Transistor astable multivibrator problem

OK, I didn't know that May be this is the problem I will try to fix it.
Can someone give me an article on how to calculate the snubber for some inductive load?

I've made the test and It turns out that the problem wasn't the direction of the triacs so the only thing that left is the size of the C3 & C5 I think they are too big as when triac is turned off the voltage is about 30V which I think is too much for my motors. May be if the motors are more powerful there wouldn't be such problem. The motor I'm using are 6W on 220V.

The snubber networks are suppposed to compensate for the phase angle change across the triacs that are due to the motor's inductance. You have two levels of snubbers, one where you have C3 & C5, and the other that uses C4 & C6. Either of these might be giving you problems. The only way to tell, as far as I know, is to put a scope across the devices and make sure the voltage and current are in phase during turn off. Then you need to determine what changes would bring the voltage and current back to sanity. That's the best advise I can give.

I've made some tests.
I disconnect one of the motors from the circuits and It seems that the problem with vibration disappeared. That makes me think that due to induction of the working motor the voltage of the other goes to 30V and it starts to vibrate also the capacitor of the snubber circuits are charged and when It's time to be charged by the pick of switching on the motor they just don't do there job.
So now the question is how to go around that but there is nothing coming in my mind
If someone faced such problem or know how to solve it, please help