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Headlight Leveling Replacement -> Sheared Bolts

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Docholo, Jul 31, 2015.

  1. Docholo

    Docholo Junior Member

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    Having successfully replaced a tail light assembly and the 12 volt auxiliary battery I thought
    it would be easy to replace the headlight leveling sensor on the rear-left. It has been dead for
    two or three years now but I finally feel like the headlights are pointed in the wrong direction too
    much for my liking.

    I got my best 10 mm socket on the bolt holding the arm to the axle-bar, made sure it was really
    straight and true, and after about 5 or 7 careful turns, the bolt sheared right in two. It left about
    1/2 inch of bolt stock visible in the axle bar. The top part of the bolt is embedded in the nut.

    Being a fool-hardy idiot I thought that if I went really carefully and slowly, I would be able to get
    the second one off without the same effect. I was wrong. I busted the second one despite going
    really slowly and trying to judge the amount of torque I was applying.

    These bolts seem extraordinarily fragile. They are covered in rust and tarnish but it would seem to
    me that the bolt should provide a little resistance if things are not turning correctly.

    Anyhow, I was hoping to turn a $500 dealer problem into a $60 me-fix-it problem. I think it is now
    probably going to be a $1000+ dealer problem. Anyone else ever do this? Thanks,
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Is it not possible to replace the rusted hardware? How about providing a photo so that we can understand the issue you face.
     
  3. 69shovlhed

    69shovlhed Surly tree hugger

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    did you hose the bolts with penetrating oil before you tried to remove them?
     
  4. Docholo

    Docholo Junior Member

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    Apologies, that would of been a good idea but I put it back together. The problem is that there are two threaded
    rods/bolt ends coming out of the rear axle beam. The threaded rods used to be about twice as long but I
    sheared them in half during the process of trying to remove the nuts.

    Are these threaded rods replaceable without having to dismount/replace the rear axle.

    I did not. That probably would of been a good idea. The problem is that the threaded rods
    did not put up any resistance and I was not smart enough to seek assistance before busting
    both of them.
     
  5. valde3

    valde3 Senior Member

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    If there is enough tread left in the studs just put the new nuts on them. Use penetrating oil as lubricant and carefully put the nuts to correct tread.

    If there isn’t maybe you could just drill small hole into axle beam and use something like pop-rivet to hold the bracket in place. Although in theory drilling a hole into axle bean will weaken it…

    Why did you remove the bracket from the axle? Sensor linkage can be removed from the bracket.
     
  6. ChapmanF

    ChapmanF Senior Member

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    My usual approach to an unfamiliar small rusty bolt/nut is:
    1. hose with penetrating oil
    2. using a good snug socket, try to just budge it
    3. if it budges, stop, spray more penetrant, and immediately turn it back the other way
    4. continue back-and-forthing it, by very small amounts to start with, eventually getting wider, until it's out.
    I still break a few.

    A good picture might indicate how the studs were attached to the axle beam. If they were pressed in, you might be able to drive them out and press new ones in. (They don't seem to be separately available from Toyota, but any machinist ought to be able to find you two reasonably matching studs.) Or, next more annoying, drill them out, then replace with small bolts if you have access from below to stick bolts through.

    -Chap
     
  7. Mendel Leisk

    Mendel Leisk Senior Member

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    I managed to bust the heads off a couple of 10mm (socket size) bolts on the underside. They were inconsequential, holding a seam between two plastic panels, at front corners. The bolts were TOTALLY rusted; Toyota must be spec'ing junk.
     
    #7 Mendel Leisk, Aug 1, 2015
    Last edited: Aug 1, 2015
  8. valde3

    valde3 Senior Member

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    That’s what I do with rusty fasteners as well. Many times I also wire brush the thread that is visible. I haven’t broken one where I can see the thread and could get it to budge in years (like this one).

    If the studs are welded to axle bean it’s probably best just to use pop rivet or similar since drilling those out would weaken the structure more is more work and isn’t really giving you any better results than just pop rivet.
     
    #8 valde3, Aug 1, 2015
    Last edited: Aug 1, 2015
  9. Mendel Leisk

    Mendel Leisk Senior Member

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    I don't think Liquid Wrench would have budged this:

    IMG_2683 - full size - crop.jpg
     
  10. ChapmanF

    ChapmanF Senior Member

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    I'm not at all sure about that, or at least there may be differences between fasteners in different areas of the car. I've lived and driven in road salt areas all my life, and my Prius (which is also the only Toyota) is the first 14 year old car I've ever owned where most of the bolts I take out look as good as they do. I remember commenting on it when I did my LF wheel bearing:

    But yeah, small body-panel fasteners and such don't seem to get the same love.

    -Chap
     
  11. Mendel Leisk

    Mendel Leisk Senior Member

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    Yeah, these are almost like pop rivets. They do use a permanent fastener for some of the plastic-to-plastic splices, using a pop rivet style plastic fastener. You can just see one, at right edge of pic. It's worthwhile to crawl under there periodically, back out, lube and retighten some of these small bolts. There's some aero panels near the rear trailing arm: to lube the main bolts I had to remove the little panels, and their hold-down bolts were almost seized. I think another year and the heads would have snapped off on them too.
     
  12. valde3

    valde3 Senior Member

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    Mine are already so corroded that I just applied penetrating oil on them although they probably still can’t be opened.

    What I tried to tell earlier is that for years I haven’t broken the any bolt where:
    -I can clean the treads with wire brush
    -It did start to open even the slightest bit
     
  13. 69shovlhed

    69shovlhed Surly tree hugger

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    sometimes you can heat the female fastener with a propane torch, and loosen the nut or screw. if it won't move hit it with oil while its still hot. the cooling causes it to suck some oil into the threads. repeat until it moves. I suspect a butane torch would also work good on small fasteners. I bought the very smallest tip I could find for an acetylene torch years ago. it works great on 5mm and larger nuts. I know most folks don't keep an acetylene torch handy...
     
  14. valde3

    valde3 Senior Member

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    But in a case of these bolts that I and Mendel Leisk are talking about bolt holds plastic peace on and female fastener is the car body…
     
  15. Docholo

    Docholo Junior Member

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    This worked. The nut rotated correctly quite a ways before it the bold snapped so I was able to get the bracket back on with what is left of the threads.

    This is good information. My initial strategy was to put my best socket on it, make sure everything was straight and true and then turn cautiously while trying to feel if there was anything going wrong. The problem with this is that if it feels right, it is probably wrong. Better to go slow and bury it in appropriate lubricant.

    I would agree. I am not impressed. This car has had 4 years of easy driving and then 6 years of upstate new york winters with salt spray. Maybe the fastener is fine in better environments? Mine were very rusted. Not quite Mendel's picture but about half way there.

    Thanks all!

    Now I just have to figure out if I can get the other side of the fixture out without screwing anything else up.
     
    valde3 likes this.