[YodasLuke]

left arm is bending before impact.what would cause this and how can i stop it?

If you're referring to the dreaded "chicken wing", there are many ways the left arm will bend (shortening the radius between the left shoulder and the clubhead). Here's a short list:

1. If you're standing too close to the ball, you can't have extensor action and still hit it. Thus, the arm will bend.

2. You could be moving closer to the ball during the stroke.

3. You could be keeping the clubface facing the target (steering).

4. You could be coming into impact well above plane, requiring a bent left arm to pull the clubhead toward you to keep from missing it.

5. You could be quitting.

So, depending on the problem. The cure would have to address the problem at hand.