continued from above
INTERIOR INSULATION REMOVAL
We were looking for every pound, remember? Next up was the heavy asphalt/tar sound insulation panels stuck all over the interior and trunk areas. These materials are a chore to remove, but it adds up.
A heat gun + a variety of scrapers + lots of elbow grease are the best way to remove this stuff from a BMW. Trust me, we've tried all of the methods - freezing with dry ice, power tools with wire wheels, and sandblasting - and the heat gun is the cleanest, fastest way for the BMW insulation.
17.7 pounds of tar paper came out of the interior and trunk. But it left behind this tacky adhesive goo....
The car still rolls at this point so it was shoved outside and the electric pressure washer was used to blast every surface of the chassis, inside and out. 2500 psi gets all the dirt and grease off the chassis, but it won't make a dent in the adhesive residue.
Over the years we have tried numerous degreasers and petroleum products and found that soaking the adhesive with mineral spirits works like a charm. It softens the adhesive enough to wipe it away, but doesn't damage the paint. Of course we're going to paint this entire chassis inside and out later, but having bare metal during the build process might allow it to flash rust. So .... heat gun + mineral spirits works best on this stuff.
ROOF STRUCTURE REMOVAL + CARBON ROOF PANEL
We still weren't ready to start the roll cage, and needed to do something about the power moon roof that was in the way.
Left: 72.0 pound factory sunroof cassette. Right: AJ Hartman carbon sunroof delete panel at 1.4 pounds
Like most E46 BMWs, this one had a factory retractable sunroof option. The non-M E46 almost always has a sunroof, but a few E46 M3s came without a sunroof - including the CSL.
The 72 pound power sunroof assembly (they call it a cassette) is not only a heavy thing but it gobbles up head room in these cars. We had talked early on about a carbon fiber sunroof delete panel, which we have done on a number of E46 chassis to knock weight out of the roof while gaining 2.5+ inches of headroom (like my E46 330Ci above). Another AJ Hartman pieces that is an easy "bolt-in" replacement you can swap in over a couple of hours.
Since this is a 2003 BMW M3 CSL clone of course we have to use the CSL's full carbon fiber roof panel, duh! We had AJ Hartman make an exact replica of this CSL roof panel, which Mr Chainsaw agreed was more appropriate for this build. Ryan started the roof swap by removing the two roof seam covers, then drilled out spot welds with a small spot weld cutter.
Ryan received some help from our CNC operator, also named Ryan aka: "R3". The two Ryans then finished removing the 100+ spot welds around the perimeter of the factory steel roof panel, prying the glue loose after these spots were carefully cut through. The front and rear glass removal was crucial in this step; the roof came off in a little under 6.5 hours.
continued below