Broken Bolt FYI - Page 2

scootter · #1 (**permalink**) 10-21-2010, 10:23 PM

It it a M12 1.75 pitch 150mm long. It is 6" long with a 4 1/2 shoulder so it goes all the way through the bracket.
http://www.mcmaster.com/#cap-screws/=9dpbuq 91280A749 this is the part number. the link doesn't go to the right spot.

Scott

Jerry Clayton · #2 (**permalink**) 10-22-2010, 08:17 AM

How about a pic of the broken bolt from the fractured end and also the broken end( if you have it)

scootter · #3 (**permalink**) 10-22-2010, 11:21 AM

There are pics on the first page. I held the broken one up by the bracket so you can tell were it broke in relation to the bracket, and also were the new bolt would come out to.
Let me know if those work for you. I have more pics.

Jerry Clayton · #4 (**permalink**) 10-22-2010, 12:43 PM

No---I want to see the end of the bolt for the fracture pattern

ItBites · #5 (**permalink**) 10-22-2010, 01:08 PM

You need to be using a close-tolerance NAS Shear-Bolt in this application. They are available from Pegasus Racing and maybe McMaster-Carr among other places. They can be obtained with lock-wire holes in the head and you can get lock-wire nuts for them... I would just use some loctite red, but your choice.

scootter · #6 (**permalink**) 10-22-2010, 01:35 PM

This is the best I have. Not sure if I threw the bolt away or not.

Jerry Clayton · #7 (**permalink**) 10-22-2010, 01:43 PM

your bolt broke from overstressing the last thread probably from over tightening and the bolt being at the last thread(too long) not shear!!!

This part does not even need a bolt, a trailer hitch receiver pin with a hairpin would do the job just fine. You are overtightening a fastner trying to collapse two members of a very stout piece which only needs the center tube snugged up----

scootter · #8 (**permalink**) 10-22-2010, 01:51 PM

Not exactly sure what you mean by to long? The original bolt only had a nut and washer on it. The threads stopped inside the center bushing.
Scott

Jerry Clayton · #9 (**permalink**) 10-22-2010, 01:57 PM

what I mean is that the bolt was over tightened which will cause it to break at the last thread----

Yoi do not need a overly tight bolt there---bolt tightness will only maybe keep the bolt in place

A pin such as the pin in a Reese receiver type trailer hitch with a hairpin clip will do everything you need in that location

You do not need a bolt---even a piece of thin wall tubing will do if you want to save weight for racing