Ah...Yes. You are speaking of the cad plated (usually brassy looking) bearing cartridge on the bottom side of the strut mount. The object of that skirt around the bottom is to act as a spacer . What it does is suspend the plaste that comprises the bushing housing just enough above the top spring p[late that it does not rub or grind. It will not hurt to grind it down some. I taped the beraing areas of and ground mine down about 1/18" if memory serves. This got the bearing plate closer to the top spring plate but not on it.
Also...you should...put shims underneath the bearing cartridge inside of that cone...just enough to be "exact" in thickness so the bearing is not heavily loaded.
There is one mod for this that I have done on my car that fixes this that I have not really heavily gotten into.
Its like this: On our cars, the strut rod has "ledge" on it that comes up against the underside of the upper spring plate. The stepped down rod....like what you made on the stub adaptor goes through the hole in the plate and then through the bearing.
The is decent, but relatively unadvanced compared to some late model cars.
Back in 2001 I changed the struts on a 96 mazda. It had the most unique, simple and cheap strut bearing I have ever seen. In addition to having a true ball bearing in the strut mount (similar to the come shaped cartridge the 412 has but bonded in more like the 411)....it also had a flat, two piece, grease filled UHMW bearing plate about 1/8" thick that went between the bottom of the bushing/bearing/mount assembly and that top spring plate that the coil rests against.
The difference on the Mazda is...that the top spring plate has a hole that the entire large diameter of the strut rod can pass through. So there is no ledge on the rod resting against the bottom side of the plate like our 411/412. This hole is about .060" larger in diameter than the rod.
This plastic two piece bearing plate I am describing then has a thin pair of inner locating lips that slip down around the rod so the strut rod never touches the metal of top spring plate. This inner ring...also serves to loacte this "glide" plate in the hole in the upper spring plate so it cannot slip side to side.
So....I had the holes in my top spring plates bored to fit the lips on a pair of Mazda 626 bearing glides ($18 each). I then ground down the brass looking bearing cup ...and shimed it with arbor shims inside...so the shims were the exact height to fit from the opening of the cone up to resting on the bearing itself.
So..when all done...you now have a solid spacer that rests on the ledge of the strut rod or adaptoron the bottom and flat against the bottom of the bearing cartridge. The skirt of that bearing cartridge rests against the plastic glide plate. It makes the steering much smoother, less vibration and keeps from trying to wind the spring plate up with the spring when making fast turning moves. It makes the whole strut spring assembly more responsive.
Also by altering the length of terh spacer between the bearing and ledge.... and shortening the skirt on the cartdige.....you can change lowering height.
One warning. As you change the skirt length or anything else...the strut stub protrudes further out the top. Be sure to gruind it down accordingly...or it WILL dent your hood. Been there.
All you need to do this mod is to buy a pair of those glide plates.....get a stack of spacer washers ...and have the top strut plate holes bored larger to fit the OD of the inner rim on the Mazda glide plates. The machine shop I used bored each hole for $15.
You will need to have them milled. The upper spring plates are ugly hard. If you need a sktech let me know.
But looking at one of these mazda bearings in person...and at a haynes manual of how they are installed...it will be instantly clear.
here is what the part looks like:
http://www.alloemcarparts.com/unified/? ... +1667+7105
Ray