Pleasing the ear with a quieter rear

There are few sounds in the automotive world that captivate the senses like the revs of an American V8 engine—and the 5.0L Ti-VCT V8 found in the Revology Mustang is one of the best sounding V8s ever made. 

However, to established automakers, the absence of undesirable noise, referred to as noise, vibration, and harshness, or NVH, in industry parlance, is just as important as a great-sounding engine.

As part of Revology’s OEM-like approach to building cars, the Orlando-based maker of reproduction original Ford Mustangs is focusing on continually improving the vehicles, and that includes reducing NVH.

In the company’s early days, Revology sourced most components from the same aftermarket companies that restomod builders use.  This included the Ford 9-inch rear axle assembly.  However, Revology wasn’t happy with the high-pitched whine the 9-inch ring and pinion gears make, so it went to work to find a better solution.  After a significant amount of effort, the Revology team determined that the only real solution was to migrate to the modern Ford 8.8-inch design.

To use the 8.8-inch gear set, Revology had to design a new axle housing.  The housing is composed of several cast and fabricated parts, which are fixtured and welded together in-house, then powder-coated.  The 8.8-inch gear set is produced by Ford at its Sterling Axle Plant in Sterling Heights, Michigan.  These precision-machined OEM parts not only meet Revology’s durability standards, but their demanding NVH standards as well. 

The gear set and other components are installed in the axle housings by Revology technicians.  The company made a significant investment in tools, equipment, and technician training to ensure the axle assemblies are built correctly every time.  Rich Niles, one of Revology’s expert techs, was already experienced with gear assembly, yet Revology sent him to Arizona to attend a week-long course on the intricate details.

Rich explains: “We had quality problems in the past with outsourced axle assemblies, and we wanted to be certain we would be able to build high quality assemblies right from the start.  This is a very precise process; it involves tolerances in the thousandths of an inch.”

The preparation paid off—the new axles are built properly, and the 8.8-inch gear set is virtually noise-free.  “By contrast, the old axles could sound like a blender when you let off the power,” says Niles.

Tom Scarpello, Revology founder and CEO, adds his take on the rear axle development.

“At Revology, we do a lot of things different from other companies in this space and one of those is the rear axle.  Most companies use the 9-inch axle, which dates back to 1957.  It’s used because it handles high horsepower reliably and the design makes gear changes easy.

“However, the 9-inch is noisy.  While the originals were precision machined by Ford, today’s aftermarket versions are not made to the same tolerances.  While the typical drag racer or hot rod builder may not be concerned about gear whine, our customers notice and appreciate the difference.  Making the switch was not easy, we had to redesign our rear suspension to do it.  But we do things the right way, not the easy way.”