SCFFR
01-12-2013, 06:31 AM
A few months ago I posted Part 1 of my under car exhaust system using Spin Tech low profile mufflers and oval tubes. At that time, the body was off the chassis and I realized that the rear section of the system would have to wait until the body was installed in order avoid any interference with the tires, chassis, fuel tank and body. I have since gotten the body properly fastened to the chassis and after spending a month or so on fitting and aligning the doors, trunk and hood, I thought I would jump back on the exhaust.
The front section of the exhaust turns up at the rear bulkhead and ends just to the outside of the lower control arm (3-link setup). I was able to weld up the front section without any real problems since the turns were pretty simple. However, getting up and over the rear end and then back down in a small space would be very difficult and time consuming so I decided to just mock up the section and have it made up at the local muffler shop. I've done this on some other projects and used wire and/or small copper pipe to make the bends I needed. Since the available space is so tight, I decided to use "real" pipe for the mock-up and purchased a 6" section of 2.5" flexible pipe from the local NAPA store. Unfortunately, the flexible pipe could only be bent into about a 7-8" radius which was too big for several of the curves I needed to clear the rear end.
Since the flexible pipe didn't work as planned, I decided to buy a variety of bends from Summit Racing and piece them together. I bought some 45's, 90's and a tight radius U-bends (2.5" dia) and started cutting and tack welding them into place. As Murphy would say, before you can do something you must first do something else which in this case was making some type of mounts for the pipe hangers. As shown in the pics, I fabricated some brackets and mounted them to the chassis and trunk sides (actually bolted through the square tubing) since the width of the sides is narrower than where I needed to run the tailpipes to avoid the fuel tank. I bought a few short sections of 3/16" x 1.25" flat bar and had a piece of 1/8" sheet metal for all the mounts. As I did for the main exhaust section, I used some stock exhaust hanger which I took apart to add my own muffler mount tabs. I was able to make the tight turns around the shock by cutting and welding short curve sections I cut out of the various bends. Once I got around the shock, I used the flexible piece to mock up the final bends and tailpipe since these were pretty small turns. I taped the flexible pipe in place and took it to the local muffler shop where the owner duplicated it in 2.5" pipe for $15 per side. After a little grinding and tweaking, it fit great. Once everything was positioned where I wanted it, I welded the pipes together and added a few tabs on the pipe for the exhaust hangers. Note that I used stainless band clamps to join the front and rear sections together. When I had finished all of the fabrication, I had the rear exhaust sections ceramic coated satin black to match the front sections and the mounting brackets powder coated gloss black.
I'm very pleased with how the entire under car system turned out. From a cost standpoint, it was really no cheaper than the basic side exhaust setup, just something different. I do think that it will be a little quieter when cruising and you can avoid a few burns on your leg but really its a personal choice. I started on the LH side first since the fuel tank on that side sticks out past the trunk sides. It was much easier to duplicte the location of the tailpipe on the right side of the car since the fuel tank was less of an issue. As I did with the front sections, I used some black exhaust wrap on the sections of the pipes closest to the rear bulkhead panels. The part of the project that ended up taking the most time was deciding on the length of the tailpipes. It seemed like every car I looked at with a "street" exhaust had different length tailpipes. On some, the ends barely cleared the body while on others they extended a few inches past the overriders. I originally made them to end at the back edge of the overrider but cut them back to about 1/2" past the bumper bar. Six of one, half dozen of the other. To make sure I had proper clearance with the car on the ground, I dropped it off the jackstand for the first time. There is plenty of clearance between the back side of the tire (Cooper Cobra 295's) and the chassis and shocks. I have to say that I am extremely happy with how it looks.
Link to Part 1 http://thefactoryfiveforum.com/showthread.php?7792-Under-Car-Exhaust-Part-1&highlight=exhaust
Looking forward to starting up the engine and seeing how the system sounds.
Ron
14386143871438814389
The front section of the exhaust turns up at the rear bulkhead and ends just to the outside of the lower control arm (3-link setup). I was able to weld up the front section without any real problems since the turns were pretty simple. However, getting up and over the rear end and then back down in a small space would be very difficult and time consuming so I decided to just mock up the section and have it made up at the local muffler shop. I've done this on some other projects and used wire and/or small copper pipe to make the bends I needed. Since the available space is so tight, I decided to use "real" pipe for the mock-up and purchased a 6" section of 2.5" flexible pipe from the local NAPA store. Unfortunately, the flexible pipe could only be bent into about a 7-8" radius which was too big for several of the curves I needed to clear the rear end.
Since the flexible pipe didn't work as planned, I decided to buy a variety of bends from Summit Racing and piece them together. I bought some 45's, 90's and a tight radius U-bends (2.5" dia) and started cutting and tack welding them into place. As Murphy would say, before you can do something you must first do something else which in this case was making some type of mounts for the pipe hangers. As shown in the pics, I fabricated some brackets and mounted them to the chassis and trunk sides (actually bolted through the square tubing) since the width of the sides is narrower than where I needed to run the tailpipes to avoid the fuel tank. I bought a few short sections of 3/16" x 1.25" flat bar and had a piece of 1/8" sheet metal for all the mounts. As I did for the main exhaust section, I used some stock exhaust hanger which I took apart to add my own muffler mount tabs. I was able to make the tight turns around the shock by cutting and welding short curve sections I cut out of the various bends. Once I got around the shock, I used the flexible piece to mock up the final bends and tailpipe since these were pretty small turns. I taped the flexible pipe in place and took it to the local muffler shop where the owner duplicated it in 2.5" pipe for $15 per side. After a little grinding and tweaking, it fit great. Once everything was positioned where I wanted it, I welded the pipes together and added a few tabs on the pipe for the exhaust hangers. Note that I used stainless band clamps to join the front and rear sections together. When I had finished all of the fabrication, I had the rear exhaust sections ceramic coated satin black to match the front sections and the mounting brackets powder coated gloss black.
I'm very pleased with how the entire under car system turned out. From a cost standpoint, it was really no cheaper than the basic side exhaust setup, just something different. I do think that it will be a little quieter when cruising and you can avoid a few burns on your leg but really its a personal choice. I started on the LH side first since the fuel tank on that side sticks out past the trunk sides. It was much easier to duplicte the location of the tailpipe on the right side of the car since the fuel tank was less of an issue. As I did with the front sections, I used some black exhaust wrap on the sections of the pipes closest to the rear bulkhead panels. The part of the project that ended up taking the most time was deciding on the length of the tailpipes. It seemed like every car I looked at with a "street" exhaust had different length tailpipes. On some, the ends barely cleared the body while on others they extended a few inches past the overriders. I originally made them to end at the back edge of the overrider but cut them back to about 1/2" past the bumper bar. Six of one, half dozen of the other. To make sure I had proper clearance with the car on the ground, I dropped it off the jackstand for the first time. There is plenty of clearance between the back side of the tire (Cooper Cobra 295's) and the chassis and shocks. I have to say that I am extremely happy with how it looks.
Link to Part 1 http://thefactoryfiveforum.com/showthread.php?7792-Under-Car-Exhaust-Part-1&highlight=exhaust
Looking forward to starting up the engine and seeing how the system sounds.
Ron
14386143871438814389