The sunroof cassette in a BMW E36 is an easy target for “adding lightness”. It’s nearly 40lbs of weight at the highest point in the car. So removing it will not only reduce overall weight in the car, it will also lower the center of gravity. Another easy addition to aid handling in autocross is installing a larger front sway bar (aka anti-roll bar). We’ll be tackling both of these installs in this post. This may not be the most exciting post on my blog but it offers a lot of technical details that I was looking for when performing my own research!
In the picture above you can see the whole sunroof cassette in my stripped interior. It nearly covers the entire roof area. Note that I’ve previously removed the sunroof motor and control panel. The plan is to remove this entire cassette and replace it with a simple fiberglass panel.
Once you remove about a dozen screws, the entire cassette will just fall into the interior. Maneuvering it out of the door opening may be the toughest part of the removal. My lack of a passenger seat definitely helped out…
You’ll be left with just a gaping hole in the roof and the old gasket that sealed the metal sunroof panel in place.
I used a razor blade to remove the old gasket. You’ll want to get this as clean as possible so the new gasket seals well.
The old sunroof cassette (with the motor and control panel) weighs just about 40 lbs. The new fiberglass panel weighs 3 lbs. Definitely a great weight savings!
The ECS Tuning fiberglass panel is the exact same shape as the metal panel but with the addition of a flange for mounting. The finish is really good and it’s gel coated so it can be installed directly in the car without painting (like I did).
The original screws are used to install the fiberglass panel in the car. I did need to drill 3 holes in the roof to install pop rivets to secure the panel fully. This was no problem though and very straight forward.
Once fully installed, the fiberglass panel has a great, uniform gap all the way around. A tight fit but a gasket should be added for total weatherproofing.
After some research, I decided that 3M Windo-Weld black urethane was the best solution for the gasket. Easy to install with the squeeze tube and a strong waterproof seal. Just make sure to appropriately mask the gap as I’ve heard that removing the urethane from a surface once dried is very difficult.
After a little trimming with a razor blade the finished product looks good enough for a race car. Done!
I’ve felt that my car still has too much body roll in the front and could benefit from a larger diameter sway bar (aka anti-roll bar). This should also improve turn-in and steering feel at lower speeds (like an autocross). I tried running it with the stock bar in place for a season but I think it’s time to upgrade. I purchased a larger Eibach bar with matching polyurethane bushings.
My stock sway bar measures 23.5mm while the new Eibach bar measures 28mm.
The install is really straightforward and the red bar looks nice! We’ll see how the new setup performs in the next event. Until next time!