By worf - Sat Aug 02, 2025 8:54 pm
- Sat Aug 02, 2025 8:54 pm
#315593
I'm in the process of installing rear seat shoulder belts in a client's 928 (that came, originally with only rear lap belts.)
The two retractor assemblies have been siting in boxes since... well... since they were made probably 35 years ago.
Seat belt retractors all feature some mechanism for preventing the belt from being withdrawn from the retractor under "non-normal" conditions such as a roll over. Thus, it is always the case that unless a retractor is in the exact same orientation as it would be when installed the belt cannot be "loosened" by withdrawing the belt from the retractor.
Upon unboxing these NOS retractors their belts couldn't be withdrawn from them. Even in the as-installed (or indeed installed) position.
The problem - in the case at least - was that the "rollover" mechanism had become "sticky" from sitting in a "not as installed position" in a box for 30+ years.
For 928 retractors the "rollover" mechanism is spring-loaded cup that uses a steel ball bearing. In the as-installed position the bearing's weight overcomes the force of a tiny spring thus levering down the cup. The cup features a toothed arm that can move away from the ratchet mechanism and thus allow the belt to be withdrawn from the retractor. However, it will only do this if the ball bearing levers down the cup and the bearing will only do that if the retractor is in an "as-installed" orientation. A few degrees off on any axis will prevent the bearing from levering-down the cup. This is as-designed.
This mechanism is rather finicky as you might imagine.
The fix is to remove the plastic "cap" that covers the ratchet mechanism, "work" the bearing/cup assembly to get it moving reliably and then reinstall the cap.
There are two caps on the side of the retractor. Once side's is "small" and covers the clock spring assembly that retracts the belt. The other side's cap is bigger and covers the ratcheting mechanism. Remove the "big" cover. DO NOT remove the "small" cover. Repeat: DO NOT remove the "small" cover.
Once the big cover is off you'll see the bearing/cup mechanism. How it works, where it hinges, etc., should be obvious once you can see it. With a finger, push the cup and its tooth away from the ratchet. At that point you'll be able to withdraw the belt. Work the cup up/down to get it used to moving again.
Hold the retractor in the "installed" position and verify that the belt can be withdrawn and retracted.
Pop the cap back on. Install.
The two retractor assemblies have been siting in boxes since... well... since they were made probably 35 years ago.
Seat belt retractors all feature some mechanism for preventing the belt from being withdrawn from the retractor under "non-normal" conditions such as a roll over. Thus, it is always the case that unless a retractor is in the exact same orientation as it would be when installed the belt cannot be "loosened" by withdrawing the belt from the retractor.
Upon unboxing these NOS retractors their belts couldn't be withdrawn from them. Even in the as-installed (or indeed installed) position.
The problem - in the case at least - was that the "rollover" mechanism had become "sticky" from sitting in a "not as installed position" in a box for 30+ years.
For 928 retractors the "rollover" mechanism is spring-loaded cup that uses a steel ball bearing. In the as-installed position the bearing's weight overcomes the force of a tiny spring thus levering down the cup. The cup features a toothed arm that can move away from the ratchet mechanism and thus allow the belt to be withdrawn from the retractor. However, it will only do this if the ball bearing levers down the cup and the bearing will only do that if the retractor is in an "as-installed" orientation. A few degrees off on any axis will prevent the bearing from levering-down the cup. This is as-designed.
This mechanism is rather finicky as you might imagine.
The fix is to remove the plastic "cap" that covers the ratchet mechanism, "work" the bearing/cup assembly to get it moving reliably and then reinstall the cap.
There are two caps on the side of the retractor. Once side's is "small" and covers the clock spring assembly that retracts the belt. The other side's cap is bigger and covers the ratcheting mechanism. Remove the "big" cover. DO NOT remove the "small" cover. Repeat: DO NOT remove the "small" cover.
Once the big cover is off you'll see the bearing/cup mechanism. How it works, where it hinges, etc., should be obvious once you can see it. With a finger, push the cup and its tooth away from the ratchet. At that point you'll be able to withdraw the belt. Work the cup up/down to get it used to moving again.
Hold the retractor in the "installed" position and verify that the belt can be withdrawn and retracted.
Pop the cap back on. Install.
Rick Carter, Gary Knox liked this
Hanlon’s Razor: Never attribute to malice that which is adequately explained by stupidity.
Heinlein’s Corollary: Never underestimate the power of human stupidity.
The Reddit Conjecture: Sufficiently advanced stupidity is indistinguishable from malice.
Worf’s Razor: Never attribute to stupidity that which is adequately explained by laziness.
Worf’s Identity: Sufficiently advanced laziness is indistinguishable from stupidity
Worf's Law: Once you've mitigated risk from stupidity and laziness in your endeavors, failure is usually the result of insufficient imagination.
My 928 Inspection Guide
Heinlein’s Corollary: Never underestimate the power of human stupidity.
The Reddit Conjecture: Sufficiently advanced stupidity is indistinguishable from malice.
Worf’s Razor: Never attribute to stupidity that which is adequately explained by laziness.
Worf’s Identity: Sufficiently advanced laziness is indistinguishable from stupidity
Worf's Law: Once you've mitigated risk from stupidity and laziness in your endeavors, failure is usually the result of insufficient imagination.
My 928 Inspection Guide
- By N_Jay
- By MFranke
- By NSXguy