Building a Carbon Fiber Sunroof Delete| Builds and Project Cars forum |

corradocorrer New Reader
9/11/19 9:59 a.m.

I own a 1992 Volkswagen Corrado VR6T.

As far as I know the Corrado was Volkswagen first attempt at a power sunroof. So maybe I dont have to tell you guys that it's a cluster berkeley that leaks, binds, stops working, starts working again for no reason, then lunches all the internal mechanisms in a grand finaly that may or may not result in the panel separating itself from the car at speed.

The go to solution for the Corrado guys is to swap out the sunroof assembly for a glass Passat unit. I did that. It worked well for a while but no matter how clean I kept the drains the thing would leak during a car wash, or a heavy rain. At some point I purchased a second Corrado as a daily driver. That car spoiled me because it was a non-sunroof car. So now I've got this idea in my head that I need to delete the sunroof.

My goals:

-100% water proof, main reason for doing this is i'm done with leaking sunroofs.

-More head room, I’m 6’4”.

-NVH, so much less wind noise without sunroof.

-Weight reduction, that Passat glass sunroof had to of weighed 40+ lbs.

-A gloss black panel that looks no different than the Passat glass sunroof from a distance.

-Keep it classy.

My first idea was to graft a sheet of composite onto the stripped metal frame of the old sunroof assembly. This would allow me to use the existing mounting points to bolt a fixed panel in place. The drains would be left in tact, and if at some point in the future i wanted to remove it all and go back to stock - everything would be there. I'm also hoping that I can manage to fit a non-sunroof headliner.

The sheet of composite I started with is a throw away from a local prototype shop. It's 4 layers of ultra light with a good surface finish that's sandable/paintable. It was originally formed as a full roof section, so it's got a good thickness and appeared to be stiff enough, best of all it's not a flat sheet - it's got a bit of a curve to it. I was able to cut out a section that has a near perfect match to the Corrado's roof curvature. At the time I told my self: Carbon fiber would have been neat, but this was free, and damn near perfect.

I thought I might also be able to use an OEM seal. More than anything I want to execute something that's a lot more elegant than simply riveting something in place.

These pictures are from 2016. I struggled with poor lighting in my garage; made a template for a thing; had a friend help me cut a thing to the shape of the template; stripped a busted sunroof assembly to the metal bit and binned the rest.

Corrado Sunroof Panel-0565 by Raven, on Flickr

Corrado Sunroof Panel-0552 by Raven, on Flickr

Corrado Sunroof Panel-0555 by Raven, on Flickr

Corrado Sunroof Panel-0557 by Raven, on Flickr

Corrado Sunroof Panel-0556 by Raven, on Flickr

corradocorrer New Reader
9/11/19 10:30 a.m.

To catch you guys up to present. After the progress in 2016 I moved abroad for two years and took a project car hiatus. Now that I’m back I’m egger to get started again on the project.

The replacement delete panel wasn’t exactly successful up till now. I just don’t have the skills or tools to make a piece that fits to my liking. It was decent but then after trimming one side a bit the other side would be off and then I trimmed too much and it was time to start over.

So these are fairly popular in the BMW crowd as a company called http://www.s2rtuning.com makes one that bolts in from the bottom using the factory mounting points. After learning about these a changed my focus to a bottom mount solution like the BMW one.

Here's what a carbon fiber one for an E46 looks like:

I contacted James at Spoonfed Tuning (he makes a lot of carbon fiber parts for Corrados including full front fenders) to see what he thought about making a sunroof delete. He said he's had other people ask before, but due to initial cost for tooling never went forward with it.

Damn.

OjaiM5 Reader
9/11/19 10:54 a.m.

Have you considered doing a slick top? I think this is where I am heading with my M5. Can't stand the sunroof.

Ransom GRM+ Memberand UltimaDork
9/11/19 11:14 a.m.

In reply to OjaiM5 :

I've only heard the term "slicktop" used to refer to cars that just didn't have a sunroof.

