'68 Barracuda inner grill nut "Fun Fact"

[HMBCUDA]

Actually, not so fun, so thought i'd share what i discovered yesterday & today...

that dimple is/was Plymouth's "lock-tight" I assume they assembled the inner plastic grill to the chrome inner grills "studs" then had some sort of press that smacked/squished the nut (opposite sides)on to the stud so they would not come loose. Definitely worked, that's for sure!

some have a rectangle dent.
I decided to try to get them off...thinking they were just corroded on, soaking in penetrating oil did nothing. so next step, I heated to red hot then dunked in ice water...that worked, but they were still hard to get off. that's when I noticed they seemed squished a bit...thought i was seeing things at first...So next tried to screw them on my new stainless studs...no go...OK, no problem, picked up a 8/32" tap to clean the threads.

Ha! Good old USA Steel...dam things must be hardened...go figure...

took three taps to make the 20 nuts usable...

View attachment 1715223141

 

[jos51700]

Heat them to red hot and let them air cool. THEN tap them out.

 

[HMBCUDA]

Heat them to red hot and let them air cool. THEN tap them out.

might be too late for me, I heated and dipped all in ice water to shock loose... at least that's what i read I should do to loosen rusted on nuts, etc. Worked on the broken grill surround stud & nuts well also. I could try heating and letting air cool the extra nuts i have to see if they don't tear up the tap, i might try it for fun.

 

[krazykuda]

that dimple is/was Plymouth's "lock-tight" I assume they assembled the inner plastic grill to the chrome inner grills "studs" then had some sort of press that smacked/squished the nut (opposite sides)on to the stud so they would not come loose.

Those are called "prevailing torque" nuts... They use a stake dimple to deform the threads a little so they don't loosen with vibration etc... They come into the factory from the nut supplier with the stake already in them... It's another way to have a locking thread....

They have variations of prevailing torque nuts, like the ones with the nylon on the outer end also squeezes the threads and helps keep them from loosening over time and with vibration....

 

[famous bob]

Those are called "prevailing torque" nuts... They use a stake.dimple to deform the threads a little so they don't loosen with vibration etc... They come into the factory from the nut supplier with the stake already in them... It's another way to have a locking thread....

They have variations of prevailing torque nuts, like the ones with the nylon on the outer end also squeezes the threads and helps keep them from loosening over time and with vibration....

More commonly called "nylock nuts>"

 

[jos51700]

might be too late for me, I heated and dipped all in ice water to shock loose... at least that's what i read I should do to loosen rusted on nuts, etc. Worked on the broken grill surround stud & nuts well also. I could try heating and letting air cool the extra nuts i have to see if they don't tear up the tap, i might try it for fun.

Next time use candle wax

 

[YY1]

I can confirm factory lock nuts with the rectangle stamp.

Don't know if the application on the grill is factory. My 73 had regular nuts on the grill.

Probably a LOT cheaper to just buy regular nuts.

 

[krazykuda]

I can confirm factory lock nuts with the rectangle stamp.

Don't know if the application on the grill is factory. My 73 had regular nuts on the grill.

Probably a LOT cheaper to just buy regular nuts.

You said nuts on the grille.... Ouch!!!

 

[HMBCUDA]

Those are called "prevailing torque" nuts... They use a stake.dimple to deform the threads a little so they don't loosen with vibration etc... They come into the factory from the nut supplier with the stake already in them... It's another way to have a locking thread....

They have variations of prevailing torque nuts, like the ones with the nylon on the outer end also squeezes the threads and helps keep them from loosening over time and with vibration....

Hmmm...I still have a bunch of nuts,(not on the grill, ;))... I thought they would strip my studs...or worse...strip the pot-metal inner grill threads,(or brake off), bees wax might help them slip on, and do what they are intended to do. I'll have to try a few. Thanks for the replies!