Securing Your Rocker Panel Trim, Proactively

(Rocker panel trim is the painted plastic body trim underneath the doors)

Rocker Panel advised mod1

courtesy of Long Road Racing; click to enlarge

Quite a while ago, I recall reading how those that were auto-crossing and racing their Miatas and perhaps coming in contact with those pesky orange cones, were losing their rocker panel trim (commonly, but technically incorrect, called rocker panels) and how Mazda had responded by issuing a TSB (Global MX-5 Cup Car Technical Service Bulletin #3-22-17B), which not only answered these driver’s concerns that the panels were just hanging on plastic clips, and therefore, weren’t really “fastened” to the vehicles, but it also made fastening the panels a “legal” modification for racing qualification (I’m curious as to whether Fiat has issued a similar TSB).

I recall reading the TSB, and not having a very good idea as to where the three self-tapping screws were allowed, nor where the mounting surfaces were and what these clips looked like (I didn’t try very hard, as I haven’t looked underneath there since installing the plugs my dealer forgot to install).  Then yesterday, someone posted a common forum question – “What are these plugs for, and what do I do with them?”, and with one of the replies, a very clear photo showing the clips that hold the rocker panel trim, was posted. 

chassis plug

photo courtesy of Casey Jones

Now it became clear, that dislodging the panels probably wouldn’t take too much force.  I’ve been told that driving through an unexpected large puddle at highway speed could be all it takes!

I brightened up another forum photo showing a screw in place, and it too reveals the clipping better

Rocker Panel advised mod

original photo courtesy of Good-win Racing; edited by ameridan

So even though I’m not an Auto-crosser, I think I’ve finally been inspired enough to locate some quality stainless steel self-tapping screws, to insure that some road debris won’t dislodge one of my rocker panels, by pre-drilling and installing at least 3 of those screws per panel (if you aren’t qualifying for racing, 5 might be better), along the inboard edge in the vicinity of those bottom clips, where I’m confident the actual rocker panel sheet metal is directly behind the trim.  This will prevent the panel from “shifting” out of those clips, or falling off should some of them fail under stress, as magoffin’s have.

rocker panel clip failure

photo courtesy of magoffin

It turns out that you needn’t raise the car that much to drill the holes.  Lifting the vehicle at the forward rail “pad” such that the suspended front wheel is about an inch off the ground, was plenty high enough for both drilling and driving the screws in.


About an hour after I published this article, Leon Russ posted this photo , along with his comment that road debris had just dislocated his rocker panel.  This is exactly what I wish to avoid!

rocker panel off

photo courtesy of Leon Russ

Looks like there are about 10 other green clips holding the trim panel on, in addition to the 5 white clips along the bottom edge. 

If your rocker panel does become dislodged, Tim Oyer had this advice for reinstalling:

Take all the green clips out of the body of the car (just take something thin and fairly rigid and squeeze in one side of the squeeze-clip, then gently rotate and yank it out), and put them in place on the rocker panel. Once all in place, slide the bottom clips into place, then rock the rocker upward and push the green clips into the mounting holes. It can be done easier if you lift the car up a bit, but otherwise can be done in a parking lot, no problem.  When you get home, add the screws!

Similarly, Good-win Racing describes the process:

It gets attached under the car first.

Start with taking those green plastic pop clips off the car and install them back on the rocker panel. Try to get them off the car without breaking them (i have popped them from the car with a serving fork though there is a tool made for the task). You then look at the low side of rocker panel, that low side needs to get attached under the car and SLIDE [the grey clips] into place before [aligning the] green clips along the top half of the rocker panel with their holes and snapped back in. Once bottom is properly slid into place…then top just pops on if you have those green bits aligned right (take your time to make sure ALL of them lined up nice before you pop upper half back on)..

22 thoughts on “Securing Your Rocker Panel Trim, Proactively

    • I would say whatever you can find about a ½ inch long 😉

      Looks like Glenn Long used a power tool to drive the screws in without setting the torque down, and deformed the plastic somewhat. Probably better to pre-drill and use a regular screwdriver?

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  1. Just did this with some number 10 stainless self tappers. I suggest drilling a small pilot hole. Makes it much easier. That is some tough steel! I don’t autocross but looked like a simple preemptive mod. Previous example would be a bad day!

