Yes both caliper types (4 & 6 piston) will work. We had some drawings about year ago when one of our friends who have a S car wanted also GT2 six pistons. Then we just skipped the idea and bolted my old Big Blacks (now yellows) under his car. This type of adapter can be done. We just need to move caliper to little bit different angle to get more space for mounting bolts. Have to make some CAD drawings first and see how it works out
Medium Blacks - Big Blacks - The Difference
- Thread starter John Sims
- Start date
Hilux
New member
....its the overall pad area that 1) increases the surface friction in contact with the disc and 2) its larger mass also dissipates heat better and therefore keeps more of the heat away from the pistons which are the weak link as they are the culprits that transfer this heat directly to the brake fluid 3) too small a pad and it cooks
The piston area is relative to the pressure that can be applied behind it so as to achieve the required load evenly over a larger pad area eg; 6 pot calipers pistons are small but spread even pressure over a very large pad. It is probable that a 6 pot has a similar piston area to a 4 pot as there is a fluid displacement ratio that ensures a reasonably friendly pedal pressure (master cylinder diameter to piston diameter [total])
Thats my understanding of it all having spend days and ££`s getting it right on nother cars [8|]
carlmthompson
New member
I always think of it a bit differently than that (and probably wrongly!) -
If you thing about a 12" record (sorry all those under 30 who don't know what one is!). When you place it on a turntable, the non slip mat ensures that it will turn when the motor is spun up.
When you put your finger near the centre, the record will slow down depending on how much pressure you apply. However at the centre, it takes alot of pressure to make the record lose grip and skid.
When you put your finger at the outer edge, you need less pressure to slow the record down, AND you need alot less pressure to make the record skid on the mat.
This is why I always figured (wrongly?) that larger brakes and calipers will slow you down more quickly from higher speeds, but will be more likely to skid at low speeds.
I'm sure there's some loverly equation that explains this (Leverege?), but whatever you do, if you try this experiment, try not to cut yourself.
If you thing about a 12" record (sorry all those under 30 who don't know what one is!). When you place it on a turntable, the non slip mat ensures that it will turn when the motor is spun up.
When you put your finger near the centre, the record will slow down depending on how much pressure you apply. However at the centre, it takes alot of pressure to make the record lose grip and skid.
When you put your finger at the outer edge, you need less pressure to slow the record down, AND you need alot less pressure to make the record skid on the mat.
This is why I always figured (wrongly?) that larger brakes and calipers will slow you down more quickly from higher speeds, but will be more likely to skid at low speeds.
I'm sure there's some loverly equation that explains this (Leverege?), but whatever you do, if you try this experiment, try not to cut yourself.
ORIGINAL: John Sims
......I was wondering if the greater diameter helps but, aside the increase in area I wonder if it is significantly better than the area nearer to the hub.
Obviously there is more leverage at the outer edge of the disc, but it is also traveling faster, and faster things are more difficult to stop. An interesting ponderance, but probably of little significance.
Anything bigger must be better - Big Blacks the Nº11 of 944 brakes. []
Post 4 . Come on Carl, please try to keep up [
][][]It is quite nice when someone else thinks the same way. You don't feel such a numpty.
Good point on the record analogy though. Did you notice if your finger was hotter when you did it near the centre or toward the edge. [
]carlmthompson
New member
[][]Memory span of a fish.
I haven't used a record for some time now, and the thought of going into the loft to drag out the deck to test the theory fills me with dread[]
I would make a sweeping assumption that as your finger travels further at the outside edge, it will generate more heat. I would also figure that it is easier to dissipate the heat from the outside edge as a) It's cutting through more air than at the middle, and b) on a brake disc at least, it's near the vents on the edge[8|]
Now I'll wait for someone else to get it wrong, so I can jump on the wrong end of the stick later on also!!
Edited to say, I also wanted to say that the heat will radiate outwards because of the rotational force, but figured someone would call that wrong also. Might as well go for the hatrick!
][]Memory span of a fish.I haven't used a record for some time now, and the thought of going into the loft to drag out the deck to test the theory fills me with dread[
]I would make a sweeping assumption that as your finger travels further at the outside edge, it will generate more heat. I would also figure that it is easier to dissipate the heat from the outside edge as a) It's cutting through more air than at the middle, and b) on a brake disc at least, it's near the vents on the edge[8|]
Now I'll wait for someone else to get it wrong, so I can jump on the wrong end of the stick later on also!!
Edited to say, I also wanted to say that the heat will radiate outwards because of the rotational force, but figured someone would call that wrong also. Might as well go for the hatrick!
sawood12
New member
It's the combination of pad area and the caliper clamping force that creates the friction. It's not just about the pad in isolation. If you have a larger pad you need less caliper clamping force to create the same friction. All friction is is the conversion of kinetic energy to heat energy so to create the same heat energy with a larger pad you need a lower clamping force - i.e. less pedal force for the driver. This means the heat energy is generated over a larger area so the max temp per square mm is lower for the same retardation, therfore the brake fluid is exposed to a lower max temperature in the first place. So with larger pads you are actually generating lower temperatures for the same retardation. Alternatively you could trade this off and achieve a higher retardation for the same temperature i.e. later braking (tyre grip levels permitting).
The reason Porsche went to the 6-pot calipers on the Mk2 GT3 is that it was possible to fade the brakes on the 4-pots fitted to the Mk1 so the 6-pots were solely to deal with the possibility of fade under heavy track use. It is the same advantage the BB's have over the MB's due to the increase in pad area.
I think if you come at it from the assumption that you are already achieving the maximum retardation with your smaller calipers, retardation being the constant due to the tyre grip being the limiting factor, by upgrading to larger brakes you are not going to achieve more braking but you are just lowering the temperatures involved as you need less caliper force to generate the same friction which is spread over a larger area therefore staving off the fade.
I think we are all saying the same thing but just coming at it from different angles.
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