Time for another throwback to the “Post of Everything“! As you might recall, Mikuvan had a little boo-boo on one of my mountain romps:
The entire exhaust path from the axle-clearing bend back fell off in late May when I was on the Tail of the Dragon. Yes, fell off. As in the person behind me had to dodge it.
I last redid the exhaust on this very site back in 2017, but I guess just a few years of winter road salt will do that to you. I had to zip that exhaust together with clamps in the parking lot in a day, so it was never really that well put together anyhow. To do it again, I challenged myself to make a fully welded path with a proper way to disconnect it at the downpipe if I were to have to change it again, how they say…. down the road.
Remember, despite what this site may seem to recently indicate, I am fundamentally not a “car guy”. I had to do some research on what technologies existed out there for connecting exhaust pipes besides impact-gunning a U-bolt clamp down. I settled on using V-band clamps, as they seemed both statically determinate once attached and relatively easy to work with, versus say flaring the tubes or welding on independent flanges.
I began collecting a few parts online such as the 2.25″ V-band flanges and bands. I got the piping itself just from auto parts stores for now – just regular ol’ “aluminized steel”. I’m sure this will last just as long.
In doing the same research, I got some 309 alloy welding wire to make the join between the stainless steel V-band flanges and the mystery ferrous exhaust pipe. I otherwise had plenty of regular ER70 wire.
So one night I decided to go ahead and drop the rest of the exhaust out and start measuring things up. Due to my brute force surgery on the downpipe flange to replace the mismatched nuts with big 17mm-headed M10 bolts, I was actually able to pull it off easily.
I can’t say the same at all for the rest of it. Natural Bostonian Loctite made getting everything else off an exercise in a lot of hammering and impact driving. I mean, not like I was trying to keep this or anything, but even separating that downpipe connection was a ton of effort.
The first adaptation step was turning the roughly 1-7/8 sized (or 50mm, perhaps) downpipe into the 2.25 diameter needed for the V-flange. I simply flared a 1.75″ to 2.25″ adapter slightly and slit the downpipe to shrink down its OD slightly.
I fixtured and tack welded the other end with V-band flanges to get an idea of how it’ll go together.
I then smashed the downpipe adapter onto the downpipe using my previous “flare” and “compression” fit and a hammer. The fit was tight enough that I went ahead and installed it back on the exhaust manifold, and adjusted the angle of the adapter tube to point as straight backwards as I could visually line it up. That means the flange is as straight as possible to alleviate any other bending. I then tack-welded it in place.
Step 1 completed! I fully welded the downpipe to the adapter after making sure the fit was good. This one was a little blobby because I had to be careful not to pierce through the old, thinned downpipe steel. I kept the voltage low and made two passes, and also had to close up the slits I made to let the downpipe compress into the adapter.
Next order of business was to measure the old axle hump dimensions and replicate them in the new piping.
Notice one little detail here? The 45 degree “turndown” at the end of the new setup isn’t actually a turndown tip, it’s just another piece of 45 degree bend. I was just going to cut it off to make my own turndown, as at the time, Pep Boys was out of 2.25″ turndowns.
On the new tubing it was much easier to make a clean weld all the way around. In fact, I think I found 120-volt Limewelder’s calling: lightweight tube fabrication. I mean, it’s all you can really use a 120V welder for anyhow.
The workpiece was getting long enough now that I was having to come up with more and more creative ways to fixture it.
I worked from both ends for this operation. First, I dummy-fit the downpipe, the V-band connection, and the flex pipe. Then I independently hung the main exhaust path where I wanted it, so I could take a measurement of how much gap there is between them.
A little more Creative Fixturing later and I now have the entire “downpipe-back” exhaust path completed.
And here it is! Not a single U-bolt clamp. I dunno, I think my next step might be to learn how to bend straight tubes well. I’ve seen people do intricate “pie cut” bends, but that’s several pay grades above how hard I am willing to neckbeard for something like this.
And now installed in place with the band tightened. I’m a fan of this setup, as I could conceivably (dunno why I would, but…) swap this out at any time for something else. It’s hung in the center with the flexible hanger seen in an earlier photo, and then attached at the very back by the trailer hitch like last time:
Admittedly, my custom “turndown” is a little too turnt down,and I was afraid of stubbing it accidentally on a curb or parking brick, so I trimmed it up further not long after this install.
My thoughts? I’m not planning on becoming an exhaust bending master, but I now know the capabilities of my shop. Vantruck is likely next on the list for exhaust work, as it’s had the same exposure to salt up north and I’m itching to add some stacks to the thing some day.