No the lb rating determines how easy it will lock so the lower the rating the easier it will lock
The ramp angle determines when it will lock ie
45/90 under load ( burnouts, drifting etc )
45/45 will lock under power and coasting which is under braking conditions
There's a top explanation of all this on www.intothered.dk
Type in lsd ramp angles and enter the above
Cheers Paul