AP , Brembo , Alcon

[Sweeper]

I ansked once alreayd but haven't got sufficent answer. I believe Lee can answer this one .

If there was a possibility to choose ? Which would you chosee concerning same disk diametr , around 322mm.

I've heard that AP have a **** disks , Brembo is a middle center of perf/price and Alcon is the most advanced becouse of disks structure , but most expensive.

Alcon used in formula ?
Any comments ? Porsche use Brembo , Ferrari also , Dahlback used Alcon in their Golf RSR and use them as upgrade for rs4. Why ?

Vadim.

[s2driveruk]

Audi Sport used Alcon too in their Touring cars and I think in the R8 too, no idea why when most of the rest of the racing teams as you say are split between ap and brembo....

i think i read somewhere that AP can exert more pressure (psi) over the surface of the pad but not sure if thats just the marketing talking. However to be honest for 99% of us who want to upgrade the performance of our cars, we do well to find any noticeable difference in calipers as opposed to spending the money on decent pads.

Just my euros' worth

David

[Keeper of The Kitten]

IIRC Most of F1 use something like Hitco or Carbone Industrie discs, but for road any of the quoted caliper brands sound ok to me - find a brand that does a caliper to fit the S2! AP definitely do. Alcon were def used by Indycar teams too. The main thing with the racers is wanting very high stiffness in the caliper material and structure, as it will increase responsiveness and feel in a sensitive car with a good driver, as well as being stronger. Me, I'd be happy with anything that stops the car better than the standard hardware!!!

Something I read in Racecar the other day was of interest, Rallycross driver Kenneth Hansen switched to smaller brake discs (dropping from 350mm to 310mm) because of the reduced rotational mass - bear in mind that anything that big and that heavy takes longer to accelerate (and decelerate), especially if it's being made to spin! One of the main reasons for using carbon discs in racing.

__MDC__

[NoNonsense]

Something I read in Racecar the other day was of interest, Rallycross driver Kenneth Hansen switched to smaller brake discs (dropping from 350mm to 310mm) because of the reduced rotational mass - bear in mind that anything that big and that heavy takes longer to accelerate (and decelerate), especially if it's being made to spin! One of the main reasons for using carbon discs in racing.

__MDC__

Porsche's 350mmx34mm carbon disc weighs in a 9lbs...i don't know how many kilograms that is, but it's freakin' LIGHT!

[Sweeper]

NoNonsense: And cost around 10K EUR for a pair

[Keeper of The Kitten]

Joe, that's definitely light (9lb is a bit more than 4kg) - the sportscar ones I've picked up before feel amazing after a normal disc! With the carbon disc you need a separate mounting bell too, of course, most likely to be ali or maybe ti.

With the rallycross car the discs are regular iron pieces, because the races are very short and there's no time to get heat into them. Carbon is probably outlawed too. Anyway the upshot is that smaller discs are chosen to reduce inertial drag.

What F1 teams use is a bit irrelevant really. The thing about F1 using high modulus caliper materials (like the metal matrix composites featuring unpleasant stuff like beryllium) is that the teams really do need heavy duty brake calipers - because the wheels are only 13" diameter (archaic F1 rule which probably has something to do with adhering to a road car principal) and as a result they don't have the luxury of big brake discs.

__MDC__

[Greg_S]

I cant remember where I saw it now, probably on here but Lucas (correct me if im wrong) are developing a new system with twin, plain discs on either side of the car and one caliper clamping them.

The theory being there is a greater surface area on two smaller plain discs rather than one big vented disc and so a greater friction can be made and increased cooling over the vented disc with the upshot of less rotational mass and unsprung weight.

Greg

[S2 Ant]

Yeh ive seen them as well Greg, cant remember where now tho.
Interesting idea.

[Sidspud]

because the wheels are only 13" diameter (archaic F1 rule which probably has something to do with adhering to a road car principal) and as a result they don't have the luxury of big brake discs.

Lotus had an F1 car with inboard brake disks. They were under the bodywork away from the wheels. I think they binned the idea after discovering that the suspension was twisting with the momentum of the wheel. Nice idea, but it didn't really work that well.

[Sidspud]

I cant remember where I saw it now, probably on here but Lucas (correct me if im wrong) are developing a new system with twin, plain discs on either side of the car and one caliper clamping them.

The theory being there is a greater surface area on two smaller plain discs rather than one big vented disc and so a greater friction can be made and increased cooling over the vented disc with the upshot of less rotational mass and unsprung weight.

Greg

I saw this in Evo magazine. It was either last months or the one before.

[Greg_S]

I knew I had seen it somewhere Also with the inboard brake discs, Jaguar made a few of there old cars like this with the brake discs mounted right next to the rear diff.

Greg

[Keeper of The Kitten]

The main reason F1 stopped using inboard brakes is that the shafts were susceptible to breakage - and thus catastrophic failure! Braking loads are a lot heavier than acceleration loads. In fact, inboard brakes don't twist the suspension, as they are only stopping the wheel from rotating and the calipers will be chassis mounted, hence all the reaction is transmitted into the chassis. Outboard brakes are the ones which cause suspension twisting, because the wheel turns the disc, which is clamped by the caliper on the upright - and as a result, the wheel tries to turn the whole upright.

Twin discs ain't new either! Tyrrell tried them around 1970 (watch the Roman Polanski thing about the Monaco GP with Jackie Stewart. I think it was Girling / Lockheed / AP kit?) and gave up on them due to cooling issues, maybe. One of my former colleagues worked on those brakes before later going on to work on the design of some of Lotus' championship winning cars!

Another system which has cropped up is the clutch style brakes as used by big aircraft, with full surface contact and (I think) multiple discs. Problem is, they only have to perform one big stop (when the plane lands) and we expect our brakes to perform several times over.

Those Jag axles used to be popular with the hot rod crowd, but they're horrendously heavy! Clever use of the driveshafts as suspension links meant no upper wishbone, so in effect the driveshafts had three tough jobs to do: transmit power, transmit braking torque, and transmit load into the chassis!

__MDC__

[Keeper of The Kitten]

Also, with the twin discs, bear in mind that everything has to be floating so that they can make even contact! The middle pad wouldn't work at all if they didn't do it like that.

__MDC__

[Keeper of The Kitten]

IIRC, the problem with cooling on twin discs is with the middle pad (bearing in mind that you need three pads) - but don't quote me on that!

__MDC__

[1975DCS]

Something I read in Racecar the other day was of interest, Rallycross driver Kenneth Hansen switched to smaller brake discs (dropping from 350mm to 310mm) because of the reduced rotational mass - bear in mind that anything that big and that heavy takes longer to accelerate (and decelerate), especially if it's being made to spin! One of the main reasons for using carbon discs in racing.

__MDC__

Do you have keep this Racecar (is that former CCC?) magazins? Especially this one? As I am a big of a Rallycross fan, love to read the technical stuff...