Welcome to the North American Subaru Impreza Owners Club Sunday November 23, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC General > Interior & Exterior Modification

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 09-24-2007, 07:13 PM   #1
Sausage
Scooby Specialist
 
Member#: 104998
Join Date: Jan 2006
Chapter/Region: Tri-State
Location: NNJ
Vehicle:
2007 vf39 SuperWagon
I haz teh bed gramers

Default DIY Rear Diffuser : The Writeup

This is your goal:




This is how you get there:

Cost: ~$75 depending on if you mess up or not
Labor: ~35 hrs depending on your skills
Skills: You just need to know how to measure correctly. + have some patience

Supplies (Everything can be found at lowes, home depot, and walmart):
1 piece of SHELTERSHIETH
1 Roll of Painter's Tape
1 Can of Spry Glue
1 Roll of aluminum foil
1 black piece of chalk
1 Roll of Masking tape
2 or 3 fiberglass cloths
1 fiberglass matte
2-3 cans of resin
1-2 cans of bondo bodyfiller
0-1 tube of spot puddy
1 can of primer
1 can of flat black spray paint
1 can of matte top coat
1 envelope of the roughest sandpaper you can find
1 envelope of 220 grit
3 copper tube hangers
Misc bolts for haning and attaching diffuser to bumper
3 Super cheap mini paint rollers
20 super chap (10 cents at walmart) mini brushes
(I think that's everything)

Equipment:
Sander
Sanding block
Dremel with cutting wheels
Rubber body filer tool thingy (or anything to spread bondo evenly)
Drill with various bits


Word of Advice:
Take your time and enjoy this project. This is not a weekend thing. I worked on this for about 2 months. The slower you go and the more you think about how everything goes together, the less work you'll have and the better the finished result will look. duh... but the good news is that everyone can do it. You don't need any special art skills. I'm a computer programmer and thought this was pretty easy, just labor intensive since I messed up 4 times before I got it right.

With that said, Let's get into this:


Here is what I did:

The base:

- Cut a piece of Sheltersheth that roughly outlines the bottom of the car.



- Tape up the charcoal canister edges and rub some black chalk on them.

- Press the ShelterSheth against the canister and get a good outline
of what's in the way. (canister, hoses, hook)



- Cut out the hole for the canister and plumbing.

- Do the same for the tow hook and plumbing until you can raise the
base as much as you want since there is nothing in the way.




- Line your bumper with some tape, chalk it, get an outline, and cut
to fit the shape.




- Secure the ShelterShieth in place with whatever you can get your hands on (Iused tape, which turned out to be bad ideal later on) but make sure it's solid and at the height you want.



- Tape up the bumper, canister, and just about everything under the car.
- (I didn't do this, but good idea) Put down a even layer of tape
over the whole thing, including all the SS. So when you look under
the car, everything is taped up and you don't see anything else. You
do this for 2 reasons. 1. The layers of tape smooth out the rough
corners and help blend everything together. 2. When you lay down the
resin, it reacts differently in the areas that are taped and the areas
that are not. It burns a little into the SS, but not the tape, so if
you don't tape up everything, your piece will come out wavy and you'll
have to put more work into getting a smooth curve.



- Get the spray glue and spray glue aluminum foil onto the tape
that covers your bumper. This is just to make sure no resin ends up
bonding to your bumper somehow.




- Get the fiberglass cloth and get ready. Spray down the cloth and
bumper and SS with spray glue and start gluing up the cloth. (I did it with matte in
the pics, DON't use the matte) The best way to put up the cloth, is
to start from the passenger side and work your way over to the
driver's. Don't try to put it up all in one shot, but rather roll it
on smoothly to prevent sagging parts. This is the tough part and how
hard the project will be depends on how smoothly you can get this done
right. When it's done, there shouldn't be any bubbles, dips, or
anything. The whole thing should look perfectly smooth and even. The
reason for this is once you start applying the resin, any place that
has extra material will sag like crazy and you'll end up with a crappy
bubble.



- Make sure the ends of the cloth are secure. I taped them to the
bumper and flipped them over the edge and taped them underneath.

- If you messed up and do have access cloth in places, get a couple
stapes out of a standard stapler and try pinning the extra spots in to
place. I would also recommend pinning the edges like this and any
other spots that might be loose.
* Registered users of the site do not see these ads.

