Exhaust Post your questions and suggestions about stock or aftermarket exhaust setups. Third Gen exhaust sound files and videos!

Single 3" UNDER AXLE, any tips

Thread Tools
 
Search this Thread
 
Old Sep 5, 2007 | 10:38 AM
  #1  
WhiteHawk's Avatar
Thread Starter
Member
 
Joined: Jul 2005
Posts: 290
Likes: 0
From: Detroit, MI
Car: 1991 Firebird
Engine: 350,Dart Heads,Weiand In,Roller Cam
Transmission: 2400-Stall, 700R4 w/ Kit
Axle/Gears: 4th Gen 3.42 disc (I wish)
Single 3" UNDER AXLE, any tips

So I got pulled over last night, for my exhaust, and got a "fix it" ticket...I need the least expensive and quickest solution to my problem (14 days to do it). I am planning a 3" mandrel system, y-pipe to a single, then a cheap welded muffler out back. Its just the over axle seems like a beeotch and another $50 in 3" U bends from summit along with 2 weeks at the end of my life. I'm doing all the cutting and welding myself on a car hoist.

Are there any tips and concerns to do it? The Under Axle part of it...
Reply
Old Sep 5, 2007 | 11:40 AM
  #2  
Apeiron's Avatar
Moderator
 
Joined: Jan 2000
Posts: 20,981
Likes: 11
From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Re: Single 3" UNDER AXLE, any tips

You could go under, but it's still going to need some bends. Going over the axle really isn't a big deal.
Reply
Old Sep 5, 2007 | 11:45 AM
  #3  
firebirdjosh's Avatar
Supreme Member
iTrader: (1)
 
Joined: Oct 2004
Posts: 3,361
Likes: 2
From: Worcester, MA
Car: 86 T/A
Engine: HSR 355
Transmission: 700R4
Axle/Gears: 2.77 posi
Re: Single 3" UNDER AXLE, any tips

You can buy a catback system which conveniently goes over the axle. Costs a bit more but no welding and cutting is worth it in my book- fabbing up exhaust without a lift is the most annoying task ever.
Reply
Old Sep 5, 2007 | 11:59 AM
  #4  
WhiteHawk's Avatar
Thread Starter
Member
 
Joined: Jul 2005
Posts: 290
Likes: 0
From: Detroit, MI
Car: 1991 Firebird
Engine: 350,Dart Heads,Weiand In,Roller Cam
Transmission: 2400-Stall, 700R4 w/ Kit
Axle/Gears: 4th Gen 3.42 disc (I wish)
Re: Single 3" UNDER AXLE, any tips

Originally Posted by firebirdjosh
You can buy a catback system which conveniently goes over the axle. Costs a bit more but no welding and cutting is worth it in my book- fabbing up exhaust without a lift is the most annoying task ever.
Like OEM replacement? I also just stopped by a big car recycler, unfortunately the first things they do are take off the exhaust and crush them.
Reply
Old Sep 5, 2007 | 08:01 PM
  #5  
//<86TA>\\'s Avatar
Supreme Member
15 Year Member
iTrader: (15)
 
Joined: Aug 2006
Posts: 12,812
Likes: 110
From: Central NJ
Car: 86 Trans Am
Engine: 408 stroker sbc
Transmission: TKO600
Axle/Gears: Moser full floater m9, 3:70 trutrac
Re: Single 3" UNDER AXLE, any tips

well, you could get a stock replacement, or a after market system from a variety of different companies
Reply
Old Sep 5, 2007 | 08:22 PM
  #6  
DillonRager's Avatar
Member
iTrader: (1)
 
Joined: Jul 2006
Posts: 307
Likes: 0
From: dover, OH
Re: Single 3" UNDER AXLE, any tips

check out ebay for a stock exhaust ive seen them on there pretty cheap
Reply
Old Sep 6, 2007 | 11:00 AM
  #7  
WhiteHawk's Avatar
Thread Starter
Member
 
