ryoung

When did the A8 switch from the FN-3 (single pot sliding caliper) to the HP-2 (2-pot sliding caliper)?

Did the A8L ever use the FN-3? If yes, when did the A8L switch?

JimR

Thru '99 has the single pot.

OK, I just spent 15 minutes or so looking at brake diagrams in ETKA, 98 thru 01, and I'm more confused than when I started.

2000s I think have 2-3 different designs, depending on VIN. Audi knew they needed to do something, but didn't settle out on exactly what, right away. And I think 99s all had the single pots like mine. But after looking at ETKA, I'm really unsure.

Hopefully someone else can comment more authoritatively.

KaMaKaZieP -ALUMIN8-

I think there are 3 designs

1. Single piston with the 312mm rotors w/2 pads

2. Dual piston with 325mm rotors w/4 pads

3. S8 had diferent calipers and used an even larger rotor

JimR

At least in ETKA.

ryoung

The Audiworld historical model guide says the A8 always used a 312 mm front rotor, and the A8L a 323 mm rotor.

The Bentley says an A8 with the FN-3 caliper used either a 288 or 312 mm rotor; and with the HP2 caliper, a 314 or 323 mm rotor.

Just to complete the picture, the Bentley also show four different piston sizes for the rear caliper - 36.0, 38.1, 40.8, and 42.8 mm. [I believe the S8 uses the last.]

Also in the rear, the Bentley shows three different rotor diameters - 245, 269, and 280 mm. [Also the S8 uses the last.]

JimR

I think they used whatever was available in the parts bin for a year or two there.