1 Hour per bag is a usual time . Spray the fittings in advance with a 50/50 mixture of Acetone and ATF. The best penetrating agent I have ever found/used. Change the air fittings to a compression type that swivel. Once the blocks are in place, loosen the fittings, THEN simply take a knife, or saws all and cut the bag out and remove. Ppl waist so much time trying to take them out in 1 piece. Address the shocks condition as well. You may want to simply remove the wheels, do it all, and B done. Every time you R/R the wheel it's 100$.