Joined: Jul 2005
Posts: 290
Likes: 0
From: Detroit, MI
Car: 1991 Firebird
Engine: 350,Dart Heads,Weiand In,Roller Cam
Transmission: 2400-Stall, 700R4 w/ Kit
Axle/Gears: 4th Gen 3.42 disc (I wish)
Re: Single 3" UNDER AXLE, any tips

After much deliberation, I really want to run a free flow exhaust utilizing a single pipe. Im fabing a y pipe using 2.5" into a single 3.5" and running the 3.5" under axle to a 3.5" flowmaster 40 series out back. I can get the parts to my door step for $160 from summit in one day. Will get pics when done.

Here is what i'm running now that is excessively loud...
Dual 3" Purple Hornies
Reply
Old Sep 7, 2007 | 02:51 AM
  #8  
89RS_82Z's Avatar
Supreme Member
iTrader: (2)
 
Joined: Aug 2007
Posts: 2,529
Likes: 1
From: Fairhope, AL
Car: 89RS(other cars & pics in vBgarage)
Engine: LO3, 305 TBI Mildly Modified
Transmission: BakerBuilt 700R4 w/B&M Megashifter
Axle/Gears: 3.23 Auburn Pro Series LSD
Re: Single 3" UNDER AXLE, any tips

if you want a cheap, easy, & fast way out........ put a smitty (cherry bomb, glass pack what have you) after the cat (if you have one) but anyway put it on the pipe that runs next to the drive shaft, put about a foot of pipe after the muffler then a turn down................ would cost $30 if you weld it up your self, plus no bends around the axle
Reply
Old Sep 7, 2007 | 07:17 AM
  #9  
rjt76's Avatar
Member
 
Joined: Sep 2005
Posts: 483
Likes: 0
From: maine
Car: 1986 iroc z
Engine: vortec 383
Transmission: th350
Axle/Gears: 3.73 moser 12 bolt true trac
Re: Single 3" UNDER AXLE, any tips

going under the axle sucks!
If you jack up on your veheicle for any reason the exhaust will be in the way.
The rear end drops alot more than you might think. I just removed my under the axle hack job.
Reply
Old Sep 7, 2007 | 07:25 AM
  #10  
dennisbernal91z's Avatar
Supreme Member
20 Year Member
Liked
Loved
Community Favorite
iTrader: (2)
 
Joined: Feb 2005
Posts: 4,506
Likes: 92
From: West Warwick RI, postal code: 02893
Car: Building LS3, T56 Z28
Engine: LS3
Transmission: T-56
Axle/Gears: Moser/ 4.11
Re: Single 3" UNDER AXLE, any tips

I really really think that is a bad idea. I have made an exhaust b4 and it really is easy. To make each piece I used some cardboard rolled into the shape of a pipe and did it foot or a few inches at a time for hard parts. I would just go tack welding a piece on then measure the next. I am not a welder AT ALL. And I did one side in just a few hours. I even used a saber saw to cut the pipe. It was quick easy and I had no problems. I made dumps though. But later bought a over axle 4" exhaust that needed to be HEAVILY modified for my particular setup. With the bends on hand, 2 45* and 1 90*, you can make a simple over axle in less than a days work and with no real skill whatsoever. If you can think straight and are OK with working with your hands, anyone can do it.
Reply
Old Sep 7, 2007 | 07:40 AM
  #11  
soultron's Avatar
Senior Member
iTrader: (2)
 
Joined: Feb 2006
Posts: 619
Likes: 0
From: Wilmington,NC
Car: 87 trans am
Engine: 305
Transmission: T5
Axle/Gears: 3.42 SLP rear
Re: Single 3" UNDER AXLE, any tips

I'm a fan of under the axle myself. As far as lifting goes, I go from the diff, but if you had to do it from the side you could always put a flex joint in the system.
Here's some 4th gen under-axle shot I got from a muffler shop in Texas.
I figured it'd be close to this with my 94 rear end.
The pipes are 2.5, but 3 wouldn't be much different.




