Mid-Pipe: Part the Third

The only ‘problem’ over the last race weekend was getting up the hill from my shop to the driveway, the cat-back drags on the concrete driveway as it crests the hump. It’s pretty clear that if I do that a few more times, I’m going to have a problem with a holy exhaust, and I don’t want a holy exhaust, so it was time to tweak the mid-pipe again, and take a bit of a different approach.

The main problem for me is that without a way to get the car WAY up in the air, mocking everything up, and measuring angles for cuts becomes very difficult. I won’t say impossible, because better people than I have and will continue to do it, but I couldn’t seem to make it work. How to solve that then when I don’t have easy access to a lift? Build an exhaust jig! The first step was to put together a negative that bolted up to the header and the cat-back.

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Once that was done, bolt a couple of plates to the negative so that they would properly locate the mid-pipe and weld everything in place.

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The jig helped a TON, but was not perfect. It really could stand to have another base, and another set of supports to really hold the “flanges” in place. But I’d already sunken enough time and steel into it, so I cheated. I’d already determined that a flex pipe would be added, because on the prior implementation, even with the donut gasket flange & spring bolts, the exhaust had zero give. So the flex pipe I got was a slip-fit on the tubing, which allowed a lot of room for adjustment once everything was tacked up. So basically, I got both sides of the exhaust mocked up, with the flex pipe in the middle loose.

From there, I bolted everything to the car, made final tweaks and made sure everything was actually lined up properly this time, and then tacked the flex pipe in place. Here it is, and it’s pulled the cat-back up about 1-1/8″, huge improvement. Moving that flange up too much further would create interference issues further back in the exhaust, so it’s just about perfect.

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And the finished product:

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