968 Brakes
The information here has been supplied by the Register’s Technical Adviser, Alex Eacock, who is a senior family member of EMC Motorsport.
It is possible to fit 928S4 front calipers and larger discs to a 968 (this is what the M030 cars have) but you will need an adaptor bracket or the original uprights and hubs.
In this instance a well-made adaptor bracket is the cheaper and easier option, requiring only to be bolted on. The brakes will give increased performance due to the larger pad and disc area but the downside is that you get a slightly spongier pedal due to the larger fluid reservoir in the calipers themselves. You can compensate for this by altering the master cylinder volume but from experience, this rarely has a successful outcome and if you get the valve too small then you end up with a rock solid pedal and very little happening!
A far easier way to improve the performance of your brakes is to alter the pad material and fluid. Most of our customers use this method and have great success with it for road and track. The big problem with changing pad material is that there are a huge quantity of different pad materials and the improvements are fairly subjective.
Many people will just want what the racers have but a race car needs a material that offers outright stopping power and works at the top end of the heat range, cold bite is of little issue to a racer, as the pads are always hot once warm (if you are using them properly) and if the car has ABS, then the pad 'feel' (or modulation to give it the correct term) is also fairly irrelevant as you just stand on the brakes and the car sorts the rest!
The other issue with running race materials is that a lot of modern compounds use cera-metallic, carbon-ceramic or carbon-metallic materials that need to be kept hot, so if a car has any sort of cooling, the brake pads will cool too far and not remain efficient. The flip side to this is that the sort of temperatures the wheel bearings, discs and wheels are exposed to are very extreme (one car we used to run got it's brakes that hot during a 30 minute race that the wheel weights used to partially melt and come off!).
This isn't a problem on a race car that leads a very pampered life with checks and tear-downs between races but on a road car that gets used everyday and probably only gets checked every 6000 miles, it becomes more of an issue and can lead to premature component failure.
Race pads are also designed to wear out, that is what creates the friction, with the obvious consequence of lots of very hot corrosive dust that burns itself into your nice shiny wheels!
The other point with race pads is that they can have a massive swing in bite from hot to cold, a more stable pad has very small differences in pad bite.
So, as a general guide all high performance pads have compromises, they will all be noisier than a pure road material, they will have a slightly different temperature range to a road pad and will make more dust, the trick is to work out which compromises suit you.
If you are looking to upgrade your pads for road use, you will need a low temperature compound with good modulation characteristics.
A lot of road customers use the Mintex 1144 material as this uses a low metallic compound, so has the least dust from a high performance material and low noise, so this or something similar will be fine.
These will also be fine for occasional track use when combined with a high temperature brake fluid. Don't worry about the DOT numbers when chasing a good fluid, all race fluid is DOT 4, so just check the wet boiling point on the back and work from that.
As a general recommendation, for road and occasional track use, you can use Pentosin, ATE Super racing blue or similar but be aware that high performance fluids absorb more water, so will need refreshing more frequently.
For pure trackday use, you will need a higher temperature range pad.
If your car has ABS, you will also need a pad with good release characteristics so the system can work effectively.
Normally a more ceramic based material offers the best release and the preferred choice by most customers is the Pagid range of materials. The RS4 'blue' is by far the most popular with RS29 'yellow' being the choice for drivers that push on harder and work the blues too hard.
Mintex also offer an F series range for rallying which has specifications nearer to road type use.The F4R has a wide operating range and a stable bite, with little change in bite from cold to hot.
You will need a higher range fluid to match, Castrol SRF or AP660 are the most popular.
For race use you are into the most aggressive materials with the highest operating temperatures such as Pagid RS14 'black' and Endless.
To run these materials you will need to upgrade the wheel bearing grease to a high adhesion, high temperature type and run the best sort of brake fluid such as Endless.
You will also need to delete any brake cooling you have and invest in some stainless steel braided flexi-lines.
The other important thing to consider before carrying out any upgrades is to make sure your calipers are in good working condition. We have seen many 968's with only one pad per caliper actually working against the disc due to the plates lifting at the edges. Once cleaned and freed up, that can feel like a massive brake upgrade!