tight as you can with a wrench and ratchet/socket by hand is the way I do them
yes,they are springs the whole pack/set
each "Bar" as you say... is a leaf..so they are leaf spring packs...one on each side
to lower it,I think you are removing a leaf or maybe 2 from the leaf spring pack
that will drop it down for sure
I would remove the bottom/shortest leaf from the leaf spring pack..
for lbs...45-50 foot pounds of torque should be tight enuff for the bolt that hold the leafs together
you have a torque wrench to set the lbs of torque..correct?
leave the bolts in the end of spring loose till you have it back on the ground/tires with weight of the car on the springs...then torque the 3 end bolts..30-40 lbs
if its on the jack and the rear axle is hanging down...and you torque them tight..it will damage/tear the rubber bushings and wont last long
hope that helps and you can understand what I said
I understand what you were trying to say