Last edited by Sausage; 09-25-2007 at 08:13 AM.
Sausage is offline   Reply With Quote
Old 09-24-2007, 07:14 PM   #2
Sausage
Scooby Specialist
 
Member#: 104998
Join Date: Jan 2006
Chapter/Region: Tri-State
Location: NNJ
Vehicle:
2007 vf39 SuperWagon
I haz teh bed gramers

Default



- Make a smaller batch of resin, get your mini paintroller, and go
to town. For the first layer, I would recommend only doing that spots
that are completely secure and don't have a chance of sagging. If you
do it this way, you will minimize any sagging that might happen. This is what your mini paint rollers are for. They're a godsend for putting resin on a ceiling like this and you can do about 3 layers with one roller.



- Put a full layer of resin on after the first has dried, and then
roll on another 2 layers.


- Take, everything down and clean it up. Sand out any major drips
and cut off the ends that you're not gonna use.



- Put down layer of fiberglass matte over the whole thing. Make
sure you work out any bubbles.

- After everything has dried, get the roughest sandpaper, and sand
out the trouble spots.



19.) Once it's semi smooth, make a small batch of bondo body filler
and lay it down in any divits, holes, bubbles, or imperfections you
have.



20.) Sand it all out.









The fins:

- Get some cardboard and cut out 4 fins of whatever size and shape
you want. I cut mine so that the ends of the fins match the
ends of the base. I made them about 3.5" high because based on the
curvature of my base, that height would make the bottom of the fin
parallel to the ground once everything is mounted.


- Now you need to figure out where they will all go, to do this
have someone hold the piece under the car and mark off where ends of
the license plate are. I considered the middle of the license plate
the middle of the car. So I found the midpoint of the two and marked
it. This is the middle of the car. Then, I took a right angle tool
and lined it up so the edge of the diffuser is at a right angle to the middle of the diffuser.
Then I drew my allignments lines for the fines based on this middle line.

- It turned out that each middle fin was 6" off the center and each side fin was 15.5" of
the middle fins. I used this pattern since it was the only way I
could think of to have the fins near the exhaust at about 2" away from
the muffler.

- Once you got all the marks on your diffuser, take each of the precut
fins and start shaving the underside of the fin until the curvature of
the underside of the fin matches the curvature o the diffuser.

- Once that is done, get them roughly in place and get a yard stick (or
something strait and solid) and run it over the fins to make sure
they're all still the same height. If not, trim where needed.

- Now, mark of where each fin goes and trace them onto pegboard. I used
pegboard because it's the most processed wood I could find, which meant
it was molded and it was the only thing I could find that was solid
and wasn't deformed. All other wood i found had some kind of
curvature already built in from the factory.

- So now that you cut out the fins, test fit them all and make sure
it'll all look good.




Next, since the pegboard has holes, whip out the bondo, fill the
holes, and sand it smooth.

Then get your leftover fiberglass cloth and cut pieces that match the
shape of the fin,. but leave about 1" extra cloth off the bottom of
the fin. Cut pieces for both sides. Then, what you will do is place
the cloth on the each fin and lay down the resin bonding the cloth to
the wood, but DON'T just throw it all on there. Throw it all over the
top and the sides, but the bottom of the fin should have about 1/4"
cloth on it without resin. You want the cloth around the bottom to
remain soft so that when you glass the fin to the diffuser, the cloth
will lay down a smooth curve between the fin and the diffuser.



Now it's time to glass the fins to the diffuser. What you will do
here is get a 90 degree bracket and actually screw the fin to the
bracket and the bracket to the diffuser. you will do this so that
when you lay down the glass, the fin will still remain at 90 degrees
to the diffuser until the resin hardens. This is also good because
you can easily hold the diffuser under the car and step back to make
sure the fins are strait before you throw down the resins. Assuming
the fins are aligned t0 the lines you drew, screwed in tightly, and
everything looks good. Go ahead and lay down the glass...




Last edited by Sausage; 09-25-2007 at 08:21 AM.
Sausage is offline   Reply With Quote
Old 09-24-2007, 07:14 PM   #3
Sausage
Scooby Specialist
 
Member#: 104998
Join Date: Jan 2006
Chapter/Region: Tri-State
Location: NNJ
Vehicle:
2007 vf39 SuperWagon
I haz teh bed gramers

Default

Once everything dries, take off the brackets and make sure everything
still looks good. If it does, sand the holes you made with the screws
and fill them with bondo. Then sand again

Sand down the areas you glassed where you see major bumps.

