WTF, no really WTF

[DCC]

I was installing running boards on my 3500 and the manufacturer (who will remain nameless at this point because I'm still working on a fix) decided to replace the hardened bolts that attach to frame with (what appears to be) a weaker Chinese replacement. The "WTF" bolt stripped when I put it on. This is the top of the bolt.

 

[jetrinka]

Stripped as in the threads on the bolt stripped or the threaded sert it goes in? Grade 8 bolts are typically quite strong for corresponding size. Follow the torque recommendations with a torque wrench? Or is that the sert installation tool?

 

[LateToTheParty]

That actually looks like a stainless 8.8 which I believe is the equivalent of a grade 5. Not as hefty as a grade 8, but still shouldn't have stripped.

 

[DCC]

I would like to believe that the 8.8 rating on that bolt is accurate. Def not stainless. The problem was the instructions gave torque ratings at 58 fl lbs for a 12mm bolt size. That bolt in the picture is 13 mm. So I went conservative and torqued to 58 ft lbs with a brand new Dewalt torque wrench. Literally, it was the first bolt I torqued with this wrench. Well, after looking up the torque range on a 8.8 bolt, 58 ft lbs is about double what its rated for. So, no wonder it stripped. My gripe is that 1) the manufacturer is not using a hardened steel bolt and 2) they did not update the torque table in the instructions.

 

[jetrinka]

When you look up a bolt torque table the measurements are of the bolt diameter itself not the head measurement. That looks to be about an 8mm-10mm which would have an optimal torque of about 20-40 lb/ft depending on the actual diameter.

Lets see a picture of the directions sheet

 

[jetrinka]

Really looks like the riv-nut install tool that Mopar sells to install their running boards.

 

[DCC]

Here's the instructions sheet. So, just to reiterate, that bolt is 13mm, not 12mm not 14mm.

 

[jadmt]

Jetrinka is correct. you head size is not bolt size. that is probably M10

 

[DougB]

M8 thread most likely.

Bolt Depot - Metric Bolt Head/Wrench Size

www.boltdepot.com

So >3X torque applied

That torque table is messed up. You shouldn’t list fastener size as Xmm but just below that list your hardware with the proper diameter M# call outs.

 

[Rockcrawlindude]

I was installing running boards on my 3500 and the manufacturer (who will remain nameless at this point because I'm still working on a fix) decided to replace the hardened bolts that attach to frame with (what appears to be) a weaker Chinese replacement. The "WTF" bolt stripped when I put it on. This is the top of the bolt.

View attachment 31610

Your running boards attach to the frame?

 

[DCC]

What I'm holding in my hand (in the previous picture) is the 3# M8 Bolt Plate. The reason I'm calling this out is that the instructions picture is different than what that plate is. The instructions seem to indicate there is a nut tack welded to the plate. But what I actually have is a flat head bolt tack welded.

Also, just from a structural standpoint, since this bracket is attached directly to frame, I would expect something I bit stronger.





of course the one time I need my caliper, I can't find it

 

[MEGA HO]

If it's fig 3 then the bolt is 8mm and you have overtorqued it.

 

[Rockcrawlindude]

The direction sheet clearly states that fastener part # is an M8 fastener and it also clearly states that M8 fasteners should get 16-18ft-lb

You goobered up. Now you know.

 

[jetrinka]

It also appears that that bolt is meant to be threaded in from the opposite side you have it all the way through, then put through a hole somewhere with a nut on the other side of the directions picture is correct. Likely through a hole in the mounting area on the truck. The picture clearly shows the bolt installed and going through the bracket on the same side as the welded nut on the other side.

 

[Jacob]

They should remove the 12mm and 14mm torque specs, since there isn't that size fastener listed on the contents.
Also don't overthink it. If it's a small bolt tighten it up good with a standard length 3/8" drive ratchet.

 

[H3LZSN1P3R]

Im not seeing any issue other than you way over torqued the bolt thinking the head size was the bolt size…. Also 8.8 is considered hardened for metric zinc coated fasteners you wont see 10.9 or 12.9 unless its a structural bolt usually so this is not on the manufacture in anyway so just go buy a new bolt and continue installing the steps

#3 clear depicts it how it is the nut is tacked on and the bolt is tacked on as designed

 

[DCC]

Thanks for the info guys. So, yeah, I misread that instruction sheet. For those of you wondering, here's the picture of the install from the instructions....

 

[jetrinka]

From what I see you're still safe. Go get an equivalent bolt from the hardware store and start over. Should be good to go.

 

[jadmt]

yup and for the stud just throw on a couple of washers so the nut has clean threads.

 

[Crusty old shellback]

Reminds me of a part I ordered for my K5 Blazer. Ordered a shift boot for the floor shifter.
The package that cam in said, "boot, $h!t"
I still have the package hanging in my garage as a reminder.