Reply
Old Sep 7, 2007 | 08:41 AM
  #12  
dennisbernal91z's Avatar
Supreme Member
20 Year Member
Liked
Loved
Community Favorite
iTrader: (2)
 
Joined: Feb 2005
Posts: 4,506
Likes: 92
From: West Warwick RI, postal code: 02893
Car: Building LS3, T56 Z28
Engine: LS3
Transmission: T-56
Axle/Gears: Moser/ 4.11
Re: Single 3" UNDER AXLE, any tips

I admit, not bad.

Now if I could just do that with my 4" haha.
Reply
Old Sep 7, 2007 | 08:44 AM
  #13  
subliminal's Avatar
Senior Member
iTrader: (1)
 
Joined: Nov 2003
Posts: 714
Likes: 0
From: Port St Lucie, FL
Re: Single 3" UNDER AXLE, any tips

bye bye ground clearance.
Reply
Old Sep 7, 2007 | 04:15 PM
  #14  
89RS_82Z's Avatar
Supreme Member
iTrader: (2)
 
Joined: Aug 2007
Posts: 2,529
Likes: 1
From: Fairhope, AL
Car: 89RS(other cars & pics in vBgarage)
Engine: LO3, 305 TBI Mildly Modified
Transmission: BakerBuilt 700R4 w/B&M Megashifter
Axle/Gears: 3.23 Auburn Pro Series LSD
Re: Single 3" UNDER AXLE, any tips

hell our cars almost drag everywhere now they are so low even from the factory im not knocking your idea but i would imagine you would smash the pipe if you bottomed ourt just right, hell i crushed me 3.5" tips draging somewhere........The work one them looks good new, but im sure they would get crushed, scraped or whathave you....... just my opinion, not out here to offend anybodys taste or work
Reply
Old Sep 9, 2007 | 06:16 PM
  #15  
rjt76's Avatar
Member
 
Joined: Sep 2005
Posts: 483
Likes: 0
From: maine
Car: 1986 iroc z
Engine: vortec 383
Transmission: th350
Axle/Gears: 3.73 moser 12 bolt true trac
Re: Single 3" UNDER AXLE, any tips

inspection time comes every year. with the exhaust under the axle you will see their reaction when they put it on a lift and the rear is hanging on the pipes.
not good.
Reply
Old Sep 9, 2007 | 07:59 PM
  #16  
soultron's Avatar
Senior Member
iTrader: (2)
 
Joined: Feb 2006
Posts: 619
Likes: 0
From: Wilmington,NC
Car: 87 trans am
Engine: 305
Transmission: T5
Axle/Gears: 3.42 SLP rear
Re: Single 3" UNDER AXLE, any tips

I dunno, I can't see how the exhaust could scrape anymore than it does...
but my intermediate pipe only scrapes because it's missing a hanger.
I'd think if your car scrapes under the diff you have alot bigger problems than exhaust clearance.
Reply
Old Sep 9, 2007 | 11:48 PM
  #17  
89RS_82Z's Avatar
Supreme Member
iTrader: (2)
 
Joined: Aug 2007
Posts: 2,529
Likes: 1
From: Fairhope, AL
Car: 89RS(other cars & pics in vBgarage)
Engine: LO3, 305 TBI Mildly Modified
Transmission: BakerBuilt 700R4 w/B&M Megashifter
Axle/Gears: 3.23 Auburn Pro Series LSD
Re: Single 3" UNDER AXLE, any tips

more so the mufflers under the car b4 the axle, since they are not in the "exhaust tunnel" my main problem with my big single pipe (and probelm of a friend) is speed bumps...... going out of a friends driveway, even thought i went in/out on a angle it got mine (on the plus side its tore up alot of other things and got a u-haul hung up, the front wheels were in his driveway and the back bumper was dug in the road, leaving the drive axel it the air LOL)
Reply
Old Sep 10, 2007 | 02:42 PM
  #18  
WhiteHawk's Avatar
Thread Starter
Member
 
