bigger brakes question

[nky_84]

i was always under the impression that bigger brakes ie beefed up calipers and bigger discs made a car stop better than one with small discs and pads.

I read on another forum that if a tiny set of discs and pads have the ability to lock the wheels then u will not reduce stopping distance by improving the brakes. is this true?

A improvemnet in tyres will be the only thing u could do.


I always thought that bigger means more surface area and somethin about centrefugal force.

Someone care to shine some light?

Nick

 

[PaulJC84]

The locking thing could be true but chances are that would be in the wet or on gravel.

Say i fitted big Porsche brakes to my A4 they would stop me better than smaller brakes.

They will also not over heat as much so should stop you stronger for longer.

 

[nky_84]

lockup on dry tarmac. i know they disapate heat better

 

[dummi]

its to do with type of the breaking equipment that will allow you to make use of the bigger discs, like porsche callipers with pistons on either side will offer better biting character on the disc where oem audi ones have pistons on one side pressure on the disc is uneven this causes the brakes to look up audi oem brakes are very poorly designed limiting effective disc size. many posts on here comparing the two , i talk of experience going from stock 2 piston floating caliper audi two 6 piston cayenne 3 piston each side difference is amazing car suddenly stops like it should of, next to a remap and suspension modification good brake setup is equally worthwhile performance mod IMO

 

[Rev-head]

Smaller brakes usually have 1 piston to apply presure were brembo /Porsche brakes have 4 to 6 pots thus reducing braking distance

As soupie says they dispate heater better so you do not get brake fade and you reduce your braking distance for corners

The locking issue, they might lock but they wont stop you lose control to a certain degree.........you got ABS?



What car do you drive??

 

[Ess_Three]

[ QUOTE ]
i was always under the impression that bigger brakes ie beefed up calipers and bigger discs made a car stop better than one with small discs and pads.


[/ QUOTE ]

Let's try and clear up some of the bull associated with big brakes...

Big brakes no not by default, make a car stop quicker. That's a fact.

A peroperly matched set of more efficient callipers and larger discs will...but a hotch-potch thrown together miss-match of a home grown effort, in many cases won't.
That's a fact.

[ QUOTE ]

I read on another forum that if a tiny set of discs and pads have the ability to lock the wheels then u will not reduce stopping distance by improving the brakes. is this true?


[/ QUOTE ]

Yes...it is.
But you may struggle with repeat braking.
Braking is only energy diddipation...you turn rotating energy into heat...and once the small disc has taking in as much heat as it can...it'll fade.
Then, a big disc comes into it's own....but for actual braking performance, if a small disc will lock the wheels, there is nothing to gain in single run braking performance, by fitting monster rotors.


[ QUOTE ]

A improvemnet in tyres will be the only thing u could do.


[/ QUOTE ]

A perfectly valid point...
You would not believe the number of cars you see with budget tyres and bad suspension...that fit monster brakes looking for an improvement. Stupid people...


[ QUOTE ]

I always thought that bigger means more surface area and somethin about centrefugal force.


[/ QUOTE ]

Surface area...yes.
Ability to dissipate heat...yes.

But also weight...that kills the handling due to the gyroscope effect, and additional unsprund weight for the suspension to control.

It's all pros and cons...a balancing act.
Not as cut and dried as bolting on big brakes and getting big gains. That's a fool's thought process.

 

[Ess_Three]

[ QUOTE ]
Say i fitted big Porsche brakes to my A4 they would stop me better than smaller brakes.


[/ QUOTE ]


Not the case in all instances...

If you fit Cayenne callipers with 6 huge pots, your master cylinder can't move enough fluid to make the callipers work efficiently...so you have 6 contact points of pad on disc, being operated on by a weak force.
Result? Poor pedal feel (sinks towards the floor doing little) and poor braking...and most probably longer braking distances....not to mention unbalanced braking and a risk of triggering the rear ABS.

A gain?
Not to me it's not...

A complete missmatch...not a huge improvement...but they'll look bling. /ubbthreads/images/graemlins/smirk.gif


[ QUOTE ]

They will also not over heat as much so should stop you stronger for longer.

[/ QUOTE ]

This IS true...as long as you can make them work hard enough to create more heat than the standard set up...if not...you have no gain...AND worse feeling brakes.

People need to consider piston sizes vs master cylinder size...most don't.