Then put down another layer of glass making sure the entire fin is
covered and the glass is spilling onto the diffuser...then let dry

Now that the hard part is over, it's clean up time... this is the most
time consuming part



Just get the roughest sand paper, electric stander, sanding block and
go to town. This part I really can't describe because it depends on
what you have in front of you. Just keep sanding, laying down bondo,
and re-sand again until everything is clean and smooth.



Once everything is clean and smooth, it's time to work on the mounting
portion of this thing. You'll need to mount it and make sure
everything lines up the way it should before you do a final sanding
and painting.





I started by marking the bumper holes on the diffuser. The back
bumper holes I made halfway between each fin, close the each corner,
and 3.5 cm from the edge. (I just looked good this way) Then I put a
3 along the side of the bumper, I just eyeballed those. I predrilled
my holes with a drill bit that was slightly smaller then the screws I
was going to use.

Next I test fit it and had my wife hold it in place while I marked off
3 screw holes in the bumper. I predrilled the holes in the bumper
and mounted the whole thing with 3 screws.

Then I predilled and put in the rest of the screws.

Next, I dry fitted the pipe hangers and marked off on the wheel well
where they're going to be bolted in place.

I took the diffuser off, and mounted the bottom of the pipe holders to
the diffuser. Then I drilled the holes in the car. Bolted everything
together, stepped back, and took a look.

From here, I decided I'm done so I want onto painting...




At this point, you're pretty much done... Enjoy the $450 you saved on this project, and explain to the wife that in order to get the most out of this effort you'll have to take that saved money and invest it into a bigger turbo... she'll understand

Last edited by Sausage; 09-25-2007 at 08:25 AM.
Sausage is offline   Reply With Quote
Old 09-24-2007, 07:14 PM   #4
Sausage
Scooby Specialist
 
Member#: 104998
Join Date: Jan 2006
Chapter/Region: Tri-State
Location: NNJ
Vehicle:
2007 vf39 SuperWagon
I haz teh bed gramers

Default

Q&A:

Q: How much does this weigh?
A: 4-5 lbs, but it depends on how much bondo you used. The less bondo (since it's heavier) the less weight.

Q: How much space is between this and the bottom of the car?
A: None, I made mine so that the base is nearly flat and sits right against the bottom of the wheel well. If you wanted, you could also make it curl up in the back, but there wouldn't be any point since it's already above the axle.

Last edited by Sausage; 09-25-2007 at 08:28 AM.
Sausage is offline   Reply With Quote
Old 09-24-2007, 07:14 PM   #5
Sausage
Scooby Specialist
 
Member#: 104998
Join Date: Jan 2006
Chapter/Region: Tri-State
Location: NNJ
Vehicle:
2007 vf39 SuperWagon
I haz teh bed gramers

Default

Some more Finished Pics:








Last edited by Sausage; 09-25-2007 at 08:04 AM.
Sausage is offline   Reply With Quote
Old 09-24-2007, 07:15 PM   #6
Sausage
Scooby Specialist
 
Member#: 104998
Join Date: Jan 2006
Chapter/Region: Tri-State
Location: NNJ
Vehicle:
2007 vf39 SuperWagon
I haz teh bed gramers

Default

Suggestions:

Quote:
Originally Posted by ekw View Post
my only suggestion (for those trying it at home)
is to look for hardboard for the fins.
it is made out of the same stuff as pegboard, but no holes to fill.
at HD it's in the bin next to the pegboard!

