Friday, March 5, 2010

My Audi A6 - Brake Modification

The rear rotors are also slotted. The electronic parking brake proved to be a bit of a challenge as my VAG-COM kit had not arrived. After some headscratching, we figured a solution to the problem and the brakes were installed without further drama.

The brakes were installed with no drama and they fitted perfectly.

It was time to replace the brake rotors on my Audi A6 that were wearing thin after 90,000 km. Instead of replacing with OEM rotors, I decided to replace with OEM sized two piece rotors. I also opted to continue with the EBC Red Stuff pads which had served me well when I replaced the OEM brake pads at 50,000 km.

Review of the EBC Red Stuff brake pads.
OEM brake pads lasted for 50,000 km for the first time and the EBC Red Stuff brake pads which I swapped to lasted 40,000 km before I changed it along with the rotors. At both instances, I had both the front and rear sets changed at the same time. The brake oil was replaced at the 50,000 km change but this time, they did not appear to need a change and so I did not.

I chose to swap the EBC Red Stuff pads primarily because I was mainly looking for a small increase in braking performance, and a huge reduction in brake dust. And the EBC pads did all that. Braking was sharper compared to the OEM pads which were quite inadequate for emergency braking. Braking on the OEM pads felt vague and you never got the feeling that you would stop in time when you needed to as the Audi A6 is a heavy car. As a result, I tended to brake early, just in case. The dust from the OEM pads was quick to appear as well. The swap to the EBC pads was just what I was looking for. Naturally, one cannot expect a change of brake pads to instantly produce massive stopping power. And I was not looking for that. Braking was improved slightly, and it was enough to be noticeable. And the brake dust was gone, thanks to the ceramic compound on the EBC pads. Sure, if you looked hard enough, there is still a coating of brake dust on the rims, albeit a light coloured layer.

On the surface, it would appear that the EBC pads had a shorter lifespan - 10,000 km less than the OEM pads. In fact, it is hard to make a comparison as I was driving harder on the EBC pads. In the first 50,000 km, I was mostly doing short trips within the city and at most a 150 km run to Zhuhai or a 120 km run to Guangzhou. All of which was on flat ground and decent roads. After I made the change to the EBC pads, I had made a total of 6 long trips that were between 1200 km to 1500 km each way round and along the way there were long mountainous stretches with long stretches of downhill runs where opportunities to use the brakes were plentiful. In addition, I had also started to drive the car harder.

In all, I was very satisfied with the EBC Red Stuff brake pads.

Replacement Two Piece Rotors
In a luxurious sedan like the Audi A6, you cannot and should not turn it into a sports car. What you can do is to make small improvements so that it becomes a little more fun to drive. My modifications have centred around improving the handling of the car slightly with small adjustments. Even then, I have mostly adhered to the principle of replacing OEM parts with lighter and stronger aftermarket parts as the time for replacement comes. With the brake rotors wearing thin, it also presented me with an opportunity to swap the OEM rotors with something lighter. Swapping out for lighter rotors reduces unsprung weight. A reduction in unsprung weight theoretically leads to lighter load on the suspension and this translates to better suspension response and subsquently, better ride comfort and ability to soak up the irregularities on the road surface. In addition, the loss in unsprung weight also reduces the moment of inertia which means less energy is required to get moving. And in theory, this leads to faster acceleration and throttle response. In practice, the weight reduction from taking a kilogramme off each corner could well be meaningless, or virtually impossible to detect. Experts or enthusiasts tell me that I would expect to see greater improvement if I were to swap rims and tyres for lighter versions since the weight loss at each corner would be more like 3-4 kg or more. I couldn't agree more. However, it is not the time to replace the rims or the tyres and it is the time, however, to have the rotors changed. As such, I chose to go ahead and replace the OEM rotors with lighter aftermarket ones anyway. And even if it did not produce a noticeable effect, when the time comes to change the rims and tyres, I believe the effect certainly would be very noticeable when the aftermarket rotors were paired with lighter rims and wheels.

This is the front rotor and I have also opted for a slotted rotor since it looked nice and sporty too. I do not expect to need the slots to help counter brake fade since even with the hardest driving I have done so far, I have not had any problems with brake fade. The hub is aluminium alloy and lifting it and comparing it with the OEM rotors, the weight difference was obvious. Unfortunately, I did not have a scale on hand to measure the weights but I would put it as about 1-1.5 kg weight savings.