One of the cornerstones of car crafting is engine swapping for increased performance, but for years, engine choice has also dictated the transmission to be used. However, over the past decade, a number of interesting overdrive manual transmissions have come to market, and naturally we want to stick them behind our engines, but this isn't always possible with factory parts. Traditionally, hybrid drivetrain mergers have required custom bellhousings or gearbox adapters, but these are usually only available for the most popular combinations.
McLeod has recognized the need for vast interchangeability of engines and transmissions, not just to mate late-model overdrives to classic powerplants, but also to mix and match components of varying vintage from multiple manufacturers. Its solution is a modular bellhousing system, in which the bellhousing is made up of multiple parts that can be mixed and matched to mate a broad scope of engines with a similarly broad range of manual transmissions.
The basic idea is relatively simple: Each modular bellhousing assembly is made up of four parts: the bellhousing, which bolts to the engine, the "cap," which mounts the gearbox, a spacer ring that sandwiches between the two to establish proper input shaft depth, and a reducer ring that centers the gearbox's input bearing retainer in the cap. All of the pieces are aligned using steel dowel pins, which have eccentric ends so that the centerline of the gearbox's input shaft can be precisely aligned to the crankshaft centerline.
The modular system means that, rather than making a long list of specific engine/trans combo custom bellhousings, McLeod only has to provide universal bellhousings for all of the popular engines and caps for all of the popular gearboxes, along with a selection of spacers and reducers, so that the end user can order up the combination of pieces needed to make his hybrid drivetrain come together. The bonus is the built-in adjustment for gearbox centering.
Although we've focused on mating late-model overdrive gearboxes with older engines, that's only one of the potential uses for this system. Pieces are available to do just the opposite, like mating a Muncie four-speed with an LS1, or you can crossbreed manufacturer's components, perhaps mounting a Ford Top Loader behind that LS1, or a Chrysler Hemi four-speed to your 5.0L Mustang. Some of these combos may seem odd, but the point is, if there's a bellhousing and a cap available, the two applications can be merged.
Currently, McLeod offers bellhousings for all popular GM V-8s, including Buick-Olds-Pontiac and the Gen III series, most Ford V-8s, including small-block, FE-series, Lima-series, and the modular V-8s. Gearbox applications include popular GM four-speeds, Top Loader-style Fords, Mopar A-833, plus Tremec five-speeds and six-speeds. The only obvious omissions are Mopar V-8s, but that's in the works. Grab a McLeod catalog for details or check it out on the Web site (www.mcleodind.com). The possibilities are mind-boggling.