AudiWorld Tech Articles

Tech Article Title	Author	Date
Ventilated Rear Brakes for 20v Coupe	90quattrocoupe	2005

Below you will see two possible ideas for rear vented rotors. I tried a couple of different calipers and rotors, and did the fit ups on a spare strut I had. This was easier than attempting to do all the try outs with a strut on the car.
These are a couple of different combinations using two different rotors, two different calipers, both off the same carrier.

The rotors are both 280X22mm. One rotor was off a Corrado G60 (model, not brake system) and the other rotor is off a New Beetle. The g60 rotor weighs 11lbs and the New Beetle weighs 13 lbs.
The two calipers were from a UrS4/6 rear and an A8 aluminum rear.
The carrier was from a S8.

This is a picture of the two rotors used for the fit ups. Both rotors have had the center bore increased from 65mm to 68mm. The G60 rotor was redrilled from 4X100 to 5X112. The NewBeetle/A3 was slotted from 5X100 to 5X112.

This picture shows G60 rotor with the S8 carrier install on the strut. The carrier bolts up on the opposite side of the strut mount, from where the coupe carrier bolts up. Fortunately, both sides of the S8 carrier are machined flat.

As you can see from this picture, the G60 rotor comes a little close to the inboard edge of the carrier. It was even closer before I took the next step.

I took a look at the carrier and noticed that they had excess material on the inboard edge from the bolt on area. The least amount of excess material was 1.5mm. So I had an additional 1.3mm milled off each of the carriers. This allowed breathing room for the G60 rotor.

This picture shows the gap between the S8 carrier and the bolted up A3/New Beetle rotor. It is more centered, but as others did on this forum, you need to use 2mm spacers when bolting up the S8 brake carrier to the rear hub carrier. This moves the carrier outboard.

This is the aluminum A8 caliper all bolted up using the G60 rotor with the S8 carrier. On the S8 this carrier allows the car to use the 280X22 rotor vs. the normal 276X22 rotor used on the A8. This caliper weighs slightly over 3lbs. This caliper has a slightly different Ebrake pull location, but it still pulls from the side like the coupe. You will have to ream out the brake cable stop on the caliper as the hole is slightly smaller than the one on the coupe.

The UrS4/6 caliper bolts up just the same at the A8 caliper. The Ebrake cable works exactly like the coupe. This caliper weighs in at 6 pounds.
Remember, if you end up trying one of these combinations, the A8 caliper or the S6 caliper, they are used on the opposite side of the car, from where they were normally used on either the UrS4/6 or the A8. The right caliper goes on the left side of the Coupe and the left caliper goes on the right side of the coupe.

The A8 has a slightly larger diameter piston than the S6 caliper. But I have found the UrS6 combination I use on Coupe, along with the 996/A8 323X30 rotor has been a pretty balance combination. I get no lock up in the rear, before the fronts when I have the ABS switched off.