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Anyone have ideas for a cheap and easily available material to build some experimental rear fender skirts for my Echo. I've considered corregated plastic sign material and clear packing tape. Material would need to have enough inherent rigidity to avoid any significant wind deflection.

I just want to see if I'm willing to build and install something more permanent.

Others seem to be having good luck with corregated plastic. I'm picking up a sheet of 4x8 coroplast for myself this week for wheel skirts and a front air dam.

rear fender skirts? got any example pics?

I'm using corregated plastic for my radiator block and it works like a charm. I used a belt hole punch and zip ties to secure it. Although, I don't think you'll have much luck with the packaging tape - I don't think it will hold up for very long. That being said, for longevity's sake, I would you a really GOOD brand of duct tape - 3M or something like that. Splurge on the expensive stuff. It will look like doody, but it will hold up.

Now that I'm thinking about it, strapping tape might work OK too (strapping tape is the thick threaded packaging tape).

IMHO:

3-4mm Coroplast is fantastic material for skirts, grill blocking, etc. Start with a cardboard (stiff construction paper works best) to build a template first. A spray paint that is made specifically to bond to plastic (such as Fusion) works very well with coroplast. You can spray over the Fusion "base layer" with another type of paint to color match better.

Test a smaller piece of coroplast first to see if a desired radius (such as round bumper curves or skirt bends) exceeds the "bending threshold" of the material. Coroplast can be shaped along stright lines by cutting along a "cell" and only through one "skin." To maintain a smooth radius, use two or three "slits" anywhere from 1" apart (small radius) to 2-3" apart for larger radii. If you want a "squared" corner, one slit will work fine. Again, test your shaping ideas on a scrap piece first!

Packing tape works well for areas such as grill blocks, but does not have enough strength to hold curves in the coroplast for a skirt. There is a fairly durable clear window sealing tape that is more flexible than packing tape and allows smoother "curving" of the tape to fit flush. It also help seal "gaps" between your piece and the body. If you want the ultimate in "speed tape" use aluminum duct tape. I have used this testing airplanes at speeds of 400mph+ indicated, and it holds up fine (but is very shiny:cool:) All depends on your personal decisions concerning looks v. functionality v. cost!

You can bend simple aluminum "tabs" to hook/rtv on the wheel well lip. Make the "hooking on the lip bend" very tight so it holds some tension if you tap it in place. Plan the spacing based on the curvature of the body around the edge and the thickness of your tabs. Bend the tab portion out if you need to angle the skirt away from the body. Drill a hole in the tab (for sheet metal screws later) before you mount it. Trust me on this, I have three stitches where I drilled to the bone in my finger trying to drill in place and my finger slipped due to rtv! :eek:) Rtv the tab in place and let it dry overnight. Put a shop light in the fender well behind your tab and you can see the hole (light) through the coroplast to start your screw. If you use a lnoger flourescent type light, make sure you can get it out of the well after you screw your skirt in place! :rolleyes:

Tab shape:
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Fender washers work ok with counter sunk screws, but finishing washers with a counter-sunk center are the best if you can find them. Start at the center of the skirt and expect to trim to fit unless your template was great. Mine never seem to work out as well as I would like, so I leave slighly extra and trim/shape/smooth as I go. Coroplast "shaves" fairly well with a box cutter type knife for small trimming areas - just be extremely careful! You can use a medium file to smooth, shape, bevel, the Coroplast, etc. Again, do test/practice pieces first if you can. I buy my coroplast from a smaller local sign shop that is very happy to sell me their "scrap" pieces at a greatly reduced price over a single new 4x8 sheet. They seem to appreciate me taking the smallest pieces that work for me, and they get to hang on to the larger scraps. I recently bought ~30 square feet in pieces for $10. :Banane06:
If the coroplast will be more permanent (grill block pieces that can stay in place all summer, etc.) you can rtv the piece in place. Packing tape can be used to hold the piece until the rtv dries, and can be cleaned up fairly easily after removal. It's also quite easy to remove your piece later and clean up the residual rtv.

