Headset won't stay tight.

I recently changed my fork from a Pike to a DVO Diamond. The stem is a Chromag BZA which is pretty milled out. The fork has a centimetre more travel so it's a little bit longer but not much. I use an EDC  so the steer tubes on both forks are threaded accordingly. And I left the new fork a touch longer too so there is one more 5 mm spacer now. Three instead of two. But since the change I have not been able to keep the Cane Creek headset from coming loose after about 45 minutes of riding. 

All I can think of is that the DVO steer tube has a more slippery surface and the BZA being milled out inside and windows on the side just lacks sufficient surface area to grip when torqued to max spec. I do have a Bontrager stem to try out and I will report my findings in a couple days. Anyone had a similar issue? Carbon assembly paste is another option I suppose that I could try as well. 

What say you, experts of the interweb?

Back in the day we had this problem on a Marazochi Z1 with i think a WTB stem on a brodie holeshot, the head set would loosen off whenever junior went dirt jumping, he also broke that holeshot frame , snapped several square taper BB's and from time he was little was able to break almost anything in "normal use"

what we finally did to solve the situ was instal a hedlock

http://www.mtbr.com/cat/controls/headset/azonic/head-lock/prd_361080_124crx.aspx

Do you have enough clearance between the spacers on top of the stem (if you have it setup that way) and the steerer tube?  I dont know how particular the EDC system is with how many threads need to be engaged to hold the preload on the headset.
Carbon paste or a little extra tightness on the stem bolts are both worth a try if it keeps happening.

The steer tube extends a bit above the stem and I have enough spacers above to preload properly. I am able to make it too tight so that's not the issue. It's supposed to be the stem that holds it all together but I suppose the preload assembly does add something. I can't use a headlock. Not with the EDC anyway.

If you can make the bearing preload too tight with the EDC topcap, you are right, that probably isnt the issue.  Different stem, tighter bolts or assembly paste are your best bets.

OK, with a Bontrager Line stem on today's ride, the headset remained in proper adjustment. This stem has no indows on the side and the opening into the extension is smaller. The Chromag in comparison is almost skeletal. But the Chromag has larger hardware and higher torque spec. Whatever. If the Bonty stays tight for another rider two, it's a keeper.

Posted by: andy-eunson

OK, with a Bontrager Line stem on today's ride, the headset remained in proper adjustment. This stem has no indows on the side and the opening into the extension is smaller. The Chromag in comparison is almost skeletal. But the Chromag has larger hardware and higher torque spec. Whatever. If the Bonty stays tight for another rider two, it's a keeper.

compare the stack height of the two stems as well , the Cromag could be a MM or two shorter , I have had to use a spacer or two when switching stems .

About 2 mm shorter. I meant to post that too.

My Straitline stem has a lip at the bottom that almost requires it to need a need a spacer underneath else it doesn't sit completely on the top cap.

I usually cut my steer tube to require a spacer above and below the stem to allow some adjustment. Plus I think Cane Creek dust caps or whatever top hunk of headset is called require one of their spacers which lock into an inner groove. Anther solid bumpy ride today and headset remains proper. So I bought the stem. My local shop,  Fineline, loaned it to me to see if that was the issue.