C3 ( &C2) Suspension Analysis & some fixes
Racer
Joined: Jul 2018
Posts: 411
Likes: 232
From: central Florida
2023 C3 of the Year Finalist - Modified
2020 C3 of the Year Finalist - Modified
2019 C3 of Year Finalist (track prepared)
looks like we hijacked a good suspension thread.
Race Director
Joined: Mar 2016
Posts: 14,406
Likes: 8,212
From: Napa Valley California
But it’s Leigh’s thread so he can take it anywhere he wants to take it.
Plus you can’t talk rear suspension without bringing up how the exhaust will run under it.
If there was a good sounding muffler that would fit nice and tight up under the floor, I would run a set and dump the exhaust down in front of the rear suspension like we did with Chevelles and Camaros.
And glass packs aren’t what I was thinking about.
Plus you can’t talk rear suspension without bringing up how the exhaust will run under it.
If there was a good sounding muffler that would fit nice and tight up under the floor, I would run a set and dump the exhaust down in front of the rear suspension like we did with Chevelles and Camaros.
And glass packs aren’t what I was thinking about.
Tech Contributor
Joined: Jun 2004
Posts: 20,910
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Because you didn't need to? Looks like you angle and pie cut some 3 inch pipe sections and probably have flow very very close to mandrel bends. You probably did this as you don't have a ton of ground clearance under the rear cross member and differential and ended up doing it yourself because the local shops either laughed at you, scratched their head, or took out the mortgage application when you asked them about stuffing 3 inch tubing in there. Sounds close?
I'm parsimonious (ie: cheap) by nature, so I build most of the stuff on my car. Aluminum tubing, especially elbows, is expensive, so I use straight pipe and pie cuts as you're familiar with. The exhaust system on the car is aluminum from the transmission crossmember on back to the tips. Significantly lighter than the previous steel setup, and with a coat of barbeque flat black paint over everything, it looks reasonably stock to the casual observer.
Tech Contributor
Joined: Jun 2004
Posts: 20,910
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
My apologies, leigh. I did not intend to divert this thread in any way or measure. I am enjoying the topic of this thread, hence the reason I posted the picture of my rear suspension. I just posted the light hearted question at the end of my earlier post to acknowledge that yes, I know pie cut tubing looks cheaper and less "sophisticated", but I had solid performance and performance per dollar expended reasons for the choice I made.
Again, I appreciate your time and work in this thread, and look forward to your additional content here.
Again, I appreciate your time and work in this thread, and look forward to your additional content here.
Race Director
Joined: Mar 2017
Posts: 11,953
Likes: 4,510
From: Virginia
Several excellent points.
I'm parsimonious (ie: cheap) by nature, so I build most of the stuff on my car. Aluminum tubing, especially elbows, is expensive, so I use straight pipe and pie cuts as you're familiar with. The exhaust system on the car is aluminum from the transmission crossmember on back to the tips. Significantly lighter than the previous steel setup, and with a coat of barbeque flat black paint over everything, it looks reasonably stock to the casual observer.
I'm parsimonious (ie: cheap) by nature, so I build most of the stuff on my car. Aluminum tubing, especially elbows, is expensive, so I use straight pipe and pie cuts as you're familiar with. The exhaust system on the car is aluminum from the transmission crossmember on back to the tips. Significantly lighter than the previous steel setup, and with a coat of barbeque flat black paint over everything, it looks reasonably stock to the casual observer.
That setup is pretty cool, though. I wouldn't hide it.
Racer
Joined: Jul 2018
Posts: 411
Likes: 232
From: central Florida
2023 C3 of the Year Finalist - Modified
2020 C3 of the Year Finalist - Modified
2019 C3 of Year Finalist (track prepared)
My apologies, leigh. I did not intend to divert this thread in any way or measure. I am enjoying the topic of this thread, hence the reason I posted the picture of my rear suspension. I just posted the light hearted question at the end of my earlier post to acknowledge that yes, I know pie cut tubing looks cheaper and less "sophisticated", but I had solid performance and performance per dollar expended reasons for the choice I made.
