Does Bilstein Insert need Rubber Bumpstop
 

I thought so, based on posts, and my Bentley manual. But when I tried to reassemble strut with new Bilstein HD insert, plus old Boge bumpstop, I couldn't get the top bolt to go through the mount to get a nut on it. Then I looked at the instructions sent with the inserts, and it said use no additional bumpstop because the insert has it built in. I called ASI, where I bought them, and that was verified, though the guy didn't sound totally sure of himself. So, do I need the bumpstops that were with the Boge inserts, or not? I'm sure reassembly will be much easier without them, but want to do the right thing. Thanks,

Don Ivey
'87 Carrera

My understanding is no. I didn't use an external stop with my Bilsteins.

Bilstein inserts for boge struts do not use an externally visible bump stop.

They do have bump stops, but they are contained inside the lower slider portion.

Toss the old boge bump stops.

....and if you have lowered your car, you may want to consider removing a couple of the 'sections' of the Bilstein rubber stops. Additionally, if you have the 10mm thick large washer on top of the strut, you may want to remove that as well. Disregard if your car is stock height.

hijack question -
what is the purpose of that 10mm spacer? can it be discarded or replaced with something lighter, like delrin?
thanks & sorry for the ot
Bill K

The 10mm washer and bump stops are used with Bilstein struts which have inserts/shock "cartridges" that actually do use removable bump stops. The stops are located inside the Bilstein strut housing since the Bilstein insert of this type is an inverted cartridge with the damper shaft below the damping assembly.

However the original poster has Boge struts and therefore, as others said, these 10mm spacers (massive hunks of metal by the way) and bump stops are not present. The 10mm spacers don't seem to do anything but reduce the length of the threads on the end of the shock insert. Some say it raises the height of the front end of the car a bit, but I don't see how that's possible. The shock damping is linear, so what's the difference if the shock is in full extension or slightly compressed. Ride height should be the same since the combination of torsion bar & A-arm indexing determines the front ride height.