Performance Friction Brake Parts for the E46 M3 - Full Test!

The Introduction
There is a route not far from me which I drive fairly often. One lap is around 12 miles. It usually doesn’t take much time!

It's got everything; gradient, slippy off-camber corners, bits of shellgrip, single-width passing places, nasty unsettling mid-corner bumps, two sets of esses... It’s also very brake intensive, with straight stretches followed by very tight corners. In summary, it's a lot of fun to drive along.

My fastest time from A to B along this route was in a previous car, my E34 M5.
I don't believe it's just a coincidence that the M5 also had the best brakes of any car I've ever owned. The 345mm four-pot Nürburgring brakes are superb, as anyone who's driven one would confirm. Certainly at the 'Ring, I never found them to be wanting, even after several sequential laps.

Unfortunately, that was to change when I bought my E46 M3. This car is fast, and the more I drive it the more I appreciate it. It's a true Jeykll and Hyde; well behaved in even the worst weather conditions, powerful yet frugal, civilised yet lairy. The handling is predictable, the engine is torquey and responsive, the steering feeds information gently to the driver. It even looks smart.

Unfortunately, the brakes are shit.

I understand from various M3 owners that many have found that after a few thousand miles, the performance of the OEM brakes drops off considerably, sometimes causing serious vibrations at the steering wheel. I imagine that many M3 owners might never find out that the factory brakes are lacking.

I discovered a distinct lack of stoppability about three-quarters of the way along this route. The brake pedal had gradually become spongy with very long travel, and stopping the car was a hit-and-miss affair accompanied with some graunching or some very loud squeaks from the front. Sometimes the vibration through the steering I'd heard other owners suffering from would be present.
I cruised along to give the brakes a bit of a rest, and after a few minutes, some of the pedal feel returned, but the squeaking was still there. I got out of the car to have a look (half expecting them to be on fire). Forgive the camera phone picture, but they almost were:

This behaviour was obviously a case of the friction components overheating. The next morning, they would work fine. No noise, no squishy feel, no problem.

Unfortunately, after any constant wiggly road driving for more than around ten minutes, they would be stinking and smoking. However, the brake parts were relatively new, the discs and pads had been fitted four months before.

The Replacements
Over the previous year or so a friend of mine had had an E36 M3, the brakes on which were equally disappointing. They would fade at a mere hint of a few hard stops, let alone coping with laps of the Ring. Any further punishment would warp them.
He had looked into a brand of brakes reviewed in one of the BMW Magazines, Performance Friction. The idea is that these components are designed to offer longevity and performance which will withstand track use, with little or no compromise in behaviour on the road. The parts are supposed to be stable to 800 degrees Celsius, meaning that the pads won't combust after a few hard stops. The icing on the cake is that the cost is similar to OEM replacement parts.

When it comes to car parts, especially where BMW are concerned, I'm a great believer that they generally know what they're doing, and that if something isn't working satisfactorily, it's because it's broken.
Unfortunately the many M3 drivers reporting that they are unhappy with the brakes indicates that this isn't the case.

I got in touch with Performance Friction, and was directed to a retailer. I arranged to meet Peter Collinson to talk to him about the brakes (I told you I was cynical)! He was very helpful and knowledgeable, and answered all of my tedious questions. I was very impressed with Peter and the parts, so I left with a set of new brakes.

Certainly they must be the best packaged brake parts around. The quality isn't limited to the boxes, the discs are beautifully made. The floating rotors are mounted on a separate bell, like the OEM discs. Unlike the OEM discs however, little springs are employed to offer the floating movement rather than metal bushes.

Fitting was easy, the parts really are a direct replacement.
The first thing you notice is that they look pretty cool. Those who know me will know that that’s the least of my concerns, and that I’m a big fan of function over form. Nevertheless, they look like impressive pieces of engineering.

First Impressions
I went out that night to follow the specific bedding-in instructions, which involves a number of 100mph+ stops. After bedding in, I was a little bit concerned that the brake pedal was quite soft. Since I had probably boiled the fluid several times in the past month, I had it changed the next day. The feel improved a good deal, but there was still a little bit of soft pedal – perhaps the first 10-20% of pedal travel. It's noticeable as a small amount of extra pedal pressure required to stop.
I have since learned that this is only really evident when the brakes are cold, so as far as I’m aware it’s the only point of compromise to the parts. Of course, that’s an acceptable trade off if you find the factory parts are lacking. Not a huge surprise, there must be a compromise to provide the 800 degree stability. Pleasingly though, the brakes soon warm up.

