Pontiac Manual Transmissions
by Rick Gonser
edited and "webized" by Larry Gorden
August 2005, Updated Dec 2009
Pontiac outsourced transmissions since day one, using Olds for the Hydra-Matics and Buick for their 3-speed selectors (or rail shifters)...
The following discussion is about the 3-speed transmissions used by Pontiac up through 1959
1955 & Earlier Light Duty 3-speed Standard Shift Transmission.
The light-duty Buick trans was used by Pontiac in 1955 and earlier years. It is easily distinguished by it's small physical size and 5-bolt top cover. On a scale of 1-10, with "7" being a Muncie M22, the light-duty B-O-P selector is rated as a "4"
The physical size of the sliding gear is ≈ 0.5", which is not very big. This trans will fail under excessive torque, as the miniscule slider and corresponding cluster gear(s) are simply not strong enough. High torque forces the slider away from the cluster, and a broken gear tooth is inevitable...
Gasket Set
Light Duty Gears
Light Duty Buick, Tail shaft shorter than Pontiac
1956-57 Heavy Duty 3-speed Standard Shift Transmission.
Pontiac installed the Buick heavy duty 3-speed transmission in 1956-57. The heavy-duty trans is easily distinguished by it's large physical size and corresponding 6-bolt top cover. On a scale of 1-10, with "7" being a Muncie M22, the Heavy-Duty B-O-P selector is rated as an "8"...The physical size of the sliding gear is ≈ 1", which is probably too big. This trans is nearly unbreakable, but the large size of the gears with their nearly straight-cut teeth, slows shifting @ rpm. I have used this trans behind a 450" JBP motor that produced 485 hp @ rpms. No problems, since the big stroker's power falls off at 5,100...
1958-59 Heavy Duty 3-speed Standard Shift Transmission.
The Buick trans was superceded in 1958 by the B-W T85, which is not quite as strong. According to John Sawruk, the noise and/or gear whine of the old Buick brought about it's demise. B-W T85s have 22O helix-cut gears, making them quiet as a mouse. One of the differences between M22s and M20-21s is that the Muncie engineers went back to Buick thinking, removing the high-helix gears. So, if you've ever ridden in a car with an M22, they sound a lot like the old Buick trannies...
Jerico Transmission.
For drag racing at eliminator levels, most stock trannies won't cut it. So, those who can afford it use the Jerico. Note the size and cut of the gears. Jerico Engineers were also influenced by the old Buick design. BTW, this box is rated as a "10", just like Bo Derek <grin>, and Jerico owners could care less about the noise...