Are you referring to a different approach to deleting the sunroof?

corradocorrer New Reader
9/11/19 11:39 a.m.

Despite all my searching over the years (I do regularly search for ‘sunroof delete’), I only recently found this thread on the rx7club forums. It gives me hope that a DIY in the style of the bottom mount BMW delete panels might be possible.

Link to rx7 thread (it’s a good read for anyone interested)!

And some pictures from the rx7 guy

My dad sent me the original metal sunroof panel from my car. This panel had long been removed and replaced by the Passat glass sunroof assembly. Being that it's metal it's a bit easier to work with. Compared to the Passat glass I find that the Corrado panel fits much tighter in the hole, it almost holds itself in place with no other parts of the assembly bolted in underneath.

Using these large magnets I can insure it's flush with the roof line. Then start working on modeling the underside, and follow the basic procedure outlined in the rx7 thread. I want a lip that goes all the way around and is indexed to at least four of the existing threaded holes that used to hold the sunroof assembly in place.

Some pictures from a few weeks ago:

Need more magnets by Raven, on Flickr

Cheers

corradocorrer New Reader
9/11/19 11:46 a.m.

The panel fit less good with the seal removed. I have to remove the seal because it would probably be impossible to get any kind of mold to release from said seal. I don’t think that a mold release tape over the seal would work either. Maybe it would?

I scored some Plasticine clay for free from a friend. This is the same stuff they use at the OEMs to build 3D prototypes. Its hard at room temperature but when heated gets to the consistency of playdoh. If it gets hard too fast while working with it, a heat gun can be used to soften it up again. Scraps can be collected and reused. This is an interesting article explaining how Ford (just for example) recycles thier clay. It's very easy/fun to work with, can be polished and painted or used directly as the plug for the mold.

The reason for the clay is to model the inside of the roof, model the gap from the missing seal, and index the panel to the existing bolt holes on the underside of the roof. It should be much cleaner to work with than an expanding foam, and because its light weight and sticks to things it means i dont need to turn my car upside down.

Playing with Clay by Raven, on Flickr

I'm using a toaster oven out in the garage to warm the clay. The label recommends 140F, my toaster oven dial only starts indexing at 200F. I set it a bit below 200F, the clay doesnt seem to mind but it does get a little too soft if the dial gets too close to 200F and I leave it in too long. Also its a bit uncomfortable to handle barehanded at temps above ~140F.

Playing with Clay by Raven, on Flickr

I started off with some experiments to find out what it will and will not stick to. I tried gloss painters tape, standard painters tape, painters tape with packing tape over it, aluminum foil, aluminum foil with spray adhesive, and the back of the metal sunroof panel. The results were mostly as expected but it was good to get some experience. Mostly I find that the clay sticks well to most surfaces, and more so when really smeared on. It releases best from the gloss painters tape and the packing tape. It doesn't stick well to the foil - this is good because i'm using foil to line my toaster oven tray.

Playing with Clay by Raven, on Flickr

The clay holds a fair amount of detail when released from the surfaces, it worked well around the small wrench and even takes the impression of the tape lines. I'm optimistic that this will do what i have in mind.

I removed the sunroof seal from my metal panel, this left a ~10mm gap around the whole thing. I'll use the clay to fill this gap as well as model the underside of the roof. I had to remove the seal because it will probably stick to the gel-coat of the mold, the clay will not stick.

The black aluminum drain tray was bolted up and clay was pressed into the trough and channels. I can then set the panel down and get it evenly spaced in the hole. I used the red welding magnets to keep the gap and hold the panel level to the rest of the roof.

The goal is to get the clay to stick to the black drain tray and the green sunroof panel but release from the car that I've covered in tape. Once the clay is hardened and the panel is fully supported to the drain tray I hope I can just unbolt the whole thing and drop it down out of the car.

This metal/clay monstrosity will ultimately be the plug for the mold, for the carbon fiber sunroof delete panel.

