Bilsteins won't fit 45mm strut

[BaurNiki]

Hi everyone!

I am currently installing a set of Bilsteins on my 1984 320i Baur. The problem: the shock absorber does not fit completely into the strut.

• They are 45mm struts and I ordered the correct size.
• The right one is already installed, mounted and all.
• The left one sticks out about 10cm (see photo: https://i.imgur.com/uvuVxj6.jpeg).

I also see where the problem lies: the old shock absorber is thinner at the end (photo: https://i.imgur.com/CzIDhx2.jpeg). The Bilstein has the same diameter over the entire length.

To check if I received an incorrect part, I asked a Bilstein dealer if all 45mm Bilsteins are like mine. That turned out to be the case.

The strange thing is that it does fit in the right strut. So I suspect that one has been replaced at some point.

My questions are:

• Are there different 45mm struts? Mine is from '84, so an early model.
• Are there people here who have Bilsteins in their 45mm struts? If so, what year is your car?

If no one knows, I will source a strut from after the facelift (>1987).

Thanks in advance!

[82eye]

sure there isn't anything in the bottom of the strut? they normally are installed with atf in the tubes, it will keep it from going to the bottom if there is too much.

all 85 and earlier are 45mm, all later are 51mm. if you change struts you'll need to do both sides and source new shocks for them. no idea what is wrong with your current strut.

[reelizmpro]

Did you measure it against the old shock that you removed? No reason why the new shock wouldn't fit as long as it's the same dimensions. Another cause could be something inside the strut like rust or the tube is bent and the Bilstein is slightly larger.

[BaurNiki]

Thanks for the comments! I did get all the oil out of the strut, sadly that didn't help. It really get's stuck directly to the metal. I completely cleaned the strut from the inside.

I also did measure the old shock absorber, it's exactly the same width and length. Except for the bottom ±10cm (4in). Here's the interesting thing:

• The old (probably OEM) shock absorber has a narrow bottom end. When I look up pictures of the OEM 45mm shock absorbers, they all have a narrower bottom end. See picture of mine: https://i.imgur.com/uvuVxj6.jpeg
• The Bilstein B6 45mm doesn't have that narrower bottom end. See picture, from the Bilstein website (and exactly how mine looks like): https://media.carparts-cat.com/webda...4-181522_1.JPG
• Interestingly enough, the Bilstein B4 does have a narrow bottom end, see picture: https://media.carparts-cat.com/webda...1-030499_1.JPG

What makes it even more interesting, is that it does fit my other (right hand side) strut.

Anyway. Looks like i'm going to source a another pair of struts. Even the 45mm's are getting rare here :)

[kronus]

I've had this happen with a bent strut.

if you mount up identical wheels to both struts, are the top edges of the rims an even amount away from the strut tubes?

[kronus]

also, where is here? I have a set of 51mm's for sale. They are already 5-lug converted, incidentally.