New ubolts are bent?

[joegreen]

I replaced the middle leaf in my leaf spring pack as it had cracked and half of the leaf fell off. I used new u bolts to reassemble everything. This is on a 98 ford ranger. Ford specifies 76 ftlb of torque for the u bolts. I oiled the u bolt threads so i decreased the torque by 20 percent. I tightened the nuts to 60 ftlb. I noticed that the tops of the u bolts are bending outwards. These are 1/2 in grade 5 u bolts. The torque chart that came with the u bolts said that they can be torqued to 96 ftlb. I am just surprised they are bending at 60 ftlb. Is this normal? The old u bolts were straight and not bent.

 

[user52165]

Let me guess: 98 OEM were made in USA, replacements were Chinese junk.

 

[joegreen]

These are the ubolts used. https://www.rockauto.com/en/parts/husky+spring,UA126R,leaf+spring+bolt,10353

 

[oldhp]

I wouldn't trust those at all. I've never seen U-bolts distort like that ever. I'd put the stock one's back on before I'd use those.

 

[Kestas]

Could they have bent during torqueing because the plate isn't flat?

 

[joegreen]

Originally Posted by Kestas
Could they have bent during torqueing because the plate isn't flat?

I believe that is why they bent. I'm not sure why the plate wouldn't be flat? I took the plate off then put it right back on with the new u bolts.

 

[MParr]

Inferior quality U-bolts. It's best to use OEM in this situation.

 

[Kestas]

Bending (in the elastic range) has nothing to do with the strength of steel. Bending is dependent on the material's elastic modulus, which is pretty much the same across the board for all steel alloys and all heat treatments.

I sometimes need to explain this to engineers because this material property can be counterintuitive.

I believe the plates lost some flatness from corrosion.

 

[PimTac]

Originally Posted by joegreen
These are the ubolts used. https://www.rockauto.com/en/parts/husky+spring,UA126R,leaf+spring+bolt,10353

This doesn't surprise me. They must be Chinese steel.

 

[wings&wheels]

Originally Posted by PimTac
This doesn't surprise me. They must be low grade Chinese steel.

How's this? Not defending China, but "Chinese steel" is a bit of a generalization... They are as capable of producing world class products for those that are willing to pay and have the local manufacturing and quality processes, etc. Of course, if you buy by price alone, from a cheesy supplier, etc, than you get what you deserve.

That said, this doesn't appear to be the case here, I'd wager that the plate was warped, distorted by corrosion, etc and the bolts yielded when torqued.

 

[Eddie]

The picture suggests that the bolts are not being pulled in tensile but in a bending moment. Is the plate through which the bolts are attached bent or off center. Were the bolts torqued in steps from side to side or just levered down without regard to stresses?. Don't blame the bolts just yet. Ed

 

[CR94]

Originally Posted by Kestas
... I believe the plates lost some flatness from corrosion.
More likely they lost strength from corrosion, leading to their bending under stress from the newly tightened U-bolts. Or perhaps the oil was more effective than assumed in the 20% torque reduction.

 

[PimTac]

Originally Posted by wings&wheels
Originally Posted by PimTac
This doesn't surprise me. They must be low grade Chinese steel.

How's this? Not defending China, but "Chinese steel" is a bit of a generalization... They are as capable of producing world class products for those that are willing to pay and have the local manufacturing and quality processes, etc. Of course, if you buy by price alone, from a cheesy supplier, etc, than you get what you deserve.

That said, this doesn't appear to be the case here, I'd wager that the plate was warped, distorted by corrosion, etc and the bolts yielded when torqued.

It would be appropriate to quote my original comment and then expound on that.

 

[Kestas]

I fail to see where "chinese steel" can cause this condition. Please explain the technical aspects of how the material or workmanship can be substandard instead of willy-nilly making such blanket statements. Then we'll be on point for this discussion.

 

[meep]

I don't think the bolts would all bend so uniformly unless the support forcing against them was uneven. Dollar for a donut that the washers and plates under them bent first.

 

[Driz]

Take one U off and head to the nearest trailer and spring shop. Say make me 2 sets. They're grade 8 and fine thread and you won't bend those . I think theyre around $8 each. You'll see he difference right away yours are trash.

 

[joegreen]

Originally Posted by Eddie
The picture suggests that the bolts are not being pulled in tensile but in a bending moment. Is the plate through which the bolts are attached bent or off center. Were the bolts torqued in steps from side to side or just levered down without regard to stresses?. Don't blame the bolts just yet. Ed

Yes the nuts were all evenly tightened down in a uniform pattern. First to 40ftlb then to 60ftlb