Club Cobra - Grade 5 or Grade 8 bolts

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Grade 5 or Grade 8 bolts

Discussion Tools

02-29-2016 01:02 PM - permalink

ziggy75

This may be a silly question but what fasteners should I be using to attach steering column support frame and the base fiberglass section to frame (not sure what its called). I guess to play it safe I should use grade 8 but is it necessary?

03-01-2016 04:29 AM - permalink

mdross1

No grade 8 needed there. No question is silly when you want things to be right.

03-01-2016 06:45 AM - permalink

ziggy75

Thanks, I appreciate it.

On a side note, what did you use for intermediate shaft for steering? Fiberfab manual online refers to the use of an OEM shaft that comes up as an 80s tbird part. Did you use this? It appears to be somewhat bulky and I'm concerned about clearance from the big block headers.

03-03-2016 03:58 AM - permalink

mdross1

My steering column reaches almost to the inner fender where I installed universal joint. From the joint down to the next joint I made a shaft approx. 1' long. the bottom joint is coupled onto the steering rack. The shaft and joints runs very close to the inner fender leaving plenty of room for the headers. Keep in mind I am running under car exhaust also had custom racing headers fabricated at Tubular Automotive in Mass.

03-04-2016 03:18 AM - permalink

40k Later

Just an excerpt on fasteners
As Installed on the steering column support, if it were subject to impact it will "Shear" the bolt's so in this case grade 8 would be better suited, HOWEVER, if you are in an accident neither bolt is going to make a difference so I would have to agree with mdross1 that grade 5 will suite you just fine..

Shear loads, a grade 8 bolt has difference of over 750 lbs or over 1/3 ton. Using a grade 8 fastener has a superior advantage over the grade 5. Therefore the result is if someone is using grade 5 bolts in a shear application like mounting a winch plate for example, they will fail almost 800 lbs earlier

Tension load, The grade 8 will support over 1000 lbs more or a 1/2-ton more. The grade 5 fastener has already reached its ultimate load and FAILED BEFORE the grade 8 starts to yield or stretch. Therefore, the argument that you should not use grade 8’s because they are more brittle than grade 5’s is not a true statement in most applications.

03-04-2016 07:21 PM - permalink

ziggy75

Thanks for the help on this.

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