Which Grade Bolts Should Be Used for The Curt # C16420 5th Wheel Install Brackets

Updated 03/24/2015 | Published 03/22/2015

Question:

I purchased model 16420 5th wheel rail custom kit for a 2005 Dodge 2500. Had it installed by Happy Daze RVinch in Sacramento Ca. on March 20. There are Grade 5 and Grade 8 carriage bolts installed thru the rails and bed of our truck. Does mixing grade 5 and 8 bolts affect the rating or safety of this installation? The parts list for this kit does not indicate if they are, or should be Grade 8 or 5. Please respond. Thank you

asked by: Larry P

Expert Reply:

I spoke with my Curt representative, who tells me that either Grade 8 or Grade 5 half-inch bolts are acceptable. In the past, they provided Grade 5 with their install kits, but recently changed to Grade 8. It doesn't matter which of the two bolts are used, as long as the bolts are torqued properly. Grade 8 should be torqued to 110 foot/lbs and Grade 5 should be torqued to 75 foot/lbs. Having them mixed wouldn't cause a problem.

I've linked you to a copy of the installation instructions.

expert reply by: Mike L