 

[Ess_Three]

[ QUOTE ]
its to do with type of the breaking equipment that will allow you to make use of the bigger discs, like porsche callipers with pistons on either side will offer better biting character on the disc


[/ QUOTE ]

Not true.
Pad choice dictates this far more than massice callipers and huge discs.

Massive Porsche callipers can offer LESS biting feel, and a much longer pedal push to get the brakes on - back to piston sizes vs master cylinder size again...

An OEM set of brakes with decent pads and some disc cooling can work just as well as the bling alternative, I proved that for long enough with my S3.
...and you keep the pedal feel, which, to me, is very important.


[ QUOTE ]

where oem audi ones have pistons on one side pressure on the disc is uneven this causes the brakes to look up


[/ QUOTE ]

Again, not so...
If the brakes are well maintained, they work just fine.

An example:
My Integra Type-R had standard callipers, grooves machined into standard discs and mintex pads...there was nothing that would outbrake one of those things on the track...and I did 20+ trackdays on the same disc/pad/calliper combination.
They worked faultlessly...

No need fo 4 pot callipers there...

Bolting on big brakes is not the complete answer that many believe it to be.

They look better...
But often make the car less nice to drive at 7 - 9ths.


[ QUOTE ]

audi oem brakes are very poorly designed limiting effective disc size.


[/ QUOTE ]

Again, not true.
OEM brakes are fine.

I have OEM S3 brakes on my Golf GTI and they are perfectly fine...

The standard pad material is awful, and there is not enough air getting into the discs to cool them...rectify these and these brakes are fine.
I have never been left lacking...nor had them fade.

And I don't pussyfoot about with my brakes.


[ QUOTE ]

many posts on here comparing the two , i talk of experience going from stock 2 piston floating caliper audi two 6 piston cayenne 3 piston each side difference is amazing car suddenly stops like it should of,


[/ QUOTE ]

...and my experience of many of these kits is that they look great...but make the pedal feel awful and don't offer the gain I'd expect.
They offer a gain...sure.
But how much of that is down to them replacing old and partially siezed standard stuff?


Also, nobody considers what bolting on 350mm x 30mm discs and massive callipers is doing to the handling? Killing it...that's what...

Or the brake balance...

Or the pedal feel...does nobody else heel-and-toe? Try that with a pedal you have to push into the carpet to get the discs and pads to meet...

 

[Ess_Three]

[ QUOTE ]
Smaller brakes usually have 1 piston to apply presure were brembo /Porsche brakes have 4 to 6 pots thus reducing braking distance


[/ QUOTE ]

Wrong, wrong, wrong...
This is simply not as simple as you suggest.

Get the calliper piston sizes wrong and you INCREASE stopping distances.

Did you know that a Leon Cupra R has a longer stopping distance than an S3?
Why?

Brembos!!
4 pots with larger piston area than the standard sliding piston callipers...more pedal effort to make the brakes work...longer stopping distance.

It's just not as simple as bolting on larger callipers and discs...you need to match the whole system to get the available gain.


[ QUOTE ]

As soupie says they dispate heater better so you do not get brake fade and you reduce your braking distance for corners


[/ QUOTE ]

Dissipate heat better...true.
But work better? not always...

And if you make the standard set up dissipate heat better? Then what?

The trouble with this subject is that there are too many stupid people passing on comments as experts...when they don't understand the basics nor have tried to improve things by fixing the shortcomings...
It's not as simple as bolt on the largest discs and callipers you can...that is ignorant and foolish.

 

[Ess_Three]

People need to remember that Porsche change the master cylinder to suit tha callipers.

A 911 has 4 pots all round...a turbo / C4S has a larger master cylinder to match the larger 'turbo spec' brakes.

The GT3 has the same size master cylinder as the turbo or C4S...but the pistons on the front 6 pot callipers are smaller to match the master cylinder.

They remain balanced...

Cayenne callipers have big pistons...the Cayenne has a massive master cylinder to cope.

Fitting Cayenne callipers on an Audi with a smaller master cylinder than a standard 911 is daft...as you'll not get the gains you expect.

 

[robthehungrymonkey]

Glen,
don't you find the the standard pedal feel on an S3 pretty poor? It's my main criticism with the car in fact, i have more of a problem with that than the understeer (controversial i know!) to be honest. And I was under the impression that the Brembo's would improve this?

 

[dummi]

thats fair, i have limited experience all i can say is i am so impressed at the different character a year on, and have no further gone further to check the set up yet.

do disagree with the oem brakes being fine but thats just my opinion.

