Exhaust system saga part I

[G60syncro]

Well, my exhaust had sprung a leak, it was time to do something!! First things first, where is the problem???

Ahhh... seems to be leaking here:

...and here too:

Oh! and let's not forget here as well!!!

Here come the solution... some U pipes and 2 stainless Magnaflows.... One of them came polished the other did'nt.... don't ask!!

Working on the rear section, everything laid out ready to be tacked and going in for a test fit.

That's it for tonight... tomorrow I'll be doing the over-axle bend (waaaay oversimplified here!!) and the front cat section... I also gotta finish the flanges and the flex-joint...

Part II coming up tomorrow!!!


Modified by G60syncro at 10:40 PM 9-9-2005

[dtompsett]

Nice.

How do you like the MigPac 10 MIG welder? I see the tank attached.... are you using regular MIG wire or Stainless wire?

By the way... to those looking at this... an easier solution to the rear muffler and associated bends around the rear diff would have been a Vibrant Performance #1134.... Check it out here: http://forums.audiworld.com/4000/msgs/60590.phtml

(ya... my buddy works for them.... and has the on both his 90q and 4000q.... and once I get around to building my exhaust, I'm gonna have one too!)

Let me know how you like the welder..... Dad and I are looking at buying a MIG.... haven't settled on one yet.

[G60syncro]

Quote, originally posted by dtompsett »

By the way... to those looking at this... an easier solution to the rear muffler and associated bends around the rear diff would have been a Vibrant Performance #1134.... Check it out here: http://forums.audiworld.com/4000/msgs/60590.phtml

Yeah, I'm stupid... I learned about this muffler last week, but it was too late, I already had all my supplies on hand Oh well... live and learn!!

Part II pics are coming up soon... Just did'nt have time to unload the camera!!

About the Mig pack... It's a really cool little welder, I would'nt dare building anything out of thick plate with it, but that's not why I bought it!!

I already have access to all kinds of welding equipement at the shop I work at. For home I wanted something portable that runs on 110v so I can use it anywhere. I got a tank of Argon with 2%Co2 for stainless and some 308 wire from our welding supplier.

*WARNING: DO NOT BUY A WELDER!!* You will find excuses to use it all the time... Your girlfriend will get mad at you over your fixing all of your buddies stuff and not spending enough time with her. Fabbing your own stuff is highly addictive... Be warned!!

[G60syncro]

Okay, here's the update:

One problem area I knew all along but did'nt get to photograph:

Can you say restrictive!!!

This is the finished downpipw flange... It's a 4 piece design so it can be assembled over the DP flare without messing anything.

Here's a view when installed on the cat:

Back section done!! only needs final trial fit to trim the ends and fit the polished tips.

Mid section done... shown side by side with the old piece..

The entire finished system:

It sounds awesome, nice and quiet up to 4K then it lets you know you're going too fast!! Has a nice aggressive growl when you get on the pedal, but does'nt get annoying!!

[dtompsett]

Good job man... looks awesome!

[Mr. Ninja]

lookin good

[MFZERO]

looks good man

[G60syncro]

I've been running it for a week now... It's gotten even more quiet because the copper donut seat in the cat flex joint has seated in properly... I've also noticed a slight boost in low and mid-range torque from the butt-dyno. The car definitely feels better!! The cat is one from a VR6 MkIII GLX... nice and fat and the core was mint!! No clogging or meltdowns to restrict flow. If you're looking for an El-cheapo replacement I suggest checking out a junkyard for a smashed low-mileage VR6... You may find a good deal under it!!

[boner]

what are the dimensions of the first muffler in your system. i took the remenants of mine to my buddy and he won't touch it but i can get one made pretty cheaply.

thanks

[audib5turbo]

magnaflow is the way to go...good work my fellow audi owner

[xscirocco16vx]

so how about some more detailed info about this. Where did you pick everything up, what are the measurements of the u tubes mufflers etc? Did you buy stainless tubing to go with the stainless mufflers? How much did it end up costing you to make?