Again, I appreciate your time and work in this thread, and look forward to your additional content here.
Again, I appreciate your time and work in this thread, and look forward to your additional content here.
My “thread hijacking” comment was just light hearted and talking about myself. Wasn’t directed at you or anyone else. As was stated, any rear suspension discussion is bound to include exhaust planning . If it doesn’t, you’ll likely have some bad surprises. Not my thread but I don’t seriously think anything wrong was presented here. We’re all in here to improve our toys. This is part of it. My sincere apologies If I stepped on your toes. Your contributions and ingenuity are appreciated
Racer
Joined: Jul 2018
Posts: 411
Likes: 232
From: central Florida
2023 C3 of the Year Finalist - Modified
2020 C3 of the Year Finalist - Modified
2019 C3 of Year Finalist (track prepared)
Several excellent points.
I'm parsimonious (ie: cheap) by nature, so I build most of the stuff on my car. Aluminum tubing, especially elbows, is expensive, so I use straight pipe and pie cuts as you're familiar with. The exhaust system on the car is aluminum from the transmission crossmember on back to the tips. Significantly lighter than the previous steel setup, and with a coat of barbeque flat black paint over everything, it looks reasonably stock to the casual observer.
I'm parsimonious (ie: cheap) by nature, so I build most of the stuff on my car. Aluminum tubing, especially elbows, is expensive, so I use straight pipe and pie cuts as you're familiar with. The exhaust system on the car is aluminum from the transmission crossmember on back to the tips. Significantly lighter than the previous steel setup, and with a coat of barbeque flat black paint over everything, it looks reasonably stock to the casual observer.
Aluminum?? Pure genius!! Thanks for sharing. I would have never guessed
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Tech Contributor
Joined: Jun 2004
Posts: 20,910
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
My “thread hijacking” comment was just light hearted and talking about myself. Wasn’t directed at you or anyone else. As was stated, any rear suspension discussion is bound to include exhaust planning . If it doesn’t, you’ll likely have some bad surprises. Not my thread but I don’t seriously think anything wrong was presented here. We’re all in here to improve our toys. This is part of it. My sincere apologies If I stepped on your toes. Your contributions and ingenuity are appreciated
Tech Contributor
Joined: Jun 2004
Posts: 20,910
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Thread Starter
Old Pro Solo Guy
Joined: Dec 2017
Posts: 8,095
Likes: 4,449
From: Marlton NJ
I love the oval pipe and the aluminum pipe ideas! You are so right, when you start moving suspension parts, even something as "simple" as just changing the spring to fiberglass, lowering the car, or adding more HP, it starts impacting something else in a domino effect!
So many would like to "lower" their car. But this is IRS. It ain't easy.
But from what I can tell, anything more than 1/2"-1.0" lower in the rear, you start upsetting the u-joint angles, running out of compression room, need different length shocks, raise rear diff, custom rear crossmember, cutouts in the frame rail, cutouts in the rear compartment floor, etc. etc.
That practically involves re-designing the rear IRS!!!
So I have to give a major shout-out and kudos to 69427 for so many creative modifications to his C3. Including adapting a C4 suspension and aluminum batwing to a C3 frame. And getting the geometry correct enough to work very well on the track!
I know I would love to hear more about that, if he is willing, and has the time.......
So many would like to "lower" their car. But this is IRS. It ain't easy.
But from what I can tell, anything more than 1/2"-1.0" lower in the rear, you start upsetting the u-joint angles, running out of compression room, need different length shocks, raise rear diff, custom rear crossmember, cutouts in the frame rail, cutouts in the rear compartment floor, etc. etc.
That practically involves re-designing the rear IRS!!!
So I have to give a major shout-out and kudos to 69427 for so many creative modifications to his C3. Including adapting a C4 suspension and aluminum batwing to a C3 frame. And getting the geometry correct enough to work very well on the track!
I know I would love to hear more about that, if he is willing, and has the time.......
Last edited by leigh1322; Mar 20, 2023 at 07:10 PM.
