Although having tight door hinges ensures that the doors
close properly and will not rub against the ground effects, that is
not the real reason they are so important.
The real reason is that they maintain the integrity of the body. These
cars all have unibody or monocoque, if you prefer ,type construction,
which is to say that they do not have frames upon which the body rests.
Body-on-frame construction was traditional for decades, but in the
sixties GM and other manufacturers began construction of cars which
had no frame. The body of the car itself became the frame. This method
of construction, although much lighter in weight and less expensive,
cannot possibly be as strong as body-on-frame construction. So any unibody
car will have some flex. Some more than others.
High horse power applications of over 300hp aggravate this condition.
This is one reason why GM did not introduce the 350 cubic inch engine
into the F bodies until 1987. The designers cleverly made use of every
component to reinforce the body, including the doors and even the windshield.
The reason 3rd generation F body doors are so heavy is because they
have massive reinforcements built into their construction. These reinforcements
to the door are critical to the body integrity/strength.
Once the doors are closed, the door becomes a strong, solid connection
between the door striker and upper door hinge. If the upper door hinge
is worn out, the body, especially the cowl, area is free to move about.
This movement is very small and unnoticeable at first. But eventually
small cracks begin to appear in strange places. For instance, on hard
top cars small cracks begin to appear in the roof, due the "oil
can effect", and in all of our cars at the base of the cowl area.
These small cracks at the base of the cowl are normally concealed by
the factory undercoating in the front wheel wells.
The newest of ours cars is already ten years old. The oldest is over
twenty years old, so some of this is to be expected. For those cars
that do not yet have any cracks, they can be prevented by the installation
of subframe connectors and replacing the worn door hinge pins and bushings.
If you want to test this theory, take a friend for a ride. Very slowly
drive diagonally across a parking lot speed bump with both doors held
open slightly. You will notice that the doors will now move relative
to the body. This is even true of cars with subframe connectors, only
it is to a lesser degree. In day-to-day driving the same movement occurs
if your door hinges are worn, it's just that you don`t notice it. Think
of it this way, the entire front of the car, along with the windshield
and roof, are attached to the cowl. The only support the cowl has, is
the roof and doors. In a T-top car we all know how much support the
roof is (?!) That is why people who are planning to race, generally
avoid the T-top cars.
All of these cars have stood up very well to hard use and abuse for
between ten and twenty years, but time is taking its toll. If you are
planning to keep or restore one of these cars, fix the door hinges first!
While you still can! In the long run it is a relatively inexepensive
and simple repair. If you are planning on a new paint job, repair the
door hinges first. It will be well worth the time and effort.
Wouldn't it be great to have your doors close just like they
did when they left the factory?
Those of you who do not feel that your door hinges need repair, go
out to your car, open the doors about a foot, and firmly lift up at
the rear of the door. That movement is all in the door hinges! I have
two friends who must get in and out of their cars from the passenger
side because the drivers side door hinge is so worn out.