Over the next few thousand miles, one thing that struck me was the almost total lack of any brake dust on the wheels. Obviously the brakes work, and work well, but they don’t seem to shed much dust. Since there’s a hose-pipe ban at the moment, that is definitely good news! Furthermore, other than the characteristic hum of the drilled discs, the brakes make no noises. No squeal, no squeak, no graunch, nothing.

Testing
So, I had tested the Performance Friction parts for two thousand miles, often in conditions which otherwise had had the M3 factory brakes distinctly beaten, and had not found any problems. Since my only way of measuring whether the new parts were any good had been just by building a mental picture, I was keen to perform some sort of measured tests.

With this in mind before I replaced the discs and pads, I had gone out and recorded three separate 100mph hard stops with the aim of recording some times. The times are approximate since my GPS-based datalogger records at 1Hz.

After I'd fitted the new brakes, and used them for two weeks and 2000 miles, I repeated the stop tests on the same bit of tarmac. Both days saw relatively dry weather and similar temperatures. Obviously there are still possible inaccuracies, such as differences in tyre wear with 2000 miles of use.

In order to try to make the tests as fair as possible, I drove for the same time before starting the tests, to ensure the brakes were already warm.

As the graph shows (and it's hard to argue with the figures), the car stops faster with the Performance Friction brake discs and pads than with my overheated OEM components. There's no real surprise there, and you could argue that it's not a fair test - but it is likely that all M3 brakes would offer this level of performance after a few thousand miles of use.

Possibly more interesting than the actual stopping times (I'm now impressed by the times achieved by Evo's 0-100-0 tests) is the consistency of the stops with the PF bits, each time recording exactly the same stopping times. The OEM performance however, dropped of quickly and steadily, and from the driver's seat the last stop with the OEM bits was pretty scary, barely even enough decelerative power to activate the ABS. 9 seconds from 100-0 feels like a lifetime.

Clearly a few 100-0 stops isn't enough to test the important features of good brakes - desirable features such as long life, low noise, low dust and so-on can only be tested over time. This article has been produced over 6 weeks, and 4,000 miles in total. I like to think that's a pretty extensive test.

Still, what better way to test the brakes thoroughly than by spending a weekend on the Nordschleife? None that I can think of. This is the one place that will reveal any weaknesses - brand new E39 M5 brakes (which are equally poor) have been known to be warped after just a few hundred miles' worth of laps.

At the Ring
Spin forward a couple of weeks in the brakes story. I'd been using the car for work each day in a combination of anything between hundreds of motorway miles without using the brakes, and my favourite brake-intensive twisty-turny route. One of the issues I had discovered was that when the brakes were cold, the ABS was too sensitive. I fitted a pair of track pads to the back brakes in order to redress the balance in the performance/temperature proportion and this issue has disappeared.

The compromise of the Performance Friction parts seems to be a small loss of feel at the pedal (mentioned earlier) and a need to apply more pressure to the pedal to stop the car when the brakes are cold.

After a few applications of the brakes in the morning, there isn't a problem. In my opinion, this is a fair compromise if they don't melt under hard use.

So, on to the Ring to peform some proper testing.

After the first handful of laps, everything was performing very well. The Performance Friction brakes are extremely smooth at all temperatures and no sign of any vibration or fade, no noise, none of the undesirable symptoms I'd found with the OEM parts.

The only problem I experienced all weekend was after three consecutive laps where I had three passengers and was doing my best to put in tidy and quick laps, the tyres started to overheat and became squirmy. Time to stop to give the car a break, but a relief on the basis that the brakes were faultless.

The weekend of hard use continued in much the same vein, and the brakes are continuing to perform superbly, with only the compromises in cold feel and bite. However, they do reach low operating temperature quickly enough for this to be a minor complaint.

One thing which had been mentioned to me but I struggled to believe, was that the PF pads don't produce much dust. In actual fact, they don't seem to produce any! After I returned home, I removed the front wheels - I know that in the past I've managed to burn off 2mm of pad-wear material in one weekend at the Ring, but there was no measurable difference in the depth of friction material before-and-after the trip. They are clearly going to last a long time too!

Summary
If you've managed to read through this far, congratulations!

The effective summary is simple and brief. The Performance Friction brake pads and discs are a vastly superior replacement to the factory parts at a very similar replacement cost. The compromises are minimal, and if you find you're melting the OEM components then you'll be seriously impressed.

Performance Friction's website claims that they are "The absolute best brakes on the market". I can believe it.

Cheers,
Andy Eccles