On my Allison 5 speed tranny I have to reach at least 56 mph with no loading on the engine in order to shift into 5th gear OD. Can't get it to shift at 55, 53, etc., just above 55mph.
However, there are times when traveling in extended 45 mph zones, straight and level, with the tranny in 4th at 2,300 rpm, it would be great to shift into OD and save a little gas.
In order to get it to shift into OD I have to accel to greater than 55 mph, let it shift into OD (down to 2,000 rpm), then slow my speed back down to 45 mph (where the engines loves to be) and motor merrily along till the next stop light, and do it all over again. Does this make sense?
Seems like in this day of technology, something as simple as the ability to shift into OD without having to break the speed limit by 10 mph would be standard.
Is there a secret to forcing the tranny to shift into OD at, say, 45 - 50 mph?
Thanks