Quick Question - "Notch" (slice? chunk?) out of Frame Rail Bolts for 100-series Bumper (Addicted Offroad Plate Front) (1 Viewer)

[krsabhinav]

Afternoon all. Hoping for collective wisdom. Maybe a stupid question. Did search the forum and Greater Google with both image and text, not able to find a good answer.

Addicted Offroad bumper has a frame mount that bolts to the frame rails with 6 total bolts. On our 100, 2 of the bolts are through-and-through and look fine. 4 are bottom-mount (2 short, 2 long) and may need replacement (rust).

Here's the question: in taking out the old bolts to match thread at a local fastener's, I noticed that all 4 seem to have a chunk missing out of the distal tip (photos at bottom). When I pulled the first, thought it was random damage, but all 4 seem to have identical chunks missing. Peered up in the bolt holes with naked eye and a bit of a jerry-rigged scope - doesn't appear to be protrusions up there that would cause them, at least not that I can lay eyes on.

• Are these anti-slip notches that are deliberate? Security notches somehow? Another deliberate use case I can't think of?
• If they're accidental (but how could they all be in the same way?), no need to reproduce these "notches" on the replacement bolts correct?

If it were just me driving this thing I wouldn't care so much, but if my wife is driving, dings a raccoon, and the front bumper falls off I will be in DEEP $%^+

Fuller build thread coming shortly.

Cheers,

--
ab

 

[saucebox]

Meant to be there—a new one ordered from Toyota will feature the same slot. I'm not an engineer by any stretch, but my anecdotal experience is that you'll find them in places that can collect mud/sand/crap. They're cut a little like a tap or thread cleaner to allow for field work in less than optimal conditions.

That's my guess, anyway.

 

[krsabhinav]

Meant to be there—a new one ordered from Toyota will feature the same slot. I'm not an engineer by any stretch, but my anecdotal experience is that you'll find them in places that can collect mud/sand/crap. They're cut a little like a tap or thread cleaner to allow for field work in less than optimal conditions.

That's my guess, anyway.

Very kind, thanks. I'll see if I can get the fastener guys to replace accordingly.

 

[Bennymic]

It cleans out the threads like a tap would.

 

[krsabhinav]

Not proof positive but I think the bolts and their part numbers are in this helpful thread. Credit to @abuck99

 

[JBerger]

I just installed a tow bar on our 2006 LX470 today and the tow hook, tie down bolts have the same cut. The GX we had before had the same cut on the bottom rail bolts as well.

 

[Bisho]

Self tapping bolts makes assembly easier.