C5 Rear diffuser making progress
Thread Starter
Drifting
Joined: Mar 2012
Posts: 1,517
Likes: 147
From: Jasper Alabama
C5 Rear diffuser making progress
I started this venture last year. Have invested a small fortune in parts and materials. But things are progressing. I have the diffuser roughed in and fitted to the car. I've read a lot of comments and suggestions of what everyone would like to see done with a rear diffuser for the C5. The main issue was to make one that would fit up to the stock bumper without drilling or cutting. I found a way to do this. I have backing plates behind the vent openings with four bolts on each side that screw into the diffuser. I will also use 3m doublesided body tape around the edges as well. I am working on two different styles of diffuser. One being more suttle like the stock C6 diffuser and a more aggresive style like ARP's diffuser with an under pan. I can mount this diffuser in about 15 minutes. It slides right into place and is held very secourely with the mounting plates. I am looking for a distributor to make these when complete. Here are some pics of progress so far.
Last edited by Stealth02; Feb 8, 2015 at 03:00 PM.
Melting Slicks
Joined: Sep 2012
Posts: 2,308
Likes: 159
From: LaGrange Park, IL IL
St. Jude Donor '13, '15
I know this is rough still and I have nothing but respect for your hardwork and dedication to this project. I did wonder though why the rounded edges had that flat flange looking part to it? Does that match up to the OEM molded curve of the rear fascia? And maybe it is a shadow, but does the top edge not align properly with the molded area of the OEM fascia?
My only design critique would be the width of the "blades" nearest the exhaust. The straight rear shot makes them look very flat bottomed and wide...Most diffusers I've seen have these a bit more streamlined.
I absolutely love the idea to use the lower vents to help mount this. So I'm assuming there would be a molded in stud in the diffuser itself that aligns with the vents, then bolt on from inside?
My only design critique would be the width of the "blades" nearest the exhaust. The straight rear shot makes them look very flat bottomed and wide...Most diffusers I've seen have these a bit more streamlined.
I absolutely love the idea to use the lower vents to help mount this. So I'm assuming there would be a molded in stud in the diffuser itself that aligns with the vents, then bolt on from inside?
Thread Starter
Drifting
Joined: Mar 2012
Posts: 1,517
Likes: 147
From: Jasper Alabama
I did not like the look of the breathless diffuser. It sticks out too far from the bumper. Plus you have to cut the bottom half of your rear fascia to mount it. I will post some.pics of it off the car in a bit so you can see how it mounts.
Thread Starter
Drifting
Joined: Mar 2012
Posts: 1,517
Likes: 147
From: Jasper Alabama
I know this is rough still and I have nothing but respect for your hardwork and dedication to this project. I did wonder though why the rounded edges had that flat flange looking part to it? Does that match up to the OEM molded curve of the rear fascia? And maybe it is a shadow, but does the top edge not align properly with the molded area of the OEM fascia?
My only design critique would be the width of the "blades" nearest the exhaust. The straight rear shot makes them look very flat bottomed and wide...Most diffusers I've seen have these a bit more streamlined.
I absolutely love the idea to use the lower vents to help mount this. So I'm assuming there would be a molded in stud in the diffuser itself that aligns with the vents, then bolt on from inside?
My only design critique would be the width of the "blades" nearest the exhaust. The straight rear shot makes them look very flat bottomed and wide...Most diffusers I've seen have these a bit more streamlined.
I absolutely love the idea to use the lower vents to help mount this. So I'm assuming there would be a molded in stud in the diffuser itself that aligns with the vents, then bolt on from inside?
Here is a pic of the diffuser pulled out away from the rear fascia.
Here is the backside of diffuser showing the four mounting inserts.
This pic shows the plate that goes on the backside of the fasia to hold the diffuser in place
Last edited by Stealth02; Feb 8, 2015 at 08:28 PM.
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Looks pretty good so far. Will be interesting to see how it looks and fits when you are done.
Le Mans Master
Joined: Jun 2002
Posts: 8,352
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From: In the pit, trying to love someone.
So what are you going to do about heat from the mufflers? GM put those slits there to let heat out and people still have problems with their rear bumpers warping, which is why companies like ACI sell braces for them. The C6 doesn't have vents there because the mufflers are not placed right against the bumper.
Thread Starter
Drifting
Joined: Mar 2012
Posts: 1,517
Likes: 147
From: Jasper Alabama
I'm running a B&B bullet exhaust. No mufflers against the rear fasia like the stock setup. I can put my hand on the pipes after driving. There is heat but not enough to melt the rear fascia. There is still air flow getting to the exhaust.
Drifting
Joined: Oct 2008
Posts: 1,595
Likes: 191
From: Wilmington DE
Amazing work so far been waiting forever to come up with a solution to this. Love the idea of mounting it from behind. Have you considered just making the side wings wider to fill in the "red" area? You are very close to a making a great product
Thread Starter
Drifting
Joined: Mar 2012
Posts: 1,517
Likes: 147
From: Jasper Alabama
I did look at widening the side wing but it looked too squared. Once this is all smoothed out the whole diffuser will be hydro dipped in carbon fiber then the red area will be colormatched to the bumper.
Thread Starter
Drifting
Joined: Mar 2012
Posts: 1,517
Likes: 147
From: Jasper Alabama
That's fine for track use. Not trying to enter that domain. Just trying to make a streetable piece that a lot of people are wanting. All of the diffusers that are offered for the C6 vettes are in that sense bumper add ons. ARP, C7, Carbon Creations, Supervettes.
Le Mans Master
Joined: Jul 2007
Posts: 6,094
Likes: 3,467
From: Oswego IL
Kudos to the OP for taking this on! 
It amazes me that some of the forum sponsors (with access to body shop materials and talent) who have promised they were "working on a diffuser" several months ago (or years ago) haven't developed jack squat, but an individual owner can make huge progress with his own stuff. Go figure. 
It amazes me that some of the forum sponsors (with access to body shop materials and talent) who have promised they were "working on a diffuser" several months ago (or years ago) haven't developed jack squat, but an individual owner can make huge progress with his own stuff. Go figure.
Drifting
Joined: Jan 2012
Posts: 1,883
Likes: 76
From: Portland OR
I think it looks really good, btw.
Thread Starter
Drifting
Joined: Mar 2012
Posts: 1,517
Likes: 147
From: Jasper Alabama
I would be open to whatever options are available to get this reproduced so that other C5 owners who like and want this option could be made available to them. I have studied pics of many different diffusers and am trying to make a complimenting piece to add to the rear of the C5. I've read everyone's opinions and suggestions on this subject in past threads and am trying to feed it all into my efforts. I was in hope that some one could produce this but seeing dead ends and no progress from the past threads I decided to tackle it myself. I had the images of how to acomplish it stuck in my head so I got what I needed and and went to work. Any helpful feed is appreciated and taken into consideration.
