Ductape wrote:
Thanks for sharing, my pet peeve is not the mountains, as I don't have any objection to gearing down to climb a long grade, that's expected. What I dislike is a gear change just to climb an overpass in flat country, or a moderate rolling hill.
A little work with a spreadsheet has given me my answer I believe. Taking as an example recent Newmars:
Ventana with the 360/800 will produce 2,486 lb-ft at the axle in 6th gear @ 65 mph. Disregarding accessories and drivetrain losses.
Ventana LE with the 340/700 will be only 1,759 lb-ft under the same conditions due to torque limiting in 6th gear.
Dropping the LE into 5th gear provides full torque and gets the axle up to 2,476.
So in essence 5th on the Allison 2500 equipped coaches will be equivalent of 6th in a coach with the Allison 3000 and the 360/800 engine.
That's enough to convince me to seek out a coach with the bigger trans. Not to mention running the weight numbers I'd be over GCWR on the smaller Allison with cargo in the coach plus a 6k toad.
No help here, sorry. But you're first post with all the technical info and your name had me pegging you an engineer. This post and the spreadsheets come out, now I'm convinced. Carry on.
