overdrive Morning guys .Its my understanding that in the overdrive operation , the governor controls the operation of the solenoid even if the cable is pulled out (disengaged ) that being the case , at any speed over 28 mph the governor would ground and solenoid would be activated and trying to engage all the time even with the cable out.. Seems to me this would hard on the solenoid wiring and solenoid and un necessary draw on battery power.. please enlighten me if this is incorrect or other thoughts on this... thanks Fred
You're partially correct. The solenoid is powered at any speed above 28 mph, but there's actually two coils inside the solenoid. There's a 'pull-in' coil which draws the heavier current and a 'holding' coil to keep it pulled in once it reaches its full travel. The pull-in coil is then disconnected. The holding coil draws much less current. This is switched inside the solenoid by its movement, no external wiring needed.
How does the solenoid know it’s 28 mph! Different rear end ratios would dictate different speeds with the same rpm of the drive shaft! Bones
The speedometer gears are matched by the factory to the particular rear end gear ratio in your vehicle. So the driveshaft rpm’s and wheel rpm’s are matched (ie 3.92:1). The Borg Warner overdrive gear change occurs ahead of the driveshaft, so the speedometer reading is not affected when it shifts into overdrive…..the engine rpm’s drop but the vehicle speed is not changed.
Even with the new cars - just don't know why anyone would need to shift into overdrive below 50 mph. Bought a little old lady car that she never drove over 45 mph - burned that trannie out at less than 40,000 miles .
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