What is the grade of steering box mounting bolts?

[ScottH]

Can anyone tell me what grade the stock mounting bolts for a power steering box would be? I recently installed a new steering box only to have one of the bolts break. So I would like to replace all 4 but not sure if I should use grade 5 or 8. I dont think the bolts I removed were originals as they were 3 different lengths, extra washers, etc.

Any info is appreciated.

Thanks
Scott

[rich weyand]

The book says "BOLT 7/16-14 x 1-1/4".

Usually if hardware is grade 5 or 8, it will say so.

I might use grade 5, but not 8.

[ScottH]

Thanks, from what I've seen online, either a 5 or 8 are used.
Was just hoping for some input from others that have replaced theirs.

[74CustomK20]

When I did mine and installed the bracing I used 8's. Also used 8's on anything that even remotely come near my truck...

[rich weyand]

The issue with using grade 5 and grade 8 bolts is one of torque specs. You need to torque bolts to where they deform a bit in order for them to stay tight. To do that with grade 5 and especially grade 8 bolts requires that they be torqued much more.

From this chart, a 7/16-14 (which is 7/16 NC) in grade 2 takes 24 ftlbs, in grade 5 takes 37 ftlbs, and in grade 8 takes 52 ftlbs of torque to be considered torqued up. The question then is, what kind of threads are you torquing it into, and can they take that?

It's not just a simple issue of "more is better".

https://www.boltdepot.com/fastener-i...ed-Torque.aspx

[ScottH]

Thanks guys, appreciate the info.
Gonna go with grade 5 bolts.

[65 C20]

Captain Fab has been making and selling power steering brackets for years and supplies grade 8 bolts in his kits.
I am just saying.
You say you have already had one break, why go with cheaper bolts ?

[hatzie]

Originally Posted by rich weyand

The issue with using grade 5 and grade 8 bolts is one of torque specs. You need to torque bolts to where they deform a bit in order for them to stay tight. To do that with grade 5 and especially grade 8 bolts requires that they be torqued much more.

From this chart, a 7/16-14 (which is 7/16 NC) in grade 2 takes 24 ftlbs, in grade 5 takes 37 ftlbs, and in grade 8 takes 52 ftlbs of torque to be considered torqued up. The question then is, what kind of threads are you torquing it into, and can they take that?

It's not just a simple issue of "more is better".

https://www.boltdepot.com/fastener-i...ed-Torque.aspx

Originally Posted by 65 C20

Captain Fab has been making and selling power steering brackets for years and supplies grade 8 bolts in his kits.
I am just saying.
You say you have already had one break, why go with cheaper bolts ?

Boy... Folks don't listen do they.
It's not a question of cheaper or more expensive... or even Mores' law.
The threads in the Cast Iron steering box may not put up with the torque necessary to properly tighten Grade 8 bolts.

[nvrenuf]

Mark me as another non listener...

I used grade 8 bolts. Also I went slightly longer (1/2" maybe, can't remember) on 3 of them and put Stover (pinch type) lock nuts, the 4th bolt doesn't come thru the casting.

[rich weyand]

Originally Posted by hatzie

Boy... Folks don't listen do they.

Nope. The mis-use and over-use of hardened fasteners is fairly common. With experience, you learn that the most common cause of fastener failure is failure to torque them to specification.