Bench seat bolts, difference

[General23cmp]

I’m ready to install my recovered seat in the truck, and I have 16 bolts. 8 go to attach the tracks to the seat and 8 attach the tracks to the floor. The two sets of 8 bolts are different, and I don’t recall which went where. One set has a sharp tip on the end of the threads and the other has a “dog tip” end which is blunt. The bolts will thread into either sets of threads (same pitch), so the question is, which bolts go in the floor and which go into the seat frame?

The sharp tip could be useful to go through the carpet, but I know a seat belt bolt uses a blunt tip. The sharp tip could also work well going into some of the seat cover on one end. So, I could see it going either way. What is correct?

[ThreeQuarter]

I’m in the middle of rebuilding the seat in my ‘68. All my bolts have the same tip, but I have some different lengths. The shortest bolts go through the floor. The bolts that go into the seat frame are considerably longer, and the front ones are a little longer than the rear ones. Given that there are at least three different seat/track types in our pickups, this may not be helpful for yours.

[toolboxchev]

I going to be a pointer, someone else will confirm. The sharp tip bolts go through the floor.

[Getter-Done]

The short bolts go in the floor as stated above.
A little trick I use some times when trying to determine length is,

The nut pocket is about 1/4 thick.
So you need at-least that much bolt sticking out .

With the seat track firmly in position,

Use the Longest bolt as a Reference,

Put that long bolt In each hole
Keep track of the holes that the bolt stick out of more than the others.
Those are the ones that get the shorter bolts.

I have one seat that has 3 different bolt lengths.

I hope this helps you.









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[TKCR]

I’m usually over on the 73-87 side, but I do have a seat from a 68. But I have found that there are 2 sizes of bolts, when it comes to the tracks to the seat frame, and then the bolts for the tracks to the floor.
1st pic, these bolts are the ones that attach the tracks to the frame. Disregard the bolts at the bottom of the pic, those are for the 81-87 seat specifically.
2nd pic, these are slightly larger bolts. These are usually the ones that bolt into the cab floor.

[Getter-Done]

Originally Posted by Getter-Done

The short bolts go in the floor as stated above.
A little trick I use some times when trying to determine length is,

The nut pocket is about 1/4 thick.
So you need at-least that much bolt sticking out .

With the seat track firmly in position,

Use the Longest bolt as a Reference,

Put that long bolt In each hole
Keep track of the holes that the bolt stick out of more than the others.
Those are the ones that get the shorter bolts.

I have one seat that has 3 different bolt lengths.

I hope this helps you.









.

Just checked my seat with the different bolt lengths.

1st picture is the upper front seat-track bolt it is the longest.

2nd picture is the upper back seat track bolt is the middle length bolt.

The bolts that go in the floor will be the shortest ones.














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[71CHEVYSHORTBED402]

My 1971 takes (GR 5) 1/2" (wrench) recessed hex tapered bolts with spin washers top and bottom. The bolt threads are 5/16-18 x 7/8. I always measure from the spin washer. The bolts are stamped "RBM".

[General23cmp]

Originally Posted by 71CHEVYSHORTBED402

My 1971 takes (GR 5) 1/2" (wrench) recessed hex tapered bolts with spin washers top and bottom. The bolt threads are 5/16-18 x 7/8. I always measure from the spin washer. The bolts are stamped "RBM".

Are the dimensions above for the bolts to the brackets to seat frame? This sounds like the size I have.

I definitely do not have 3 sizes of bolts as some have said they have. I have two sets of 8, and except the pointed ends on one set, they are essentially the same bolts. There is a chance that the second set of 8 is from another frame to seat rail set I had before, and perhaps I don’t have the rail to cab floor bolts on me. Are these all the same size thread/bolt diameter to go from seat to rail and rail to cab, or is one a bigger diameter bolt?

[71CHEVYSHORTBED402]

Originally Posted by General23cmp

Are the dimensions above for the bolts to the brackets to seat frame? This sounds like the size I have.

I definitely do not have 3 sizes of bolts as some have said they have. I have two sets of 8, and except the pointed ends on one set, they are essentially the same bolts. There is a chance that the second set of 8 is from another frame to seat rail set I had before, and perhaps I don’t have the rail to cab floor bolts on me. Are these all the same size thread/bolt diameter to go from seat to rail and rail to cab, or is one a bigger diameter bolt?

All 16 the same. I can only speak for a bench seat, though I can't imagine why others would be different. They're "body" bolts of sorts (i.e. tapered end). If the truck has a 5/16" fixed nut or takes a 5/16" U-Nut then it uses them and I'm 99% sure they were all grade 5. What varies is the head type, some have spin washers others don't. The ones for my 71 bench have a spin washer.

[General23cmp]

I found this drawing which appears to show all 16 being the same. This seems to be how mine is set up too.

[71CHEVYSHORTBED402]

Originally Posted by General23cmp

I found this drawing which appears to show all 16 being the same. This seems to be how mine is set up too.

Real descriptive too I noticed, those are spin washers. Edit: I take it back The bolt on the right shows a spin flat washer. The one on the left could pass as a spin split-washer. I don't have a seat in front of me, but it's not a spin washer for certain. Very few of those were were used, if I remember right the bolt to ground the headlights is one example.

I've read engineer opinions split washers are useless to begin with, better off with just a flat washer. Then again if GM says split washer it's good enough for me.