Joined: Jul 2005
Posts: 290
Likes: 0
From: Detroit, MI
Car: 1991 Firebird
Engine: 350,Dart Heads,Weiand In,Roller Cam
Transmission: 2400-Stall, 700R4 w/ Kit
Axle/Gears: 4th Gen 3.42 disc (I wish)
Re: Single 3" UNDER AXLE, any tips

I suppose the 3.5" pipe would make up for the nasty flow reduced techno bends (angle straight pipes together to make the U shape)...but that is a lot of work, and I must complete this in 7 days, and working 5 days a week with my weekends full of other plans, leaves me with 3 hours a day after work (cause I have to drive to my tools which is a 2 hour round trip)...and it would be nice to complete it in 6 hours. Well see what I can pull off gents
Reply
Old Sep 13, 2007 | 11:26 AM
  #19  
WhiteHawk's Avatar
Thread Starter
Member
 
Joined: Jul 2005
Posts: 290
Likes: 0
From: Detroit, MI
Car: 1991 Firebird
Engine: 350,Dart Heads,Weiand In,Roller Cam
Transmission: 2400-Stall, 700R4 w/ Kit
Axle/Gears: 4th Gen 3.42 disc (I wish)
Re: Single 3" UNDER AXLE, any tips

Just finished it last night (2x2.5" into 1x3.5" under axle), it is pretty sick guys. Sounds freaking mean, regrettfully, tone like a tang 5.0, but much louder and more earth shaking. I took it for a quick spin, I gotta reprogram my pump shot and she stalled on me at the light...I just hope my custom Y-pipe only gained me in my RPM range.
Reply
Old Sep 13, 2007 | 11:46 AM
  #20  
Stephen's Avatar
Banned
iTrader: (12)
 
Joined: Jul 1999
Posts: 12,212
Likes: 13
From: Bertram (outside Austin), TX
Car: 87 GTA
Engine: L98
Transmission: 700R4
Axle/Gears: Dana M78 3.27 posi
Re: Single 3" UNDER AXLE, any tips

For a 'fix-it' quick fix, why not just turn it out to the side, before the rear tires? Behind the doors, you'll still be legal, like the Viper exit, but without the full side pipes.

That would take care of the fix-it ticket..
Reply
Old Sep 13, 2007 | 12:11 PM
  #21  
strokermotor91's Avatar
Member
 
Joined: Oct 2006
Posts: 187
Likes: 0
From: Fallon, NV
Car: 91 Camaro RS
Engine: Small Block
Transmission: TH350 w/ 3000 stall convertor
Axle/Gears: 3.73 w/ powertrax locker
Re: Single 3" UNDER AXLE, any tips

heres a picture of mine with the muffler under the axle. its not really all that bad.
Reply
Old Sep 13, 2007 | 12:27 PM
  #22  
dennisbernal91z's Avatar
Supreme Member
20 Year Member
Liked
Loved
Community Favorite
iTrader: (2)
 
Joined: Feb 2005
Posts: 4,506
Likes: 92
From: West Warwick RI, postal code: 02893
Car: Building LS3, T56 Z28
Engine: LS3
Transmission: T-56
Axle/Gears: Moser/ 4.11
Re: Single 3" UNDER AXLE, any tips

I would never do that.

When i wanted a quick fix, I did this.



