Rear Wheel Skirt using water heater drain pan

[cfg83]

Hello -

(Subsequent edits in red)

After working with blackjackel on his rear wheel skirt, I decided to work on mine. I was also influenced by the positive feedback of Xringer's Short Skirt's thread.

My philosophy is to try to find a "ready-made" part I can re-use for mods. I have been looking for a "pie-pan" with a big enough circumference to fit on my car for over a year. I found this 26" diameter plastic drain pan at Home Depot for $10 (you can also get this pan in metal) :



I did a test fit on my car and it was "close enough" for me :



These are three Paint-Shop-Pro mockups of the plastic pan in different configurations :



I settled on drain pan cut in half with a 10 degree angle. I like it because it is angled to match the "upsweep" of the rear bumper, and one drain pan will be enough for both rear wheels :



Here it is in reality on my car :



Front/Back detail views (the front could have front wheel spoilers, i.e. mudflaps, extend down) :



Connection Description :



Benefits :

0 - 99% reversible. If I take them off, there are only little holes I drilled where I connected them, and in places that are not viewable.

1 - Solid ready-made shape that already "wraps around" the tire.

2 - Relatively easy to remove. Unscrew three bolts and cut the Zipties.

3 - All plastic. If the connections fail, I think it would do less damage to the wheel (or someone else).

4 - Close tolerances. I can put my hand under it, so that's about 1/2" clearance.

Problems :

1 - It's a PITA to install.

2 - Still not the right size (kind of fixed in post #13). The metal pan would have been more "malleable", but I am leery of attaching metal if I don't absolutely have to (see benefit #3 above).

3 - The gaps are bad for aero. I intend to address this with stick-on spongy insulation tape (fixed in post #12).

4 - The front-most Ziptie is lame aesthetically. This was the fastest secure way to install it. I have an idea how to perfect that, but I need to do more research on connections (fixed in post #14).

5 - Hard corner angles are not aero-friendly. But, for a more ambitiuous builder, the heater drain pan could be the "foundation" for a more aero-clean implementation.

At this point I have one skirt on. I will test drive it tomorrow on the freeway and see how it holds up.

CarloSW2

[azraelswrd]

Nice breakdown. I'm interested to see how sturdy that setup is at speed given the gaps and the plastic composition but I like where you're going.

[cfg83]

Hello -

I didn't have any problems on the way to work today. My commute is a good test because the 710 freeway is in bad shape because of all the trucks. I held a mirror out of the car to look down on the cover and I didn't see any vibration or scraping against the tire.

When I parked my car at work I inspected the cover. I did see that the front (visible) Ziptie was loose. I pulled it another quarter inch and it got tight again. I am going to mark it with a Sharpie to see if it is coming loose during the drive. It could just be that it wasn't tight enough to begin with, and the commute just loosened it up. I don't mind this problem because the front Ziptie is a temporary solution. I am trying to figure out other ways to solve the front connection.

I inspected the tire and I didn't see any problems. I was looking for scuff and/or wear damage, but I didn't see anything. I was also looking for wear on the center of the wheelcover, but I didn't see anything. What I should do is put some (removeable) paint marks on the tire and see if there is wear. A silver Sharpie might do the trick.

CarloSW2

[metroschultz]

I'm going to steal your idea,
Hopefully I can implement it before my West by-god Virginia trip.
Thanx.
S.

[blackjackel]

glad to see that the whole setup is working for you, my wheelskirts haven't moved a INCH since we installed them and i've been using my car ever since we put them on.... that made me think we shoulda done a 1/4" clearance rather than 3/4"...

Do you plan on painting your wheel skirts to match car color or leave em black? Originally i thought it wouldn't look so good but because the tires are normally black it looks quite... normal!

I do think the angle is a bit steep though which may or may not cause turbulence... might need to do a tuft test.

But anyways, it looks great from what I can see, and you can barely see the white zip tie from more than a few feet away so its not as much as a problem as it seems..


I can't wait for feedback on how many mpg's those helped you squeeze out!

[cfg83]

metroschultz -

Originally Posted by metroschultz

I'm going to steal your idea,
Hopefully I can implement it before my West by-god Virginia trip.
Thanx.
S.

