Rough '85 drivers door was impossible to shut. The pins and bushings were still original so I ordered a pin and bush set from Mid America.

Plan was to do the hinges, then the weather seals, then adjust the glass as everything is out. This car has passed though a few hands and the hinge bolts had definitely been played with in the past (bolts have been loosened and a collection of overspray edges) possibly to try and makeup for the top hinge slop.




Did one hinge at a time. Bottom hinge wasn't actually too bad but still was rebuilt. Top was very rough though — both of the old bushings were cracked and one was loose and sipping around in the bore.

Lucking the bore wasn't too worn and I was able to press in the new bushings. Used the bolt and a socket trick so as not to damage the bushings and then tapped in the pin.

First question - are the splines on the pin enough to hold? This kit doesn't have a retainer of any kind. I've read that a little MIG tack might be a good idea?

Snugging up the bolts I had that horrible moment when you can feel a bolt just keep spinning and spinning. Top hinge, middle thread just pulled clean out. Not sure if I over torqued it — the only specs I could find online was 30Nm (22ft lb) or if the threads were already damaged or if I didn't support the door right with my jack?

Second and main question - how do I replace the backing plate (the FSM calls it a "weld nut") which is inside the A Pillar. How do I access it? And when I do, make a new plate or buy a replacement? I think tapping a larger thread might not fly as the larger bolt head might interfere with the upper hinge spring/doubt you'll get a socket on? Would also reduce the adjustability unless I enlarged the A pillar hole too.





(note, that's copper anti seize not rust)

Any help or support appreciated. I had to walk away and take a few deep breaths. 30 minute job...

 

I would just tap it to the next size up in SAE or metric and use a button head bolt or even a regular head allen head bolt.

 

I'm thinking maybe to helicoil it.

 

I don’t think there is enough meat for a good helicoil install.

 

If you can get to the backside of the backing plate, I would get a longer bolt of the correct thread specs, a nut and a lockwasher. Make your door adjustments by snugging up the other 2 bolts...and when you're happy with where the door is at...hit the longer bolt/lockwasher/nut combo with an impact....the lockwasher should grab and stop the nut from turning while tightening the bolt....worst case scenario, have a helper secure the nut while you tighten the bolt👍
edit: maybe the bolt is already long enough...nut and lockwasher....fixed!
edit-edit: to access remove the sill plate, halo trim on that side and likely the knee bolster....when attempting to remove the sill plate, use a heat gun on the rear corner transition....there is body sealer underneath that's gonna be sticking enough to break the sill plate trying to remove it!

One more time! There is access, the opening for the door wiring is there...it's small and it'll be tricky...like getting creative with a flexible magnet, etc...but getting a lockwasher and nut down there is possible! Also, there's also sticky seam sealer at the front of the sill plate as well...definitely use a little heat and gently pull!

Sticky seam sealer that fights the removal of the sill plate.

Access hole that sits right above the bottom door hinge.

Wider perspective.

 

You might be right.

 

Would I be able to reach the upper hinge bolts from there though?

 

With the wiring boot out of the way, I believe it's possible, I admit, this approach would definitely be a challenge and time consuming....but I'm also convinced it would be possible. To keep it simple, the advice to tap the next biggest size and use the appropriate fasten might be your best bet👍

Upper hinge in relation to access hole.

 

Original bolt is M8x1.25. Backing plate seems to be 5-6mm thick. I actually just found a video of someone helicoiling a door but not sure how much material they had to work with as it was a Chevelle
But maybe stepping up to M10 is the go.

Regarding of how tight these bolts should be, does the 22lb-ft/30Nm sound about right? Really don't want any more stripped while trying to get this door lined up.

 

M8x1.25 is a normal coarse thread.
The next coarse is M9x1.25 but that is very unusual. The tapping drill is 7.8 mm so there is probably enough meat to get a good enough thread.
M10x1.5 is very common and the tapping drill is 8.5 mm so different thread pitch is not an issue.

If you can't get a nut on the inside, then tapping M10x1.5 would be my choise.

 

If you had available a 'nut-sert' insertion/collapsing tool there is very likely an M8x1.25 nut-sert that's of sufficient length to pass through the lock plate and you could use original hardware or maybe just a bit longer bolt.

This link might not have a correctly dimensioned one, but you could get a visual idea of what I'm suggesting maybe. This would be my choice if I had the car in hand and could confirm measurements.

Atlas AEL Spintite Rivetnut, Steel, M8X1.25 [0.70-3.81mm Grip, .027-.150] Large Flange Head

 

id helicoil it, with red loctite.

 

Thought I should post an update. Went with the helicoil + loctite in the end. Access to the hole was too tight for the drill, so removed both hinges while hanging the door with an engine crane plus supported by a floor jack and scooted it out of the way. Quite a few attempts getting it back in the correct position both front to back and also pulling the top edge away from the body. Closes much better and hoping it will be even better with the weather stripping is replaced (Corvette Rubber) and the glass adjusted properly. Thinking about upgrading to the non ribbon regulators and painting the door handles so will probably do it all at once.