Seat Track Bolts

[Leif A.]

I was swapping seats in the car today (I do this every couple of years for even wear) and noticed the eight bolts holding the seats in place. Thought I would post a picture of them. I know there is always conversation about which bolt is correct and what goes where, so I thought this might be of interest to some. I don't see where any two are the same. Lots can happen in 50 years.

[Joe L.]

Re: Seat Track Bolts

I was swapping seats in the car today (I do this every couple of years for even wear) and noticed the eight bolts holding the seats in place. Thought I would post a picture of them. I know there is always conversation about which bolt is correct and what goes where, so I thought this might be of interest to some. I don't see where any two are the same. Lots can happen in 50 years.

Leif-----


The bolt marked "9.8" is a metric bolt. I can guarantee you it was not there at the beginning.

[Leif A.]

Re: Seat Track Bolts

Leif-----


The bolt marked "9.8" is a metric bolt. I can guarantee you it was not there at the beginning.

I saw that, as well, and that's what made me look at the rest. I went back with a matched set of "E" headmark bolts. Fortunately, that metric bolt didn't mess up the captured nut. I'll keep these for posterity.

[Joe L.]

Re: Seat Track Bolts

I saw that, as well, and that's what made me look at the rest. I went back with a matched set of "E" headmark bolts. Fortunately, that metric bolt didn't mess up the captured nut. I'll keep these for posterity.

Leif------


Attached are photos of a guaranteed original GM #3847757. Of course, manufacturer's ID mark could vary.

Note the material grade markings. This grade marking indicates a GM 275M. That's a rather unusual grade. I would say that any of your bolts that display this material grade marking, regardless of manufacturer's ID, are original to the car. One doesn't find this type of bolt in a hardware store.

[Leif A.]

Re: Seat Track Bolts

Interesting Joe. Six of the eight have the three lines at 3,6,& 9 o'clock. There is an "E" in one, an "L" in another, an "X" in another and other markings in others. Many suppliers of the same spec bolt all dumped into a single bin...not surprising. Thanks for your pictures and explanations. Additionally, some have pointed tips and others flat tips.

[Henry J.]

Re: Seat Track Bolts

Joe, would you be good enough, please, to measure the length of the known original 3847757 bolt you have pictured?

I have measured the seat track bolts in my 66 and have them listed in my notes as being 13/16" long. I, like others, have found it impossible to find GM documentation confirming length but have seen them reported in the archives as being both 13/16" and 7/8". Thank you.

[Joe L.]

Re: Seat Track Bolts

Joe, would you be good enough, please, to measure the length of the known original 3847757 bolt you have pictured?

I have measured the seat track bolts in my 66 and have them listed in my notes as being 13/16" long. I, like others, have found it impossible to find GM documentation confirming length but have seen them reported in the archives as being both 13/16" and 7/8". Thank you.

Henry-----

The bolt is, from underhead to tip 0.807" in length. The captive washer occupies 0.0615" of this length.

I would not expect every bolt of this part number to be exactly the same, though. I'm sure there was a manufacturing tolerance provided in the specs.

[Ron G.]

[Ronald L.]

Re: Seat Track Bolts

Guys - the factory was NOT a dumping ground of a bunch of different suppliers. Forget it, No OEM worked that way. There are to much garbage and hopium created and twisted into forum propagated non-facts by people that have zero automotive manufacturing experience.

A part is sourced for that year to a supplier for One application/ location in the assembly plant.

Pointed Seat track bolts were used on the out side ones - for a reason - to quickly get them installed with the dog point or pinch point as it is called.

Where there was decent risk of getting scratched with that 'sharp when new' point, they used flat tip, the part numbers are different in your assembly manual, and there has been a decent amount of study from 65,66 and 67 on the usage changes for all 4 seat attach points.


Seat track bolts head marks on mid years can be verified on known Bench Mark cars. It is no mystery what supplier was used for each application, it was shown on the drawing the Engineer provided to Purchasing, to then go make the parts. Back then as it is now.