[G60syncro]

Hmmm... that's a tought one to answer just like that... Making it was pretty much a cut-to-fit and weld as you go kinda deal... I'll do my best to give you as much details as possible.

I did all the flanges at my shop... so it's just a quickie CAD drawing I threw together. I'll try to clean it up a bit so it looks like something to someone else than me!! The whole system is stainless, I would have done some things differently but time and money were lined up against me!!

Parts needed:
-1x #14363 Magnaflow 2.5" center/offset muffler.
-1x or use #14326 which is a tight squeeze but cheaper and easier to get
-1x #14218 Magnaflow 2.5"/2.25"-dual muffler
-1x or use #14258 which is a tight squeeze but cheaper and easier to get
-1x 2.25" U bend
-3x 2.5" U bends
-2x polished exhaust tips (I got the 15$ ones at Canadian Tire.)
-18" of 1/8 x 3/4 stainless flat bar (try to rummage through the odds and ends at a metal supplier, size is'nt that critical, it's for the hangers!!)

Total cost: around 500$ and I got a spool of SS wire and a tank of welding gas as well!!

For the joints, it's up to you... I hate slip joints with U-bolts!! They are a PITA to take apart!! However flanged joints don't have as much give, so you need to be a little more accurate!! I ended up making a new factory-style 4 bolt flange for the flex joint, Then a rigid 3 bolt flange between the cat and mid-section and finally another 3 bolt flange but with a machined SS donut seal.

Once you got all the parts, you can start the basic layout of the rear section. Since I used the cheap and easy to find mufflers, I had to squeeze it in across the back of the car. I had to cut the inlet and the outlet towards the rear of the car almost flush with the muffler canister. Leave the outlet towards the front alone!!

Now we're gonna work on the outlet that goes out under the bumper... Ignore the pictures and do as I say... Take your 2.25" U bend and cut it in half so you have two 90* sections. Tack the shorter one to the rear outlet you just cut off. Take your longer 90* and cut the curved section at 45*... Now you have a straight with a 45 on the end and a small 45* elbow. Tack the piece of 2.25" outlet you cut off on the end of the long pipe with the 45 and then the 45 elbow. Now you have a piece thet goes "long straight-45*-straight-45*" Looks complicated, but trust me, it'll be less of a pain to fit later!! I line it up so I had roughly 4" between centers, trust your eye for that. I suggest you prop the muffler under the car and see how it looks in the bumper notch. DON'T TRIM THE ENDS YET!!!!

Moving on to the other side of the muffler... Take a 2.5" U bend and cut the longest leg at the point where the radius starts. Keep the long straight for the mid section. Tack that J pipe to the muffler as in the picture above. Now's the time to prop it back up under the car and figure out the hanger locations.

<insert hanger closeup here>

DON'T FORGET, DO NOT TRIM THE OUTLET PIPES YET!!

Like the transcontinental railway, an exhaust has to start on either end and meet at the same place in the middle!! That's why I left the rear section in the car (it should have it's hangers installed by now!) and got to work on the front part. If your cat is alright, you're lucky!! If not, it's one more thing to worry about. Basically the idea is to have the cat outlet centered in the tunnel and pretty much flush with the floor. Once that is established we can get to work on the mid section.

Take that piece of straight pipe you set aside and weld it to the offset side of the center muffler. Line it up straight and you can weld a full bead all around!! The mid muffler will sit and an odd slant to clear the propshaft and so that the outlet points into the hole in the subframe where the pipe is supposed to pass. Again, exact fit will depend if you took the shorter easier to fit mufflers or the cheaper easier to find ones that don't give you an inch to spare. I went back under the car with my pipe/muffler combo and proppred it in place with blocks so I could line up the hanger... I just made a 90* bend 3/4" from the end of a 4" piece of flatbar and welded it in place. Don't sweat it, you'll be able to adjust it with vise-grips later and trim it to length before bracing it solid. Now work your way up into the rear crossmember, it's roughly 45* up from the centered outlet into the "hole" in the frame and then 30* back down to almost level with the ground... Check the lengths and cut to fit here!!

