Big brakes for Mk IV? - go big or go home!

[Manaz]

I guess when modding a car, some people want to look at all aspects

Why would you increase power and improve handling and just leave the brakes as standard

I would rather have the complete package, and big brakes are also nice on the eyes and sexy behind big wheels

This is why my car has R32 brakes on it but no power upgrades just yet. I'm sorting suspension (PSS9s), brakes (R32 brakes, braided lines, done), chassis (front swaybar done, rear swaybar and Unibrace coming soon, front bracing coming shortly after that), a few interior tweaks to improve drivability (on the way), etc. Then, when I'm sure the car can stop and turn the way I want/need it to, I'll consider extra power.

[Manaz]

not necessarily. you are right about the weight, but having larger brakes doesn't mean they are heavier.

You can also simply buy lighter rotors - ECS sell 2-piece rotors for the R32 for instance with an alloy hub, and this reduces the weight considerably - but there's a cost involved, and that's the ability for the rotors to soak up heat. Almost everything you do with a car is a compromise - there's rarely a benefit without a corresponding penalty.

If the pads are further out from the centre of the hub (i.e. with larger diameter rotors) then there is also a greater retardation effect for the same pedal pressure due to the extra implied torque induced due to the larger radius....like using a longer spanner to undo a tight nut...but in reverse.

Absolutely - if you apply more pressure (as the pads are bigger) further from the centre of rotation, the overall braking force is increased.

Yes that's true, just that the point was being made that bigger doesn't always mean better all the time. You need to make sure that your supposed upgrade is exactly that and you're actually not going to go backwards.
Cheers,
Trent

Someone on Vortex did a lot of number crunching on this sort of stuff. If I remember correctly, there was a small difference in short-term braking performance (say a single stop from speed) due to the increased radius (and thus high torque that the brakes are able to produce) which would probably have been higher but for the extra unsprung weight which increases rotational inertia, but the biggest benefit was on repeated stops from speed, where the larger size of the brakes meant better ability to hold heat and thus not start gassing the friction material or boiling the fluid.

The other benefit to R32 brakes is that they are a twin-piston design with a larger pad - meaning a larger friction surface (and thus more overall friction), and pressure applied more evenly to the pad (so it's more effective).

Theres nothing wrong with the R32 braking system...not once did i get fading from them doin supersprints.
The car was ballistic,i out breaked Porsches no problem so why upgrade?

That's almost certainly down to driver rather than equipment - the R32 brakes are good, no question, but I'd be very surprised if they were able to outbrake a Porsche setup under equal circumstances.