For years I have wondered why the PNs for the rear brake calipers on my UrS4s are backasswards, i.e. odd = right and even = left instead of the other way around:
The C4 UrS rear brake caliper numbers are:
447615423 = right rear caliper
447615424 = left rear caliper
The other day I started investigating and was told that when Audi used an existing part from another (older) model, they didn't necessarily and most likely did NOT change the PN. So this would explain why a C4 part might start with "44" (= C3 Type 44) instead of "4A" (as in 4A0 = C4). However this does not explain the 423 = right and 424 = left. Or does it?
It was further pointed out that it is likely that in the first application of the 447615423 caliper, it was very likely on the left side of vehicle, not the right. This would make 423 = odd = left = following the naming convention. Furthermore, if this is true, then because the 447615423 on the C4 UrS4 is on the rear side of the right rear rotor, the 447615423 on the Type 44 that it started out on had to be on the front side of the left rear rotor (maybe...even I'm confused now).
I've asked my friend Kate, the friendly parts girl, about 447615423 and she says that the earliest application of that caliper was on the rear beam axle of a 1985 Audi 100 fwd turbo avant (because the turbo + avant = greater braking needs).
What I am hoping for is a photo of said caliper on the beam axle of said Audi fwd turbo avant. Might be rainbow rocking unicorn poo but I have to ask.
The C4 UrS rear brake caliper numbers are:
447615423 = right rear caliper
447615424 = left rear caliper
The other day I started investigating and was told that when Audi used an existing part from another (older) model, they didn't necessarily and most likely did NOT change the PN. So this would explain why a C4 part might start with "44" (= C3 Type 44) instead of "4A" (as in 4A0 = C4). However this does not explain the 423 = right and 424 = left. Or does it?
It was further pointed out that it is likely that in the first application of the 447615423 caliper, it was very likely on the left side of vehicle, not the right. This would make 423 = odd = left = following the naming convention. Furthermore, if this is true, then because the 447615423 on the C4 UrS4 is on the rear side of the right rear rotor, the 447615423 on the Type 44 that it started out on had to be on the front side of the left rear rotor (maybe...even I'm confused now).
I've asked my friend Kate, the friendly parts girl, about 447615423 and she says that the earliest application of that caliper was on the rear beam axle of a 1985 Audi 100 fwd turbo avant (because the turbo + avant = greater braking needs).
What I am hoping for is a photo of said caliper on the beam axle of said Audi fwd turbo avant. Might be rainbow rocking unicorn poo but I have to ask.