks :)

 

---------- Post added at 12:56 AM ---------- Previous post was at 12:54 AM ----------

 

as per my first post... the closer to the edge of a spinning object the braking force is applied the quicker it will stop.

 

however if you lock the wheels then there is no improvement.

 

 

if your theory is correct that they are no better then why before ABS did higher performance cars have bigger brakes that a small MK1 golf for example?

 

Please explain how better brakes improve the mechanical grip from your tyres. Thanks :)

[owen g60 10]

If youre basing all this on tyres... get better tyres to take advantage of the brakes.

 

 

Put budget tyres on say an Aston martin DB7... and the best you can get on a corrado... try stopping both from 60 to 0

 

Guarantee the Aston will stop first due to the larger size of brakes

[timmaaah 0]

If youre basing all this on tyres... get better tyres to take advantage of the brakes.

 

 

Put budget tyres on say an Aston martin DB7... and the best you can get on a corrado... try stopping both from 60 to 0

 

Guarantee the Aston will stop first due to the larger size of brakes

 

I'm not basing this on anything - I want to know why people think that bigger brakes equal shorter stopping distances or are 'just better' (sic).

 

Look -

 

You are travelling at 60mph with standard brakes - you have to brake hard, but not quite hard enough for the ABS to kick in, which does so when the wheel locks up.

 

You are travelling at 60 mph with bigger brakes - you have to brake hard, but not quite hard enough for the ABS to kick in, which does so when the wheel locks up.

 

How can bigger brakes work/stop better? The ABS will cut in regardless when the mechanical grip stops :)

 

---------- Post added at 1:09 AM ---------- Previous post was at 1:06 AM ----------

 

If youre basing all this on tyres... get better tyres to take advantage of the brakes.

 

 

Put budget tyres on say an Aston martin DB7... and the best you can get on a corrado... try stopping both from 60 to 0

 

Guarantee the Aston will stop first due to the larger size of brakes

 

The Aston will have a bigger surface area of the tyre giving much more mechanical grip btw.

[owen g60 10]

I'm not basing this on anything - I want to know why people think that bigger brakes equal shorter stopping distances or are 'just better' (sic).

 

Look -

 

You are travelling at 60mph with standard brakes - you have to brake hard, but not quite hard enough for the ABS to kick in, which does so when the wheel locks up.

 

You are travelling at 60 mph with bigger brakes - you have to brake hard, but not quite hard enough for the ABS to kick in, which does so when the wheel locks up.

 

How can bigger brakes work/stop better? :)

 

well back to my first post.

 

You are dissipating the rotational energy quicker due to being closer to the edge of the wheel... just like stopping the drum in a washing machine as i described first time round

[timmaaah 0]

well back to my first post.

 

You are dissipating the rotational energy quicker due to being closer to the edge of the wheel... just like stopping the drum in a washing machine as i described first time round

 

No - it's nothing like that to be honest. You are ignoring the tyre aspect completely. Stop and think about it - it matters not how quickly you can stop the rotation - it's all about the road grip. You can stop the rotation slowly or quickly, but it's the tyres that have the ultimate say, not the brakes. Bigger brakes will not impart more grip into the tyres.

 

A washing machine drum is just spinning - yes, you can stop it easily regardless of where you stop it. A car is not a washing machine drum - in your analogy the drum is the brake disc, your hands are the callipers/pads.....where is the wheel/tyre?

Edited August 29, 2012 by timmaaah

[owen g60 10]

Well as you stated the abs hasnt kicked in this means the tyres are still gripping... ABS kicks in just after you lock your wheels!!!

 

therefor my statements have been correct

[timmaaah 0]

Well as you stated the abs hasnt kicked in this means the tyres are still gripping... ABS kicks in just after you lock your wheels!!!

 

therefor my statements have been correct

 

Except they aren't.

 

Braking force is dictated by tyre grip - bigger disks CANNOT increase that grip :scratch:

 

---------- Post added at 1:23 AM ---------- Previous post was at 1:20 AM ----------

 

Please explain:

 

You are travelling at 60mph with standard brakes - you have to brake hard, but not quite hard enough for the ABS to kick in, which does so when the wheel locks up.

 

You are travelling at 60 mph with bigger brakes - you have to brake hard, but not quite hard enough for the ABS to kick in, which does so when the wheel locks up.

 

How do the bigger brakes make the tyre lock up at a later point?

