scoobyc

iTrader: (2)

Hello SN,

Currently having a bit of debate/think about whether Brembo/AP's are actually better than normal 4pot scoob brakes.

How does the different caliper design actually change braking for the better?

If you can lock a wheel you can lock a wheel. A different caliper isnt going to get you stopping any quicker.

Can anyone explain/scientifically explain how these are better? Does s 3cm wider disk really make any difference?

Has anyone carried out any tests to justify the costs of such upgrades?

Im aware that anyone who spends 1800 quid on brakes, is going to think they are **** hot.

If your running the same material pad disk and fluid, i dont see how that 3cm / extra 2 pots is going to make any difference.

Look forward to your responses.

Chris

scoobyc

iTrader: (2)

This is what i expect:

would say as my brakes get hotter the bite line to pressure changes
so the force needed to be applied is no longer linear
making braking less predictable/consistent
perhaps a differently designed caliper/larger pad to disk area can make this more of a linear experiance
how though im not too sure.

TonyBurns

iTrader: (3)

You need to speak with someone more technical in the brake department, but trust me, my first classic i changed my brakes from 294mm to 308mm brembo/ap discs and mintex 1144 pads, and she stopped a damn sight quicker
But its also down to the pad, discs as well as the ammount of area pressure? that the piston covers.
Oh and it also helps with heat disipation (discs, calpers etc)

Tony

EddScott

This is a debate I've read about on other forums.

If the contact between car and road is through the tyres, is it not the tyres that govern the point at which the car breaks traction?

It was my understanding that bigger brakes really only meant longer lasting as heat increases. I had 4 pots, then changed to godspeed bigger brakes with the 4 pots (which I didn't like as it was very heavy and changed the feel of the car) I then had wilwoods 6 pots which again didn't really feel that much different.

I feel slightly unsure that when people spend £1500 on brakes and say its absolutely awesome win win that it isn't just that they've spent £1500 on brakes and its not really that much different and don't want to say as much and look silly. Either that or I drive like a ***** and don't use the brakes hard enough to warrant big brakes.

scoobyc

iTrader: (2)

This is another dangerous thing about forum opinions. Most caliper upgrade will coem with a different disk/pad. No question the disk/pads makes a big difference in tolerating heat and hot bite. But does the caliper? I suspect most of the improvement from peoples changed setups are the better disk/pad/fluid, rather than the caliper/larger disk itself..

As said below. If you can lock a wheel, you can already stop as quickly as possible. So why have a bigger disk/caliper?

does 30mm larger disk actually make any difference at all to heat management when your taking of a few hundred degrees? I cant imagine it does?


You've hit the nail on the head there. This is what i want to know. Is it the case that if you spend 1800 quid on brakes your gonna think they are the nuts.




This is the exact problem which i would like to learn more about.

Hopefully some race experianced guys can pop along and let us know the ins and outs of whats happening.

I suspect the only difference is the "feel", is there any sceintific proof to explain the suggested improvement?

KINGHORN

iTrader: (1)

lol

are you actualy suggesting here that at 100 mph a set of say justy brakes on an impreza could stop in the same distance as a set of sti brembos.

its an imposibility,

the larger diameter disk allows more stopping power to applied, for the same clamping pressure, you get more stopping and no locking.

you really think that the manufactures and race teams etc have it wrong????

scoobyc

iTrader: (2)

Lets look at this from a open pit trackday perspective.

scoobyc

iTrader: (2)

my 4 pots could probably lock up my wheels at 100 so yes i coudl stop just as quickly. By this i mean, if i can lock my brakes, my caliper/pads already have enough bite n pressure to stop the car beyond its maxium level of grip provided by the tyres.


Im not so much suggesting the race teams etc are wrong. but that i dont udnerstand WHY they are better.

I want some actual proof/explaination before i go and spend my hard earned.

Aztec Performance Ltd

iTrader: (234)

There is a lot more to braking than simply being able to lock the wheels. Why would you want to lock the wheels? You don't, you want to be able to have well controlled stopping ability, stop after stop.

Any roadcar can lock it's wheels (or engage ABS), but give them 3 or 4 heated stops and they will fail to stop.

Brake Discs - There is a fair bit to discs than meats the eye. The bigger the disc, the greater the leverage to stop the car. Think of it trying to undo a tight bolt with a short lever and long lever. Then you have the discs ability to dissipate heat, two piece designs, floating discs, internal vane structure etc.