    Liked by 1 person

    • Thank you Dan. I haven’t gotten around to it yet. Were you able to do this with the vehicle on the ground? or lifted up somewhat? Not thinking I’ll be able to do it without getting the car out in some lot and jacking it up, is what is holding me back, as I have a tiny one-car garage.

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      • Used a floor jack and raised it a few inches to be able to get the drill under there. Plus to see better.
        Read somewhere else that someone was concerned what was behind the metal. I pulled the sills off and there are slots under there that you can see into the channel. It is completely empty. The wire harness runs the length of the sills [further inboard] on both sides. That put my heart at ease!

        Liked by 2 people

  2. danotech63 – when you say the wire harness runs the length of the sills, is it in the channel? Or does the harness run alongside the channel? If it’s in the channel and the self tapping screws and harness start to rub on each other, that could cause some bad results.

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  3. If you enlarge the first photo, you’ll see specifically where along the outboard edge, the placement of the screws is recommended by Mazda. There should be no concern of hitting wiring, unless you choose different locations. I haven’t inspected closer though, as danotech63 has.

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  4. danotech63,
    Reading your June 11th comment again, I realized that these trim panels aren’t technically “rocker panels”, and that the difficulty you had pre-drilling the holes, since “self-tapping” screws weren’t grabbing, was because high-strength steel is used in the actual rocker panels.

    On unibody automobiles where the body and frame of the vehicle are one, rocker panels provide the structural reinforcement that keeps the bottom of the vehicle from sagging in the middle. On more modern cars and trucks designed with front and rear crumple zones, the high strength of rocker panels is essential in creating a passenger cabin area that does not deform in an accident the way hood and trunk sections are designed to. more details on – https://www.carid.com/articles/rocker-panels.html

    I revised my article title accordingly.

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  5. Wondering if the method described in the TSB is a good idea for road vehicles.
    That looks like a rather exposed area and with driving a screw into the body you might end up with a rust problem later. From the pictures it doesn’t seem that one has access to the far side so that one could seal the hole.

    What about drilling into the grey plastic clip and tightening the ‘panel’ with a washer? Even if that doesn’t prevent it from becoming dislodged it should at least not fall off. In theory that is…

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    • Tobias, I’m not a BIW expert, but rocker panels are generally more prone to rust than any other area of the car. Because trim is used to cover that area nowadays, you won’t normally see that rust until it is so bad, the trim can no longer remain in place. None of the holes for the 15 clips in the article’s last photo are sealed, so I’m afraid I don’t share your concern for these additional holes.

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      • Dan, you’re right.
        However the area behind the trim seems to be painted so there hopefully also is paint around the holes and their edges which should prevent rust from forming from the outside.
        A hole drilled after painting wouldn’t have any protection. I think that with the TSB method the rust risk might indeed be higher.

        Water getting past the clips and forming rust on the inside is a different issue though, and as you said, 2 further holes won’t make a difference. I hope that Mazda has also thought of this 😉

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  6. I faced the “flying rocker panel” problem on my ND a few months ago, i got stuck on the mud on the side of the road, the panel made contact with the ground and got loose (ooops, my fault).
    On the ND its fixed by 10 green clips on the top (D10E51SJ3), 5 grey clips on the bottom (BP4L51SJ3) and another one inside the front wheel arch (BGV456145).
    While waiting for the parts to arrive, i drove several weeks without it, taking the precaution to cover the holes with tape. [sentence edited]

    Hope this helps someone 😉

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  7. I finally did this project on my own vehicle today 😉

    You sure need a high quality, sharp drill bit for that high-strength steel! I don’t plan on driving through any mud, but regardless, now I’ll feel confident that a surprise large puddle won’t sabotage me.

    Liked by 1 person

  8. I don’t know if Mazda wrote a TSB for the additional screws, but if you read this thread (especially the last 4 comments), autocrossing cones had the same effect on rocker panel trim on the NCs too, so I don’t see how it couldn’t hurt.