Cost me all of a weekend and $90. Problem was it shook the house when I pulled up and I don't think cops like when you do that. haha. So I swapped it out for a 4" catback that flows even better. and sounds far more bad ***.
Reply
Old Sep 13, 2007 | 12:33 PM
  #23  
Stephen's Avatar
Banned
iTrader: (12)
 
Joined: Jul 1999
Posts: 12,212
Likes: 13
From: Bertram (outside Austin), TX
Car: 87 GTA
Engine: L98
Transmission: 700R4
Axle/Gears: Dana M78 3.27 posi
Re: Single 3" UNDER AXLE, any tips

But, under car exits aren't legal, so they won't fix a ticket. Of course, duals on 3rd gens aren't legal anyways.

Take your under car dumps, turn the tips to the outside, and 2' more pipe per side, and you'd have had side exits, eliminating the under car drone, reducing the interior sound level.

Last edited by Stephen; Sep 13, 2007 at 12:38 PM.
Reply
Old Sep 13, 2007 | 01:43 PM
  #24  
dennisbernal91z's Avatar
Supreme Member
20 Year Member
Liked
Loved
Community Favorite
iTrader: (2)
 
Joined: Feb 2005
Posts: 4,506
Likes: 92
From: West Warwick RI, postal code: 02893
Car: Building LS3, T56 Z28
Engine: LS3
Transmission: T-56
Axle/Gears: Moser/ 4.11
Re: Single 3" UNDER AXLE, any tips

Oh I know. I am fully aware. this was just to get my to the paint shop.

Either way, I didn't want to be shooting exhaust out like that.

I may do it next year, using all oval pipes. But I think that will wait till I do the super charger and stop driving it every day
Reply
Old Sep 19, 2007 | 06:41 AM
  #25  
WhiteHawk's Avatar
Thread Starter
Member
 
Joined: Jul 2005
Posts: 290
Likes: 0
From: Detroit, MI
Car: 1991 Firebird
Engine: 350,Dart Heads,Weiand In,Roller Cam
Transmission: 2400-Stall, 700R4 w/ Kit
Axle/Gears: 4th Gen 3.42 disc (I wish)
Re: Single 3" UNDER AXLE, any tips

Here it is, 2x2.5" into 1x3.5" through a 3.5" 40 series:







If I were to do it again, I wouldn't be so rushed to get it done, and do more fitting instead of assuming. It functions, and sounds very good.
Reply
Old Sep 19, 2007 | 09:14 AM
  #26  
327_TPI_77_Maro's Avatar
Supreme Member
iTrader: (8)
 
Joined: Sep 2004
Posts: 1,896
Likes: 0
From: Charles County, Maryland
Car: 2000 BMW M5
Re: Single 3" UNDER AXLE, any tips

Under the axle. LOL. That's one way to take a major shortcut. There is a reason most people will not do an exhaust like that, but whatever floats your boat.
Reply
Old Sep 21, 2007 | 07:53 AM
  #27  
WhiteHawk's Avatar
Thread Starter
Member
 
Joined: Jul 2005
Posts: 290
Likes: 0
From: Detroit, MI
Car: 1991 Firebird
Engine: 350,Dart Heads,Weiand In,Roller Cam
Transmission: 2400-Stall, 700R4 w/ Kit
Axle/Gears: 4th Gen 3.42 disc (I wish)
Re: Single 3" UNDER AXLE, any tips

Originally Posted by 327_TPI_77_Maro
Under the axle. LOL. That's one way to take a major shortcut. There is a reason most people will not do an exhaust like that, but whatever floats your boat.
I got my ticket waived atleast my friend, in years to come I will have the time/money/resources to accomplish the ideals.

Winter is almost here, and my dream for this winter is the turbocharger, so its going to be replumbed then.
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
jrdturbo
Firebirds for Sale
26
Mar 31, 2016 02:58 PM
Thaney9
Tech / General Engine
4
Oct 15, 2015 06:37 AM
dusterbd
TPI
0
Sep 29, 2015 08:40 AM
Night rider327
Engine/Drivetrain/Suspension Parts for Sale
0
Sep 25, 2015 04:47 AM




All times are GMT -5. The time now is 03:51 AM.