derek - get us a video.
the jerk isn't about driving the bar up or driving yourself down. it's about driving the bar up AND driving yourself down. both have to happen.
the keys to a solid dip and drive are:
1) position - solid rack, i.e. bar on shoulders, not on arms. Hand contact with bar willl vary as will elbow height. basic rule is to get your elbows as close to vertical while keeping the bar securely on the shoulders. likewise for the hands--as deep as they can be without compromising the rack. finally, the foot position. typically right under the hips, but I'd had success actually moving m feet out, toeing out more, and pushing my knees out more, i.e. much more like my squat than my pull. find the strongest, most solid position for yourself--the easiest way is to push press heavy and see from where you can push the most weight.
2) air--you must fill the entire torso, not just the chest. force your stomach out as far as posssible while inhaling and only after that clamp down the abdominal musculature. you need to create a wide base, but it must be solid too, i.e. fully pressurized. fill up wiith air, clamp down, and wait for 2 seconds before dipping. that extra time will make a huge difference.
3) dip - first, it must be vertical. any forward inclination will not work. you'll probably feel like you're leaning backward. second, it must nnot be too deep. too deep and you'll reach a very mechanically disadvantaged position--stop when you're still strong--again, check your push press depth for a good idea of the correct depth. finally, control the speed. if you dip too quickly, the bar will separate from the rack and be crashing down on you as you're coming back up--clearly this will make your drive much harder. a controlled descent will allow a faster transition and a more powerful drive.
4) transition - the transition from dip to drive must be quick. if it's slow, you're probably dipping too deep.
5) drive - just like the dip, the drive must be perfectly vertical. you'll need to get your head out of the way of the bar--do not try to push the bar out around your chin. the drive needs to be aggressive and complete--often people cut the drive short because they're too concerned with getting themselves under the bar--it will be much easier to get under the bar if you drive it higher. this is comparable to pulling yourself under a snatch before you finish your full extension during the second pull.
6) feet - first, the receiving position must be sound--the feet in the split should be just as wide as your squat. the depth must be such that the torso and bar are midpoint between the front and back foot, and the depth of the lunge must be adjusted according to the weight.
7) bar path - because the bar starts in front of the head and finishes over or even slighhtly behind it, clearly one of two things must happen - the bar moved back or the lifter moved forward. once the bar weighs more than the lifter, the choice is clearly the latter. that means that as the bar passes the lifters face, he/she must drive him/herself through the arms to position his/her body under the bar.