our 128 rear brake rotors

[NorthernDancer]

I believe our 128 rear brake rotors are 34 21 6 855 005. They are 300x20, min thickness 18.4 and weigh 6.51 Kg (14.32 lbs) and are unique to the E82 and E88. Someday, maybe they'll be NLA.
The euro E87 130 and I think most E90's use 34 21 6 864 901. They are 300x20, 18.4 min tkness and weigh 6.587Kg (14.49 lbs)
Can anyone comment why we could not use the euro/E9x rotor if an when our become NLA?
Further checking indicates "our" 005 rotor is used in Europe on 118, 120 and 125 so should be available for a very long time, however still, if we can use the 901, all the better b/c they will be in stock in North America.

[TboneS54]

Aren't the hubs different though? There's more to a rotor than total outside diameter and thickness.

[juld0zer]

E82 hubs are 10mm longer. Parts will be available for a long while to come

[Olgeezer1]

I'm using the BMW Performance brake kit, front and back. My understanding is that the rears are the same as 328i's, the difference being a slightly larger piston. So it would seem like there shouldn't be any issue using the rear rotors for a 328i. I know in changing rear pads that there's no difference.

[asbrr]

Originally Posted by Olgeezer1

I'm using the BMW Performance brake kit, front and back. My understanding is that the rears are the same as 328i's, the difference being a slightly larger piston. So it would seem like there shouldn't be any issue using the rear rotors for a 328i. I know in changing rear pads that there's no difference.

While the rotor diameter and thickness are the same, it's the rotor "hat" that will be different. Visually you can see the 128i hat is "deeper" than the 328i hat....it's like we have "built in spacers" on the 128i.

Now as the calipers can be swapped (only the piston size is slightly bigger on the 328i as you say) - I'm not sure they locate in exactly the same spot on either car, meaning that could by why fitting a 328i rotor on a 128i won't work without swapping hubs etc.

[asbrr]

Originally Posted by asbrr

While the rotor diameter and thickness are the same, it's the rotor "hat" that will be different. Visually you can see the 128i hat is "deeper" than the 328i hat....it's like we have "built in spacers" on the 128i.

Now as the calipers can be swapped (only the piston size is slightly bigger on the 328i as you say) - I'm not sure they locate in exactly the same spot on either car, meaning that could by why fitting a 328i rotor on a 128i won't work without swapping hubs etc.

Actually - I recall another thread from andrey_gta where he suggested using rear brake rotors from the 328i to gain "more room" for wider rims/tires without rubbing. So the rotors probably will work, but you will have effectively 10mm less offset (meaning the wheel will sit 10mm more inboard/inward)...

[juld0zer]

Originally Posted by asbrr

Actually - I recall another thread from andrey_gta where he suggested using rear brake rotors from the 328i to gain "more room" for wider rims/tires without rubbing. So the rotors probably will work, but you will have effectively 10mm less offset (meaning the wheel will sit 10mm more inboard/inward)...

You still need to swap the hubs (and wheel bearings as they get destroyed when you pull/press the hub out)

[chris_flies]

These parts are going to be around for a VERY long time. Hell, E30 rotors are still in production (a good market, too, since they're raced a lot now).

You must use 128i rear rotors on a 128i. (Duh!)

If you do the E9x hub mod, THEN, and only then, you can use the 328i rotors. (Also duh!)

Calipers are an entirely different story. The short version is to just get 135i rear suspension knuckles (or 335i and accomplish the E9x hub mod at the same time).