Broken shock bolt

[bernhard]

Anyone want to explain how I managed to break the rear most shock bolt on my 712 in 2 places?? Was a fun project getting it out for sure!


Shock bolt by bernhard Leitner, on Flickr

[audiocontr]

Mind bullets?

[Jimm391730]

I bet you can bend spoons, too...

[totaljoint]

Impure thoughts.

[edzz]

Improper cosmic alignment.

[cruzoropeza]

Glitch in the matrix

[Pinzgauer Pete]

The Dark Force

[totaljoint]

Stress fractures occur in screws when the bolt transverses areas with different modulus of elasticity ie; steel, rubber mount, nut etc..... I'll bet if you line your bolt up, you'll see each fracture align with such an area. Obviously, when the first fracture occurred, it did not relive the stress at the second junction, so that subsequently failed as well.

Or.... something in the Alaskan water.

[texas pinzgauer]

...and you posted this in the wrong caragory on the forum. That's why it broke!

[bernhard]

Well the bolt is only is single sheer not double so how the last 6 threads just broke off while being incased in solid steel inside the axle is still something I can’t totally understand. I posted it here cause I had already fixed the problem was just posting for conversations sake. bored at work i guess!

[M Wehrman]

The fact that you have all the pieces amazes me!
Mark

[bernhard]

The parts were all corroded in place! The fact I got them out without resorting to violence is the amazing part!

[Jim LaGuardia]

Multiple fractures on the same bolt can be caused by frequency vibration resonance , a bad shock, or an uneven forging on the bolt blank. Always a pain to extract.

[GenevaPinz]

The parts were all corroded in place! The fact I got them out without resorting to violence is the amazing part!

So how did you do it.......??? :?: :?: :?: ?? :?: :?: ?

[bernhard]

GenevaPinz

The long part was stuck inside the shock sleeve and hitting it with a hammer and using a press ended up pushing the sleeve out of the shock. I then removed the sleeve from the bolt and pressed it back into the shock. The long threaded portion I carefully center punched drilled and used an easy out bolt extractor. The short little treaded part I was actually able to spin using a long scribe needle and then used a magnet to pull it the rest of the way out. About an hour’s worth of work.. I got lucky!

Jim,

I like your explanation the best so far. I can defiantly see a resonance causing that bolt to break in 2 spots. I used to run a machine called a (high cycle fatigue tester) its only purpose was to break parts using a light load but a frequency between 30-200hz. Parts that would take weeks to break with a hydraulic tester would break within hours on this thing! It also used to break bolts with alarming regularity! Never saw one break in 2 spots however.