 

[PaulJC84]

Just as well your around here then Glen to correct us all.

So do you have any preferece to pad and disc combinations. I notice you mention Mintex in one of your posts. I currently have those on my car. Find the alright, some would probably not like them that much as they squeek at very low speeds but i dont really care about that.

One of my mates on his old car had pretty big Tarox 6pots on his civic the braking was pretty good as well but it used to chew up disks. He had to get them skimmed quite often.

Another friend has a Ecsort with AP Racing 4pots i think maybe 6 will be interesting to see how they perform as i guess the master brake cylinder will not have been replaced.

I never had even thought about people replacing the brake cylinder i guess people when getting these huge brake setups should also be looking into these and new hoses.

Cheers.

 

[Just Plain Old]

Yep, I read the same on another forum, evo-net in my case,,,,,,,,,, apparently it's true.

I'm going to try my new ECS Discs out soon, once AMD put in some 'pagid', is that the name? pads.

If I never post again You'll know the result was not what I was hoping for!! /ubbthreads/images/graemlins/grin.gif

 

[Just Plain Old]

That was in answer to the original question!!

 

[Ess_Three]

[ QUOTE ]
Glen,
don't you find the the standard pedal feel on an S3 pretty poor?


[/ QUOTE ]


No...not poor.
Over-servo'd perhaps...but in standard form, the feel is just fine.


[ QUOTE ]

It's my main criticism with the car in fact, i have more of a problem with that than the understeer (controversial i know!) to be honest.


[/ QUOTE ]

I drove for years with standard discs and callipers (OK...the standard discs had been grooved!) and a set of EBC Green pads...and I never came accross too many people who could out-brake me on the road.

They was fine...


[ QUOTE ]

And I was under the impression that the Brembo's would improve this?

[/ QUOTE ]

That depends on the Brembos...

If you fit Leon Cupra R brembos that were designed for a 23.4mm master cylinder (same as the S3) then they are fine.

But fit 911 callipers (or heaven forbid Cayenne) which have way bigger pistons set for a 25mm or higher MS...then you loose feel and the ability to procuce the force.

I prefer some feel to my brakes...switch like performance at the end of the pedal stroke in exchange for 'look' is de-tuning in my view.

I'll take the lightest brakes I can that will do the job, and provide the best feel possible....every day.
Looks are far less important than performance in my book.

 

[Ess_Three]

[ QUOTE ]
thats fair, i have limited experience all i can say is i am so impressed at the different character a year on, and have no further gone further to check the set up yet.

do disagree with the oem brakes being fine but thats just my opinion.

[/ QUOTE ]

Sadly, in the case of the old S4...I doubt anything can sort the brakes out!
They are worse than awful.

The whole car is a disgrace to drive, in my view...fast, but no cornering panache at all...and the braking is scary!
anyway, I digress...

David R fitted a very fine Stoptech kit - for once a company who actually do proper R&D and develop a bespoke kit ratyher than bolting on the biggest and most bling callipers they can to impress the Saxo owners - and the Stoptech brakes were still way behind the performance on my S3 out on the road.
Lots of cash spent...not the desired result delivered, sadly.


So, in the case of the old S4...maybe you have got an improvememt...but I'd sceptical it's as good as is possible.

 

[Ess_Three]

[ QUOTE ]
Just as well your around here then Glen to correct us all.


[/ QUOTE ]

I'm not setting out to correct anyone...merely to point a few facts out...and help peoples understanding of a subject that is well known for lightening the owners wallet substantially in exchange for litte - or no - gains except the placebo effect.


[ QUOTE ]

So do you have any preferece to pad and disc combinations. I notice you mention Mintex in one of your posts. I currently have those on my car. Find the alright, some would probably not like them that much as they squeek at very low speeds but i dont really care about that.


[/ QUOTE ]

For discs the Black Diamond grooved discs are good.
I wouldn't give aftermarket cross drilled discs house space...so stick to grooved.

As for pads...Mintex M1144s are OK...as are EBC Reds...
I'd avoid the Black Diamond Predators...they are dire.

I think I'll try the Ferodo DS2500s next...David R was very impressed with them...and he's capable of making a sunjective assessment that I'd trust.
So maybe those...


[ QUOTE ]

One of my mates on his old car had pretty big Tarox 6pots on his civic the braking was pretty good as well but it used to chew up disks. He had to get them skimmed quite often.


[/ QUOTE ]

I've never been impressed with the Tarox callipers, TBH.


