Plating a Sunroof on a Competition Car

[dc2100k]

Is there any standard thickness of sheet steel that is appropriate for this? Car is 1990 BMW 318is to be used as targa/historic rally car and will have a cage.

I plan to remove the headlining and sunroof cassette, then plating over the sunroof aperture with a wide margin. Should I put additional plates at each of the corners on the inside in order to stiffen them up, and possibly bond some small angle to the underside of the main plate for stiffness? I’m going to plate in a single sheet of flat steel with the minimum of shaping required, and pop rivet around the perimeter at 50mm intervals. Usually people use silicon sealant to seal this up but I’m considering using Gripbond Pro adhesive on the overlap and some seam sealer on the inside. The exterior of the sunroof will be rattle canned and for the inside I was going to cover with a bit of foam camping mat and glue on a dark grey carpet tile where it is visible through the original headlining hole.

Anybody done this before can give me any pointers? Cheers.

Edited by dc2100k on Monday 8th June 13:32

[C.A.R.]

If it's going to be a competition car and be caged etc. why not go for a fibreglass option? Or GRP, or even carbon (££)?

A quick google suggests these are pretty common and can be had for as little as £200.

[dc2100k]

In an ideal world I would do something fancy but a square metre of 1mm sheet steel is only about £20 so it is a budget option really. Also the silhouette of the car needs to be unchanged and lots of these competition roofs have air vents which won't comply.

I'm more wondering if 1mm will be thick enough, or 1.5mm or even 2mm but that's starting to get pretty chunky!

[kambites]

dc2100k said:

I'm more wondering if 1mm will be thick enough, or 1.5mm or even 2mm but that's starting to get pretty chunky!

I doubt the actual roof pannel is as thick as 1mm. Given that it's not going to be structural, anything will do.

[dc2100k]

I know the Mk2 Golf GTI racing series requires 1.2mm (18swg) steel sheet riveted to the roof so that's probably not a bad place to start. I'll stiffen it up on the inside as feels appropriate.

[kambites]

Ah you're going to rivet it? I assumed you were going to weld it on.

[dc2100k]

Hi kambites, clearly it would look better welded but I believe this is a massive job to do without distorting the roof so I'm just going to go basic on it! It's a rally car, will be covered in scratches and dents anyway!

[kambites]

Fair enough.

You may well want something stronger then, and you'll probably want a fairly big overlap and several rows of rivets to lessen the risk of it being ripped off if you roll.

[Evoluzione]

I did it properly by making a sun roof shaped former from some MDF and bashed out a sunroof panel with a flange on it. This sat inside the hole with the flange of that sat against the flange in the roof. I just welded the two together underneath so zero distortion and a perfect looking roof. Filled the gap in between on top with panel sealant and painted it. It looked factory perfect.