[Benjevw 10]

But..... Bigger brakes are better though. I can see what your saying but the fact you can't get your head around it is making me lol

[Sanj 0]

Its all about Physics. The idea is that to stop a car you must change the Kinetic energy, and to do this you change it to heat energy as generated by the pads rubbing against the brakes disc, the heat is then dissipated and the car stops as there is no longer any kinetic energy. Smaller discs have a smaller surface area and therefore heat dissipation takes longer. With a bigger disc the surface area is larger and therefore the heat dissipated is much faster, so kinetic energy is converted faster to heat energy and therefore stops the car faster. The vented discs have an even greater surface area and therefore dissipate the heat energy faster than a solid disc.

 

ABS works on the basis that the pulses generated by the system aid in the cooling of the discs. By rapidly pulsing the pad to disc contact the system prevents the disc from over heating which causes brake fade and lock. because for that fraction of a second when the pad is not in contact with the disc when the ABS is on the disc is cooling.

 

Tyres are just part of the equation to remove kinetic energy from the car and a good surface contact between road and tyre speeds up the conversion of kinetic energy to latent energy.

[tony_ack 0]

 

You are travelling at 60mph with standard brakes - you have to brake hard, but not quite hard enough for the ABS to kick in, which does so when the wheel locks up.

 

You are travelling at 60 mph with bigger brakes - you have to brake hard, but not quite hard enough for the ABS to kick in, which does so when the wheel locks up.

 

How do the bigger brakes make the tyre lock up at a later point?

 

They don't really. There may be a small effect from having a bigger initial bite, which will transfer weight to the front quicker, bogging the front of the car and increase front tyre grip slightly (conversely decreasing rear grip).

 

The only other thing is that bigger brakes will work better at speeds where you can't lock the wheels (or may allow you to lock the wheels with bigger brakes, where you couldn't with standard ones :-) )

[VR6 0]

Corrados don't have ABS.

[mariojoshi 1]

timmaaah - You are clearly so utterly convinced that you are right - that it doesn't actually matter what anyone tells you (founded on science, fact or otherwise) because in your head - it doesn't change your thought pattern.

 

I cannot explain the physics, nor do I know the answer to your question and would even go as far as to admitting that your statements do have a fair amount of logic behind them.

 

My assumption is that bigger brakes are better because KevHaywire said so. That's what most of the 'fact' round here is based on ;)

[davidwort 0]

Corrados don't have ABS.

 

well one of mine doesn't

 

and bald tyres are better for braking

 

4 reasons I can think of for bigger brakes so far:

1) faster car, needs to shed all of that kinetic energy to stop, bigger disk and pad needed to shed all that heat

2) heavier car, a 4wd R32 weighs a lot more than even a VR Corrado

3) you drive so hard that smaller brakes have no chance to cool and you get brake fade

4) they look nicer behind big wheels

 

and 4 reasons not to fit bigger brakes

1) they are heavier and create more rotating mass and suspension (unsprung?) weight

2) your existing brakes work fine, don't fade etc in your normal driving conditions

3) smaller disks and pads may actually brake better in day to day driving where you need quick biting, brakes that over-cool are as bad as over heating brakes

4) they cost more

[Pete 0]

I'll have a go.

 

what everyone says is either partial or wholly correct, but you have to look at the thing in context.

 

Does a bigger disc stop you faster? That depends on the total setup of the car, speed done and history of the journey etc.

Will fatter tyres stop you faster? Again it depends on other elements of the set up.

 

If you jam the brake on then your going to lock up whatever you have fitted, but if you don't hit the brake like a clutch pedal then you can modulate the braking yourself and as previously mentioned a large disc will help you apply more retardation force by dispersing the heat and providing more surface area for the pad to grip to. Small discs need the pad to pushed harder against it, like gripping something with your fingertips needs more effort. This makes the pad glaze over and means you need even more pedal force to stop, which will make you more likely to lock up.

 

In that sense bigger discs WILL stop you faster.

 

Also consider the hard braking scenarios needs to also be done in context. Is it your 15th hard stop in 3 minutes (ie on a track) where smaller discs will overheat much faster and you will have more brake fade.

 

What is true is that other factors can be more immediate depending on the mix. Brake pad compound is a buch better part to tweak than disc size, though again its a trade off because better pads for hard driving don't always work so well from cold.

