Double clutch...


...or half clutch.
Does it matter to the clutch if it is run on a jackshaft at 1/2 engine speed?
Obviously it would have to be set up for the lower RPMs.
Would it make a difference in longevity?

Thanks. Tom
double clutch is a technique for shifting non synchro truck transmissions:)
Clutch does not care. It may help with durability, a lot would depend on the abuse and power.
Still it has to engage and disengage with some slip involved, 1/2 engagement speed has got to improve things.
When I double clutch my tri - axel, I clutch the gear out of the position and then I clutch the gear in to the next position. Saves on wear and tear. Although, there are times when I don't use the clutch at all. All points of amusement aside, it does not matter. You already answered the end effect.
I see a lot of times where people run as much as 2 ½ - 3 to 1 on the primary. Now that means, yes, the clutch is spinning 2 ½ - 3 times slower than the engine clutch, but it’s absorbing 2 ½ - 3 times more torque. This means you’re trading less heat at the expense of more effort.
Having two chains and four sprockets has to be absorbing some horsepower. That primary chain is spinning really fast.
If you’re racing a two cycle, and you can’t get a conventional two sprocket setup to a low enough ratio, then the power losses of the jackshaft might be justified. It’s a tradeoff.
Seems to me if you don’t need the lower ratio you can achieve with a jackshaft, there’s no need for it.

Comments, compliments, criticisms and questions always welcome.
If the data does not support the theory, get a new theory.
I do need a jackshaft to get the proper ratio in my application. I know there will be some parasitic power loss. Thats not the problem, actually chain clearance is. I will run a jackshaft whether the clutch is on the engine or jackshaft.

Is it a problem getting clutches set up at the lesser RPMs?

And I do know about trucks... been driving them for 40 years. Now I sound old. : (