The Sound of Satisfaction

The Sound of Satisfaction

Sometimes we’ll have to change an exhaust setup to achieve the sound that both we and the customer desire. This is one of those times.

After we finished the previous rendition of the Z4M exhaust, even with the resonators and mufflers that we used, we still had a bit of rasp and drone coming through that we noticed during some vehicle testing. We knew that it wasn’t something we’d like to drive around with, and usually when we aren’t 100% happy with how a sound turned out, we know the owner won’t be, either. Seeing as how it was a long term project, we’ve finally got a small stretch of time now to retool the exhaust, and that’s exactly what we did. As we mentioned last time, the rear section of the exhaust will be changed up to mirror our E39 M5 Rear Section offerings. Since we have the resonators together already, the next step was to finish up the exhaust tips; after doing some measurements, we found that the E39 Rear Section jig would provide the perfect tip spacing for the Z4M as well, so that’s how we made the tips.


With the tips finished and welded to the resonators, we used a jack to suspend the exhaust in the location that we wanted. With the exhaust positioned where we want it, we were then able to tack together the section that would run from the existing exhaust piping to the new rear section.


As always, there was plenty of test-fitting along the way to ensure the metal didn’t move or otherwise distort during welding, which can cause pipes to line up improperly.


From there, the last remaining step was to fabricate the hangers. Since the E39 and E85 have different exhaust hanger layouts, this one was fabricated on the fly rather than following the jig. We’d bend the metal for the hangers as we placed the resonators where we wanted them, then tack the new hangers on to ensure that everything was positioned correctly. Finally, it’s back to the table for the final-final welds on this new exhaust setup.


And with that, we’re done! We bolted up the new exhaust to its hangers and everything came out wonderfully; tips are positioned exactly how we want them, and there’s no slack or unwanted play once everything’s bolted in place — this can lead to tips rattling against the bumper, which is a wholly unsatisfactory noise. Speaking of noise, though, the dual-resonator setup that we utilize on the E39 M5 has really helped out this Z4M, also; the exhaust has quieted down a bit, killed the little bit of rasp and given a bassier, more subdued sound to this motor. The owner’s not one to be flashy, and this new setup will suit him perfectly in that regard.


That just about wraps up today’s blog post. Don’t forget, we have a fun service project that’ll be rolling through these doors sometime in the very near future, so don’t get too far away! Have a great day!

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