 

Fatter tyres can make a startling improvement to braking, but if they are bald or hard rubber or it's very wet they will be worse. Stiffer suspension can help to a degree, but go too stiff and it can make it worse also.

 

Sooooo..... Long story short if your doing 100mph, and hit the brake with some mechanical sympathy, you will slow down faster in a car with sticky tyres, bigger brakes and a warmed up brake pad with lots of abrasive content. That's why super cars and race cars run all of the above with sometimes ABS systems that run much higher pulse rates.

 

Slam on at 30 in a car with 320mm discs but worn 165 tyres and oem pads and you'll skid very easily.

 

So the answer is yes with an if, or no with a but hahaha

Edited August 29, 2012 by Pete

[VR6 0]

A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction).

 

Can the plane take off?

[Pete 0]

Ooh, ooh, I know, I know!!!

[dragon green 4]

A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction).

 

Can the plane take off?

 

Has Nursey been letting you watch re-runs of Mythbusters again ?

[OllieVR6 0]

A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction).

 

Can the plane take off?

 

Hmm...I want to have a go but I don't want to look stupid :bonk:

 

As far as I know, its the air moving across the wings that allows a plane to fly. Now if the plane is staying in one place, even though the wheels are spinning, air is not flowing across the wings....so I say no...is that right?

[Jim Bowen 1]

I have bigger discs to stop small farmland animals sneeking between the wheel and discs, closes the gap up, also stops snakes!!

[Roger Blassberg 0]

It's about converting heat energy into kinetic energy and vice versa.

 

A small engine with low gearing will accelerate a car at the same rate as a big engine with high gearing, but not for long because it can't convert heat energy into kinetic energy at a sufficient rate.

 

A small brake with low heat capacity will retard a car at the same rate as a big brake, but not for long because it can't get rid of heat energy and will overheat until either the pad/disc contact surface loses its friction characteristics or the brake fluid boils.

Big brakes are needed for consistent operation; small brakes will work for a very short period but will overheat and fade, and will wear out much more quickly as the contact surfaces are smaller.

 

Best wishes

 

RB

[sexybourbon 0]

Haha major beef with brakes !!

My vr has standard disks and pads at standard vr size , iv also been in jaimiehameys vr with the 312 upgrade and i think he a braided hoses aswell , how it works exactly i dont know im not that technical but his car stops alot lot faster than mine lol i thought my face was gonna fall off in to my lap !!

Bigger brakes make for better stopping , otherwise they wouldnt make bigger brakes would they

[CazzaVR 0]

trollaaah!

[VAG-hag 0]

A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction).

 

Can the plane take off?

 

been watching science abuse have we??

 

---------- Post added at 12:36 PM ---------- Previous post was at 12:34 PM ----------

 

Bigger brakes look loads better so stop you quicker..... clean cars go faster & go faster stripes = wow!!

 

---------- Post added at 12:40 PM ---------- Previous post was at 12:36 PM ----------

 

Original question: what is the point of bigger brakes?

 

Several answers:

 

Kerb appeal

Heat Displacement due to far too much brake fade from the milk bottle top sized standard setup

Surface area covered - linked to above

[Pete 0]

Haha major beef with brakes !!

My vr has standard disks and pads at standard vr size , iv also been in jaimiehameys vr with the 312 upgrade and i think he a braided hoses aswell , how it works exactly i dont know im not that technical but his car stops alot lot faster than mine lol i thought my face was gonna fall off in to my lap !!

Bigger brakes make for better stopping , otherwise they wouldnt make bigger brakes would they

 

The braided hoses help with pedal feel and response, because they are stiffer the don't move around so much and "tense up" when you push the pedal.

 

I run my vx220 on a fast road/track setup with mintex abrasive pads on standard discs and the stopping power is immense, but I got even more eye watering improvement by fitting toyo R1R tyres to it so you can really lean on the brakes even more.

 

That said the car is light so doesn't need that surface area to keep the brakes cool.

 

Energy =1/2 Mass x velocity(sq).

Edited August 29, 2012 by Pete

[Timbo 0]

Hmm...I want to have a go but I don't want to look stupid :bonk:

 

As far as I know, its the air moving across the wings that allows a plane to fly. Now if the plane is staying in one place, even though the wheels are spinning, air is not flowing across the wings....so I say no...is that right?

 

Planes don't get their locomotion from the wheels, so it makes no difference if it's on a conveyor or not. The conveyor only serves to spin the wheels faster when it's still in contact with the ground.