Seat Belt Hacks - Autoliv with Pretensioner

[Citroënbender]

Nanny-staters, look away now. This isn’t your thread.

A few details that might help people save on a repair (eg, chafed and unroadworthy webbing) or swap sides for a belt. Common sense, experience and good practice should be followed…

This is NOT about defeating pretensioners, or physically repairing them by parts replacement. I may touch on the latter in a subsequent post.

The belts here are from a twelve year old Peugeot. They have an integrated single stage pyrotechnic pretensioner, but otherwise are not particularly different to a Falcon or Territory belt. Note the small hooked metal arm bent up near the fixing bolt. This is the dummy-proof way of determining which side the assembly technicians fit it to. It’s easily flattened to exchange with the other side.



“Handing” (as in, right or left-hand side) of the belt is primarily determined by the ball/cage sub-assemblies indicated here. If you squint, you can see differences in them. Left seatbelt is left side of picture, right follows suit. Put the belt on the wrong side and it won’t permit you to pull the webbing out, even slowly. It’s the part which causes the belt to bind up when inverted, or suddenly accelerating, or slowing.

Some seatbelts are installed without a rake angle. They still have what I would call a cant or inwards lean, but as nearly all car bodies are symmetrical this number is unlikely to vary between sides. Main point of this comment is on some (not many) cars you can interchange belts left to right without much fiddling. The colour coding is incidental and manufacturer specific - not any standard.

The “finger” at the top of this sub-assembly is modulated by the ball’s position and acts to block a sprag ring, that is connected to a force multiplying mechanism under the white cover, to mechanically lock the belt when blocked. This (under the cover) is the same mechanism which responds to inertial change, locking the reel when pulled sharply

With that sub-assembly carefully prised out, you can gently pull the belt to full extension. The belt can be observed trapped where it passes through a slot in the metal reel. Here, the belt has been removed for clarity; this is the “seating” side of the reel where the belt physically terminates. It’s a noticeably wider recess. The reel can be jammed against unwanted retraction with a screwdriver or fine nose locking pliers on an area out the way of your work.

If you prise up the seated end of the belt from the reel, this is what’s inside. A slip-fit nylon dowel keeping the loop expanded so it may not pull through. Remove the dowel and you can ease the belt completely free of the mechanism. Really handy if it’s totally filthy and needs deep cleaning.

If you’re curious, or didn’t manage to keep the reel from suddenly winding back in after you removed the webbing, here’s the ribbon spring. It’s greased with what looks/feels/smells like moly grease.

If it abruptly rewound, I suggest you carefully remove the cover and check both the fixed outer end and drive hub are still correctly engaged, then refit the cover. As the screws are self threading and this isn’t their first rodeo, consider using a dab of thread locker. Make a mark somewhere on the reel and count how many whole turns of tension may be applied before the ribbon spring can be felt to start binding up. Gently and slowly remove one to one-and-a-half turns and that’s your reassembly preload.

[roKWiz]

NSW nanny state or Victoria nanny state ??

[Citroënbender]

Terra Australis, generally. I meant the people who bleat for more laws and think that other people shouldn’t be allowed to DIY…

[roKWiz]

Wonder what you would have done with this one out of a 50 year old Kenworth.

They don't use a ball but a little weighted bell on the end of a balance rod.
Belt was shot anyway.