On Sat, 17 Nov 2012 18:39:13 -0700, Ashton Crusher wrote:
> I just looked at my 7 foot door. It has a center bearing.
> IMHO they should all have a center bearing, or at least a bushing.
I don't disagree.
Thanks for looking. I appreciate that since I only have my doors
to go by.
I may end up putting either a nylon bushing in there, or better
yet, a steel bearing. I think the original installer cheaped
out, saving himself a couple of bucks - but the homeowner loses.
> The bearing combined with the rod prevents the bending
I think it would prevent the 'sagging' of the one-inch hollow
rod that goes across the door. I don't know if the bearing
would prevent the bracket from bending 7 coils inward when the
door is open - simply because the bracket is supposed to be
stationary.
> Your spring seems too long to me for a 7 foot door.
It's calculated
> However, a longer spring means more coils
I didn't count the coils - but the new spring is thicker
gauge wire - so - any one coil is thicker. The reason for
the thicker gauge wire is merely for duty cycles.
Since the wire is thicker, to lift the same door, the
spring will be either longer, or a larger ID. Since I kept
the ID at 2", the spring has to be longer to lift the same
door.
> I think you are fooling yourself by thinking that the
> "bigger" (i.e. longer) spring is providing you with
> extra "power".
You're absolutely right. I would be fooling myself if I
thought that. The 'only' reason for the longer spring is
I opted for a thicker gauge (0.250" rather than 0.243").
The only way you can get the same force with the thicker
gauge wire is to either opt for a larger ID or for a
longer spring. I opted for the longer spring.
But it should have the same force as the shorter spring
with the thinner gauge. It should only have a longer
duty cycle (by far).
Of course, it's ironic if this longer-duty cycle spring
tears the mounting plate off the wall. Certainly, I need
to find a solution.
For the next person who replaces their garage door spring,
I suggest looking first BEFORE it breaks, to see how it's
working.