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    FEP Super Member gr79's Avatar
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    Jun 2009
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    Default Seat belt button/latch spring repair (79)

    Spring time. Showed up in a different way today.

    High use wears out parts on older cars. Including safety items.
    "Buckle Up" has turned into a temporary no go.
    Buckle down time to solve this (can't) "Reach up and pull them belts real tight one more time..".

    Problem:
    DS latch has been acting up for a while now.
    Can insert seat belt buckle fine, but will not latch, no click. Latch button not returning; not popping back up.
    Took many tries to get belt buckle to latch. Lubed, no change. Now nothing. Not good.

    Found:
    In an area of a car, of which have never gone before, what existed there, or what would be found.
    Took latch assy apart. Basic latch assys consist of housing, cover, button, plate w/spring underneath. Cover is a press fit.
    Wondered what made and how the button popped up. Reverse probe of why it did not.
    Bingo. Found broken latch plate spring. Metal fatigue, many cycles.
    Was not apparent at first. The spring is hidden beneath the plate. Broken piece was wedged under plate.

    Notes on parts:
    The 'bump' on the dark colored plates latch the buckle. Plate's spring supports plate, plus keeps the button up.
    Pushing the latch button pushes down on the sprung plate and releases the belt buckle.
    When inserted, belt buckle closes switch contact for Fasten Belt warning.

    Disassembly of seat belt buckle latch:
    Finally found out the trick to remove latch cover for access to latch parts. Takes 30 sec.
    No removal of latch/belt assy from car required.
    Small flat blade screwdriver is the only tool needed. Reassemble: press latch cover back on with firm palm pressure.
    Found 40 years of debris inside latch, easily cleaned with old toothbrush, shop rag, cleaner.

    Pic: 79 button latch plate springs (plates shown upside down). Pass side (top), broken ds (bottom).
    DS spring is shorter for Fasten Belts switch clearance. Also, DS plate end shape is open to fit around switch.
    Attachment 126899
    Pass spring (top) fits ds plate, but is too long. DS has shorter spring to clear Fasten Belt reminder light/buzzer switch.

    The fix:
    Time to visit pic-a-part for couple new springs. The rest of belt assy is good. Rather fix for a <dollar than buy all new.
    Also eliminates work unbolting anything, if even possible any more.
    May use a dab of dielectric grease on the end of replacement spring. No lube was found. Possible wear marks in pics.
    The latch button graphic design is called Starburst. Many other brands used same mechanism, different button logo.

    79 pass side latch assy. Plate with spring, cover, button. Pass side latch housing is 'hollow' inside, no switch.
    Attachment 126898

    79 drivers side latch assy. Spring (end tab with 'dot') is hidden below plate. Pry plate up and out to access spring.
    Raised 'bump' on plate retains buckle, supports button. Button pushes down on plate 'bump' to release buckle.
    Attachment 126901
    Found a little bronze tab in the debris. Looks to have came from the switch contact plate, left side of coiled spring.

    79 Mustang drivers side latch housing with latch parts removed.
    Seat belt buckle end makes contact with the switch when inserted.
    Attachment 126900
    Last edited by gr79; 03-18-2019 at 09:28 PM. Reason: proofreading

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