1. creuzy

    creuzy Junior Member

    Joined:
    Apr 11, 2019
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    Location:
    Maine
    Vehicle:
    2013 Prius
    Model:
    Four
    I took off the underbody panel today on my 2013 Gen 3 and found the "REINFORCEMENT SUB-ASSY, SIDE RAIL, REAR LH;REINFORCEMENT, FRONT SUSPENSION MEMBER, LH (51108-12010)" to be very rusty. The right-hand rail looked fine for its age.

    Two questions:
    Why might the left side be so much worse than the right?

    Does anyone here have any experience replacing this part? It seems like it is just bolted on and I'm hoping it is as simple (ha!) as unbolting the rusty one and swapping in a new one.

    IMG_20251005_192003237.jpg IMG_20251005_191956691.jpg
     
  2. Mendel Leisk

    Mendel Leisk MMX GEN III

    Joined:
    Oct 17, 2010
    59,640
    41,020
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    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Amayama is significantly cheaper for me, $105~ CDN, with shipping:

    IMG_1944.jpeg

    Checking a US Portland, Maine dealership price (through Toyota USA parts site), the part alone is $109~ USD.

    lots of road salt in you’re area? It takes periodic attention to the underside, rustproofing measures, to at least slow the rust down. From the factory it seems like a thin coat of black paint is all the ferrous steel gets, and it doesn’t last long.

    If it was mine, I would thoroughly brush the new one with boiled linseed oil (or something like Fluid Film, if you want) before installing, do the same to the area it’s bolting onto, and the connection bolts after install.

    I can dig up the bolt torque specs in a bit.
     
    #2 Mendel Leisk, Oct 6, 2025 at 6:56 AM
    Last edited: Oct 6, 2025 at 7:23 AM
  3. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    113,339
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    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    maybe the way the aero panels are connected causes one side to retain moisture more than the other