Body Bolts repetetive Torquing

tyhuck · January 17, 2012

I have a BL on my truck and it has grade 8.8 metric ( = grade 5 standard) bolts holding the body down. I have been in the process of fabbing up some steps that mount ot the body bolts just like most nerf bars do. During the constant installation and removal of the bolts, I have developed a couple of concerns.

1. Is it OK to continually torque these bolts over and over, or do they give a little every time you torque them down? Also, what are the odds of one sheering off or snapping because of these torquing cylces?

2. The steps are 2x4 - 1/8 wall rectangular tubing with a 1" schedule 40 pipe welded to the outside, and 3x2 - 1/4" angle iron mounts. Ide say they weigh 30 - 40 lbs each. The rails stick out about a foot at most and are mounted to all 3 cab mounting bolts. Should I be concerned about the vibration of the steps putting excess strain on the grade 5 bolts?

3. Would replacing the bolts with a 10.9 (grade 8) bolts help to aleviate some of my fear, and is it a good idea to do so?

00Silverado4x4 · January 17, 2012

Not a truck professional but from a military standard you should be able retorque those with no concern. Also I thought the bolt were already 10.9 after all even those tiny bolts that used to hold on lower air dam were 10.9 grade. Now I'll have to go out and look at mine.

tyhuck · January 18, 2012

The factory bolts may have been. But, the ones that came with my Performance Accessories 3" body lift were only 8.8s.

tyhuck · January 18, 2012

_{Know of anywhere I can find 7" grade 8 bolts?}

tesnoboy · January 18, 2012

_{Know of anywhere I can find 7" grade 8 bolts?}

Caterpillar Dealer maybe?

00Silverado4x4 · January 18, 2012

Fastenal. They seem to everything in hardware.

Gurrzt · January 18, 2012

Why keep retorqueing (sp), use some green or blue locktite (what is applicable), or a lock washer and be done with it. When you retorque, you have a chance of "chaseing the threads" that is stretching the bolt, depending on how much torque needs to be applied.

tyhuck · January 18, 2012

Im not continually torquing them after they are installed. I put red Locktite on them to hold them in place. I am refering to the constant installation, tightening, and removal during the build process of the steps. I must have taken them off a dozen times per side making sure that everything still fit right. I know that some people say that certain bolts are designed to be torqued once and after that, they will begin to give and eventually break. I just wanted to make sure that every time I re-installed the bolts wasnt going to cause the bolt to stretch, twist, or eventually fail.

jblakeney · January 18, 2012

8.8 bolts bend and stretch before breaking. 10.9 will break. At least that's aways been my experience.. .. ..

As long as the bolts don't have tty on the head, your good on torqueing old bolts.

Jbo

Gurrzt · January 18, 2012

Im not continually torquing them after they are installed. I put red Locktite on them to hold them in place. I am refering to the constant installation, tightening, and removal during the build process of the steps. I must have taken them off a dozen times per side making sure that everything still fit right. I know that some people say that certain bolts are designed to be torqued once and after that, they will begin to give and eventually break. I just wanted to make sure that every time I re-installed the bolts wasnt going to cause the bolt to stretch, twist, or eventually fail.

Sir, using "red" locktite will certainly make it near impossible to ever get those bolts out again.