ive been told to use softer springs for weight transfer. What other things would help? Especially with combatting camber etc. Start with positive camber??

If we're talking purely about suspension design, then with the Datsun IRS (i.e. semi-trailing arm), you generally don't get them to hook up particularly well. Because it cambers up with weight transfer (meaning smaller contact patch) you tend to loose grip under accleration. Other systems such as full trailing arm are better in this regard as camber doesn't increase with suspension travel.

However, if you're keeping the IRS, then your best bet is to get some big arse sticky tyres and run lower tyre pressures. You could also incorporate some anti-squat in the rear end geometry, which will also help to a degree. In drags you generally want soft rear springs to get the weight over the back wheels. This is totally contradictory to good handling for corners, hence expect it to roll a heap and handle poorly - but thems the trade offs. The other problem is that on a Datsun, you end up with the situation mentioned above - more neg camber and hence less grip. Softer rear suspension may work, but I image there'd be a pretty big trade off/fine line between soft springs/weight transfer giving more grip or too much neg camber and loss of grip.
Starting off with longer springs/taller ride height (ie positive camber) will work as long as the suspension is under continual compression down the quarter - the minute it get back to positive you'll start loosing traction and the car will become unstable. Forget driving it on the road with positive camber - it'll be mighty untidy around corners.



Some of the drag guy's should be able to help you out more.

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