Has anyone Broken a 10.9 Grade Bolt?

[FJ40LVR]

Yesterday on the way home I noticed a distict click when throttling on, pulled over and did a quick visual inspection....nothing looked out of the ordinary.
Limped home as easy as I could and started to check over everything closely.....could not find anything wrong with the suspension, excess slack, driveline, etc.

After a frustrating hour searching for the source of the problem, including several more short trips down the block to listen for the origination of the noise (getting worried that I had a gear problem in the rear) I started to go over all suspension pieces and retourque to check for loose nuts, etc.

When I got to the lower link (axle end) on the drivers side I found the Grade 10.9 bolt sitting perfectly in the link, snapped cleanly in the middle, with both the bolt end and and the nut end still intact on both side.....visually perfect.

I would like to know if anyone has had this happen before? This is the first time I have seen this type of steel break.

 

[hj60]

Steel can become work hardened from repeated impacts. Hardened steel becomes brittle.
If there's anything lose/worn in there, 30 years of slight movement could do it.
You have the right idea taking a wrench to all the bolts. They can loosen up over time.

 

[BMAN]

I assume that because this was a link bolt that you're talking about the runner? Either way it's not unheard of.

 

[FJ40LVR]

It was on the 4runner, not the landcruiser - sorry should have been more specific. And the hardware was only about a year and a half old...I must be harder on my rig than I thought.

 

[Azrocks]

I'm not a metal expert but I've heard before that harder is not always better depending on the application. For example, a grade 8 may be better for that app because it can flex better. Not saying this is the case but maybe something to look into.

 

[inkpot]

I'm not a metal expert but I've heard before that harder is not always better depending on the application. For example, a grade 8 may be better for that app because it can flex better. Not saying this is the case but maybe something to look into.

Howdy! Yea, that sound about right. I've got a book all about nuts n bolts n applications, but I always fall asleep when I start reading it. John