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  9. Hello everyone, taking sort of adavnatge of this secluded times caused by this nightmare, I ve decided to get this thing fixed. Took my dremel, drill bit for metal of a smaller size of a self tapping stainless steel screw and all hope to place few of them as indicated and instructed by the previous posts. Well, I might do something wrong. The dremel of course enter the plastic panel but by no means started to drill the metal rocker rim underneath. Th point was to make a sort of easy access for the screw that I wanted to screw in. I could not get throug. Dremel is dremel , dremel srill bit are of good quality and made for stainless still, places where I drilled as per pics. Don t know what I am doing wrong. Result is a hole on the plastic outside, nothing or so in the metakl rocker panel ( I believe) and myself even more pissed off for what looked like a super easy job. The other idea I had, it was to drill the top of plastic rectangular grey plastic bits ( rocker panel moulding retainer) that keep the piece in place and screw a small screw with a big washer that should prevent the panel to completly fall, if detached ..but it looks like if hit, the plastic retainer should break and thus its washer attached. Hope someone can help me on this.

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  10. Claudio,

    I had a Harbour Freight (cheap) bit that broke on my first hole, so until I found a good, quality, sharp (not dull) bit, it was not easy, as we are talking hi-strength steel in that area. You also need to use a good drill – not a dremel tool, so that you can exert a good engagement force.

    The screws I used don’t require a washer, as it is “built-in”.

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  11. I unfortunately didn’t get to read this article until it was too late. I was driving cross country and ran over some unavoidable small debris on a small highway which led to my entire rocker panel trim flying off (very unexpected since the debris looked like cardboard). I drive a 2017 jet black fiat classica and am now looking for the best way to replace the passenger side rocker panel trim without breaking the bank. Does the fiat warranty cover this? Do I order the part myself since it doesn’t look to be very hard to put on? Where would I even find the part in California? I’m not the best with cars and thought I’d get advice from experts before making any costly decisions. Thank you! Please help!

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    • I doubt the warranty will cover the damage, but your insurance should (after you meet the deductible), and the pre-painted trim should be available through your dealer. Hand the TSB to the body shop installer, and have them add the screws too. 🙂

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  12. My rocker panel trim came dislodged. I need to take it off before applying the process of reinstalling as described.

    How does it come off without cracking/breaking the green clamps or risers that the green clamps are attached to?

    I’m thinking:

    1. Remove body push pins at front and back wheel wells; two each side.
    2. Slide the panel trim rearward past the gray clamps.
    3. Hopefully, sliding the rocker panel trim rearward will dislodge all green clips without breaking them or their risers.
    4. I may be able to simply slide the rocker panel forward and have all clamps realign, or… I’ll probably have to remove the panel trim completely and follow the reinstall procedure:

    A. Remove Green Clips from car.
    B. Place Green Clips on Rocker Panel Trim.
    C. Position LOWER Rocker Panel Trim onto positioned gray clips by aligning and sliding the panel forward 1.5 to 2 inches.
    D. Realign ALL green clips on panel trim (if moved) to be in position of their rocker panel body counter hole.
    E. Pivot panel trim upward and PRESS IN green clips into the body.

    My concerns are:

    1. When removing the panel trim from the vehicle, what is the best way to dislodge the panel trim from the rocker panel without breaking the panel trim, green clips, or clip risers? [Take a rubber mallet and gently tap the rocker panel TRIM rearward from the front wheel well area?

    2. How do you remove the plastic rocker panel trim from the green clips if still attached to the rocker panel body without damaging or marking the trim itself?

    3. There appears to be two side guides on the rocker panel sides in the front and back that the panel trim slides into in addition to where the lower panel gray clips that the panel trim also slides into. I’m wondering how to ensure the panel trim slides into these side guides AND the lower gray clamps at the same time while the green clips are on the panel trim before the green clips have been pressed into their respective rocker panel holes.

    Issue: The passenger rocker panel trim was pushed rearward 1.5-2 inches during vehicle transport. The trucker pushed the trim forward, which placed the rocker panel trim back into place, but the rear is off one green clip and it’s side guide causing the panel to stick out while resting on the green clip. Same with the very front side guide where the panel trim sticks out a bit.

    The body shop said they can do it but releases themselves from all liability should the rocker panel trim break, which they say is commonplace [they stated they can’t get behind it to pry it off because that will scratch the paint.]

    I figure I can do a better job, knowing where the lift points are for the car (#1) preventing additional damage from that, and (#2), I’ll be very careful and do my research to ensure I do it correctly, which is why I’m writing this inquiry now.