Calipers - Different calipers have different abilities to dissipate heat and have different flex characteristics. Made of different materials and of different construction methods (2 piece, monoblock). The number of pistons is not relevant. An AP caliper will be better than a cheap caliper with double the pistons.

Pads - different compounds are suitable for different things. OEM pads, fast road pads, track pads, endurance pads etc are all quite different and have a wide range of operating temps, bite characteristics, wear rates, residues etc.

In short, you want braking that is controllable, consistent and will last.

The initial outlay of a decent braking setup can be expensive but it is isn't that bad if you are regularly going through one piece discs at a fast rate.

There is no comparison between say a true AP 4 Pot setup and your current one. Even if you used the same uprated pads in both.

Hope it helps




AZTEC PERFORMANCE ONLINE STORE - WHOLESALE PRICES DIRECT TO THE PUBLIC

scoobyc

iTrader: (2)

Ok i want more information...

Firstly. lets discount the disk/pad set and look at the caliper itself.

As the upgrade would keep the same master cylinder, the same brake assist pressure will be retained. however if the caliper uses a bigger pad, then the same force will apply more friction which is fair enough.

Say after 10 laps of donny, you flying down the back straight coming to the sharpe right left.

Assuming the pad hasnt gone, why will the uprated caliper be more consistent?

I can only imagine its becauase:

The caliper has dissappated more heat/lets less heat escape into the fluid.

Or

soemthing to do with the deisgn of the fluid channels to compensate for the different flow of the fluid when hot.

Is there significant difference between the flex of the metal of the caliper between 4pot n ap's when hot to make a difference?


If it was all about dissapating heat, you could theoretically use fluid which is a very high boiling point and not need new calipers. But this isnt true so there must be more to it...

More info please. Diagrams/vids/tech specs would be nice to see to.

Is there any way to compare these brakes in anything other than laptimes and the "feel" of them when used properly?

Aztec Performance Ltd

iTrader: (234)

Give the tech guys at AP a ring. They will be happy to have a long chat with you and explain everything you need to know and then some 024 7663 9595

scoobyc

iTrader: (2)

Needs documenting on the internet somewhere.

Aztec Performance Ltd

iTrader: (234)

Give them a ring and then document it

EddScott

Its not that you want to lock the wheels. At a certain braking force the tyres will break traction from the road. At this point, the size and cost of the brakes becomes nill as the tyres have failed to retain their grip.

So having a bigger disc allows less force required to eventually cause this to happen.

I read somewhere that some of these calipers with 8 or 10 pots isn't actually a good thing. They just aren't built to a strong enough design to allow 4 pots to work effectively.

The heat dissapation would seem the main reason to upgrade the brakes. So over prolonged track work the brakes remain consistent. The question is at what point do the standard brakes fail to work under the individuals spirited driving style?

As I said, I went from std 4 pots to big discs and 4 pots and then big disc 6 pots and didn't really feel like the car was stopping any quicker. Personally I don't think I drive hard enough for it to be an issue.

scoobyc

iTrader: (2)

tbh im not convinced with the heat dissapation theory as the 100% solution.

Perhaps more the way it deals with the heat.

Lets talk about the caliper and heat then. As far as i know (discounting the pads disk etc) the main effect of heat is on the fluid itself. Rather than the heat having an effect on the caliper itself.

What effect does lots of heat have on the caliper itself? more flex?

dunx

iTrader: (3)

For a given cost there will be a variety of solutions, water cooled AP's will out perform your four pots.

As stated, it's about repeatability, heat dissipation, and pedal feel.

A larger swept area provides more friction, to slow the car. Thicker better designed rotors can dissipate more heat more quickly, and stronger callipers will flex less....

Keeping the fluid cool is the killer, I have boiled brand new fluid in mine, till I calmed down and drove it properly... on track of course !

My PF rotors and pads have improved my car's stopping power, so Ap's seem un-necessary, except if I were to turn it into a trackday toy.

dunx

If you have the money then it's not an issue....

Puff The Magic Wagon!

iTrader: (2)

Don't forget that smaller pistons (as in AP4s) require less pressure for the same breaking effect - less overall area.

P1SWRT

iTrader: (2)

I'm not technical either BUT when I fitted AP 6 pots + Mintex pads to my P1 I initially thought what a waste of money.
Stopping distance didnt seem to improve greatly the only gain was that resistance to fade improved 1000% from the standard 4 pot subaru set up which used to fade quite often (and hence my reason to fit the AP's at a cost of £1,500.00).

