Torquing lock nuts with nylon inserts - FAIL?

[440beep]

So I thought I would be smart and tried using a lock nut with a nylon insert on a rear shackle with poly inserts, I torqued it based on the recommended torque setting (45 ft lbs for a Coronet), and as it was getting near tight, the damn threaded part of the shackle sheared completely off. WTF would cause this? Does the nylon insert change the torque requirements? Would the poly inserts change the torque since the poly is more stiff than rubber? Or wonder if it was made in China? Can't believe the threaded part of the shackle bolt completely broke off.

 

[slimt]

I didnt think you were suppose to torque nylon inserted nuts.. a standard nut with a lock washer would be better I would think,,.

 

[dadsbee]

Can't believe the threaded part of the shackle bolt completely broke off.

I can, it's called cheap steel ! Mine were labelled " made in the USA" .

 

[threewood]

That's crazy. I thought the internal threads of nylock nuts were less because of the insert so I would have thought the nut would have stripped.

 

[ckessel]

Could have had an existing issue and the nylocks just polished it off.

 

[miller]

Does the nylon insert change the torque requirements?

No. Same torque value.
Round motors uses over 100 of them...actually required, since they do the job.

Cheap steel bolts strip/crack, because they are cheap!

 

[hunt2elk]

I can, it's called cheap steel ! Mine were labelled " made in the USA" .
View attachment 686166

That's scary, and only 45 lbs? Mind posting where you bought that one?

 

[miller]

That's scary, and only 45 lbs?

Just adding...45 lbs? Foot? Sounds a little high, and on those shackle bolts, self-locking nuts for those are usually all steel.

 

[hunt2elk]

Fairly certain that the torque spec for B-body shackle nuts is 45 ft. lbs.

 

[440beep]

Yes, per the FSM for a Coronet (I have a Super Bee) the shackle nut torque requirement is 45 ftlbs, there was no guessing on my part what to torque to.

My shackles are the Mancini Racing shackles, and I'm interested to hear what Dadsbee used. Even though Dadsbee's shackles stated "Made in USA" wonder if the steel used was Made in China. Glad I kept my original shackles, may just have to clean them up and reuse them. But need to speak with Mancini about this.

 

[Speedbird]

What's a torque wrench?
(Dry humor)

 

[dadsbee]

Bad thread cutting causing the stress point and cheap steel. I bought mine from the local jobber and can't remember the manufacturer, but they did have "Made in the USA" right on the box. But like a lot of stuff, that could mean anything from the final welding of the stud to one side bracket was done in the USA, or the cardboard box was made in the USA. (I'll see if I still have the box, I think I kept them with the normal rubbers inside as I switched to polys)

Mine that broke wasn't even tight yet, where as the other three had no issues going to torque value of 45ft-lbs.

EDITED to add pictures of broken shackle bolt and AC Delco box!

 

[Mike67]

Did the nut fail or the bolt??? Pic looks like the bolt, may need to move to a higher grade bolt.
I would think that the nylon insert would cause a false reading.

 

[440beep]

You can't move to higher grade bolt, the bolt is pressed/welded into and is part of the shackle.

Did the nut fail or the bolt??? Pic looks like the bolt, may need to move to a higher grade bolt.
I would think that the nylon insert would cause a false reading.

 

[440beep]

Just spoke with Mancini and a replacement is being sent out today. Mancini stated these shackles are made in Buffalo, NY, but again, where is the actual steel made. Rob also stated that he's heard this before, and that since poly bushings were being used instead of rubber the poly doesn't "squish" like rubber so perhaps you don't need to torque to the factory 45 ftlbs. I know this time around I will not be and might loosen the other side a bit.

 

[beanhead]

Bad thread cutting causing the stress point and cheap steel. I bought mine from the local jobber and can't remember the manufacturer, but they did have "Made in the USA" right on the box. But like a lot of stuff, that could mean anything from the final welding of the stud to one side bracket was done in the USA, or the cardboard box was made in the USA. (I'll see if I still have the box, I think I kept them with the normal rubbers inside as I switched to polys)

Mine that broke wasn't even tight yet, where as the other three had no issues going to torque value of 45ft-lbs.

EDITED to add pictures of broken shackle bolt and AC Delco box!
View attachment 686331 View attachment 686332

(It could also mean they were made in the USA...unfortunately we produce junk parts too...)

 

[dvw]

Be glad it happened now. 45ft lbs is nothing for that diameter.
Doug

 

[Fran Blacker]

Maybe you could cut out broken bolt and go to Fastenal and buy a shoulder bolt. All you have to weld in new bolt and hope Fastenal bolts are better. You can also buy grade 8 nuts with nylon inserts.https://www.fastenal.com/products/f...~|categoryl3:"602314 Socket Shoulder Bolts"|~

 

[Don Frelier]

45 ft-lbs of torque on any nut is the same, the type of nut makes no difference.
The box did say GM on it.
I used these, no problems:

 

[Mike67]

You can't move to higher grade bolt, the bolt is pressed/welded into and is part of the shackle.

I know which one you're talking about now!
Thanks!