[thoughtful]

we are also a second year team, we tried the same direct drive that you are talking about, but we got some time to test it and we also tried it on carpet and up the ramp and got that jerky motion. We then found out it was our 40 AMP breakers. Once we had to problem narrowed down, we found out that the shafts were perfectly alligned. Things to make sure, all shafts are straight, the more perfect the better. Also they shafts on motors should be secured by some bearings, block bearins if you ask me. Than your wheel shafts should be perfectly alligned, with a mechnaism that allows you to tenion yor chain.

So basically,
Shafts should be alligned perfectly, the chains should be right tension not too much, but also not too little and also i would never recommend gearing up, always gear down.

Now the gear boxes you talk about, if they are not custom than you may not run into that much problems but if they are custom makes sure to have accurate measuring equipment that allows you to be precise to atleast 1/200 of an inch. Also have the spacers ready, make sure no component in the gear box is allowed to have any play(move).

Last but not least make sure the gears dont bind, the best way of checking this is, put a piece of paper and mesh your gears if the peice of papers slids through easily tht means you have a clearence of 4/1000 inch which is optimum for helicul gears. Also make sure you dont have that much of a slip, the lesser the better. Slip means that you have a little bit of movement between your gears, this can cause additional friction you may not want.

Also did you work out the speed you want to be going on and the RPM you want before you designed the gearbox?.

Also if you dont understand sitll, PM me and i'll spend some time on MSN with you snd walk you through all the parts and we might find out what is causing the poblem.