Rear aero project - Civic notchback coupe

[brucepick]

Originally Posted by Cd

... why not just have it extend from the roofline ? It could be mounted on a hinged edge so it could swing upwards with the trunk. It would them match the template curve without the additional drag of a flat spoiler design.
Of course it would have to be transparent...

Actually this is a very tempting thought. After all, the side panels are very close to the template curve so why not put the center panel on the template and really get it right?? The trouble is, all the neat solutions in the existing concept go out the window (nearly literally), or you might say out the roof.

For an mpg competition or a car show, I maybe could just make it out of cheap plastic and tape it on. Build it and use it, then take it off. But for long term use with full trunk access... ... ...

The toughest challenge I see in extending a panel from the roofline is that the roofline is bowed upward at the middle, when you view from the rear. This makes for problems in hinging the panel for trunk access. Couple that with the preference for a panel that curves downward towards rear per the template, and that means the panel would have a compound curve, not easy to build or even to fake.

The hinge for the horizontal panel - to enable opening the trunk - is what I'm having a very difficult time picturing, due to the bowed roofline. I think the widest possible spaced hinges would be two, about a foot apart, centered on the roof transverse line. The outer corners of the panel, where the roof meets the C-pillar, would have to be free to hinge the panel up to open the trunk. I could anchor those front corners with removable screws, and would have to remove them before releasing the trunk latch. Even so, I fear the plastic would eventually crack when lifting it up supported only by two hinges at the forward end.

To give it the compound curve, I could cut a lengthwise slit in the panel, and slightly overlap the edges. Or turn the slit into a V-cut and just bring the two edges together. Either way, the plastic panel is weakened by the cut, and would need fasteners down the center.

Cd, ya got any ideas on this stuff?

[California98Civic]

I hope Cd has answers for your questions, and I don't want to distract from your request for his thouhts:

Originally Posted by brucepick

Cd, ya got any ideas on this stuff?

But I have a different suggestion. What if trunk access were significantly rethought. What if the trunk lid itself were modified so that the lid only lifted 6" and the aft portion of the lid, with the tail lights, swung down like a tail gate? The clear kammback would not need to move anymore.

Originally Posted by brucepick

The toughest challenge I see in extending a panel from the roofline is that the roofline is bowed upward at the middle, when you view from the rear. This makes for problems in hinging the panel for trunk access. Couple that with the preference for a panel that curves downward towards rear per the template, and that means the panel would have a compound curve, not easy to build or even to fake.

The hinge for the horizontal panel - to enable opening the trunk - is what I'm having a very difficult time picturing, due to the bowed roofline. I think the widest possible spaced hinges would be two, about a foot apart, centered on the roof transverse line. The outer corners of the panel, where the roof meets the C-pillar, would have to be free to hinge the panel up to open the trunk. I could anchor those front corners with removable screws, and would have to remove them before releasing the trunk latch. Even so, I fear the plastic would eventually crack when lifting it up supported only by two hinges at the forward end.

To give it the compound curve, I could cut a lengthwise slit in the panel, and slightly overlap the edges. Or turn the slit into a V-cut and just bring the two edges together. Either way, the plastic panel is weakened by the cut, and would need fasteners down the center.

Cd, ya got any ideas on this stuff?

[brucepick]

Now you're thinking outside the box, um trunk!!

Originally Posted by California98Civic

...
But I have a different suggestion. What if trunk access were significantly rethought. What if the trunk lid itself were modified so that the lid only lifted 6" and the aft portion of the lid, with the tail lights, swung down like a tail gate? The clear kammback would not need to move anymore.

[MetroMPG]

Subscribed!

[brucepick]

MetroMPG (or anyone else with a good suggestion on this),

Any tips on how to attach the side panels to the C-pillar and the quarter panel? This is turning out to be important; the clever mount brackets I built won't pull the forward and rear corners of the side panels against the body.


I suggested rubber expansion plugs (aka well nuts) to a friend of mine.

Flange side (right) is where screw goes in.


The plug is inserted in opposite direction here; the flange is on left side under the washer.

My friend is concerned about:

A) There's additional folded-over steel layers at the top where the roof & C-pillar meet, put there for strength. Probably don't want to drill into there where it's supposed to have strength? But that's exactly where one of my attachment points needs to be. I haven't come up with a fix for that issue.

B) The expansion plugs will allow rust sooner or later. We've both seen it happen, but 10+ years after a roof rack was installed. I think I can delay rusting long enough by priming the drilled holes and maybe also some silicone glue smeared on the expansion plug before inserting it.

I still like expansion plugs but I'm open to other suggestions.

[Sven7]

I'm going to go out on a limb here and say depending on how big the whole is there shouldn't be a problem. The "mohican line" is there not only for a little bit of strength, but to hide the body welds. I don't think it will cause the car to collapse upon itself but you might not want to roll it.

Priming the drill holes sounds like a fine idea, and silicone should hold up reasonably well. I'd use housing grade caulk that's made to withstand UV rays.

[Cd]

Originally Posted by California98Civic

I hope Cd has answers for your questions, and I don't want to distract from your request for his thouhts:

But I have a different suggestion. What if trunk access were significantly rethought. What if the trunk lid itself were modified so that the lid only lifted 6" and the aft portion of the lid, with the tail lights, swung down like a tail gate? The clear kammback would not need to move anymore.

I think the fold down tailgate idea is a brilliant idea ! ( and reversible )
Just remove your stock trunk and find tailgate from a 92-95 Civic Hatch.
Everything bolts right up and it even has a lock to hold the new Kammback in place.

[Cd]

Hmmm ...or does it ? I think i posted too fast on that.

I'll do some measurements and post back.

The nice thing about using a stock tailgate is that is has a rugged construction and looks professional if you were to paint it to match the car ( good luck finding a silver 92-95 Civic hatch at the salvage yard )

[brucepick]

Originally Posted by Cd

Hmmm ...or does it ? I think i posted too fast on that.

I'll do some measurements and post back.

The nice thing about using a stock tailgate is that is has a rugged construction and looks professional if you were to paint it to match the car ( good luck finding a silver 92-95 Civic hatch at the salvage yard )

Nice idea but mine has a trunk not a hatch. I can't imagine the hatch lid would fit where the trunk lid is now.

[Sven7]

It's also an EK. I don't know if the trunks swapped between generations.

You could always fab something up but it would probably look bad and work badly (no offense to your fabrication skills- thinking about this from a designer's perspective).

Have you thought about mounting trunk levers up by the top of the C pillars? Some trunk lids now lift up as they open to clear the compound curves. You'll see this on most recliner foot rests too. Basically it would be two levers of different sizes on each side. Instead of opening parallel as matching levers do, it would tilt to the front. The longer the levers, the higher up the thing lifts to clear the roof. You could add a small strut or spring to ease opening.

That way, the entire thing would lift up like a liftback and might actually close and seal right if you do it well. Or, you could hinge the Kammback separately. This would probably be easier to do. You could line the bottom end of the thing with rubber tubing to seal it and attach some simple elastic hooks on the back to secure it.