The following article gives detailed instructions on repairing the rear spoiler on a BMW. Even though we have used a 2013 M3 to perform this repair, this article can be applied to any BMW vehicle with a rear spoiler with minor modifications.
If the rear spoiler on your BMW is loose or is beginning to peel away from the trunk lid, then you are in need of a rear spoiler repair.
It is a popular misconception that the rear factory spoilers on many BMWs are “mechanically” attached to the body (ie: screwed or riveted on). Factory spoilers are actually attached to the trunk lid with an adhesive, and after years of use have been known to separate from the trunk lid. The rear spoiler on your BMW is under excessive pressure, especially during high speed driving. As its adhesive becomes old and brittle, these loads can actually cause the spoiler to separate from the trunk lid creating a dangerous projectile.
There are several obstacles that you may want to consider when doing a rear spoiler repair on your BMW. First, you may have to replace the spoiler. If the spoiler was attached with a factory adhesive, it is going to still have the glue attached to it (as well as some paint) which is almost impossible to remove. It is often much easier to purchase a replacement spoiler than trying to recondition the old one.
Second, if your spoiler is attached with a factory adhesive your are probably going to lose some clear coat (and maybe paint) during the removal process. It is important to take this into consideration if you are planning on changing your spoiler design.
Finally, there are many suggestions online offering advice on anchoring your rear spoiler to the trunk lid. The BMW Repair Guide only recommends using Dow’s Betalink K1 polyurethane adhesive system to attach a rear spoiler to your trunk lid. Dow Betalink K1 is a BMW factory adhesive that will give you years of confidence in your spoiler’s attachment to your vehicle. Please see our parts list below for ordering Betalink K1. Click her for a brochure on Betalink K1 explaining the product in more detail.
The most important steps in a rear spoiler repair are removal of the existing spoiler and the adhesive left on the paint. It is critical to use the correct removal technique so you don’t damage any surrounding paint that is not hidden by the spoiler, and that you are left with a nice clean surface. We have found that softening the underlying adhesive first with a heat gun then using 50 lb braided fishing line is the most effective method of removing the rear spoiler from the trunk lid. Use 3M spray adhesive remover and a plastic scraper or plastic razor blade to remove the old adhesive from the paint. Please see our supplies list below for links to all of these products.
DO NOT USE THE 3M Adhesive Eraser Wheel to remove any old glue stuck to the trunk lid. The eraser wheel will also erase your paint…right down to the bare metal if you are not careful. If the wheel slips while you are “erasing” the adhesive, you will be repainting your whole trunk lid.
1. Spoiler adhesive (required) – As discussed above, we only recommend using Betalink K1 for attaching a spoiler to the trunk lid of your BMW. Don’t be fooled by less expensive adhesives that claim they can do the same job.
- To begin the rear spoiler repair, use a heat gun to soften the old adhesive. Use long sweeping motions; avoid holding the gun in one spot for longer than a second. Use caution – the heat gun can damage your paint. If you use a slow sweeping motion down the length of the spoiler you will avoid any damage.
- Cut a piece of the braided fishing line approximately 48″ long. Use a back and forth “sawing motion” to quickly cut through the adhesive separating the rear spoiler from the trunk lid.
- Spray the 3M Adhesive Remover liberally over the remaining glue letting it soak for about a minute. Note the clear coat and paint damage on our M3 from when the spoiler was removed.
- Use a plastic scraper to remove the adhesive and