Pontiac Repair: wiper linkage comes loose, pontiac grand prix, arm assembly

Question
QUESTION: I have a 2000 Pontiac Grand Prix. The linkage from the transmission to the wiper arm assembly popped off at the transmission end. I replaced the assembly (new dealer part) and have the same problem. I also replaced the transmission.It works without the wipers attached or with the drivers side on. Put both arms on and the linkage arm pops off when they reach the vertical position.I cycled the motor before I tightened the screw for the trans. Why does the linkage keep coming off at its farthest point of travel?

ANSWER: Hi terry:
what was the original issue here? There is a special proceedure you need to follow to "time" the wipers properly. That shouldn't effect the trnamission popping off though unless you have to wound up wrong meaning you have the trnamission on backwards when it turns on it may bind up and then throws the linkage off the park arm. I'll assume that it is actually popping off the park arm?? with out seeing this I can't tell you what is going on here. It is possable to put the tranmission on backwards. when you have it hooked up and the wipers are timed properly and you tuen the wipers on they should swwep from the bottom up not from the top down if then go down first you have it hooked up backwards. I'm not trying to confuse you here I'm just trying to think out loud what could be going on.


---------- FOLLOW-UP ----------

QUESTION: The transmission isn't coming off the motor, the linkage is coming off the transmission. I turned on the wiper motor and shut it off before installing the trans, then installed the wipers and started the motor. when the motor brings the wipers to the top of its travel the linkage comes off the trans. This started about 3 years ago, I put the linkage back on and didn't have a problem untill now. Since I had this problem before replacing the parts I am stumped about whats causing it. The ball socket was worn on the original part, thats why I started with the linkage assembly. I need to know how to set the trans. (put it in sync)

Answer
to time them correctly. put the wipers in the slowest delay spped and turn the key to run. when the motor shuts off in the delay mode turn the key off. then the bottom of the park arm there is a lever and on the wiper motor assembly there is a tab that the lever rides against. place the lever about 5-7MM away from it touching the tab. tighten the bolt that attaches the park arm to the motor then attach the trasmission to the park arm. turn the key back on and turn the wipers on to low let them cycle a few times then turn the wipers off the trnamission should then park. good luck :)