i purchased new shaft seals for my evo ix and they arrived wednesday, since i work alot i asked a friend if he could install them thursday and he did. i get off work and my car was not finished, he had problems.
my question, is there any downfall to installing the seals backwards. he said one slightly bent trying to put it in the right way but didnt think there would be a problem with them going in with the lip down, i just wanna know befor i give him the ok to put the throttle back on the car.

 

Yes there is a problem. The seals are engineered to withstand a specific boost pressure based on being installed the way they are supposed to be. If you look at the lip, it proturudes a little bit onto the throttle shaft when installed properly. This and the convex design of the seal casing helps it to hold pressure when under boost. If it is installed backwards it will act like a flutter valve or a one way valve allowing boost to leak past the throttle shaft. BTW which seals did you get? I hope all works out well for you. Feel free to pm me if you have questions that I can help you with.

Josh