General Bla
I've been researching whats required to do a carbon roof on the E46 coupe and might document here in case others want to follow the same path including the required LVVTA certification etc. One or two might think this is over capitalising somewhat on the ex 318 so will also document my reasoning 🧐
Got sunroof, don't want sunroof
Weight savings (mostly in the sunroof delete)
Want black interior so would need to do a new head liner anyhoo ... yes, the tail wags the dog
It's within the realm of the DIY'er
Have the opportunity to help manufacture the roof itself via vacuum infusion
Just looks cool !!!
On Certification
I'm always keen to do things properly so I got in touch with the LVVTA to see if there is any certification interest in replacing the skin. As there is no definitive information for this procedure they took it to their Technical Working Group (TWG) for consideration. After a bit of back and forth the below statement was arrived at which provides the framework for doing the job.
"Based on the information provided, assuming that the procedure involves removing only the sunroof cassette and single layer of roof skin, that any spot-welded areas (particularly along the roof seams and apron areas) are either unaltered or restored to OEM specification using a compatible repair process, that the central roof bow is attached in a way that replicates the OE method of attachment, TWG are happy with the principle of this idea. However, the final approval must come from an LVV Certifier, and in addition to the above, they must be satisfied that the structure of the vehicle has not been altered by this modification beyond a safe tolerance of OE. They must also be satisfied that the bonding agents used to reattach the new roof skin are appropriate for the intended use."
I've been in touch with my certifier and he has outlined the inspections he would need for this:
After the steel skin has been removed and the hood bow fitted
After the new roof goes on but before glass installed
Once everything is completed
The Process
There are many videos on YouTube of people doing the procedure, some of the better ones are linked below.
Showing the roof skin being a single layer coming off the structural members: https://youtu.be/GhTOA7Cl9fk?t=140
Showing a bit more of the overall process: https://www.youtube.com/watch?v=wmC-gooNM0M
The official procedure from BMW for replacement of the M3 CSL roof can be found here, which will be the process of installation for me: https://www.newtis.info/tisv2/a/en/e46-m3-csl-cou/repair-manuals/41-body/41-31-roof/4K9opCv
What Next
Need final confirmation the mold is indeed to suit the E46 coupe then I need to locate some spare cash. May take a little while until the next update but that's where things are at currently.