I take it RTV is a caulk of some kind? I plan on doing skirts and a full frontal block once I dial in what the car is able to do. If I get real adventurous, I may put in a block on the bottom of the car as well. And maybe the side mirrors... and a boat tail... hmm... this may get out of hand ;).

RTV is a sealant/adhesive/gasket material that you can buy in smaller tubes. It also can be gotten in a few different colors (for different heat ratings/strength, etc) like red or black that may match your car. I have used silicone caulk also with pretty good results, although it is not as good an adhesive as RTV, and the clear didn't dry as clear as I would have liked in my hood gap seals. How well anything aheres to your coroplast depends on whether or not it was "Corona treated" or not to remove residual surface chemicals that don't like adhesives. (no, not that type of Corona... ;) If it wasn't treated, it is difficult to bond with glue other than superglue, but most that I have bought seemed to have been pre-treated and various types of good tape bond well, and RTV bonded fairly well (not perfectly though).

Oh, it definitely can get out of hand :eek:

Aluminum flashing is cheap and easy to work with(cuts your hands very easily of course),but only rigid when you tension/stretch it.If you double or triple layer-maybe with cardboard sandwiched in between two layers, it would be more rigid.Obviously, it looks like the coroplast is better.

Where do you buy this coroplast-how much is it??
Thanks,
Charlie

Sign shops sell it. I was quoted $30 a sheet of 4x8.

The local sign shop is the only place I could find any immediately in town. I've heard an alternate source is a plastic supply house. I picked up my 4'x8' sheet for $35.

Sign shops are the easiest if you can transport a sheet. Ask if you can pick through their "scraps" that work for your project pieces, and typically you can get a break on the price of 50% off or more. My shop sold me 30sq ft (in pieces) for $10, and they were easier to get home.

trackermpg,
Hey, thanks for the PM with ##.I am saving it and will get in touch in a week or so if that is ok.Today I'm trying to make my 1980 MC less of a death machine.I've managed to cause the rear brake backing plate to be cockeyed.My 1st solution was to not torque the axle bolt very tight so it-backing plate- would bind.HUGE ERROR;the wheel pulled loose under power,bent the screw on the chain adj gadget on one side,and threw the chain.Luckily it was at 20 mph.

I plan to attempt to skirt my guzzling 1998(202,300 miles) Suburban.I'm thinking about lowering the little factory OEM chin spoiler it has-it is 10-11" off the highway now-and maybe skirt the entire front and side of it to within maybe 6" of the road surface.It gets stunning decent -21.3 mpg at 70 mpg(3000 mile roundtrip 5-18-08 to 5-26-08) with the CC on-no DWL- 45 psi tires,Mobil I 5W30, worn tires,and a hitch carrier.Most of the mpg belongs to GM,I guess.The tire pressure,slightly decreased speed,worn tires,syn oil,cc on was probably worth 1-1.5 mpg?? No way to know really other than testing it.It has the tall 3.42 rear end.

Bottom line is I'll be stuck with it for a while-long while.I think/hope it has 25 mpg hy potential with aero improvements,and at 60- 65 mph and a bit of DWL.I've removed the rear most seat-69 lbs-and might remove part of the second row-maybe 30 lbs-and the spare(65 lbs in town only removal).If I get a new starter or starter motor,I'll shut down at lights and get 17 around town instead of my current 14 mpg on very short(4 mile) trips.

Thanks,
Charlie

Thanks,
Charlie

One of the guys in the local RC airplane club purchased a large amount from an on-line supplier (that sells to sign shops) and got a very good price.

Anyways he was selling to us RC plane makers for cheap money.
IIRC, it cost me less that $20 for eight 2'x4' sheets in mixed colors.
(I guess it's easier to ship 2'x4' sheets).

I used some to make SPAD RC air planes.
http://s46.photobucket.com/albums/f147/Xringer/SPA3D/?action=view&current=654d.jpg

There's always a lot of Coroplas around during an election year..
Just call up the local DNC office and they will deliver for free..:woot: