M22: its the magic RPO code for GMs ultimate musclecar four-speed. Immortalized by street racers and gearheads, its known for its brutal gear whine. If youve never ridden in an M22-shifted car, pop Two Lane Blacktop into your VCR and turn up the volume when James Taylor rows the gears on the menacing 55 Chevy. To some, the M22s voice is just plain annoying, but we think its pure bliss.
When we needed a tough manual trans to back up the 501hp 455 in our 65 LeMans project, the legendary M22 came up in conversation. But the law of supply and demand has pushed prices of these rare birds well into the stratosphere, and, truth be told, they still werent all that strong. Sure, the M22s straighter-cut helical gears put less end-to-end stress on the case and gearset, but the Muncies weak aluminum case could still flex under load and spit the teeth clean off the gears.
Recently we heard that Auto Gear Company (AGC) had re-engineered the Muncie case to keep the gears lined up even under the most brutal loading. Problem solved. For around $300, we picked up AGCs stock-appearing Super Case, which features thicker walls for less flex, uses a larger front bearing to absorb more torque, and is cast in higher-quality aluminum. AGC also supplied a beautiful Italian-made reproduction M22 gearset so we wouldnt have to sift through swap meet junk. And considering this will be seeing nearly 600 lb-ft of Pontiac torque, AGCs new cast-iron midplate seemed like a worthy upgrade for our bulletproof M22.
Aided by GearZones instructional video and builder Ron Worthens experienced assembly guidance, heres how we built the ultimate Muncieproof that theyre not just for show cars anymore.
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