How Does a Clutchless Tranny work?
 

like a jericho, lenco, etc.... how do they work and shift....

I've never been around one but always hear about them and wondered. I know a few of you are racers and should know.

Im just throwing it out there as im curious also. But doesnt it have something to do with straight cut gears opposed to slanted cut?

My understanding is this. They use friction bands and planitary gear sets like an automatic trans. with no levers pulled, it's in neutral. Pull the levers and they apply the bands, locking the ring gears and giving you movment.

I can chime in on the Jerico. First off, the term "clutchless" applies to shifting, you still need a clutch to launch. The clutch set up usually consists of a Long style pp with a sintered iron disc. The advantage is slippage on the launch and very low static (pedal) pressure. This type of set up requires some initial adjustment, but once dialed in it works very well (launches very hard). Cost for the pp and disc will cost over $1000. Shifting without the clutch is possible due to a dog ring/ear set up in place of the normal synchronizers found in most street transmissions. Straight cut gears are used as well. I drive a "clutch assisted" Jerico 4 speed where the clutch may or may not be used on gear changes. After much testing, my car will run a higher trap speed and lower ET if I use the clutch as opposed to cracking the throttle and pulling the stick back. The big drawback is that when I do use the clutch, the car will stand right up on the 1-2 shift if the track is good (see photo). It is nearly impossible to miss a shift with this style of tranmission and driving it is a blast.