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DIY: CSL Trunk Conversion E90/92
Published by Tyspeed
DIY: CSL Trunk Conversion E90/92

Hello all,

I Promised my customer that I would post a little more of an in-depth look at what it took to perform the CSL trunk conversion on his e90. As it is described through ECS tuning, and many other sites where carbon fiber/fiberglass trunks are available, mounting an aftermarket deck lid is "perfect fit, and easy installation". RIGHT!

Having performed various installations before from fender flares to CF hoods, and other components I had an idea already of what was ahead of us. The customer quite simply thought because "HE READ ON THE FORUMS" that it was as simple as having the panel painted, and slapping it on there..... Anyway, I have put together a little write up as to what steps were involved below, and some pics of the final product.

The total cost for this customer between purchasing the trunk, paint, and installation was about $1,300.00 Not cheap, but it really transformed the look of this e90!

Step 1:

Bring panel prepped for paint to a decent, respected body shop with proper tooling. Many people expect a perfect paint job for $200. This is not possible.

Paint= prep = time = money

So if you want it done correctly you will have to spend money. The paint supplies, and labor for painting of this trunk lid came in at about $450 all said and done. This was not the cost of installation of the trunk on the vehicle.

We received the trunk fresh out of the booth and immediately began wet-sanding with 1500 Paper to smooth any imperfections and correct any excessive orange peel.

After using some McGuire's step 1 compound and polish, as well as some cheap labor , the result:

Great! we're done right????


Next step, we removed the wiring harness and all accessories (more parts than you'd think from the OEM trunk. Be careful when removing the harness not get get stuck on any sharp edges that could lead to wiring harness damage.

Then we loosely installed the bare aftermarket CSL trunk in place of the OEM , using the 4 machine threaded bolts, fitting them just snug to the new CSL trunk.

Now comes the fun part! Re-assembly.

We found several modifications will need to be made to the trunk in order to use it as an OEM piece. The majority of this work will not need to be performed if you are using this for a track car. My customer will still be using his as a daily driver so it had to retain OEM fit/finish.

First, You must cut a rounded-triangle hole in the lower corner to fit the harness plug. Use a piece of tape and a marker on the OEM trunk to transfer the pattern, as this is not done on the ECS CSL trunk:

Then you can proceed to run the harness through:

Now we must drill holes in several places of the inner frame to accomodate the harness attachment points, and various accessories. The drill bit sizes vary, but we needed to drill holes for the OEM trunk latch mechanism, the roundel badge, and more as you will read below.

You will find that the holes for the license plate lights, trunk release handle are too small, and are not exactly cut. We used a medium sized file with a flat edge and handle to carefully enlarge the holes to fit all the components. It will require a healthy amount of sanding and shaping. Note the shape of the light hole on the left, and the distortion of the release handle. Another requirement will be to feather the edges of the fiber glass thinner in the areas of these pieces. We found that the edges were too thick to allow the parts to mount as designed, which is by "hooking" the edge of the opening on one side, and using a push spring on the other. This is a tedious and important step, as going to far, and the accessories will not stay in place/fall out.

After some time fitting all the little bits, and properly routing/securing the trunk harness, it was time to mount the inner trunk carpeting.
You will find on the ECS CSL trunk there are no provisions for this, and the trunk will not have cutouts in the mold to fit the 2 detents in the carpet. You will need to cut these parts out:

This is to allow the molded "inner grab handles" of the carpet to fit inside the trunk. BE careful if using a cutoff tool or grinder to not penetrate the outside layer of fiberglass as you will ruin your brand new trunk.

You must finally lay up the carpet against the trunk and while a partner holds in place, carefully mark the holes to be drilled for the push-pin clips to retain the carpet in place.

Now you are basically done.

***One other suggestion, is to only install 1 Trunk lid lifting strut. This is because they are normally used together to raise a much heavier, steel trunk. The fiberglass trunk is SIGNIFICANTLY lighter and can crack easily, especially at the mounting points. We found that 1 strut was idea for proper function and least possible chance of damage during use. ***

Some finished installation pictures complete with aftermarket tails which required some fitting in itself, as well as re-pinning the connectors on the trunk harness due to fitting NON-LCI tail lamps, to an LCI (2011) 335i. Ill let the car owner explain more on that.....

Thanks for checking out this DIY, and I hope its useful.

Tyler Pappas

Owner/Operator Tyspeed Automotive
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By ritchwell on 11-18-2015, 05:18 PM
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Thanks Tyler for the write up, I ask him to post here in order to help the community of the csl trunk conversion purchase from ecs tuning. As for the reason why do I have pre lci after market tail lights instead of putting my stock oem ones is that when I purchase the trunk in August the sales person who helped me purchase the trunk made a big boo boo and put the pre-lci trunk version in the check out cart. Did not know the mishap after the trunk has been painted and installed by Tyler. Don't want to go in great detail because I will put a post regarding my experience with ecs customer service in the vendor comment/review/feedback section. As you can see things did not go well with ecs so I bought an aftermarket tail light, the lights looks awesome although I prefer the oem tail light look. The fitment of the lights are not perfect but it can be attributed with some imperfection of the trunk and the aftermarket lights. Anyways I hope my input was helpful.
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