Was reading this old thread. Found it very informative. Will be redoing my rear B4's this weekend.

 

For anyone that is interested, I just went through this with Bilstein support, Germany. The outcome was that the big washer that comes with the b4 should go between the flat strut shaft shoulder and the top spring support (in place of conical washer ‘8’ in the OEM part diagram below). The large concave washer that comes from factory in position ‘12’, on top of the whole stack, underneath the lock nut, should be reused.

I suppose this means that anyone who has just chosen to turn the small OEM conical washer (8) upside down is fine too. For me, I’ll be taken mine apart and rebuilding this weekend.

I have no knocking issues, at least with current setup, where I have no washer in position 8.

 

Which takes you back to square one. Fit them that way then, if you've issues you can always then fit them the way I posted. Keep us updated as to not confuse others. I would leave them as you have, without #8 but using the stock concaved top washer. That's how I and most others ended up fitting them. The penny washer is not a perfect fit, really they should have put even just a small taper onto the tube and washer, that way you get a snug fitment that can withstand angled side loading forces.

Always check the top spring perch for any ovaling, where the shock tube passes through.
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