Question about clutch

Bit of a technical question here: I've noticed that 1st gear and reverse behave differently than the others when you are engaging the gear. Reverse feels kinda like it partially engages when you put it in gear, even before you let off the clutch. I've noticed this cause sometimes I will bring the truck out of reverse into neutral while it's still rolling, and it feels (and hears) like you've taken a load off the engine, Why does this happen?

Also, first gear can only be engaged (even with clutch fully on the floor) if you are going below about 10 mph.many faster and the gears will grind. This is in contrast to say, 2nd gear, which you could put in gear even if the truck is going 80, you just wouldn't want to let off the clutch. So why does this happen? What is different about 1st and reverse?

 

http://www.tacomaworld.com/forum/1s...ransmission-issues-need-help.html#post8490580