Dog leg gearboxes

[Jas11n]

Sorry to bust in on the thread but can I ask a question?
I'm into my motorbikes, and they all have sequential gearboxes. I always use no clutch on the upshift, but do on the downshift.
Why aren't these type of gearboxes used on cars? so much easier than the "H" pattern, and without the need for the clutch on upshifting once on the go.
Just wondered thats all

[Greg_S]

Could be to do with the amount of torque that car engines produce compared to bikes? Just a guess though.

[Keeper of The Kitten]

No, you can get sequential mechanisms for cars - the gear shifting within the box isn't really that different for any type, with forks being used to move the sliding wheels (whether they are synchro sliding wheels or dog rings, both move in a similar fashion).

The device on most mechanical sequential systems is a barrel cam that moves the selector forks, and the barrel itself is ratcheted up and down. The barrel has a machined groove timed to allow one sliding wheel to slip into place while the others stay in a neutral position, the next action disengages it briefly and engages to the next gear, and so on.

The system only needs to operate in two directions, like a normal "H" pattern, to allow forward and aft movement (which dictates the position of a sliding wheel) and the side-to-side movement (which dictates the wheel being acted upon by moving a different shift fork and holding the others in a neutral position).

One reason that "H" pattern is still used is the ability to skip gears and to find neutral easily, whereas sequential systems have to go through the gears and all the way down to 1st before neutral can be selected. However, sequential systems do allow for faster changes and less likelihood of getting the wrong gear. The shifts themselves are usually eased through upchanges by ignition cut, and on the electronically controlled paddle shift systems, a small cylinder acts on the throttle to "blip" it and smooth out the downshifts without declutching.

__MDC__