Thursday, July 12, 2012

exhaust work one

I placed an order with verocious motorsports online which included a (1) 4" long x 3" dia stainless steel (including ends) turbo flex joint, (3) 90* 3/8" stainless steel hangers, (2) rubber exhaust isolators, (1) 1' long x 3" dia stainless steel tube, (1) stainless steel EGT bung, and (1) 3" vibrant stainless steel v-band clamp with flanges. Great service.





I used the foot piece of tube to extend either ends of the downpipe, attaching v-band flanges forward/aft. The EGT bung went near the front flange of the downpipe in the lower part of the small extension. I also had v-band flanges on both ends previously, but for some reason the second flange set didn't match up now, almost like they weren't mated machined flanges. This may have had something to do with the trip to TDC Auto, but either way, when I flipped the downpipe into the correct orientation, I used the old v-bland flange that actually did match the turbo adapter, and tossed the other miss-matched pair.




I mocked the downpipe, cutting the aft extension to the right length and angle before tig welding and wrappings. Note the perfect o2 bung location. Since I didn't know where the exact position of the aft flange or the rest of the downpipe needed to be, not to mention relative to the exhaust, I needed to mount the downpipe first as a starting point. After positioning the downpipe by itself, I had the bungs and front flange and extension welded in one visit, and the aft flange and extension, not to mention the entire exhaust after it's mock up, welded in the second visit.

WETSU Welding to the rescue. Thanks Tony.

Because of the distance of the entire exhaust (ie a little error in angle or location six feet out would make a huge difference in the final location of the muffler tip),  I decided I could not mock the exhaust like I did the first part of the downpipe, with tape. I borrowed a light duty mig welder from a friend at work and tacked the mid/aft hangers, flex joint, flanges, and aft downpipe extension into place before driving it to Tony's.




Yes, that's a full, single piece exhaust on proper stands, being back purged with 1oo % argon during tig welding said hangers, flex coupler, and v-band flange.




And yes, the pair of z's are still chillin in the garage.

The flex joint is sized to slip over the pipe, which aids in mock up and welding. I was able to angle either side of the exhaust tube and play with the installed overlap to get the final angle and position of the flange face perfect during mock up without pre-stressing the flex joint at all. Based on the amount of work TDC Auto did to the forward section, I was impressed that I didn't even have to cut and re-angle the exhaust tube and create another joint to align everything. When I first mocked up the exhaust, the front flange was about a foot from where it needed to be, but now with the flex section installed and the hangers in the correct positions, it was perfect.



Tony covered the entire radial thickness of the stainless end caps of the flex section with weld. This capped off the ends, permanently anchoring the stainless braids.

When welding the flange I followed the od weld from the id with the back purging hose since we could no longer plug the end of the exhaust to create the atmosphere while welding in the same area.








To get great welds, the surfaces must be just as clean. We touched up the joints and flange faces prior to welding to remove the excess left over from the tack welder.

I've got a few videos of the below v-band flange welding process while back purging that I'll post later. The welds look just as good on the inside as they do on the outside.





From here we mocked up the downpipe for the last time, securing it to the table with a solidly mounted chain fixture, plugging the ends, and back purging it as with the exhaust. It helps significantly having the right tools for the job. One great example you can see is the braided ground that is looped around the stainless tube of the downpipe, as well on the midsection of the exhaust above.







Back at the barn.




The exhaust hangers could have actually thrown off the entire fitment pretty easily. The forward flange face angles and location, mid section height relative to the bottom of the car, and exhaust tip to rear valence are easily changed based on minor movements of the exhaust hangers.

During mock up I lined the mid hanger to the rubber hanger and tacked it into place. Because of the hanger arrow end, I could not slip it into the rubber hanger as it would sit when installed, so the exhaust sat just rearward. Hopefully when it was pulled forward to be installed it would still sit as planned. I could not even access the rear hanger as it was entirely behind the rear valence, so I marked the center top of the muffler, relating the installed position to where the rubber hanger was, and tacked the hanger accordingly. It would have been very easy to get the mid hanger at the wrong angle/height/location, let along the rear.

As it turned out, both hangers broke off, one completely, during the ride over to Tony's. The tack welds weren't enough to hold them, but were enough to re-attach them in the same location by aligning the remnants left on either side. I was still pretty worried nonetheless.




The welds look amazing, as usual. For those of you who were wondering, the mid hanger on the exhaust attaches to an opposing hanger and isolator on the transmission cradle. Nothing was tacked to the bottom of the car or floorpans. I may or may not have installed pictures of this specifically, it was getting late in the day and only took two seconds to weld the last hanger to the transmission mount and I didn't get any shots of it during fabrication or mock up.

As a final note, do not expect to easily install the rubber isolators over the hangers, tack them in place, and remove them. I did this during the first mock up and I had to remove the entire transmission mount from the car, spending the next 3o mins trying to remove the isolator from the hangers. In the end, I had to break the tack weld, feed the hanger all the way through the isolator to remove it from the non-arrow side, and start the mock up completely over.


Only in South Carolina ...

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