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Rust: rear running gear issue.

Discussion in 'Gen II Prius Care, Maintenance and Troubleshooting' started by jqmello, May 17, 2012.

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  1. jqmello

    jqmello Junior Member

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    Hi,
    So, our wonderful, efficient, sleek prius came to us used... well, more like drove hard and put up wet... and the Carfax indicates that in it's first 6 years of life it prowled the streets of Massachusetts.

    While I was rotating the tires at their 1 yr, 10k mark (look great so far!) I noticed that the brake drums in rear were not the only thing that was rusty... and the rear swing-arm shouldn't be quite so bubbly! I investigated first with my fingers, flaking off the thin paint shell left by the rust bubbles, then with a wire brush. The rust was concentrated around the welds on the rear swing arm, and pretty continuous, even around the main bushing attaching to the body. I investigated further and noticed rust bubbles on the entire swing arm and even rust starting to form on the torsion bar.

    I din't have naval jelly (was at my parents) to halt the rust, so after knocking down what was easily accessible from the wheel well I cleaned the area with a rag and then carb cleaner, then immediately hit it with some black rustoleum.

    Sorry, no pictures - again, at my parents and didn't have the camera.

    How worried should I be about this development? It's apparently been going on for some time. I think to really treat the rust properly I'd have to drop the entire rear suspension.
  2. edthefox5

    edthefox5 Senior Member

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    I wouldn't worry about surface rust, it is what it is. You can kill yourself removing it and painting it but small return for alot of work.
    Put that effort into more important work like trans fluid replacement.

    The issue is whats happening to the bushings. Your probably hearing some clunking going on from the dried up bushing.
    Go to Home Depot and buy a spray can of CSP. Its made by PB Blaster and is spray grease. Its a good product as the grease stays where you put it and it doesn't smell like other PB products. Buy 5 cans. Your going to need it. Do not use WD40. Spray the hell out of the bushing area. Get the grease in there. You can spray it on the surface rust and it will stop further rusting also. While your there pull the drums off and deal with that mess. Apply synthetic grease to the pivot points and spray grease to the parking pawl and spring assy. Whatever you do, do not apply the brakes with the drums off.

    The real problem is up front. That's going to be a rusted mess to.
    Same deal spray grease on all pivot points and control arm bushings and pretty much anything thats rusted. It will stop the clunk and squeek. This is how I maintain the chassis's on my cars and there's no rust anywhere.

    While under the front inspect the cv joint rubber boots. There's 4 of them. Get a tear in any boot and its cv joint time.
    I like Black Magic Protectant. Its a good product. Spray it on the boots and wipe off and re-apply to get road dirt off.
    Your overdue for CV joints though.

    And get the trans fluid and Inverter coolant replaced.

    Good luck!
  3. jqmello

    jqmello Junior Member

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    Thanks for the advice. I have a can of white lithium grease spray (liquid wrench?) but it's about used up - I'll definitely look into the PB stuff you mentioned.

    The rear trailing arm is obviously some pretty heavy material, I'm just a little concerned that it was quite so extensive. I'll not sweat it, but see if I can inspect the heck out of the front.

    Things like transaxle and inverter fluid changes were done at 110k and 100k miles, respectively. I'll have to take a close look at my CV joints, although I check my boots pretty regularly, and on other cars have merely replaced the boot (not entire cv joint) without ill effect.
  4. Mike500

    Mike500 Interessen-Gemeinschaft Prius

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    For those who keep on saying that "cars are fully protected from rust at the factory," take note.

    I still do my own rustproofing job on all of my cars; have done so for the last 40 years. I've NEVER had any of my cars experience penetration from the inside or "rust bubbles." And, I've lived on the coast right by the ocean.
  5. jqmello

    jqmello Junior Member

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    Hah! as if! Manufacturers HAVE gotten a lot better with the coating methods and dipping, but no car is going to be sealed. At least they aren't rusting on the lots like imports in the 70's/80's. It may last a while but not forever. Ours came with the rust - it got 100k miles of head start on me... so hopefully I can manage to slow it down enough that it'll be other things that kill the car - in another 100 - 150k miles.
  6. Britprius

    Britprius Senior Member

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    At a minimum disconnect the 12 volt battery before removing the rear drums. If the brake pump starts with the drums off (opening the drivers door can cause this) the brake pistons can be ejected requiring the brakes to be bled. This requires the service computer to complete.
  7. Mike500

    Mike500 Interessen-Gemeinschaft Prius

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    I have a can of "phosphoric acid" rust conversion spray that's been lying around for several years. I have it, just in case. But I haven't used it. It is made by in the "Turtle Wax" Brand, but is is also available under many brand names and even at WalMart.

    It converts rust to "iron phosphate," which is the main component of gun "bluing" and "blackening" coatings used on tools.

    In most all manufacturing processes having to do with iron or steel, the parts are "pickled" in phosphoric acid or phosphate solutions, before they are painted.

    If the rust bothers you, just scrape off the "bubbles" and flakes down to a layer of hard surface rust, spary on the "rust converter," wait a few days, and then paint it with some cheap black paint. The $.97 black spray cans sold at Home Depot are probably the best. They are basically the same paint as the $4 can, sold under the "budget" no name label. The cans sold at Lowe's, made by Valspar, are not as good.
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