E46 M3 - Inner Rear Wheel Arch Panel Replacement

Discussion in 'Redish Motorsport' started by [email protected], Jan 10, 2016.

  1. 10 Jan 2016 at 5:53 PM #1
    James@Redish

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    This E46 M3 was suffering from rotten & corroded inner rear wheel arch panels (possibly due to mud collection).

    To do this repair we opted to remove the rear axle assembly so we could 'stand' in the wheel arch and access the area properly so not to miss anything.

    We purchased the genuine BMW replacement panels, and set to work carefully removing the old inner rear wheel arches so not to disturb too much outer wheel arch/wing panel or paint.

    Once the old panels were removed, we neutralised the metal & outer wing join with POR-15 Metal Prep which also coats the metal with a zinc phosphate layer to aid next level adhesion.

    Then we coated the rear of the new panels & hidden areas of the rear of the outer wing with a weld through primer so there would be zero bare metal left.

    Once the new panels were shaped, and welded in, and welds flushed, we could coat everything in 2 layers of POR-15 Rust Preventative Paint (the best rust protection paint on the market in our opinion).

    Then it was keyed to allow a coat of High Build Primer.

    Then sprayable seam sealer was applied in a high pressure low volume way to almost inject seam sealer into joins and panel meeting points.
    We also brushed seam sealer into the arch 'return' (which is usually where the mud collects) and shaped it so that water/mud couldn't sit in the arch return ever again.
    Then continued the sprayable seam sealer over the new panel to leave a textured finish and offer some sound protection against road noise entering the rear cabin.

    Then we finished with Body Colour Paint which in this case was Silver Grey A08, then a top coat of clear lacquer to offer protection, seal the paint & sealer, and allow water to bead/bound off.

    Then once inside the rear boot/cabin area we also painted the back side of the rear inner arch panel with POR-15 Rust Preventative Paint, and then finished the area with a decent amount of cavity wax.

    I think it's safe to say these rear inner arches will never corrode again.

    Then it was off to the bodyshop for them to professionally finish the outer wheel arch panel lips where the outside wing lip paint obviously discolours due to the heat from the welding.

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  2. 18 Feb 2016 at 3:41 PM #2
    MattHaley

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    Nice job:thumbsup:
    Have you got part numbers for the inner arch panels? And do you know if you can get a similar panel for the outer arches?
     
  3. 18 Feb 2016 at 6:15 PM #3
    E46CoupeM3

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    Nice job, I see original panel is cut inside a row of spot welds on the inside of the original panel rather than opening the original seam to save time effort etc.

    Only thing I have found is that most weld through primers I have used will scratch off with a finger nail so I generally only use them in the joint area and don't expect any paint on top of them to stay on. I also tend to use a small rotary wire brush to clean off the weld through visible in the holes before plug welding, it makes for a better smoother weld. Oh and finally I tend to use an aerosol can of primer or weld through for convenience to soak the plug welded joint, usually from above so capillary action saturates the joins so there is no where for moisture to get in.
     
    Last edited: Feb 18, 2016
  4. 18 Feb 2016 at 6:18 PM #4
    E46CoupeM3

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  5. 28 Feb 2016 at 11:03 PM #5
    Geoff

    Geoff A mere Chipper

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    Just trying to look through this link but can't find the relevant part numbers that correlate to the parts shown in the picture above, my car is due to go in and have the same job done to it in the coming weeks and would love to track down these panels myself prior to it going in. Any help would be appreciated.
     
  6. 5 Mar 2016 at 10:24 AM #6
    Phatty

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    Same here. Just had to cut out the drivers side too. Just been into the local main dealers and they can't find the repair panels either, just a complete inner rear quarter listed for M3's at over £300.

    Would be grateful of the part numbers please.
     
  7. 5 Mar 2016 at 1:24 PM #7
    James@Redish

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    Hi guys,

    The parts numbers for these panels are:

    41217890677
    41217890678

    Unfortunately, I don't believe you can get JUST the arch piece - it comes with the whole inner structure like our pictures below.
    Then you just remove and use the section you require.

    They are approx £700 ish (including VAT) for a pair of panels.

    Hope this helps.
    Best regards,
    James

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  8. 6 Mar 2016 at 8:27 AM #8
    Geoff

    Geoff A mere Chipper

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    Cheers for the response James, appreciate it! Out of interest on your customers car, what was the tell tale signs that the inner arch had gone? Was there much blistering on the outer arch? I know my inners are in a similar state so I'm keen to know.
     
  9. 6 Mar 2016 at 2:02 PM #9
    Phatty

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    Oh bugger :-((
     
  10. 6 Mar 2016 at 2:55 PM #10
    zed650

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    I would imagine you just need to take the wheel off,give it a good clean and have a good look yourself :thumbsup:
     
  11. 28 Aug 2016 at 8:13 PM #11
    colin1976

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