Delete the roof windows by Raven, on Flickr

I just used my bare hands to stuff as much clay into the gaps and my fingers to smooth out the top of the surface. Extra clay can be scraped away, then re-heated and used again.

Delete the roof windows by Raven, on Flickr

Mind the gap by Raven, on Flickr

Double two hearted was good.

Delete the roof windows by Raven, on Flickr

Next steps:

1. complete the metal/clay plug

2. get the plug to release out of the car

3. mount the plug to some plywood

4. start making the mold.

corradocorrer New Reader
9/11/19 11:57 a.m.

This brings us to last night. The plug is out of the car.

Removing it should have been a two man job, but I gave it a try on my own. The plug released from the car better than expected however the upper lip was lightly damaged and even cracked in two places because i wasn't able to drop it down completely straight on my own. It's a bit awkward and now also heavy.

The Plug by Raven, on Flickr

Next I need to make sure that the plug doesn't have any negative slopes, cavities, hard edges, that kind of stuff. I started hacking away at the excess.

The Plug by Raven, on Flickr

Look at that height across the back. There's our missing headroom.

The Plug by Raven, on Flickr

I then started to get the lip at the top fixed, I used a combination of straight edges and old templates I had made of the sunroof opening. It was looking good.

The Plug by Raven, on Flickr

But then a problem. On the leading edge the passenger side is significantly lower than the driver side. See if you can tell by these pictures:

The Plug by Raven, on Flickr

Driver side:

The Plug by Raven, on Flickr

Passenger side:

The Plug by Raven, on Flickr

I'm hoping that it's just the black tray that bent. There's some indication that it might be. It's curious that the panel was sitting so flush in the car and now it looks like its been wonked low in the one corner. Tonight I'll get some help to bolt the plug back into the car and check that it is indeed flush to the car. So long as it's flush to the car I shouldn't have to care if it's flush to the bench.

OjaiM5 Reader
9/11/19 12:07 p.m.

Ransom said:
In reply to OjaiM5 :

I've only heard the term "slicktop" used to refer to cars that just didn't have a sunroof.

Are you referring to a different approach to deleting the sunroof?

I think I am going to weld in a panel making it a home job slicktop. Looks like you are well on your way with the Carbon. Good luck!

corradocorrer New Reader
9/11/19 12:09 p.m.

OjaiM5 said:
Have you considered doing a slick top? I think this is where I am heading with my M5. Can't stand the sunroof.

Normally when they do a full carbon fiber roof it involves removing the spot welds and cutting out the original metal roof, then bonding this pre-molded sheet in place to the remaining roof supports and cross braces. Gluing a giant sheet of carbon fiber over the existing metal doesn't sound like the most elegant solution.

+1 vote for 'Slick Top' referring to a non son roof car form the factory.

corradocorrer New Reader
9/11/19 12:12 p.m.

OjaiM5 said:
Looks like you are well on your way with the Carbon. Good luck!

Dont let the progress fool you. I have no idea what I'm doing.

TurnerX19 Dork
9/11/19 3:19 p.m.

Don't be surprised if the irregularity in your buck is a perfect match to the car.. Stuff that is hidden on a finished car is often asymetric.

TVR Scott GRM+ Memberand HalfDork
9/11/19 7:09 p.m.

Looks pretty cool. Keep working at it. I've done a lot of composite work and there's no substitute for experience. Don't feel bad if you mess up and have do redo something.

On that note, make sure you make your first parts from fiberglass!

corradocorrer New Reader
9/13/19 7:14 a.m.

Crisis averted. @TurnerX19, you were right the drain pan is asymmetric. I guess it makes sense that the tray has a slope/tilt to it as this would prevent water from stagnating in the gutter.

I bolted the plug assembly back in and it is indeed still flush to the car. I'm not however happy with the way it's not perfectly centered in the hole. I think I'm going to re-do it.

My buddies that came over the other night suggested I ditch the metal panel from the plug and make the plug entirely out of clay. It's definitely something to think about, probably worth a try since I'm going to re-do it anyway.