BCM Community

Can an Allison 740 trans be modified so that you could just shift it manually through each gear and not have it linked to the engine speed. I remember back in the early 60's/70's many automatics for racing were modified so you had to shift them manually. B&M was a company that modified the old GM hydromatics.

You can do that now. It's just the trans always starts in 1st and goes through the gears. Two things-I don't think you'd be pleased at shifting it manually all the time. If you disconnect the throttle modulator, it will shift hard all the time. Also, there are safety items built into the transmission. For instance-if you overspeed it, even if you have it in a certain gear, it will up shift to save the transmission.

When around town, I usually put the trans in 2nd. Then manually shift up when getting on the freeway. The trans many times waits to long to down shift, so I down shift manually also. If the transmission is shifting manually only, what would you think if someone else had to drive the bus? The Allison 740 is quite possibly the most reliable truck/bus transmission ever made (it is used in truck/bus hot rods). Just keep it as is.

Allison and others made what is called a power shift transmission for off road equipment. Caterpillar had an 8spd trans that you shifted three times- 1st would cover 1-3, 2nd would cover 4-6, 3rd would cover 7-8. Good Luck, TomC