what are the differences between the brake rotors of an s4 to an s5? will the s5 rotors fit correctly on the s4??

 

Yep they are interchangable, as long as both are 5 lug

 

Interchangable to a certain degree...there are regular
5-lug that have smaller (1 piston) brakes and rotors and there are 5-lug that have the big (4 caliper) brakes and rotors.
I have a 89 GTU that has the smaller brakes and a 91 coupe that have the bigger brakes. Both are 5-lug and the front rotors on both are vented but are different sizes and the rear rotors are non-vented on the GTU and vented on the coupe.
Hope this helps.

 

i thought the calipers were interchangable on the 5 lug?

 

Oops...my bad...the front rotors should be the same, but the rear are different depending if you have vented or non-vented.