Last edited by Sausage; 09-25-2007 at 09:30 AM.
Sausage is offline   Reply With Quote
Old 09-24-2007, 08:28 PM   #7
Matt_H
NASIOC Supporter
 
Member#: 107000
Join Date: Feb 2006
Chapter/Region: MAIC
Location: Bristow, VA
Vehicle:
2008 STI <3 TXS and
Andrewtech

Default

Awesome man! Glad to see you tough it out and finish!
Matt_H is offline   Reply With Quote
Old 09-24-2007, 08:37 PM   #8
WRXDriftR
Scooby Guru
 
Member#: 65065
Join Date: Jun 2004
Chapter/Region: Tri-State
Location: NJ
Vehicle:
04 WRX/ STi Hybrid
6MT, VF43

Default

what is the final weight of it?
does it seal to the bottom of the car closer to the axel or is there space for air to flow up over it and get trapped behind the bumper?
WRXDriftR is offline   Reply With Quote
Old 09-24-2007, 08:38 PM   #9
KENisFISX
Scooby Newbie
 
Member#: 154541
Join Date: Jul 2007
Chapter/Region: Tri-State
Location: Beachwood, NJ
Vehicle:
2007 Impreza TR WRX
Black

Default

he said on the other thread it was like 4 or 5 lbs
KENisFISX is offline   Reply With Quote
Old 09-24-2007, 08:48 PM   #10
ATK
Scooby Specialist
 
Member#: 123698
Join Date: Aug 2006
Chapter/Region: NWIC
Location: Finn Hill
Vehicle:
2004 WRX Sportwagon
PSM

Default

I've been following your other thread, but I guess I'll start questions on here.

Can you post pics of the diffuser from the front of the car to the back? I'm just curious how you curled up the front or what you connected it to so it doesn't act like a parachute when on the highway.
ATK is offline   Reply With Quote
Old 09-24-2007, 10:02 PM   #11
SinisterSkube
Scooby Specialist
 
Member#: 96012
Join Date: Sep 2005
Location: indy
Vehicle:
2005 WRX sedan
WRB

Default

i like...... i do eet
SinisterSkube is offline   Reply With Quote
Old 09-24-2007, 10:30 PM   #12
Sausage
Scooby Specialist
 
Member#: 104998
Join Date: Jan 2006
Chapter/Region: Tri-State
Location: NNJ
Vehicle:
2007 vf39 SuperWagon
I haz teh bed gramers

Default

Honestly, since this a DIY you could make it any way you want. If you want it to curl up, it wouldn't be hard. But it's about the level of the sway bar and since the axels are in the way, there really isn't much room for air to get trapped. I'd say it probably sits closer to the bottom of the car then the HKS or APR

But this one sits right against the bottom of the spare tire well.

And yeah it weights 4-5 lbs, not much at all, and it's nice and sturdy.
Sausage is offline   Reply With Quote
Old 09-24-2007, 10:32 PM   #13
hella_sti
Scooby Specialist
 
Member#: 139289
Join Date: Jan 2007
Chapter/Region: MWSOC
Location: ND
Vehicle:
2003 WRX Wagon
PSM

Default

thats a helluva lotta work, nice job!
hella_sti is offline   Reply With Quote
Old 09-24-2007, 10:46 PM   #14
KENisFISX
Scooby Newbie
 
Member#: 154541
Join Date: Jul 2007
Chapter/Region: Tri-State
Location: Beachwood, NJ
Vehicle:
2007 Impreza TR WRX
Black

Default

i'll put up the extra $100 and make it carbon fiber when i do it, but i'm gonna make a fiberglass one first to see if i can make it right or if i'll screw it up. www.fiberlay.com FTW
KENisFISX is offline   Reply With Quote
Old 09-24-2007, 11:03 PM   #15
njxnoise
Scooby Newbie
 
Member#: 156244
Join Date: Aug 2007
Chapter/Region: Tri-State
Location: Central New Jersey
Vehicle:
2002 WRX
WR Blue

Default

Whats the hour count you took to make this? haha. Seriously though, nice one.
njxnoise is offline   Reply With Quote
Old 09-24-2007, 11:04 PM   #16
Sausage
Scooby Specialist
 
Member#: 104998
Join Date: Jan 2006
Chapter/Region: Tri-State
Location: NNJ
Vehicle:
2007 vf39 SuperWagon
I haz teh bed gramers

Default

When you do, take some pics and if you want we'll throw it in the write up. That'll rock
Sausage is offline   Reply With Quote
Old 09-24-2007, 11:33 PM   #17
vf15hammer
Scooby Specialist
 
Member#: 150385
Join Date: Jun 2007
Chapter/Region: TXIC
Location: Pasa-get-down-dena...TX
Vehicle:
60% TXIC
40% SCIC

Default

Quote:
Originally Posted by Sausage View Post
Honestly, since this a DIY you could make it any way you want. If you want it to curl up, it wouldn't be hard. But it's about the level of the sway bar and since the axels are in the way, there really isn't much room for air to get trapped. I'd say it probably sits closer to the bottom of the car then the HKS or APR
Wow, mine sits a few inches below the spare tire well and I'm as far up as I can go without moving the mounting points.

