"dean" wrote in message
oups.com...
My few-months-old Sears 3/4HP garage door opener, lifts a double door
up nice and smooth. However, when it goes down again, its like the
motor is instantly up to speed and the door knocks its way down for a
few seconds, jolting everything hard.

As far as I know there are two adjusters that determine where the
upmost and downmost points are, but I am not sure if there is any way
to adjust the descent start. Put in a spring between the arm and the
door?

Thanks for any tips!

DeanB

I suspect your torsion springs need adjustment.
Do the following test with the door in the down position...
Disconnect the door from the opener, if my theory is correct your door will
be difficult to lift and will not stay in any up position. If this is true
your torsion springs need adjustment. When your springs are correctly
adjusted the door should be fairly easy to lift and will reach a balance
point when it is about 4' to 6' from the floor. Adjusting torsion springs
can be a bit dangerous, I suggest you read the info from this web page, then
make a decision if you want to DIY or use the yellow pages.
http://truetex.com/garage.htm