Sheared-off bolt

[John Hofstetter <hofs@domain.elided>]

>From: Terry Rust <trust@domain.elided>
>Subject: Hydraluic clutch ???
>
>First let me apologize for asking a non ih specific question, but y'all are
>the best reference set I've found, and it could apply to an IH. My Jeep has
>a CNC hydraulic clutch set up in it, the MC attaches to the pedal via a
>5/16 bolt through a "heim joint". this has worked fine for a while but
>yesterday the bolt sheared off at the pedal interface. It sheared cleanly
>with no evidence of deformation or thread damage. I need to replace the
>bolt obviously and picked up some grade 5 and grade 8 to put in there, the
>one that sheared was a grade 8. So my question is, is this an application
>where a softer bolt (grade5) works better than a harder (gr 8) one, or do I
>need to look into other ways to connect the two parts together? If the
>latter, suggestions would be nice. I'm thinking that maybe a hitch pin with
>a hair clip instead of a bolt, but that wouldn't be as rigid an assembly.
>any thoughts or suggestions will be greatfully accepted, I'm glad it failed
>in the parking lot where I just jumped a curb rather than at a red light
>where I might jump a car.
>
>TIA
>
>Terry  Rust

Terry,
I'm amazed that a grade 8 bolt sheared off. Did the remains of the bolt, 
if you found any remains, show wear? 
I have a couple of thoughts that may or may not be helpful. If I were 
using a bolt, I'd use a grade 8 and make sure that all wear surfaces on 
the bolt were shoulder and not thread. I would think a hardened pin with 
a hair clip or a washer and cotter pin would be better, but as you 
suggest, I'd want to minimize extra slop caused by excessive length. 

One of our digesters is a fasteners expert, although he hasn't joined in 
the drilling-the bolt-for-a-wire controversy that seems to be going on 
right now, and maybe he'll offer an opinion too. 

I wonder if a parts house doesn't have a selection of pins in various 
lengths that you could use with a washer and cotter key, to do the job 
right. 
John H.