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  13. [Warning: Long Post]

    Your information is a good reference as to how you put a rocker panel trim *back on*. Does anyone know the step-by-step process for taking the rocker panel trim off safely so as to not damage any green clip risers or the panel trim itself?

    My rocker panel trim got dislodged in vehicle transport and although back in place, it’s off the clips in some areas.

    The entire rocker panel trim shifted rearward 2 inches. The trucker pushed it forward and back into place, but a few green clips didn’t align so it’s buldging out a little in the back and an area in the front. Only one of the underside gray clips at the rear are in place.

    All gray clips are present; they just aren’t in their slots.

    I’ve seen internet pictures of the rockerpanel body with the green clips attached, and internet pictures of the underside gray clamps either attached or broken off… but I’ve never seen a picture of the inside of the rocker panel where the green clips are attached. Thus, although I know the green clips attach the panel trim onto the rockerpanel by snapping into rockerpanel body holes, I don’t know how the other sides of these green clips are attached at the panel itself.

    I see the green clips have a flat side that faces the panel trim, and thus I’m guessing the green clips *slide* into place at the inner trim panel just as the lower panel trim gray clips *slide* into the lower panel trim slots.

    The reason all this text is important is because when my rockerpanel panel trim slid rearward 2 inches, the green clips didn’t pop off at all, but stayed in place on the rocker panel body.

    When the rockerpanel trim was then pushed forward back into place by the truck driver NOT knowing what he was doing, [and got lucky engaging the rear lower gray clip into place], the panel trim did indeed seem to go back into place, and with proper alignment of the clips, might have actually positioned correctly.

    The rockerpanel looks firmly planted in some areas even though the entire panel had shifted prior. This is telling me that the green clips aren’t hard-fastened at the trim inner side and might indeed just *slide* into place with proper repositioning without removing the panel at all and chance damaging something. There no damage whatsoever as it sits now, and even looks OK unless you look closely at where it slightly buldges out from the rockerpanel. Every shop that has looked at this says it looks like an easy fix but that the panel trim might break in the process ($800-$1400) as is “common”. None state they’ve actually done it before.

    You can see my concern.

    Point: Every suggestion I’ve read talks about putting the panel back on by first removing the green clips from the rockerpanel body, repositioning those clips onto the inside of the rockerpanel trim inner side, and then after the entire lower panel trim is slid onto the gray clips below, rock the panel trim upward so as to clip the green clips into their aligned holes.

    But by design, it appears that the panel starts out rearward, and then with precision, slides forward onto both gray and green clips into place.

    Perhaps during assembly line production with many workers assisting, this precision was possible… getting both lower gray clips aligned and the upper panel green clips aligned so it all just slides forward into place, as my rockerpanel *almost* did.

    One person operation is different, as the OP described [lower gray clips aligned first, green clips aligned and snapped after positioned on gray clips].

    It’s a bummer my entire panel *almost* looks like it’s on perfectly. The non-aligned clips seem to necessitate complete removal of the trim off the car, and thus potentially damaging a perfectly looking rockerpanel trim. I’ve done nothing yet while I research a safe removal process or get information I might not have considered.

    Because the body shop is clear that it might break and that they aren’t liable, and since there are unique lifting points for this car, I’ll probably attempt this myself after someone, somewhere, who’s actually safely removed the rockerpanel trim, relays a safe removal process.

    I found one garage that does Miata’s and lifts our type car correctly, but the owner acknowledged that he doesn’t know what he’s getting into until he actually gets into it, which is fair. I’ll probably go there and chance it… but my ideal would be to leave nothing to chance.

    I[ did recently find one person who has removed the panel trim by prying back the rockerpanel trim at the top, and with a clip-removal tool, pop out the green clips until it’s off… but our communication got disrupted while I searched for the tool, lifts, and jacks.

    If indeed the entire panel simply shifts rearward [as it did before] for removal and access to those green clips, I’d rather do that than “pry” the panel trim back for green clip access and removal.

    So… very long prolog… does anyone have experience removing the Fiat 124 Spider Rockerpanel Trim from the rockerpanel? Mine is the passenger side rockerpanel if it matters.

    Thank you.

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