Front shock protector tube difference

[T.Hanson]

The stock parts drawing features a foam cylinder that slides over the piston shaft with a small black vinyl Shiner's fez cap cover for that.

The Bilstein shock in the front strut (just apart) uses a much longer bellows type sleeve with a tight fitting collar end on top, loose fit around the shock tube, no tie wrap (?).

Are both systems just different solutions for keeping the shaft clean ? I.e, the Bilstein bellows tube, loose fit around the shock isn't missing the foam insert, no big deal, good as the stock things.

[Mike W.]

The foam is the aux spring, the overload. A bit crude, but it works. Bilsteins have internal bump stops and don't require it. The rubber boot that comes with them fits tight IIRC, it is snug up top and goes over the gland nut at the bottom.

[wkohler]

The other thing to remember is that Bilsteins are actually upside-down shock absorbers, which is why the "piston" is so large. The piston would be the shock body on a conventional twin-tube damper.