At that point you should be very near the driveaxle flange. I joined the cat to the mid-pipe by eyeballing the angle and length I needed to cut off the long leg of my second U bend. Was'nt much, something like 5-10* into the radius. Now remember I built my own cat by using the original one and welding new piping on it!! Your's may vary. With careful cutting, I managed to get the twisties done with the short piece of my 2nd pipe and part of the curve. We still have a full U bend left and some odd and ends here and there. Once everything is tacked, you should crawl out from under the car with something like this in your hands:

DON'T FORGET, DO NOT TRIM THE OUTLET PIPES YET!!

This is the part that separates the men from the boys!! At this point, if you feel like quitting, toss the rear section in the trunk and install the mid section... drive off to the nearest muffler shop. The car will be driveable and the noise will be bearable for a drive or two.

Back on the rear section, take your 3rd U bend and cut it at 90*. The short piece should be enough to take you up and over the crossmember. Line up the 90* in the hole in the crossmember and on your rear muffler so you can mark where to cut the J bend to length as shown in this trial fitting:

I HOPE YOU DID NOT TRIM THE OUTLET PIPES YET!!

There should be less that 10" separating both sections... I spaced my flanges 1/4" apart with washers on the mid pipe and just cut and welded the reamaining tidbits to fit until the connection was made. After that I reinforced some of the weaker tacks and bolted the whole thing down with the donut seal and shook the crap out of it to make sure nothing is knocking or rubbing.

Now I hope you did'nt cut the oulet before, because NOW is the time to do it!! You could just cut the pipes off at a slight angle and call it a day... I bought 2.5" polished SS tips at Canadian Tire that were meant for 2" pipe... The way they work is that they slip over the pipe and are secured with setscrews. They are in fact 2.25" that flares out to 2.5" with a rolled edge. So I just cut off the setscrew part and welded them directly to my pipe. I staggered them by about 1/4" so the one near the center of the car is further back... that way, when viewed while standing behind the car, it flows with the curve of the bumper... Small detail but it does make or break the looks!!

Now yank the whole thing out and finish all the weld beads all around. I also braced the hangers and put a little crossbar between the twin outlet like the original exhaust.

I installed it using new hangers and all stainless nuts, bolts and lockwashers. Do one final shake to make sure it's nice and tight with no knocking... Do one last checkup to make sure you've got clearance all around, then drop the car back down on the ground.

I love how smooth it sounds at idle and up to 3-4K... Then when you gun it, it just rips right up to redline with a very satisfying bark... VR's can eat my shorts, nothing else than a 5cyl can give me that tingle down my spine!!

[xscirocco16vx]

WOW! Now thats called getting more than you barganed for! Nice writeup! Thanks alot.

[apavlov]

Wow, i like it. It would be sweet if you somehow got a picture and vids of the finished product. There doesn't seem to be enough 5-cyl vids on the net.

[audiquattroturbo]

good thread, i decided to go with the complete bosal system which is a direct fit for the 90.
http://https://b2b.bosalnafta....0.gif

Modified by audiquattroturbo at 3:47 PM 1-3-2006

[dtompsett]

Back from the dead... forgot to post this here...

My stainless exhaust build on my 90q. http://forums.audiworld.com/9080/msgs/361967.phtml

[ratquat]

beautiful work need to do some of that myself got my car highcentered on my muffler the other day... oops! don't ghostride the whip at night drunk with no lights

[skaterjay85]

i think i own that exhaust system now, rubs a little

[Nash20thAE]

Nice...need to take care of a nasty exhaust leak and figure I'll replace the whole shebang! Gonna order some parts tomorrow.