Lug nut sheared off on '65 Eldo

[Chuck Swanson]

Drove three miles to a local Cruise night and when I got there heard a rattling coming from drivers rear hub cap.  One lug nut sheared off and 3 other lug nuts were loose.  Luckily the wheel didn't come off.  Tightened them all before heading back home.   The last ride before tonight heard a clicking type/thump noise from the rear wheel.  I can reproduce the noise by pushing down on the car on the rear drivers side, and you can hear the loud click/thump from the one side only when you push down...pass side fine.  I think it might be the rear air shock, as I hit a big pothole in my 1/4 mile long driveway last month, since repaired.  It looks like some black oil may be leaking out of that shock only (air shocks have oil too??).  My theory is the lug nuts may have been loose already, and the bad shock may have loosened them futher with the vibration.  I also may have put too much air in them before first ride of season, since then let some out.  Too much air, then big pothole maybe caused?   Concerned about the lug nut shearing off of course.  I installed new air shocks 3 yrs ago. 

Also, will now be popping my hub caps before each season the check torque on all of my cars.  Thanks, Chuck

[savemy67]

Hello Chuck,

The dynamics of any particular component failure can be unique, so what follows is speculation.  But, you should thoroughly check a few things in addition to checking the lug nut torque.

Your post indicates the wheel was held on by only one lug nut, and that one "lug nut sheared off" (by which I assume you meant the stud sheared off).  Since the cone-centering feature of the other four lug nuts was diminished, driving/braking/impact forces could have caused the wheel to act as a chisel on the stud that sheared off.

You may want to examine all the studs for that wheel, looking for signs of impact on the threads.  You may also want to look at the mounting holes in the wheel for an out-of-round condition or damage to the cone shaped recess.

If any of the remaining four studs show evidence of damage, you may want to replace all of them.  You can either remove the axle and use a press to remove and replace the studs, or you can drill out the studs, being careful not to enlarge the hole in the axle flange, and replace the studs using a couple of lug nuts and an impact gun.  The press method is preferred because...

An impact gun is the imprecise application of brute force - even with a torque stick.  Using an impact gun to draw in the studs through the axle flange, or using an impact gun to mount the wheels, places a stress on the studs that could over time weaken the studs.  Hopefully, you have a torque wrench that you use to tighten the lug nuts.  I also suggest that you clean the threads on all the studs, and use anti-seize.  Good luck and be safe.

Respectfully submitted,
Christopher Winter

[Scot Minesinger]

Also, I have heard of replacement drums on the rear, dragging and slowing the car down, and of course this also stresses the lugs.  My friend owns a 1968 and he had to have the drums machined a slight bit of the back so they clear and do not drag.  It was a minimal amount and occurred when wheel heated up a little.  To test for this get the car good and warmed up, put car in N, block front wheels, jack up the back and try to spin the rear tires by hand.  Just a check to rule it out.

[fishnjim]

One should always note the mileage when these things are discussed.   Failure occurs based on # of cycles.  More miles = more cycles.   There's no way to know the history of your '65, and that will determine a lot of what could be wrong.   
It's not a big task to replace ALL the studs on all four wheels, and get new lugnuts, then you don't have to worry.  And yes, press and torque wrench, not like the tire jockeys.   Always check the threads when you change a tire and look for stripped of broken threads.   A little lube on them also, so the torque is correct.   Balance the wheels and tires also.
The rear end could be "trash" too.   So need to pull the axles and check the bearings, lash, etc..   Things don't last indefinite and this is over 50 years old.   So some heavy maintenance might be called for, especially if the POs didn't do what's necessary/on schedule or it sat.
I don't know of any "air" shocks that have oil in them.   Probably moisture from the air source and corrosion.   "Gas" shocks have some oil in them for lube.