I have 305mm Brembo brakes with floating discs.
But i also see Abarth 595/695 Brembo brakes with fixed discs.

What are the differences. ??

The Pretender said:

I have 305mm Brembo brakes with floating discs.
But i also see Abarth 595/695 Brembo brakes with fixed discs.

What are the differences. ??

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Not a great deal,

Mainly floating discs allow some movement in the brake disc surface so that the pads can exert equal pressure on each side of the disc.

On conventional brakes usually the piston pushes the back/inner pad into the disc first and the movement and floating parts of the calliper then pull the outer pad in, so generally the inner pad wears first.

With fixed calipers there is no calliper movement the brake fluid goes into the pistons when you brake and in theory the pads move equally towards the disc, any slight variation on the location of the disc between the pads means that one side will always exert more pressure of the disc is not perfectly aligned. Then there is the obvious problem that the calipers will not always be perfectly equal with slight resistance in one piston compared to another the pads on one side could move a fraction slower or meet the disc a millisecond or so later than the other side of the calliper, having a floating disc means that the disc centres itself between the calliper to keep everything equal and the braking even.

In your case if you have floating calipers it also means considerably more money when it comes to having new brake discs other than that there is no real performance gain.

Another aspect is the weight. The floating discs are around 1,5kg lighter per piece compared to the conventinal ones.

But from the facelift on, Fiat is mounting the one piece discs in factory for the competizione and esseesse. (see)

But already before, many people who needed to replace the discs, didn´t by the expensive floating ones https://www.bremboparts.com/europe/en/catalogue/disc/09-B085-13 , but those the Alfa Romeo MiTo 1.4t uses as they are much cheaper:

https://www.bremboparts.com/europe/en/catalogue/disc/09-8004-4X

But there are also other alternatives that work if you don´t need holes...

Fiat Coupé 20V
https://www.bremboparts.com/europe/en/catalogue/disc/09-6843-11

Lancia DeltaIII
https://www.bremboparts.com/europe/en/catalogue/disc/09-A444-11

Alfa Romeo Mito
https://www.bremboparts.com/europe/en/catalogue/disc/09-8004-41

1.5 Kg less unsprung mass per corner at the front, is worth the extra money, IMHO.

The Pretender said:

1.5 Kg less unsprung mass per corner at the front, is worth the extra money, IMHO.

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Wait until you have a bill for 600€ and a viable option that’s only 200€ ?

Even the biposto a £30k car didn’t bother with floating discs, on a 595 they are more vanity than they are function. Speaking of the biposto they had rather clever little horse shoe shapes in the disc surface which allowed venting of the pads but didn’t put holes through the discs

Yes, I think you speak of those: https://www.ebay.co.uk/itm/Abarth-5...-Front-Brake-Discs-180-BHP-305mm/254836493320

But regarding the shape of holes and grooves in brake discs you can start an endless discussion, same like what´s the best oil.

ATE has their Power-Discs, Brembo the Max, Textar again something special.
But in the end, I think material and heat treatment matter more than the grooves.

By the way, the standard drilled one piece 305mm disc with the P/N 0052041114 seems not to be delivered by Brembo any more, as you don´t find an equivalent in their Catalogue.

I think reagarding the dimensions, the DeltaIII disc would fit IMO best, it´s also the lightest among the one piece discs. Perhaps the aftermarket has some drilled or grooved versions available...

My 911 has drilled and vented discs and I would expect it to have. They have to be able to pull it down to a stop from nearly 200mph. The Fiat/Abarth? No chance, it tops out at about 130mph ( not that I would like to risk that in it! ) the average shopping car is not far off that! Vanity only to have drilled or grooved discs unless you do a lot of track days or are intent on losing your licence you just don't need them. You get more benefit from ensuring your brake fluid is changed regularly, and your calipers are free to move correctly .

RedAbarthMTA said:

My 911 has drilled and vented discs and I would expect it to have. They have to be able to pull it down to a stop from nearly 200mph. The Fiat/Abarth? No chance, it tops out at about 130mph ( not that I would like to risk that in it! ) the average shopping car is not far off that! Vanity only to have drilled or grooved discs unless you do a lot of track days or are intent on losing your licence you just don't need them. You get more benefit from ensuring your brake fluid is changed regularly, and your calipers are free to move correctly .

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147 MpH.

Yeah OK willy waving over ! The difference is minimal. What I say still stands, you do not need drilled and grooved discs in a road car. Unless as I said you do track days etc. Only then could you need to get rid of more heat and stop brake fade and the first step in doing that is to use good fresh brake fluid.

The Pretender said:

147 MpH.

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That’s still not actually that fast for a performance car, quick for a fiat but slow compared to a lot of big engined german offerings.

Plenty of much quicker cars that still don’t have floating discs. Something like the golf R doesn’t use multi pot calipers. Brakes on a Golf R are going to be considerably cheaper than floating discs on an Abarth.

RedAbarthMTA said:

.... What I say still stands, you do not need drilled and grooved discs in a road car. ....

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You do not need a 911.....

Now coming back to the topic, I think the main reason for the big brake system is the track use and the pressure from other competitors in this car class, that also offer fixed caliper systems. The Brembo fixed caliper made from Aluminium in combination with the drilled floating discs is not havier than the standard 595 brake system.

I attached an interesting comparison.

You completely miss the point, choosing and needing are totally different things.

Same with the brakes my friend. And you must have in mind in Germany with a lot of unlimited highways, you can bring quite easily the standard brake to its limit. If you need to decelerate from over 125mph to 60mph quite frequently do to trucks pulling out...

Sorry there is an mistake in my overview, i mean the Lancia Delta III not the Thema III.

By the way for the Delta III is also a Disc with 330mm diameter and PCD 4x98mm available....

https://www.bremboparts.com/europe/en/catalogue/disc/09-A500-11

I prefer over dimensional brakes, better too much then too little brake power.