Looking for a memory refresh on the difference between Koni strut and a bilstien strut.
I have a set of Koni 3.5 " struts.
Is the actual tube diameter bigger on the Koni?

thanks
Andy

Thinking they are all the same size.

Diameter on all Konis should be the same?

3.5 or 3.0 usually refers to the bolt spacing for the brake caliper mount.

Koni takes a koni insert
Bilstein takes a bilstein insert
Boge takes a boge, bilstein or koni insert (as long as its the proper model insert)

Thats what I remember...I guess I just never knew the reason.

Andy

Hmm. Maybe I’m misunderstanding.

Bilstein struts are actually an inverted mono tube that reduces unsprung weight to a limited degree. Very different design than Koni or Boge. Bilstein struts have relative motion between the strut insert and the strut body, guided by linear bearings. Very similar to a motorcycle fork motion.

Strut insert body diameter is larger on Bilsterin since it essentially is almost the same size as the strut body it slides within. I don’t have parts in front of me but I think all three have esentially the same strut body tube diameter as stated above.

Bending forces on Bilstein are borne by the strut insert body. Koni and Boge bending forces are borne by the strut damping rod.

Koni strut dampers are twin tube design. If I recall Boge are twin tube dampers also.

Mono tubes typically are lighter, cool better, and have better damping characteristics than twin tube dampers.

Sorry if I’m missing the point of the original question.

this falls under why ask why....whats the difference between a Boge strut that accepts Koni or Bilstien and say a Koni strut that only accepts Koni.

Koni struts are designed for Koni inserts and Bilstein struts are designed for Bilstein inserts. In both cases I don't know of another supplier making parts to fit. Boge struts are designed for Boge inserts, but both Koni & Bilstein make inserts that will fit; I'm sure there are other suppliers that make inserts that fit as well. But in any case, the inserts are designed specifically for the strut. So a Koni insert for a Koni strut will not fit a Boge strut.

If you search the Bilstein catalog for 914 (even 914/6), you will find inserts for only Boge struts. But if you search for 911, you find inserts for either Boge or Bilstein struts. The cartridges look very different. I have Bilstein in my Boge struts and they dropped right in.