I've read the BK2 axle mod in the tech section and installed them per the write up using Losi 3016 spacers for the "3/32 collars" as others have done. However, there seems to be a noticable amount of clearance remaining allowing the axle to slide in and out. Do I need to use the 2 AE shims also? Even so, there is more clearance than 2 shims.  If you recommend installing the two shims, which side do you recommend - inboard or out?  I remember quite a bit of this movement on the original AE B4 setup with 2 outside shim/washers, but the BK2 seems to be a bit more. Please correct me if I'm wrong -- Regardless of the amount of clearance/slack, I'm assuming that when the wheel nut is tightened, any clearance is "taken up" and allows the roll pin to engage deeper into the wheel slot.

Yes, you'll still need the shims on the outside, as well. With the BKII axles you want to add .100" and only .100" of spacers inside the hub, which is the width of those Losi 3016 spacers. That done, the outer drive pin is in the correct width to push the rear of the car to the maximum allowed width, and the inside is far enough in that B4 cvd's can give as much droop as you want. 

Personally, I put the Losi spacers inside and then just added shims as needed outside to take up the slack on the axle; I don't know how that compares to the regular AE shims.

This may seem trivial to some, but I thought I should ask about the following issue to clear everything up on the new 4 gear US Track setup.  What camber link and ball cup combo are you using on the rear to achieve the 1 degree of negative camber?  I ask this as the standard AE 7230 ball cups and AE 6263/1406* 2.00" turnbuckles do not shorten enough with out running out of threads. Are you simply cutting down the ballcups or using a shorter turnbuckle?  I would also think that if one were to use the E-Speed extenders, an even shorter turnbuckle would be needed.  Please advise.

I use (and have used from the very beginning with my X - 6) Lunsford turnbuckles, and unfortunately not any particular set. I use Losi's Grey HD ballcups all around. Perhaps to the slight detriment of the Family, I just have a bag in my parts box with like 30 or so random turnbuckles collected over the years, and so when building a car I just pick out the ones I want and put them on.  The ones on there are pretty short, in fact, I believe they may be the steering turnbuckles we use for our X - 5.  I'm at school at the moment, if I remember I'll take a quick measurement tonight. As for the E-Speed hangers, I actually keep two sets of rear camber links built; one short set for regular use and then one super-short set for use with the hangers.

With the lunsford turnbuckles and losi ballcups, I don't cut down the ballcups at all, even if I have to shorten them up to the point where the threads have disappeared (slightly).  Obviously you can't go overboard, but if I need to go from 0 to -1 deg. of camber and there aren't any threads showing, I don't worry but just tighten them up further.

Also, I am observing the need for a large amount of preload on the front associated shocks with the black springs to achieve the desired ride height.  Are the AE 8232 black springs the correct springs to use on the new associated setup?

Yeah, especially with the two turn extension, those spring collars are pretty far down there.

And finally, would you have any objections to drilling an additional inboard hole on the 1st generation shock tower to achieve the #2 top position of the rear shocks on the 4 gear base setup with the CF tower?  It seems to me that this would work as I've read that the outer two holes were removed and two inner holes were added to the new CF tower.

I'd have no objections at all, in fact, I ran most of this past year in just such a "0" hole myself.  Look carefully at my X - 6 from Belgium and you can count the stock four holes in the old molded tower, and my shocks are definitely in.

Hope that covers everything!  Glad to answer your questions, let me know if you've got any more.

Thanks for the info Paul.  I would appreciate a measurement of your rear camber links when you get a chance.  Lunsford sells them in .125" increments and I would like to have a good number to start with.

Another question that I thought of as I read your reply has to do with the extended turns of the shock rod ends.  Not to pick apart Chazz's post where he explained this earlier, but does the number of turns extended mean turns extended or threads showing?  I ask this because if you look closely at an associated shock rod, the threads do not go all the way to the actual shock shaft; the end is turned down and the threads do not go all the way "up" on the turned down section.  The associated manuals lead one to assembly the rod ends all the way to the actual shock shaft diameter, not the end of the threads.  From my experience, one needs about two turns extended to see about one thread.  In your setup, I'm assuming you mean turns extended, not threads showing as Chazz's post reads.  Could you please clear this up?  We all know what assuming does. . .

My method is a "back-off" kind of method.  I put the shock end on all the way - until it bottoms out - and then unscrew it carefully the desired amount.  I really go in half-turn intervals.

Once I have both shock shafts built, I use my calipers to measure the overall length of the shock shaft and end (top of shaft to bottom of end), and make sure its the same for both sides.

So, for example the associated setup sheet says "2 turn ext." for the bottom of the front shock.  Does that mean you do 2 half turns since you go in half turn intervals, or two full rotations (4 half turns)?

2 full rotations, sorry, I should have been more clear.  I simply meant that I go in half turn adjustments, so you might see like 1.5 turns someday or something.  1 turn ext. is a full turn.

If you use the RPM shock ends for assoc. shocks it moves the spring up on the body without limiting up travel. I use these ends whenever I run a spring other than the browns.

I've got the camberlink extenders on there right now, and the turnbuckle length is 5/8" (not counting threads, 'cause they're in the ballcups...).  I expect the turnbuckles I use when not running the E Speed parts are around 3/4" or 7/8", but those are currently buried away.