[Schurkey]

Wire-brush the dirt and rust, see what's underneath.

First Guess: Just discolored from the pressure and movement of the bolt head.

There needs to be enough metal remaining for the Heli-Coil to be secured with, once you run the oversized thread insert tap through the hole. You already know that the full, proper thread engagement to the Heli-Coil is not going to be there because the hole is already larger than the tap drill; or even the drill one size larger than the tap drill.

Try it, see what happens. Make sure you're tapping straight 'n' true.

[dataway]

Get a sharp pick and pick at the edge to see if you can bring up a strand of an old coil.

Wondering ... is the base part so expensive or hard to find that it doesn't make sense to just get a new one?

[tjs72lemans]

It sure looks like it has an insert in it. It might be a heli coil, but the whole surface looks the same. The top surface with the burr seems to be a different material than the inner structure. Picking it would help if it was a heli coil, but a thread insert would be solid and not pick out.

[mgarblik]

Although a heli-coil, Time Cert, or one of many different thread repairs will fix this another option exists. It might just be easier to give Steve Barcak of Pntiac Heaven a call. It's almost certain he has a nice, rust free spindle he can sell you. His prices are very reasonable, and then you have a stock, replacement part with no "fixes".

[kyle_blake]

Hi, curious if anyone has a pic of normal knuckle?

I wire brushed bottom and upper and you can see they both look like a bushing or insert?

You know if you look closely at this kit You can see it has 2 bushings:

https://www.carid.com/1969-pontiac-g...638224895.html

But then it doesn't explain why my normal caliper bolt works on the top hole?

Darn I wish I didn't throw out the old pins.

I'll ask dorman if the new pins are same as stock pins, thread wise. Doubt it

Mystery continues, more it looks like some sort of insert.

I am up in Canada so not sure who would sell a knuckle up here, maybe early birds in the East of Canada.

[Schurkey]

Put your existing pins back in the knuckle. See if the polished area on the knuckle is EXACTLY where the head of the pin rides.

First Guess: Not an insert. Wear marks.

Why contact Dorman? It's right in the advertisement you posted.

[kyle_blake]

Hi

Attached

I should be calling it a sleeve in the knuckle not a bushing. Right i see that now, it is oversized on dorman site.

[kyle_blake]

I tried picking away at the threads and there isn't a heli coil in there.

By all accounts this looks stock unless someone can show me another knuckle.

Just realized the dorman kit, the sleeve in it is suppose to go in the caliper, not in the knuckle pressed in.

I double checked my drill bit size and I must of grabbed the wrong one to start 25/64. Sorry guys, the 29/64 would for sure cut open the hole to accept a heli-coil.

I'll try the job again.

[kyle_blake]

Well i bought the kit, 7/16 20 unf. used drill 29/64. inserted the tap - then had grind off the extra coil part hanging out the knuckle. red loc tite around the hole before heli coil installed. not a lot of loc tite.

She held perfect and repair is done.

thanks everyone.

Curious, when i spin rotor with new pads and rotors,new bearings and after pressing the brake pedal to reseat the pads.. does your pads drag a bit? So many other cars i've worked on spin so free as if there is no resistance but this car makes it a bit tough to turn.

[Schurkey]

That's not installed properly. The insert coil is too close to the edge of the casting. Should have removed another half-coil from the back side.

But if it's glued-in with Locktite anaerobic threadlocker, it may work.

The problem is that the end coil may tend to pull out of position.

[kyle_blake]

this is facing the knuckle straight on. my friend tapped and i believe inserted the coil from the front side. ran it down and the cut it off at the backside. good eye, i saw that piece coil when i got to my computer.

the pin would be entering from the other side. i'll have a closer look next time it's off.