mx5cartalk.com

Hi
Out of interest Tony Diamond, in England, makes and sells a big front brake conversion for MX5's based on Subaru WRX components.
300mm rotors,4 pot calipers and mounting brackets. 500 pound sterling.
It is my understanding he will sell us the brackets on their own so we can source our own bits and save freight. WRX 4 pot calipers are as cheap a chips
You should find Tony on facebook.
If you do get any info would you mind sharing it here
Cheers
Steven

you don't have any links? Or are you finishing for information that you can't find and hoping someone will share it?

And the question anyone who will even be interested is:
Do these fit under 15 inch wheels?

The big AP brakes that I just sold (ex Chris W's 'Blue Rocket') were 280mm diameter, with radial mount calipers, and they were a very tight fit under 15in 6ULs.

NO WAY would 300mm rings fit 15s - well maybe with some insane offset, but not otherwise.

Just guessing, but I reckon they have been made for the 17 or 18s that those people use.

Surely they would be significantly heavier then the 11.75” wilwood kits?


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greenMachine wrote:The big AP brakes that I just sold (ex Chris W's 'Blue Rocket') were 280mm diameter, with radial mount calipers, and they were a very tight fit under 15in 6ULs.

NO WAY would 300mm rings fit 15s - well maybe with some insane offset, but not otherwise.

Just guessing, but I reckon they have been made for the 17 or 18s that those people use.

Re-remembering this. I think that the tightness I was remembering above was the packaging of the caliper and ring of that particular setup. I don't think I did more than a cursory fit of the assembly into a rim, but from memory(?!) there was a comfortable fit - whether that means a 300mm ring would fit I am not prepared to say one way or the other.

Regarding weight, while light weight is good, there is a trade-off between thermal capacity and weight. This may be more of a consideration for big HP turbo cars, but the heavy (25mm) rings of that kit did not seem to slow Chris down - well they did in a braking sense, but not lap times . Would he have been quicker (or had better handling) with thinner rings - who knows, not me anyway. Having said that, the NB8B stock calipers and disks weigh a ton - if they are the benchmark for weight.

Whether these would work with 15" wheels will depend on the bulk of the calliper and where it is positioned (i.e. the depth of the disc hat).

For reference, 298 mm discs (11,75") with Wilwood Dynapro calipers positioned carefully will fit SOME 15" wheels, but clearance is very very tight.

greenMachine wrote:.... Having said that, the NB8B stock calipers and disks weigh a ton ....

No, only 44 kg all up! Yes, I weighed the full set (not including backing plates). The front brakes each weigh more than the light weight 15 inch wheel and tyre you need to fit around them. I went from NB8B to NA6 brakes and was about half a second faster at SMSP GP circuit. Now with more power I need NA8s, I think.

StillIC wrote:

greenMachine wrote:.... Having said that, the NB8B stock calipers and disks weigh a ton ....

No, only 44 kg all up! Yes, I weighed the full set (not including backing plates). The front brakes each weigh more than the light weight 15 inch wheel and tyre you need to fit around them. I went from NB8B to NA6 brakes and was about half a second faster at SMSP GP circuit. Now with more power I need NA8s, I think.

Oh no, I got it wrong again ... I know when I replaced the NB8A brakes with the Wilwoods there was a massive saving in weight, some kgs per corner.

I am certainly interested in a front brake kit, alloy four pot, radial mount, alloy hats, maybe a relocated rear caliper. But it needs to be engineered, and therefore 'engineerable'. I think that the biggest problem is that the ADRs call for dust seals, and I don't think the Dynalights (of which I just happen to have a spare set) are available with that. Maybe I need to talk to an engineer and see what is possible ....

Anyone had a car engineered with new brakes?

For what its worth
The manufacturer, Tony Diamond, says they fit under 15 inch wheels

Link?

You will find them on EBay UK

Ok, found an item link but it is only for the bracket.

Anyone know if these calipers are iron or aluminium - look like iron, but that may not be conclusive. One piece iron disk.

IF the calipers are alloy, or if alloy calipers are available, and IF two-piece rotors are available with alloy hats, I might be interested.

I am messaging him for more info and will update this thread if/when I hear back.

there is an array of different calipers for WRXs. i think the red ones are alloy.

you be good to know what those rotors came off, then can search up a better rotor package.

Some interesting facts about steel and aluminium:
Steel is about 3 times the density of Al, or 3 times the mass for the same dimensions.
Steel is about 3 times stiffer than Al, for the same dimensions.
The bending stiffness of a solid section increases as a cubic function (^3) of the depth in bending. So, if you double the thickness of, say, a solid bar in bending, it is 2^3 (=8) times stiffer. If you triple the thickness it becomes 27 times stiffer.

So what?
Well, for two solid sections in bending, one steel versus one aluminium:
For the same thickness, steel is 3 x stiffer but 3 x heavier than aluminium.
For the same stiffness, steel is 1/1.44 (say 2/3) the thickness but 2 x heavier than aluminium.
For the same mass, the steel is 1/3 the thickness but only 1/9 the stiffness of aluminium .

Again, so what?
Well, substitute "stiffness" for "pedal feel and an ability to compress a spinning rotor squarely" and you can see that it is possible to get a steel brake caliper of the same ability as an aluminium one, but it is only about 2/3 the thickness, thus leaving a little extra room for a larger diameter rotor (for a given wheel diameter). The only penalty is mass at ~ twice as heavy for the casting, all else being equal. Or for the same diameter rotor, steel gives a 3 times stiffer caliper and improvement in pedal feel and ability to clamp the disc, for a 3 times greater mass penalty in the casting.