Seat belt bolts

[kens65fb]

What size are the bolts for the seatbelts, that attach to the factory holes in the floor ?

[SkinnyG]

DOT requires 7/16" UNF, or 1/2" UNC.

[The Rocknrod]

Originally Posted by kens65fb

What size are the bolts for the seatbelts, that attach to the factory holes in the floor ?

That's a good question. Not sure, however here is a good thread on the subject - http://67-72chevytrucks.com/vboard/s...=679368&page=2
I just looked at an old thread I posted and the stock holes I have are 7/16" fine thread.
http://67-72chevytrucks.com/vboard/s...7&postcount=11
This is the type of bolts you use. Don't cheap out - https://www.julianos.com/Grade-8-7-1...p/ju010100.htm

https://www.classicindustries.com/pr...oaAncvEALw_wcB
https://www.opgi.com/interior-access...d-plated-1-14-

[ACK]

Apologizes for going OSHA, but can't over emphasize that the big @ss washer in Rocknrod's 1st link is what keeps the bolt from pulling through the floor should the vehicle comes to a violent stop. It takes little force to pull a single bolt head through sheet metal upon impact, so think of that washer as life insurance.

[AcampoDave]

Just to add to ACK's point about using big arse washers when not using factory holes...Juliano's has an answer for that and I use them
https://www.julianos.com/Juliano-s-A...p/ju010600.htm

[kens65fb]

Originally Posted by ACK

Apologizes for going OSHA, but can't over emphasize that the big @ss washer in Rocknrod's 1st link is what keeps the bolt from pulling through the floor should the vehicle comes to a violent stop. It takes little force to pull a single bolt head through sheet metal upon impact, so think of that washer as life insurance.

Just to be clear.
My truck has the factory threaded holes in the floor, do I need nuts & washers under the truck floor as well ?

[AcampoDave]

No, factory holes are used with the bolts like Rocknrod posted.

[kens65fb]

Originally Posted by AcampoDave

No, factory holes are used with the bolts like Rocknrod posted.

The bolt Rocknrod posted is for shoulder belts, I need the bolt that goes into the floor.

[AcampoDave]

My '66 had factory lap belts which were anchored with a shouldered bolt like the pic. That way the belt anchors could swivel a bit on the bolts. I personally would just go down to the hardware store and get a grade 8 bolt that fits and cinch them down tightly.

[The Rocknrod]

Originally Posted by kens65fb

The bolt Rocknrod posted is for shoulder belts, I need the bolt that goes into the floor.

Just to be clear they're called "shoulder bolts" because of the un-threaded larger shoulder below the hex hex. Not because they are used just on shoulder belts.

[ACK]

In short, if there's an anchor plate under the truck, most likely a rectangular piece of thick stamped sheet metal with a nut welded in the middle, you should look for 7/16"-20 x 1.25" bolts as mentioned above. As a side, the '64 - '66 shop manuals don't mention seat belts at all, however, I'm quite sure the assembly manual does. I agree with AcampoDave, grade 8 bolts are the way to go.