What is the shortest length you can run on a four bar setup I'm looking at maby 12 in for mine is that to short should I try to run longer bars the car is a shortend model A with not a lot of room out back
That's a little short. It will "work" on an A, as you won't need much suspension travel. The issue with short bars is that, when the suspension moves, the fore-aft movement of the axle is exaggerated, versus longer bars. That could cause the rear axle to steer the car over bumps. The handling could be a little funky.
Ah I see what you are saying it will pull one side forward when in compression I'll try to work a way to make them longer