Knocking in my steerer tube, tightening fail.

Ola! I have an irritating knocking between the steerer tube of my forks and the steerer tube of the frame. The frame is steel and the forks are full carbon. I've got one of those expanding bungs for carbon tubes and have done it all up as tight as I can without real fear of stripping the threads in the expander. A while ago I took it along to our very own Jimbilly who was able to fix it no problem. But since I took it apart to swap the stem over for a shorter one I've now got a slight knocking if I apply the front brake and rock the front wheel back and forth. It's done up as tight as I dare (I have already mullered one expanding bung by tightening it so much I stripped the thread!). What to do apart from take it to my LBS, any ideas for a simple fix? Or is there something obvious I'm missing? Thanks.

:-)

Your headset isn't adjusted properly, not the stem.

You're trying to tighten down the stem while the stem bolts are still clamping the stem to the steerer tube.

Loosen the stem bolts, then tighten the stem/star nut bolt until there is no more knocking, then tighten the stem bolts again, making sure the stem/front wheel stay aligned.

sams spot on.

i wouldnt go too crazy tightening the star bolt too, just get it so the knocking stops, tighten clamp bolts then star nut again.

I think Sam's right. There's a good guide on how to adjust a threadless headset about halfway down this page;

http://www.parktool.com/repair/readhowto.asp?id=65

Excellent, thanks guys. Would you believe I did exactly the same thing before with the previous stem and just completely forgot about not tightening the stem to the steerer before tightening it all up. Ha! :s

I'll have a go tonight but I'm sure this will sort it, cheers.

All done, knocking now gone. Sam was right. Thanks again! :-)