Axle is still in front but I might have to modify mine cause I think I would like it more like yours...
vf15hammer is offline   Reply With Quote
Old 09-25-2007, 04:11 AM   #18
john_tran
Scooby Specialist
 
Member#: 90516
Join Date: Jul 2005
Location: Torrance
Vehicle:
2007 WRX, R.I.P.06TR
Satin Pearl White

Default

very nice DIY... i just wish i had the patience and skill to do it.
john_tran is offline   Reply With Quote
Old 09-25-2007, 09:05 AM   #19
ekw
Scooby Specialist
 
Member#: 92141
Join Date: Jul 2005
Chapter/Region: Tri-State
Location: in a guardrail near you
Vehicle:
2004 WRB STi TiC,RCE
Kartboy &Cobb-Jorge tuned

Default

nice work & great write up!
my only suggestion (for those trying it at home)
is to look for hardboard for the fins.
it is made out of the same stuff as pegboard, but no holes to fill.
at HD it's in the bin next to the pegboard!
ekw is offline   Reply With Quote
Old 09-25-2007, 10:24 AM   #20
th1rd3y3
Scooby Specialist
 
Member#: 83054
Join Date: Mar 2005
Chapter/Region: Tri-State
Location: Williamsport, PA
Vehicle:
'11 SWP
STI

Default

WOW! That looks really good. Good write-up to boot!

Too bad I'm WAY to impatient to do it myself.
th1rd3y3 is offline   Reply With Quote
Old 09-25-2007, 07:13 PM   #21
RobK0000
Scooby Specialist
 
Member#: 62230
Join Date: May 2004
Chapter/Region: NESIC
Default

I was going to attempt this but Carbon fiber was to expensive at the moment, Plus im still making that hood. But ill make one next, if time allows and it will be Carbon Fiber. Nice write up and good creativity.

Final Grade
A+

Rob K,
RobK0000 is offline   Reply With Quote
Old 09-25-2007, 07:17 PM   #22
EJ2point0
Scooby Specialist
 
Member#: 103062
Join Date: Dec 2005
Chapter/Region: NESIC
Location: CT
Vehicle:
' YEN

Default

very impressive
EJ2point0 is offline   Reply With Quote
Old 09-25-2007, 07:18 PM   #23
silverwrx666
Scooby Specialist
 
Member#: 86514
Join Date: May 2005
Chapter/Region: NESIC
Location: Plaistow Nh
Vehicle:
07 swp sti,86 k10,
91 lexus LS400

Default

nice work

I would love to do it
if I only had a garage
silverwrx666 is offline   Reply With Quote
Old 09-25-2007, 07:48 PM   #24
siwrx
Scooby Newbie
 
Member#: 153322
Join Date: Jul 2007
Chapter/Region: Tri-State
Location: Staten Island, NY
Vehicle:
2004 WRX
Silver

Default

I love the way it looks. Nice job and great write up man.
siwrx is offline   Reply With Quote
Old 09-25-2007, 08:18 PM   #25
B00st3dWRX
*** Banned ***
 
Member#: 140978
Join Date: Feb 2007
Chapter/Region: SCIC
Location: L.A., Ca and B-ham, WA
Vehicle:
02 WRX WRB
i-Nertia Dynamics

Default

awesome work....def a project I will have to do.
B00st3dWRX is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
DIY Fender Rolling : The corrected bat method Bad Noodle Tire & Wheel 94 05-12-2014 08:39 PM
DIY Solid Front Lip : The Writeup Sausage Interior & Exterior Modification 72 05-25-2011 11:37 AM
Group Project: DIY Rear Diffuser Sausage Interior & Exterior Modification 194 11-02-2009 11:54 AM
been working on my DIY rear diffuser... naggg Interior & Exterior Modification 29 03-25-2009 12:43 PM
DIY REAR diffuser subiLOVR03 Interior & Exterior Modification 14 10-17-2007 07:34 PM


All times are GMT -4. The time now is 01:16 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.