3rdGen F-Body Sagging Doors

The newest 3rdgen F-body cars are already 10 years old, some including my 1982 Z28 are over 20 years old. As these wonderful cars continue to be driven everyday they get older.  With age, certain things that happen slowly will eventually get our attention.  Squeaking and groaning body noises with every bump in the road, cracks begin to appear in the body, the doors sag and hit the ground effects, and the door latch gets damaged more and more every time you close the door.

These are all the end result of a unibody type construction.  The cars were never intended to last this long. Of course they lasted long enough for the warranty to run out!  Other cars that have a more traditional body-on-frame type construction do not have these problems.  And yet they have relatively weak body structure.

Our cars have been made without any "real" frame at all. There is a subframe at both the front and rear of the car, and a floor pan, 2 doors, and a roof.  The installation of aftermarket weld in subframe connectors (to "connect" the front and rear subframes and rocker panels) can significantly reinforce the body structure.  This really helps eliminate most of the body noises, and incipient body cracking that most of us have seen or heard about. 

But one remaining problem with our cars is much more challenging. The infamous "sagging door" problem! This problem has led to the demise of many good 3rdgen cars, whose owners simply could not be bothered with, or did not have the means to repair them. I have two friends who used to get into their Camaros from the passenger side everyday, because loose hinges made the driver's door sag so badly.  Beyond the day-to-day aggravation of loose doors, there is another (possibly more important reason) to have tight door hinges.

When GM designed the 3rdgen F-body they had to use every body construction trick possible.  One trick was to reinforce the doors, upper hinges, and door latch/striker area.  This enabled the engineers to now use the doors to reinforce the body, cowl and roof areas of the car.  You can demonstrate this to yourself by having a friend ride with you to a parking lot, that has speed bumps.  Open both doors slightly and drive diagonally across a speed bump.  You will notice that the doors move independently of the body as you drive.   If you remove the inner door panel, you will notice two heavy steel reinforcements that run from the rear of the door in the door latch area, to the front of the door.  One is right across the center of the door connecting the front and rear. The other one connects the door latch area directly to the upper door hinge attachment.  So, a strong door latch / striker, massive door reinforcements, and big strong UPPER hinge equal improved body structural integrity.  Further evidence of this is  that the upper door hinge pins and bushings are at least twice the size of the lower hinge.  And best of all, the UPPER door hinge pins and bushings are not replaceable!  GM has made no provision to repair or rebuild this upper hinge. The original and replacement hinges are both one-piece assemblies, and the hinge is MIG welded to the door from the inside, so you have no access to the welds! 

Here is the "official" GM solution to the worn out upper door hinge.  

  1. Completely remove the door from the vehicle. 
  2. Scribe the location of the upper hinge where it attaches to the door. 
  3. Guess at the location of the welds. Then drill them out from the outside of the door with a " drill.  A slight amount of weld may still retain the hinge to the panel.  If so, drive a chisel between the panel and the hinge to separate the hinge from the panel (that's a joke; I have done 2 of these jobs.  Of the 8 welds I drilled out, I missed on 7 of them.  Slight amount of weld my butt). 
  4. Once the hinge has been removed.  Locate the replacement hinge on the door.  Now drill 4 entirely different holes to BOLT the new hinge to the door with a threaded reinforcing plate inside the door (before you bolt the new hinge on you will notice that the area where the hinge attaches to the door now looks like Swiss cheese). 
  5. The original hinge is attached to the body with 3 bolts, but the replacement hinge has only 2. So you must use a piece of paper and a pencil to poke a hole through the paper to locate the hole and transfer it to the new hinge (I'm not making this stuff up! This is the procedure outlined in 10-5-20 Doors of the GM service manual). 
  6. Reinstall the door back onto the car. If you have done anything wrong during this elaborate procedure. You'll know it!

I have done this whole process twice,  and decided that I was never going to do that again for anyone!  Then I got my 1986 IROCZ.  Same deal, worn out upper door hinge.  Damn!  I thought about it long and hard.  The answer was to replace only the hinge pins and bushings.  

In other words, a hinge repair kit was a better solution than wholesale replacement of the entire assembly.  So I had a new set of upper hinge pins & bushings custom made for this car.  Perfect! I did the job in about an hour.  No cutting, drilling, etc.  Over time, other 3rdgen owners became aware of my design, and wanted some for their own cars.  As a result, I made some improvements to my original design, and now offer them to all 3rdgen owners.

Here is my solution

  1. Support the door somehow (floor jack, engine hoist, sober friends, etc). 
  2. Using a compact die grinder (i.e. Dremel tool) Grind off the small end of the upper hinge pins where the factory has riveted / swaged them on. 
  3. Remove the lower hinge spring and hinge pin. 
  4. Tap out the old upper hinge pins; pull the door "slightly" away from the car body. And remove the old upper hinge bushings (and lower if you want to replace them also. 
  5. Install my new upper bushings. Move the door carefully back into position and install my upper hinge pins. 
  6. Reinstall the lower hinge pin and spring. 

You're done!  I have done this job in as little as 47 minutes, but I tell  most people to plan it to take about 2 hours.



Thanx, ANDYZ28

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