Join Date: Dec 2001
Location: Belleville, Illinois
Thanked 22 Times in 17 Posts
Re: T5 clutchless shifting
The transmission input shaft is spinning at crankshaft speed because it's connected through the (engaged) clutch to the crankshaft. You have to time your shifts so that the engine, and the transmission input shaft, have slowed down to the right speed to match the rest of the transmission in the next gear.
Normally, with the clutch disengaged, the synchronizer slows (or speeds up) the input shaft to match the speed of the next gear as you select it, and blocks engagement until the speeds are matched. The fact that you can do your clutchless shifting easily suggests that the synchronizers are somewhat worn. Usually, if the speeds aren't exactly right when you first try the shift, the snychros will block the shift, and then keep it blocked, even when the speeds are made right.
Talking there about synchronizers in general. The T5 may behave differently.
Motorcycle transmissions do not have synchronizers. The parts are light weight, and the ratios are close together. That allows you to pop from one gear to the next with only a brief decrease in power to take the pressure off the gears and allow them to disengage. Same with race car transmissions.