# Rear bumper gap revisited (long)



## biodan (Apr 9, 2003)

We're all aware of the rear bumper cover gap that can occur on new and used E46M3's.

With the service bulletin in hand, i was unable to convince my dealer to fix my bumper gap. The service manager put a mirror below my rear bumper cover and saw all the R-compound marks (didn't clean the bottoms! doh) and said (1) it was a wear item and (2) the bulletin was put out in 98 and the E46 bumper gap problems were solved in production. I will be curious to examine new M3's and see if they have the clip.

Rather than argue, i bought the clips (part 51 12 4 015 053 for $6) and figured i'd do it myself. However, i discovered that the instructions were not entirely accurate... the figure shows cutting a flap out of the 'plasticized undercoating from the lip'. However, my lip was metal and could not be easily cut with the recommended utility knife. I considered briefly using my Dremel tool with metal cutting blade... Instead i devised a shim hack which will be tested for stability. For one, two single-piece shims could be made.

Here's a montage of the exterior. Left is before, Right is after inserting the shims.









*Methodology*
Upon closer examination, i noticed that the rear bumper cover sits on a black plastic carrier that had was screwed into the chassis. The bumper cover has a ridge that sits along a channel in that black plastic carrier. However, there is a fair amount of play below and adjacent to the bumper cover ridge. So i wedged a couple of home-made shims below and on the outer edge of the ridge. This allowed me to raise the bumper cover, but while not entirely flush, its an improvement. If it continues to bug me, i'll reconsider my options.

Here is a shot of the passenger's rear wheel well. The horizonatal whitish curve is the 'lip' and the black tube at the right is the gas-fill tube.









Here is a montage of the wheel well. On the left are 2 rectangles corresponding to the positions where i put the shims (made of cut zip-tie sections about 2" long stacked atop each other to give 3x thickness...taped with PVC tape). The orange rectange was 1 zip-tie wide. However, the green rectange was 2 zip-tie widths (also 3x thick). I left the end of 1 zip-tie on each shim to allow for removal but found that the shims are wedged in very tight and are difficult to remove. It will be interesting to see how long (or miles) it takes for them to come out from vibration.


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## The HACK (Dec 19, 2001)

You know what else you can do to alleviate the problem? loosen the bumper shock absorber support from inside the trunk, and lift the entire bumper assembly up a little and then re-tighten the nuts. That'll give you about 2mm play on the bumper height and will make it easier for the clip to stay on.


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## biodan (Apr 9, 2003)

*did you read what i wrote?*

The lip was not plastic as the instructions claimed. It was metal. I'd have to do some serious cutting... Something i'd rather not do at this stage.

Also that ledge is wider than the instructions said and the bumper ledge itself is not a square edge, its rounded so the clip could easily come off. They do recommend using a windshield adhesive to prevent corrosion.



The HACK said:


> You know what else you can do to alleviate the problem? loosen the bumper shock absorber support from inside the trunk, and lift the entire bumper assembly up a little and then re-tighten the nuts. That'll give you about 2mm play on the bumper height and will make it easier for the clip to stay on.


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