[ QUOTE ]

Another friend has a Ecsort with AP Racing 4pots i think maybe 6 will be interesting to see how they perform as i guess the master brake cylinder will not have been replaced.


[/ QUOTE ]

AP make some stunning kit...but you have to ensure it's the road stuff (for road use) and not the competition stuff.

Human nature decrees that anyone given the choice between 'race' or 'road' will pich 'race' as it's bound to be better.
How stupid.
Competition callipers often don't have much in the way of dust / dirt shields...and the callipers are used to being stripped and re-built often to keep them in tip-top condition. Road drivers don't do this...and they wonder why their callipers are siezing up!

[ QUOTE ]

I never had even thought about people replacing the brake cylinder i guess people when getting these huge brake setups should also be looking into these and new hoses.


[/ QUOTE ]

I remember the MS trick from the Mk2 GTI days...16v brakes = 16v MS.

People should satisfy themselves that the kit they are looking at is correctly developed.
I'm not saying bigger brakes aren't better...mostly they are.
What i am saying is that miss-matched big brakes can be worse than new OEM...but cost you a lot more...and look more bling.

I'm afraid I distrust every company that can't show me R&D facts and figures to back up their claims...it must be the Engineer in me coming out!
Brakes are a minefield...big red callipers and huge discs must be better eh?
Well, no.
Not always.

 

[Rev-head]

Very enlighting

The brakes on my Ur S4 are scary sometimes i must agree UFO's not the best design in the world

 

[dummi]

well maybe my setup only applies to the a6 i guess, too true about the handling on big audi's.

 

[DavidR]

[ QUOTE ]
I think I'll try the Ferodo DS2500s next...David R was very impressed with them...and he's capable of making a sunjective assessment that I'd trust.
So maybe those...

[/ QUOTE ]

Superb for very fast road and track use but I hear from the new keeper that with daily road / commuting use they started to squeal badly and lose some initial bite.

Bear in mind that when I had the S3 it sat in the garage most of the week and only really came out for proper drives, with decent brake temperatures and track days - for those that commute and use their cars as a daily driver a less aggressive pad may be best - the galfer pad (which is brembo OEM on the GT kit) was great for this application, but not so great for track.

Confirms my thoughts that there is NO pad / disc combination that does road and track well.

 

[robthehungrymonkey]

[ QUOTE ]
[ QUOTE ]
Glen,
don't you find the the standard pedal feel on an S3 pretty poor?


[/ QUOTE ]


No...not poor.
Over-servo'd perhaps...but in standard form, the feel is just fine.


[/ QUOTE ]

Maybe it's my driving ability that could be the problem, but I find it really hard to heel and toe in the S3. The brake (once it starts to bite) is too far past the accelerator for consistent heel and toeing, that said, I'm in no way an expert at the technique. I also feel that the pedal it too "soft" i,e, a firmer pedal would allow more control when jabbing the accel as you have to "float" your foot. Know what I mean?

I don't find they lack any stopping power though, have "achieved" brake fade once, and that was in scotland and the most committed bit of driving i've ever done, so I don't feel that to be a problem in everyday use either.

 

[Ess_Three]

[ QUOTE ]

Maybe it's my driving ability that could be the problem,


[/ QUOTE ]

I wouldn't question your driving ability...but I guess it's perhaps a driving style thing.


[ QUOTE ]

but I find it really hard to heel and toe in the S3.


[/ QUOTE ]

I think the electronic throttle that won't let you blip when you want to, doesn't help...nor the heavy flywheel...but I agree, it's not easy. I didn't bother.


[ QUOTE ]

The brake (once it starts to bite) is too far past the accelerator for consistent heel and toeing, that said, I'm in no way an expert at the technique. I also feel that the pedal it too "soft" i,e, a firmer pedal would allow more control when jabbing the accel as you have to "float" your foot. Know what I mean?


[/ QUOTE ]

I know exactly what you mean...
I liked the S3 brakes...and thought my 911 brakes were wooden feeling. But now, I find the 911 brakes deliver exactly what you describe...firm pedal, easy to modulate etc...
I guess you adapt to what you have.


[ QUOTE ]

I don't find they lack any stopping power though, have "achieved" brake fade once, and that was in scotland and the most committed bit of driving i've ever done, so I don't feel that to be a problem in everyday use either.

[/ QUOTE ]

True... /ubbthreads/images/graemlins/grin.gif