bmwe21.net forums

Jeroen wrote:As per their own on line catalog they have 1 model B8 front shock for all E21 which is the number you are referencing. Even though I'd prefer a tight fit myself as well the thinner one should fit allright and will be centered by the top nut.

This option never occurred to me. So you're suggesting to use the 39mm insert inside a 45 mm housing. Just drop it in? But even though it's centered by the top nut, won't the bottom end move around?

This means it could be that Bilstein intentionally list the same insert for both diameter struts for E21's.

Do you think the thinner insert will have any effects on performance/handling versus the thicker?

Well it may be a bit less heavy duty because of its diameter but for street use that can never be an issue. Under full tension I'm pretty sure it won't go anywhere so yes I believe this is intentional.

Seems the correct part number for the NLA B8 45mm is P36-0201 (BILSTEIN F4-P36-0201-H3).

Jeroen, could you check with your friend who told you these were back in production and get some more details?

One more thing Jeroen: If you are saying the 39mm shock can be used in the 45mm housing, that means a regular B6 4 cyl insert would work just as well. Or are there other differences?

That part P36-0201 is the old part no and NLA I believe?

I did compare B6 and B8 shocks once, abt 8 years ago and by hand compressing them. Back then I was pretty sure they were the same length but the inbound force required for the B8 shock was higher, ergo stiffer damper. Back then I was evaluating for my Baur and decided for the softer B6.

That's what I am saying. NLA. But thats the only part number that claims it the insert is 45mm thick.

Naturally the B8 is stiffer than the B6. What I am asking is aside from the diameter of the insert, what physical difference is there between 4 cyl and 6 cyl inserts?

Well expect the characteristics are adjusted to the difference in weight on the front axle (4/6 cyl.), but I don't think there are other physical differences.

Ok I know that answers to this question might may vary a lot, but, under normal use, when should bilsteins be replaced? how many km? And would this be reduced by years? (I mean a car sitting in a parking lot with not many km, but sitting for years-aren't the shocks affected by weight as well?)

Yup, hard to tell. On the average Greek road I guess it might last less longer and it mostly has to do with use, how and how much. The Bilsteins under the 320iS already last 10 years and still feel pretty good. Not too many km's (abt 35.000) but including some track and enough fast road.

What I do know is that they last a hell of a lot longer than the average Sachs, Boge, Monroe etc. At least twice as long. Combined with the better characteristics Billies are always worth the extra money imo.

Jeroen wrote:Yup, hard to tell. On the average Greek road I guess it might last less longer and it mostly has to do with use, how and how much. The Bilsteins under the 320iS already last 10 years and still feel pretty good. Not too many km's (abt 35.000) but including some track and enough fast road.

What I do know is that they last a hell of a lot longer than the average Sachs, Boge, Monroe etc. At least twice as long. Combined with the better characteristics Billies are always worth the extra money imo.

You are guessing right about Greek roads, unfortunately. Lots of hard times for suspensions, especially low ones
I have to check again my archive which I don't have with me at the moment, but my current B6 were fitted new back in 2004 ? and about 55-58000 km since then
(With Apex springs 4cm lower-which I don't know whether they might finally affect dampers' life)
After my recent replacement of most of the car's bushes, and very recently front top mounts (New Meyle from W+N, I read all W+N issues after having ordered them, but seem ok so far), car feels very well, and it really feels like Billies are still ok