However when I took the P1 to Spain to watch a round of the WRC........
the AP's came into their own when I did a 'test run' around a couple of the stages. (you need to go to understand how twisty the stages are) No fade at all and constant pedal feel at high speed and low speed and mainly left foot braking.

There was no looking back after that, complete confidence in my brake set up and took the P1 up a level in my opinion.


So in conclusion if you want some bling to talk about in the pub or at the next scoobymeet, buy some.
If you want to spend a load of cash on something that you don't need on a daily driver - buy some
If you want to use your car on a race track buy some
If you drive within the law of the land and could spend your hard earnt on something else instead don't bother.

afterthought...
My std 4 pots with brembo discs and mintex pads worked well on the rally car, I guess weight of the car played its part

HTH
Rob

trails

iTrader: (41)

disk thickness is a big variable; thicker disks dissipate heat more efficiently and larger disks reduce the average pad temperature...both of which help reduce brake fade.

bob r

iTrader: (46)

I changed my standard 4 pots to the Prodrive 330mm set up.

The Prodrive calipers are noticeably larger than the 4 pots but as they are Aluminium they are alot lighter and obviously discipate the heat easier being Ali.
Also the large dimension of the Prodrive caliper should mean the brake fluid is kept cooler than if using 4 pot calipers.

The Prodrive pads are larger also, which as already stated allows more leverage on the larger discs which inturn means more stopping power.

I must agree tho..........that if you have huge brakes but poor contact with the road [skinny/bald tyres] then the brakes would be of no benefit.

scoobyc

iTrader: (2)

The fade you experianced with the 4 pots. was that with the same disk and pad setup as your AP's?


I need to really see a test of 4 pot's with ds2500 then put on some AP's with the same ds2500's on suitably equivilent disks and give them both a hammering on track and see what the difference is.

So what benifits does the caliper provide? Why would a 4 pot 330mm godspeed upgrade not be as good as an AP with the same size disk pad fluid etc?

scoobyc

iTrader: (2)

I was under the impression that brake fade under hard braking is caused by a gas developing between the Pad and the disk. How would the larger caliper overcome this?

is it a case that the larger pad area gets proportionally less hot?

Is alloy that much better at not transducting heat to the fluid than the normal 4 pots?

bob r

iTrader: (46)

I am sure the Godspeed upgrade only allows the discs to be increased in size but retains the original pad size therefore the AP set up is going to give better stopping power as the pad is bigger.

TonyBurns

iTrader: (3)

Most standard calipers are cast iron, heavy and retain heat, you dont want heat to be retained, you want to disipate it, ie get rid.
Alloy calipers heat up and lose heat quicker than cast iron ones, its a charateristic of that metal/mix of metals.
As Bob'5 has stated, give AP a ring, they will give you all the technical answers you need
Oh and did i mention heat?

Tony

scoobyc

iTrader: (2)

Ok so caliper wise the main effecting difference is the metal its made from which is better at loosing heat than the normal 4 pots.




Im sure these calipers will make a difference.

Cant find much on google re documentation / testing of these things.

addison

I changed for brembo's
The difference is big; they give so much more feel when braking.
With standard I had to push the brake pedal with brembo’s I just
Gentle touch the brake pedal

allsop83

iTrader: (9)

Been said a couple of times before.....if you are looking for good, reliable, experienced testing results or opinions on braking charachteristics (spelling!!?!??!) and braking products- call AP and they will tell you everything you want to know, WITH the added bonus of testing experience behind them.

You are in the wrong place for the answers I feel you seem to want.

stiler83

I'm having a lazy dad today so not going to write a whole load of science about braking systems...but I am going to point you in the direction of these resources

StopTech : Balanced Brake Upgrades

High-Performance Brake Systems: Design, Selection, and Installation S-A Design: Amazon.co.uk: James Walker: Books

EddScott

This pretty much sums it up quite nicely. The Willwoods I had looked pretty but I don't think I ever needed them. Not many people will admit that they are not a "driving god" and therefore may not need £1500 brakes.


The pad is actually bigger. The kit increases the width of the caliper to accomodate the disc and the pads do cover the disc area. However, the force on the pad isn't even and I think you can get a / shape occuring. You can also use standard pads.

Is there any truth in what I said earlier in that some of the brake kits with lots of pistons are actually because the caliper isn't strong enough to cope with 4/6? Bit like what puff said. The caliper would warp if there were only 4 pots so they use 8 and make the higher the number of pots a ***** waving contest?

scoobyc

iTrader: (2)

Thanks.

Will give those a read.

I guess to determind how a caliper is better we need to work out what the fade actually is in respect to high temperatures.

ta