Seat belts/inertia reel on 81 F150

[Pete Whitstone]

On my 81, no matter how hard/fast I pull the seat belts, they don't lock and stop the belt from coming out. Most seat belts from that era will lock pretty quickly when you give them a hard tug. So is there something wrong with my seat belts, or does Ford use a different design that doesn't lock until the forces are what they would actually be in a crash?

I'd hate to find out the hard way that my seat belts don't really work. Both the driver and passenger side seem to act the same way, so either they're both broke/worn out, or that's the way they are designed and they are fine. Any way to test them?

Thanks,
Pete

[Dorsai]

Interesting...either we have the same failure, or the belts don't lock from a rapid pull - I just checked on my 1980.  Couldn't get them to lock up no matter what I tried.

[1986F150Six]

Try pulling the belts while braking sharply [deceleration].

[Pete Whitstone]

1986F150Six wrote

Try pulling the belts while braking sharply [deceleration].

Ah, excellent point. I'll try that next time I drive the truck. Thanks!

[myrl883]

They're probably just fine. You answered your question in the title of your post. The retractors are inertia sensitive, so they need to see rapid deceleration before they lock. They stay loose for comfort when their "job" isn't needed.

[Pete Whitstone]

myrl883 wrote

They're probably just fine. You answered your question in the title of your post. The retractors are inertia sensitive, so they need to see rapid deceleration before they lock. They stay loose for comfort when their "job" isn't needed.

I have other cars from the 80's that have an inertia reel, but they don't need to see decelerative forces to activate. They work similar to the way a distributor advance works - centrifugal weights held in by springs. Yank on the seat belt and the inertia reel spins hard enough to make the weights fly out, and on the outside of the weights is a cog similar to what you would find on a ratchet strap. All they take to activate is a good tug on the belt. If the Ford system also requires deceleration, then it's a different animal than the inertia reels I'm talking about.

Is it just a spring-loaded bar that flies forward under braking and locks the reel? Like a stick on bicycle wheel spokes, so to speak?

[Gary Lewis]

The ones in Big Blue catch you if you lean forward too quickly to open the kick panel vents.  Janey had fits with that last week.  Took several tries to get to the vent.

[HBF84]

I was curious about the same thing and making sure the belts were not broken.  I pulled the plastic surround to inspect the reel that the belt winds up on.  There is a ratchet system and a pendulum.  When the pendulum swings forward (due to deceleration), a piece of metal inserts into the ratchet and stops the belt from coming unwinding any further.  Otherwise, when the pendulum is in the neutral position, the ratchet is free to wind and unwind.  

[delco1946]

HBF84 wrote

I was curious about the same thing and making sure the belts were not broken.  I pulled the plastic surround to inspect the reel that the belt winds up on.  There is a ratchet system and a pendulum.  When the pendulum swings forward (due to deceleration), a piece of metal inserts into the ratchet and stops the belt from coming unwinding any further.  Otherwise, when the pendulum is in the neutral position, the ratchet is free to wind and unwind.

I second this (regarding the need for deceleration). My seat belts (1981 F250) will often catch while decelerating, and i don't consider myself to be an aggressive driver/braker either.

[Rusty_S85]

Original belts on my '82 F150 will lock if you pull it out and then tug quickly on it.  Ive locked it many times with the shoulder belt slightly loose as my current seats are too low and it rides on my neck almost.

Will be interesting to see if my driverside NOS seat belt assembly will work the same way.