Yes please. I am going to keep modifying the first post with red "EDITS" to show good/bad parts of the implementation as I discover them. One thing to keep in mind is that the mod is an "exploit". If your wheel-well is not the right circumference, then it might not work for you. Mine is not ideal, I wish the drain pan was maybe 1" larger in diameter.

You can test the viability by measurement, and then "try it out" in the Home Depot parking lot :



If it doesn't fit, you can walk back in and return it, no harm no foul.

CarloSW2

[cfg83]

Me -

Originally Posted by cfg83

Hello -

...

When I parked my car at work I inspected the cover. I did see that the front (visible) Ziptie was loose. I pulled it another quarter inch and it got tight again. I am going to mark it with a Sharpie to see if it is coming loose during the drive. It could just be that it wasn't tight enough to begin with, and the commute just loosened it up. I don't mind this problem because the front Ziptie is a temporary solution. I am trying to figure out other ways to solve the front connection.

...

After my commute home I checked the Ziptie and it hadn't budged. This tells me that it just got a little loose on the drive in.

I keep looking for signs of wear but I don't see any. No marks on the tires at all.

With my finger I can whack the long pastic edge with my fingers and it wobbles. However, when I stick a mirror out the window, I can't see any wobble. At some point I may reinforce that with a metal piece to maintain rigidity, because I am guessing that there must be some "MPH + Road Quality" resonance that will cause it to wobble while driving.

CarloSW2

[cfg83]

blackjackel -

Originally Posted by blackjackel

glad to see that the whole setup is working for you, my wheelskirts haven't moved a INCH since we installed them and i've been using my car ever since we put them on.... that made me think we shoulda done a 1/4" clearance rather than 3/4"... [/I]

In hindsight you are right, but I think we made the "safe" choice at the time. I think I have less "fear" because I have plastic and experience working with your solution. I wanted 3/4 inch also, but the geometry of the drain pan "dictated" some of my choices. For your design, with the added weight of the covers, two more magnet attachment points may be in order, one on each side of the vertical attachment (imagine a 5 spoke semi-circle).

Do you plan on painting your wheel skirts to match car color or leave em black? Originally i thought it wouldn't look so good but because the tires are normally black it looks quite... normal!

I think I will keep it black. Aesthetically, I like the "balance" of two wheel-wells. If I go white, I will be creating a "solid wall" of white toward the back of the car that I may not like (not a good description, but I think you know what I mean). I have done paint-shop-pro mock-ups, but I haven't liked them.

I am also copy-catting lovemysan because his "basic black" wheel skirt also looks good.

Evile thought : I can now "mount" black magnet tape on the skirt and change my MPG ratings at will. Someone could scoff when they look at my wheel skirt, and then see my MPG and "think again".

I do think the angle is a bit steep though which may or may not cause turbulence... might need to do a tuft test.

Yeah, it's also a "cheat". Most cars taper inwards toward the back, which causes the "bulge" that you and I were building into your wheel skirt, and which MetroMPG commented on. Solving for this bulge requires the an extension on the back bumper. I bypass that problem (and sacrifice aero) by "not going lower".

[I]But anyways, it looks great from what I can see, and you can barely see the white zip tie from more than a few feet away so its not as much as a problem as it seems..

I can't wait for feedback on how many mpg's those helped you squeeze out!

We're hitting August, so hopefully I can get a good run into work this week or the next. If only we had a coast-down test site in LA!!!!!!!!

CarloSW2

[azraelswrd]

Probably have to leave L.A. and head for the county outskirts to get some elbow space.

[cfg83]

Hello -

Here's some front/back closeups of the wheel in relation to the skirt.

Front of Rear Driver's side tire :


Rear of Rear Driver's side tire :


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Question: I am looking for something like this to solve my frontal attachment :

Brass Chicago Screws Eyelets Screws for book Binding File Screws male female Folder Screws Brass Chicago Nickel Plated Screws Male screw Female Screws Extensions


However, I want "hardware store" strength versions, not "stationaries folder" strength. Hrrrmmmmmm ... do you think the stationaries' strength would be strong enough for the daily grind? This is an ideal solution because I want the flush ends for closing the rear door.

CarloSW2