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One of the problems with brake upgrade kits I was finding was the cost. I did not have the money required to buy such a kit all in one go. I therefore started to look at what options were available to upgrade the brakes while keeping the costs down. If was able to buy the parts individually I could spread the cost over several months which would make the purchase of the parts easier to manage.
Doing some research it didn't take long to work out that the best route to follow, was the same route that Audi took. When the Audi RS2 was introduced, the braking system had been upgraded to cope with the extra power of the car. As the RS2 is very similar to the S2, I was hoping the parts would all fit. There was one problem though. The RS2 brakes were Porsche 968 CS brakes. In order to ensure they worked according to the Porsche design, they also needed Porsche wheels. The Porsche 17" wheel is specially designed to cool the brakes by drawing circulating air and directing it towards the calipers. Porsche wheels use a different fitment from Audi with a pcd spacing of 5x130mm. This meant that the brake discs would not be suitable unless I changed the hubs. This would also mean changing the wheels which was not something I wanted to do.
I was convinced that I would be able to get brake discs which would match the dimensions required, so I started sourcing the parts I would need.
The following parts are required to upgrade the brakes on an Audi S2 to RS2 spec:
Calipers Audi Reference 8A0 615 105 E / 8A0 615 106 E
The RS2 used an Audi unique version of the Porsche 968 Club Sport caliper. It was painted red and used slightly different pads. The pad housing is not as wide which means that Porsche pads cannot be used. Since Porsches are more common than the RS2 I was able to source a pair of 2nd hand calipers. These are the black calipers which you can see in the picture below.
Mounting Bracket Audi Reference 8A0 615 125 A
This is a custom mouting bracket which allows the Porsche caliper to be mounted on to the existing S2 suspension. The same part is used on both sides of the car.
Bolts for Mounting Bracket/Caliper Audi Reference N 100 880 01 / N 100 436 02
There are two pairs of bolts used for each side. The short bolt secures the bracket to the car and the long bolt fits through the caliper and secures the caliper to the bracket.
Anti-Squeal Damping Washer Audi Reference 8A0 615 231 D
This inserts into the pistons and is stuck to the rear of the pad. This is to help with brake noise. There are 4 of these in total.
Brake Pads Audi Reference 8A0 698 151 E
Since I am using the Porsche calipers, any standard Porsche 968 Club Sport pad can be used. The picture below is of a Jurid pad which was purchased while in Germany. These are not on the car anymore due to amount of dust which they produced.
Brake Hose/Pipe Audi Reference 8A0 611 769
This is basically an Audi hose (893 611 707) which has been converted to work with the Porsche caliper by fitting a short (approx 2 inches long) right angled brake pipe into one end. No picture is available for this but one will follow shortly.
Brake Disc Audi reference 441 615 301 AA
This was the single biggest source of problems with this brake upgrade. Originally I had 2 piece discs installed. These were the same dimensions as the Porsche disc (304x32mm). The only difference was the centre bell was designed to fit the Audi S2 hub.
I had problems with these discs for two reasons. Firstly, the rear of the disc was not large enough to accomodate the brake pad. This left a band of about 10mm of unused pad material. The other problem was clearance on the front of the disc. It was ok when the pads were new, but as the pads wore down, the backing plate of the disc started fouling the centre bell of the disc. This meant they could not be used at all and resulted in the car needing two new front wheel bearings.
I have now compromised by using a disc from the Audi A8. This disc comes supplied as 314mm in diameter and therefore needs reduced in size to 304mm to use. It is also only 30mm thick as opposed to the required 32mm. This means that the pads cannot be allowed to wear down to minimum levels and the air gap between the two disc surfaces is smaller. This may lead to problems with heat dissipation although so far, I have not enountered any problems.
A picture of the modified A8 disc will follow shortly.