My Kammback'ed VX

[MazdaMatt]

impressive hack Definately trim the bottom edge horrizontal, though. TUFT TEST TIME

[BrianAbington]

not bad...looks nice but plexi scratches very easily.

[cmittle]

Not to be picky but for clarity what material are you using? You mention plexiglass and polycarbonate which are 2 different things. Polycarbonate is better known as Lexan, and plexiglass is a trade name of cast acrylic. Plexiglass will thermoform but is more brittle than polycarbonate. If you try to drill holes in plexiglass without being extremely careful it will crack and that crack spreads very easily/quickly where I see Lexan (polycarbonate) being the better choice for this application. That being said I believe that Lexan is more expensive than plexiglass.

I do like what you made and I'm glad you posted so much information and pictures showing us how to mimic it. I'm just trying to help anyone who may be following your instructions so they know what material would work best.

[MazdaMatt]

I was at home depot, a sheet of plexy was 20 bucks, the same sized sheet of lexan was 120 bucks. So if you're not sure, look at your bill!

[TomO]

Thanks for all the encouragement and kudos.

I am planning on trimming the bottom edge to a degree that is parallel to the ground (horizontal).

Originally Posted by cfg83

TomO -

WOW! I really like this one. Practical and pretty. What is the thickness of the Polycarbonate glass?!?!?!?!

CarloSW2

It's 1/8" I believe. Very sturdy after I heated and curved it. I don't feel a need for a center support, it doesn't flop or anything.

Originally Posted by Tango Charlie

Very, very nice, TomO.
Why are you the first to use plexi? Everyone should be using this for kammbacks!
It looks like the top follows the same angle as the roof of the car. Would it be better if it tapered down just a bit, keeping within that notorious 15 degrees?

p.s. Your wife is way too picky. It looks AWESOME.

I was wondering why anyone didn't make one in plexi by now... I had some laying around and gave it a shot and am pleased with it so far.

The sides are not anchored permanently yet so I can actually change the angle of the slope by removing the tape and repositioning the sides. Once I figure out the proper angle I will mount the sides with an aluminum "L" bracket. I will still have the edges trimmed with Gaffer's tape though as I like the look of it.

Here is a quick snapshot of most of the car as I could get with my Cell:


If someone could photochop that wing radius on there for me (photoshop 7 won't work on my Intel Macs running Leopard) that would be awesome!

I'm not worried about scratches because even if it does scratch it still won't affect visibility as Coroplast would've.

I had this 4' x 8' piece of Plexi sitting up at my parents' cabin not being used for anything, so I don't know where, exactly, it came from. I imagine that Home Depot, Lowe's, Menards, or any other larger home improvement store would be able to order it or carries it. That size sheet is actually enough to make two Kammbacks out of as I only used half of the sheet.

[TomO]

Originally Posted by cmittle

Not to be picky but for clarity what material are you using? You mention plexiglass and polycarbonate which are 2 different things. <snip> If you try to drill holes in plexiglass without being extremely careful it will crack and that crack spreads very easily/quickly where I see Lexan (polycarbonate) being the better choice for this application.

Thanks for clarifying this for me, I always thought that polycarbonate, Lexan, and Plexiglass were the same thing and there were just varying degrees of it. From what you've said, I have plexiglass. I was using self-drilling screws along the top, allowing the rotation of the screw to melt the plexi and then go through it and secure it to the OEM spoiler. I cracked it in one small spot, but the crack didn't spread after I secured it.

Originally Posted by cmittle

I do like what you made and I'm glad you posted so much information and pictures showing us how to mimic it. I'm just trying to help anyone who may be following your instructions so they know what material would work best.

Thanks for the help, always good to have people that know what they're talking about.

[Cd]

Nice work !
I'm glad to see someone actually modding a VX instead of the usual CX ( or DX like mine .

[MetroMPG]

Originally Posted by TomO

The sides are not anchored permanently yet so I can actually change the angle of the slope by removing the tape and repositioning the sides.

You mean the roof slope? That would be good. Extending the roof line as you've done will give you a small benefit, but you really want to continue tapering downwards.

Without even doing the "ideal teardrop" photochop, I'd say you could confidently increase the taper to around 10 degrees more than the roof angle just ahead the attachment point.

The good news is you don't need the photochop: you could put tufts on the plexi and play with angles to ensure you've still got attached flow... immediately verified in your rear view mirror!

[TomO]

Originally Posted by MetroMPG

You mean the roof slope? That would be good. Extending the roof line as you've done will give you a small benefit, but you really want to continue tapering downwards.

Yes, I can still adjust the downward slope of the roof of the kammback.
I want to shoot for a 15° angle as measured against the ground, or a 15° increase in pitch from the roofline?

Originally Posted by MetroMPG

Without even doing the "ideal teardrop" photochop, I'd say you could confidently increase the taper to around 10 degrees more than the roof angle just ahead the attachment point.

I'm going to grab a protractor and measure a 15° pitch from the roofline and then a 15° pitch from the ground and see what one works better.

Originally Posted by MetroMPG

The good news is you don't need the photochop: you could put tufts on the plexi and play with angles to ensure you've still got attached flow... immediately verified in your rear view mirror!

True, although driving and concentrating on the tufts might be interesting, lol.

I am having issues with my MAP sensor over the last week though and testing may have to hold off until I get the car to stop randomly throwing the MAP sensor code.

[Tango Charlie]

I can't wait to see the video of the tuft tests!
Hint, hint!