Shifting into OD

[NavlAv8r]

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

[rmmpe]

Hey Airdale,
My Allison 6 speed does the same thing. Oftentimes I'll get it to 6th and back down to 50 or so and stay in 6th.
At 48 it's 5th gear all the way.

[GaryKD]

Hi Navl Av8R,
I do not know if this is good for you or not. Is there a button one can push (sometimes called economy mode) that changes the shift points? If so try it. With the light on and in economy mode the shift points will change. The tranny will shift sooner going up and not down shift until almost lugging the engine. Again, I'm not sure if this feature is part of your coach.

[NavlAv8r]

Gary

Thanks for the reply. I only have a column shifter and an overdrive on/off switch. All I can do is manually downshift with OD either off or on. However, when I do that it only downshifts and it does nothing to make it upshift into OD.

The manual does not say anything about being able to change the shift points. Maybe the 2000 tranny allows that but not my 1000.