Chevrolet: 64 powergluide, valve body, powerglide

Question
Harold,
 I own a 64 vette powerglide. When the engine and tranny are cold, it will upshift and down shift correctly. However, when it warms up, it will upshift with a little bang going into drive. When it downshifts from drive to low, it really BANGS into low. Any idea what my problem could be? Really appreciate your help. Thanks

                        Russ

Answer
I dont have alot of experiance with powerglides, but it could just be the valves sticking in the valve body due to dirty fluid. When the car is cold all of the dirt will settle to the bottom of the pan and it will shift ok, but after you have been driving it and all of the dirt starts getting stirred up, you have a problem.
I would suggest that you replace the filter in the trans and then have the fluid flushed.