ok, spring rate is not the most critical in the drift IMHO. What you need to do is first off eliminate body roll period!!!!
The first thing that helps in this is bigger anti sway bars.
stiffening up your suspension is also a factor but not the deciding one . leave the bigger swaybars out and you will get the body roll with the stock anti sway bars.
The idea is you want the car to slide flat. When you get body roll in a pitch it gets ugly and uncontrollable.
Yes you can drift with open differentials but expect to swap sides in your drift i.e. drift left then start drifting right. This is because at a certain point in the drift with your open differential it will start spinning the opposite wheel and the spinning wheel will get traction and stop spinning this pitchs the car to the opposite lock direction steering wise.
This is way hardcore drifters use L.S.D.'s because with a LSD your car will spin both wheels equally allowing it to stay in the right hand or left hand drift you initiate.
ok the next thing in car control that I feel is important is adjustable camber settings and toe.
dialing in negative camber is your friend when you are cornering hard or in a hard drift.
basically with stock camber your wheel leans in the corner and actually loses some tread contact . If you apply negative camber to your wheel it will plant the tire flatter on the road in cornering or wheel turning, thus allowing better traction and control. Especially in th drift where you need it.
The side effect of this is your tires will lean when not in the corner and wear more on the inside.
cops hate this and AAA says its dangerous.
If you are serious about this stuff you will not care <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/laugh.gif" border="0" valign="absmiddle" alt=':laugh:'>
I have done 85 mph in the pouring rain thru s turns on the bayshore freeway frontage road in Palo Alto ca in my 69 2 door Datsun 510 when I had a 1.25 degrees of negative camber on the front wheels with Datsun comp swaybars and ST springs and bilstein shocks.
most drifters run at least 1 degree of negative camber on their wheels.
a good set of coilovers will be enough for drifting with larger swaybars.
hell, even KYB AGX's with springs will work if you get Whiteline swaybars and some kind of camber toe adjustment.
The cool thing about the Whiteline swaybars is you can dial in your roll stiffness according to what you need due to road conditions or suspension setup . This is done thru blade holes on the swaybars that allow you to change the pickup point of the endlink.
ok thats about it in a nutshell. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/hehe.gif" border="0" valign="absmiddle" alt=':hehe:'>