bkb840 on 2006-01-10 at 09:09:54
After examining all, I humbly believe, possible ways to gain more headroom than the stock 35.9" in my '97 840, I settled on the only viable option: eliminating the sunroof. For those who might be making do with the same problem (from my earlier queries here on RF there are quite a few who are over 6'3", and therefore whose driving posture is a slouch), here's what I did:
First, I ordered a non-sunroof headliner, in the appropriate color, from Germany, via Gault ($273.75), with retaining clips, the latter turning out to be unnecessary as the originals can be re-used. Next, I removed the old headliner and everything to do with the sunroof. This is where my DIY efforts ended.
Next, I had an excellent sheet metal guy weld in a cross frame support (a-c, b-d), in the opening, about an inch below the exterior roof line, which essentially replicates the BMW spec on non-sunroof E31s, and incidentally provides significantly more structural rigidity than U.S. sunroof models enjoy.
Next, he covered the opening with a slightly larger piece of "waterproofed" steel and welded it in place, which was most time-consuming. To eliminate any potential for waves and burbles, he welded only 1 inch at a time, on opposite sides, doing all of two parallel sides, before doing the other two, perpendicular sides. Actual welding time was probably only 3-4 hours, but it took 10 days.
After grinding and making the exterior paint-ready, he sealed the inside, insulated both above (75%) and below (25%) the cross-member, and installed the new headliner. The new roof is being painted today.
I've gained almost 2.5 inches. All in, it cost about $2000. In my case, the replacement headliner pretty much perfectly matched the remaining pillar liners, dove gray, so I didn't need to buy those. Can't guess whether this color match would be universal.
Not at all sure how many headliners are available, but I'm pretty sure that BMW won't be making any more, so if you want/need the headroom, now might be a good time to go for it.
