I have a dumb question.



The front and rear rotor housings have different part numbers, what is the physical difference between the two?

EGR ports

The fresh air passages around the exhaust port. Swapping front and rear housings effectively blocks them off, and the car may be hard to get to pass emissions.

S5 and later doesnt have egr.

https://www.nopistons.com/forums/pub...R#>/unsure.gif



The holes you can see in the side of the LIM is where the EGR valve attaches.

i stand corrected.

EGR valves are good for throwing against a wall!



Could you use a two front housings?

yeah, you can. if you look in the bottom corner of the housing, theres a passage drilled on one side of each housing, the difference between front and rear is that passage, its easy to drill a new one

Thanks Mike! FD housing are hard enough to come by, now try cutting down the number available by 50% by only wanting the rear! Plus, for some reason, people are asking more for rear housings... go figure!

For some strange reason, about 90% of the FD's I've rebuilt have blown the rear, supposedly something to do with the twin turbo setup