Bolts for triangular thingy on firewall below column

[Johnnyb]

For some reason I can't get the bolt size right on the column support. Does anybody know what size bolt/thread goes there?

THX,
JB

 

[jamesroney]

For some reason I can't get the bolt size right on the column support. Does anybody know what size bolt/thread goes there?

THX,
JB

5/16 x 18 x 7/8 dog point hex head sems cap screw with special prevailing torque fender washer.

The factory bolts are unlike any others on the Bronco. Unique and not available in the master body kit from AMK. The firewall uses a square knock out hole and a cage nut.

 

[Johnnyb]

Well then I think I've got the right bolts. Unfortunately they're being an SOB and go into the firewall as if they are cross threaded. It may just be crud in the cage nuts, I'll try shooting them with PV blaster and then putting some anti-sleaze on the bolts. I thought I was going crazy or had the wrong thread pitch.
I wanted to double check before I broke one of the nuts out of the cage.
Of course I'm doing this last after everything is in the way.

Thanks @jamesroney !

 

[Yeller]

Run a thread chaser through them

 

[EPB72]

I have access to the cage nuts if needed . NOS at work...

 

[jamesroney]

Run a thread chaser through them

Yes, AND...

1. remove the existing cage nut from the firewall floor.
2. Securely mount the old cage nut in your vice, using the springy side to hold it.
3. Do what @Yeller said
4. Reinstall cage nut in sheet metal.
5. Clean threads on bolts and apply anti seize.
6. Install bolt into cage nuts. If you cannot run them all the way in and out by hand...go back to step 1.

The reason for this is that a cage nut is designed to have almost zero resistance to rotation in the unloaded state. Once you get them tight, they are very strong. But the little spring retainer cannot counter the torque of the thread chasing tap. Worse, if you use the tap properly, you will rotate, then counter rotate, then rotate again. This causes the cage nut to spin out of the hole, and break the spring "ears."

I always start with 3 brand new cage nuts and then start the process. I would estimate that I get about 66% success rate. One of them always seems to break.
Your mileage may vary.