shaft
mon:
squat - 4 sets
leg press - 2 sets
leg curls - 3 sets
This looks good so far... your hitting your legs right from the start theres nothing wrong here.
tuesday:
bench press - 3 sets
dips - 3 sets
side laterals - 2 sets
tricep pushdown - 4 sets
Your starting off with a heavy chest movement, then another great mass-builder for the pecs, and then your moving onto a side-delt isolation movement. I would drop the side-laterals and replace them with dumbbell flyes. I would drop the tricep pushdowns and replace them with lying ez-curl bar extensions for your triceps.
thursday:
deadlift - 4 sets
chins - 4 sets
cable rows - 3 sets
rear delts - 2 sets
dumbell curls - 3 sets
forearm work
This day looks okay I guess starting out with a heavy back mass-builder then moving onto chins. That looks good cable rows are a good movement for finishing off your lats/rhomboids. I would suggest using a strict isolation movement for your rear delts like reverse pec-deck flyes or something along that nature. I also would suggest adding some trap work in here today and dropping your shrugs from Friday's workout. Deadlifts really involve your traps and training them one day after another will overtrain them completely. Maybe replace rear delts with a trap movement. I would get rid of dumbbell curls and replace them with standing barbell curls and finish off with some good forearm work like you have.
friday:
shrugs - 3 sets
dumbell shoulder press - 4 sets
side laterals - 3 sets
calves - 3 sets
abs
Here I would suggest dropping the shrugs like I said before. Dumbbell shoulder presses are a good mass builder for the delts, side laterals are good too... and then finishing with calves and abs seems okay to me. Your modified routine in my opinion should look like this...
S- Rest.
M- Quads, hamstrings.
T- Chest, triceps.
W- Rest.
Th- Back, traps, biceps, forearms.
F- Shoulders, calves, abs.
Sa- Rest.
Good luck!!