Leaf spring shackle bolts

I am at work and I am going by the hardware store on the way home, I want to pick up some new shackle bolts.

Does anyone know off hand what size (length / size 3/8"?) bolts I need. 1970 CJ5 w/BDS 2.5" springs, stock shackles.

Any help......thanks

 

If they are the same as intermediates, they are 7/16 (fine thread). Then figure 1 3/4 long for the spring, another 1/2 for shackle, and enough for the nut. So, 2.75" long. 2.5" may be enough.

 

7/16 fine thread, 3" long IIRC. Leaves just enough for a washer on each side and a metal locking nut. You are planning on using grade 8, aren't you?

 

Be sure to use grade 8 hardware

 

I think I will go for the 2.75" -to -3" depending on the amount of theads....better to have alittle extra.
Yes I am going to use grade 8 bolts.

Thanks

 

Just curious, why grade 8? Will a lower grade shear or something?

 

Actually grade 8 is for tensile strength, Grade 5 is for shear strength. If you want a strong bolt for a leaf spring, look at the grade 5 bolts. Grade 8 would be for stuff like bumper bolts where the pull would be end to end not on the side of the shank.

 

There is no (zero) tension on a shackle bolt only shear. Not counting the tension from tightening the nut. Use hard bolts. Make sure they are long enough to keep the threads out of the shear. Nuts should almost touch the threads.

JB

 

No,No,No, this is a myth, who keeps perpetuating this?????
A grade 5 will have reached its yield strength surpassd that and sheared off before a grade 8 bolt begans to deform or yield. A grade 5 bolt is not superior to a grade 8 in any condition at all period!!!!!!!!!!!!!!!!

The shear of a grade 5 bolt in 7/16" is 11,270# , the same size grade 8 is 13,680# the tension on the same grade 5 bolt is 13,338# the grade 8 is 16,673#, so you can see the grade 5 would have already failed befoer the grade 8 started to deform.

To all in doubt read this article; http://www.rockcrawler.com/techreports/fasteners/index.asp or break out a machinist handbook.